Update release notes

Remove stray debug line
Don't apply the CPU affinity hack to nix-shell (and other Perl programs)
2013-09-10 11:21:30 +02:00 · 2013-09-06 17:20:19 +02:00 · 2013-09-06 16:36:56 +02:00 · 2013-09-06 15:18:07 +02:00 · 2013-09-06 14:58:05 +02:00 · 2013-09-03 21:21:14 +02:00
190 changed files with 7946 additions and 4125 deletions
@@ -35,8 +35,11 @@ Makefile.in

 # /doc/manual/
 /doc/manual/manual.html
+/doc/manual/manual.xmli
+/doc/manual/manual.pdf
 /doc/manual/manual.is-valid
 /doc/manual/*.1
+/doc/manual/*.5
 /doc/manual/*.8
 /doc/manual/images
 /doc/manual/version.txt
@@ -60,14 +63,12 @@ Makefile.in
 /scripts/GeneratePatches.pm
 /scripts/download-using-manifests.pl
 /scripts/copy-from-other-stores.pl
+/scripts/download-from-binary-cache.pl
 /scripts/find-runtime-roots.pl
 /scripts/build-remote.pl
 /scripts/nix-reduce-build
 /scripts/nix-http-export.cgi

-# /src/bin2c/
-/src/bin2c/bin2c
-
 # /src/bsdiff-4.3/
 /src/bsdiff-4.3/bsdiff
 /src/bsdiff-4.3/bspatch
@@ -85,15 +86,12 @@ Makefile.in

 # /src/nix-env/
 /src/nix-env/nix-env
-/src/nix-env/help.txt.hh

 # /src/nix-hash/
 /src/nix-hash/nix-hash
-/src/nix-hash/help.txt.hh

 # /src/nix-instantiate/
 /src/nix-instantiate/nix-instantiate
-/src/nix-instantiate/help.txt.hh

 # /src/nix-log2xml/
 /src/nix-log2xml/nix-log2xml
@@ -104,15 +102,12 @@ Makefile.in

 # /src/nix-setuid-helper/
 /src/nix-setuid-helper/nix-setuid-helper
-/src/nix-setuid-helper/help.txt.hh

 # /src/nix-store/
-/src/nix-store/help.txt.hh
 /src/nix-store/nix-store

-# /src/nix-worker/
-/src/nix-worker/nix-worker
-/src/nix-worker/help.txt.hh
+# /src/nix-daemon/
+/src/nix-daemon/nix-daemon

 # /tests/
 /tests/test-tmp
@@ -1,6 +1,6 @@
 SUBDIRS = src perl scripts corepkgs doc misc tests
 EXTRA_DIST = substitute.mk nix.spec nix.spec.in bootstrap.sh \
-  NEWS version misc/systemd/nix-worker.service
+  NEWS version misc/systemd/nix-daemon.service

 pkginclude_HEADERS = config.h

@@ -27,11 +27,9 @@ init-state:
 	$(INSTALL) $(INIT_FLAGS) -d $(DESTDIR)$(localstatedir)/nix/profiles
 	$(INSTALL) $(INIT_FLAGS) -d $(DESTDIR)$(localstatedir)/nix/gcroots
 	$(INSTALL) $(INIT_FLAGS) -d $(DESTDIR)$(localstatedir)/nix/temproots
-	ln -sfn $(localstatedir)/nix/profiles $(DESTDIR)$(localstatedir)/nix/gcroots/profiles
 	$(INSTALL) $(INIT_FLAGS) -d $(DESTDIR)$(localstatedir)/nix/userpool
 	-$(INSTALL) $(INIT_FLAGS) -d $(DESTDIR)$(storedir)
 	$(INSTALL) $(INIT_FLAGS) $(GROUP_WRITABLE) -d $(DESTDIR)$(localstatedir)/nix/manifests
-	ln -sfn $(localstatedir)/nix/manifests $(DESTDIR)$(localstatedir)/nix/gcroots/manifests

 else

@@ -25,12 +25,12 @@ AC_ARG_WITH(system, AC_HELP_STRING([--with-system=SYSTEM],

   case "$host_os" in
     linux-gnu*)
-	# For backward compatibility, strip the `-gnu' part.
-	system="$machine_name-linux";;
+        # For backward compatibility, strip the `-gnu' part.
+        system="$machine_name-linux";;
     *)
        # Strip the version number from names such as `gnu0.3',
        # `darwin10.2.0', etc.
-	system="$machine_name-`echo $host_os | "$SED" -e's/@<:@0-9.@:>@*$//g'`";;
+        system="$machine_name-`echo $host_os | "$SED" -e's/@<:@0-9.@:>@*$//g'`";;
   esac])

 sys_name=$(uname -s | tr 'A-Z ' 'a-z_')
@@ -40,7 +40,7 @@ case $sys_name in
        sys_name=cygwin
        ;;
 esac
-   
+
 AC_MSG_RESULT($system)
 AC_SUBST(system)
 AC_DEFINE_UNQUOTED(SYSTEM, ["$system"], [platform identifier (`cpu-os')])
@@ -68,6 +68,8 @@ if test "$sys_name" = sunos; then
 fi


+CFLAGS=${CFLAGS:--g -O3 -Wall}
+CXXFLAGS=${CXXFLAGS:--g -O3 -Wall}
 AC_PROG_CC
 AC_PROG_CXX

@@ -106,6 +108,7 @@ AC_LANG_POP(C++)
 # Check for chroot support (requires chroot() and bind mounts).
 AC_CHECK_FUNCS([chroot])
 AC_CHECK_FUNCS([unshare])
+AC_CHECK_FUNCS([statvfs])
 AC_CHECK_HEADERS([sched.h])
 AC_CHECK_HEADERS([sys/param.h])
 AC_CHECK_HEADERS([sys/mount.h], [], [],
@@ -115,6 +118,31 @@ AC_CHECK_HEADERS([sys/mount.h], [], [],
 ])


+# Check for vfork.
+#AC_FUNC_FORK()
+
+
+# Check for lutimes, optionally used for changing the mtime of
+# symlinks.
+AC_CHECK_FUNCS([lutimes])
+
+
+# Check for sched_setaffinity.
+AC_CHECK_FUNCS([sched_setaffinity])
+
+
+# Check whether the store optimiser can optimise symlinks.
+AC_MSG_CHECKING([whether it is possible to create a link to a symlink])
+ln -s bla tmp_link
+if ln tmp_link tmp_link2 2> /dev/null; then
+    AC_MSG_RESULT(yes)
+    AC_DEFINE(CAN_LINK_SYMLINK, 1, [Whether link() works on symlinks.])
+else
+    AC_MSG_RESULT(no)
+fi
+rm -f tmp_link tmp_link2
+
+
 # Check for <locale>.
 AC_LANG_PUSH(C++)
 AC_CHECK_HEADERS([locale])
@@ -161,9 +189,10 @@ NEED_PROG(perl, perl)
 NEED_PROG(sed, sed)
 NEED_PROG(tar, tar)
 NEED_PROG(bzip2, bzip2)
+NEED_PROG(gzip, gzip)
+NEED_PROG(xz, xz)
 AC_PATH_PROG(dot, dot)
 AC_PATH_PROG(dblatex, dblatex)
-AC_PATH_PROG(gzip, gzip)
 AC_PATH_PROG(pv, pv, pv)


@@ -249,7 +278,7 @@ if test "$gc" = yes; then
 fi


-# Check for the required Perl dependencies (DBI and DBD::SQLite).
+# Check for the required Perl dependencies (DBI, DBD::SQLite and WWW::Curl).
 perlFlags="-I$perllibdir"

 AC_ARG_WITH(dbi, AC_HELP_STRING([--with-dbi=PATH],
@@ -260,13 +289,24 @@ AC_ARG_WITH(dbd-sqlite, AC_HELP_STRING([--with-dbd-sqlite=PATH],
  [prefix of the Perl DBD::SQLite library]),
  perlFlags="$perlFlags -I$withval")

+AC_ARG_WITH(www-curl, AC_HELP_STRING([--with-www-curl=PATH],
+  [prefix of the Perl WWW::Curl library]),
+  perlFlags="$perlFlags -I$withval")
+
 AC_MSG_CHECKING([whether DBD::SQLite works])
 if ! $perl $perlFlags -e 'use DBI; use DBD::SQLite;' 2>&5; then
    AC_MSG_RESULT(no)
    AC_MSG_FAILURE([The Perl modules DBI and/or DBD::SQLite are missing.])
 fi
 AC_MSG_RESULT(yes)
-  
+
+AC_MSG_CHECKING([whether WWW::Curl works])
+if ! $perl $perlFlags -e 'use WWW::Curl;' 2>&5; then
+    AC_MSG_RESULT(no)
+    AC_MSG_FAILURE([The Perl module WWW::Curl is missing.])
+fi
+AC_MSG_RESULT(yes)
+
 AC_SUBST(perlFlags)


@@ -310,10 +350,20 @@ eval dynlib_suffix=$shrext_cmds
 AC_SUBST(dynlib_suffix)


+# Do we have GNU tar?
+AC_MSG_CHECKING([if you have a recent GNU tar])
+if $tar --version 2> /dev/null | grep -q GNU && tar cvf /dev/null --warning=no-timestamp ./config.log > /dev/null; then
+    AC_MSG_RESULT(yes)
+    tarFlags="--warning=no-timestamp"
+else
+    AC_MSG_RESULT(no)
+fi
+AC_SUBST(tarFlags)
+
+
 AM_CONFIG_HEADER([config.h])
 AC_CONFIG_FILES([Makefile
   src/Makefile
-   src/bin2c/Makefile
   src/boost/Makefile
   src/boost/format/Makefile
   src/libutil/Makefile
@@ -324,7 +374,7 @@ AC_CONFIG_FILES([Makefile
   src/libexpr/Makefile
   src/nix-instantiate/Makefile
   src/nix-env/Makefile
-   src/nix-worker/Makefile
+   src/nix-daemon/Makefile
   src/nix-setuid-helper/Makefile
   src/nix-log2xml/Makefile
   src/bsdiff-4.3/Makefile
@@ -1,6 +1,7 @@
 all-local: config.nix

-files = nar.nix buildenv.nix buildenv.pl unpack-channel.nix unpack-channel.sh derivation.nix fetchurl.nix
+files = nar.nix buildenv.nix buildenv.pl unpack-channel.nix derivation.nix fetchurl.nix \
+	imported-drv-to-derivation.nix

 install-exec-local:
 	$(INSTALL) -d $(DESTDIR)$(datadir)/nix/corepkgs
@@ -2,18 +2,22 @@ with import <nix/config.nix>;

 { derivations, manifest }:

-derivation { 
+derivation {
  name = "user-environment";
  system = builtins.currentSystem;
  builder = perl;
  args = [ "-w" ./buildenv.pl ];
-  
+
  manifest = manifest;

  # !!! grmbl, need structured data for passing this in a clean way.
-  paths = derivations;
-  active = map (x: if x ? meta && x.meta ? active then x.meta.active else "true") derivations;
-  priority = map (x: if x ? meta && x.meta ? priority then x.meta.priority else "5") derivations;
+  derivations =
+    map (d:
+      [ (d.meta.active or "true")
+        (d.meta.priority or 5)
+        (builtins.length d.outputs)
+      ] ++ map (output: builtins.getAttr output d) d.outputs)
+      derivations;

  # Building user environments remotely just causes huge amounts of
  # network traffic, so don't do that.
@@ -36,19 +36,16 @@ sub createLinks {
        if ($srcFile =~ /\/propagated-build-inputs$/ ||
            $srcFile =~ /\/nix-support$/ ||
            $srcFile =~ /\/perllocal.pod$/ ||
-            $srcFile =~ /\/easy-install.pth$/ ||
-            $srcFile =~ /\/site.py$/ ||
-            $srcFile =~ /\/site.pyc$/ ||
            $srcFile =~ /\/info\/dir$/ ||
            $srcFile =~ /\/log$/)
        {
            # Do nothing.
-	}
+        }

        elsif (-d $srcFile) {

            lstat $dstFile;
-            
+
            if (-d _) {
                createLinks($srcFile, $dstFile, $priority);
            }
@@ -56,10 +53,10 @@ sub createLinks {
            elsif (-l _) {
                my $target = readlink $dstFile or die;
                if (!-d $target) {
-                    die "collission between directory `$srcFile' and non-directory `$target'";
+                    die "collision between directory `$srcFile' and non-directory `$target'";
                }
                unlink $dstFile or die "error unlinking `$dstFile': $!";
-                mkdir $dstFile, 0755 || 
+                mkdir $dstFile, 0755 ||
                    die "error creating directory `$dstFile': $!";
                createLinks($target, $dstFile, $priorities{$dstFile});
                createLinks($srcFile, $dstFile, $priority);
@@ -78,15 +75,15 @@ sub createLinks {
            if (-l $dstFile) {
                my $target = readlink $dstFile;
                my $prevPriority = $priorities{$dstFile};
-                die ( "Collission between `$srcFile' and `$target'. "
-                    . "Suggested solution: use `nix-env --set-flag "
+                die ( "collision between `$srcFile' and `$target'; "
+                    . "use `nix-env --set-flag "
                    . "priority NUMBER PKGNAME' to change the priority of "
-                    . "one of the conflicting packages.\n" )
+                    . "one of the conflicting packages\n" )
                    if $prevPriority == $priority;
                next if $prevPriority < $priority;
                unlink $dstFile or die;
            }
-            
+
            symlink($srcFile, $dstFile) ||
                die "error creating link `$dstFile': $!";
            $priorities{$dstFile} = $priority;
@@ -125,27 +122,29 @@ sub addPkg {

 # Convert the stuff we get from the environment back into a coherent
 # data type.
-my @paths = split ' ', $ENV{"paths"};
-my @active = split ' ', $ENV{"active"};
-my @priority = split ' ', $ENV{"priority"};
-
-die if scalar @paths != scalar @active;
-die if scalar @paths != scalar @priority;
-
-my %pkgs;
-
-for (my $n = 0; $n < scalar @paths; $n++) {
-    $pkgs{$paths[$n]} =
-        { active => $active[$n]
-        , priority => $priority[$n] };
+my @pkgs;
+my @derivations = split ' ', $ENV{"derivations"};
+while (scalar @derivations) {
+    my $active = shift @derivations;
+    my $priority = shift @derivations;
+    my $outputs = shift @derivations;
+    for (my $n = 0; $n < $outputs; $n++) {
+        my $path = shift @derivations;
+        push @pkgs,
+            { path => $path
+            , active => $active ne "false"
+            , priority => int($priority) };
+    }
 }


 # Symlink to the packages that have been installed explicitly by the
-# user.
-foreach my $pkg (sort (keys %pkgs)) {
+# user.  Process in priority order to reduce unnecessary
+# symlink/unlink steps.
+@pkgs = sort { $a->{priority} <=> $b->{priority} || $a->{path} cmp $b->{path} } @pkgs;
+foreach my $pkg (@pkgs) {
    #print $pkg, " ", $pkgs{$pkg}->{priority}, "\n";
-    addPkg($pkg, $pkgs{$pkg}->{priority}) if $pkgs{$pkg}->{active} ne "false";
+    addPkg($pkg->{path}, $pkg->{priority}) if $pkg->{active};
 }


@@ -6,8 +6,11 @@ in {
  perl = "@perl@";
  shell = "@shell@";
  coreutils = "@coreutils@";
-  bzip2 = fromEnv "NIX_BZIP2" "@bzip2@";
+  bzip2 = "@bzip2@";
+  gzip = "@gzip@";
+  xz = "@xz@";
  tar = "@tar@";
+  tarFlags = "@tarFlags@";
  tr = "@tr@";
  curl = "@curl@";
  nixBinDir = fromEnv "NIX_BIN_DIR" "@bindir@";
@@ -6,7 +6,7 @@ drvAttrs @ { outputs ? [ "out" ], ... }:
 let

  strict = derivationStrict drvAttrs;
-  
+
  commonAttrs = drvAttrs // (builtins.listToAttrs outputsList) //
    { all = map (x: x.value) outputsList;
      inherit drvAttrs;
@@ -21,7 +21,7 @@ let
        inherit outputName;
      };
    };
-    
+
  outputsList = map outputToAttrListElement outputs;
-    
+
 in (builtins.head outputsList).value
@@ -1,6 +1,6 @@
 with import <nix/config.nix>;

-{system ? builtins.currentSystem, url, outputHash ? "", outputHashAlgo ? "", md5 ? "", sha1 ? "", sha256 ? ""}:
+{system ? builtins.currentSystem, url, outputHash ? "", outputHashAlgo ? "", md5 ? "", sha1 ? "", sha256 ? "", executable ? false}:

 assert (outputHash != "" && outputHashAlgo != "")
    || md5 != "" || sha1 != "" || sha256 != "";
@@ -8,10 +8,10 @@ assert (outputHash != "" && outputHashAlgo != "")
 let

  builder = builtins.toFile "fetchurl.sh"
-    ''
+    (''
      echo "downloading $url into $out"
      ${curl} --fail --location --max-redirs 20 --insecure "$url" > "$out"
-    '';
+    '' + (if executable then "${coreutils}/chmod +x $out" else ""));

 in
    
@@ -25,6 +25,7 @@ derivation {
      if sha256 != "" then "sha256" else if sha1 != "" then "sha1" else "md5";
  outputHash = if outputHash != "" then outputHash else
      if sha256 != "" then sha256 else if sha1 != "" then sha1 else md5;
+  outputHashMode = if executable then "recursive" else "flat";
  
  inherit system url;

@@ -0,0 +1,21 @@
+attrs @ { drvPath, outputs, ... }:
+
+let
+
+  commonAttrs = (builtins.listToAttrs outputsList) //
+    { all = map (x: x.value) outputsList;
+      inherit drvPath;
+      type = "derivation";
+    };
+
+  outputToAttrListElement = outputName:
+    { name = outputName;
+      value = commonAttrs // {
+        outPath = builtins.getAttr outputName attrs;
+        inherit outputName;
+      };
+    };
+    
+  outputsList = map outputToAttrListElement outputs;
+    
+in (builtins.head outputsList).value
@@ -6,29 +6,44 @@ let
    ''
      export PATH=${nixBinDir}:${coreutils}

+      if [ $compressionType = xz ]; then
+        ext=.xz
+        compressor="| ${xz} -7"
+      elif [ $compressionType = bzip2 ]; then
+        ext=.bz2
+        compressor="| ${bzip2}"
+      else
+        ext=
+        compressor=
+      fi
+
      echo "packing ‘$storePath’..."
      mkdir $out
-      dst=$out/tmp.nar.bz2
+      dst=$out/tmp.nar$ext

      set -o pipefail
-      nix-store --dump "$storePath" | ${bzip2} > $dst
+      eval "nix-store --dump \"$storePath\" $compressor > $dst"

-      nix-hash --flat --type $hashAlgo --base32 $dst > $out/narbz2-hash
+      hash=$(nix-hash --flat --type $hashAlgo --base32 $dst)
+      echo -n $hash > $out/nar-compressed-hash

-      mv $out/tmp.nar.bz2 $out/$(cat $out/narbz2-hash).nar.bz2
+      mv $dst $out/$hash.nar$ext
    '';

 in

-{ storePath, hashAlgo }:
+{ storePath, hashAlgo, compressionType }:

 derivation {
  name = "nar";
  system = builtins.currentSystem;
  builder = shell;
  args = [ "-e" builder ];
-  inherit storePath hashAlgo;
+  inherit storePath hashAlgo compressionType;

  # Don't build in a chroot because Nix's dependencies may not be there.
  __noChroot = true;
+
+  # Remote machines may not have ${nixBinDir} or ${coreutils} in the same prefixes
+  preferLocalBuild = true;
 }
@@ -1,14 +1,39 @@
 with import <nix/config.nix>;

-{ name, channelName, src }:
+let
+
+  builder = builtins.toFile "unpack-channel.sh"
+    ''
+      mkdir $out
+      cd $out
+      xzpat="\.xz\$"
+      gzpat="\.gz\$"
+      if [[ "$src" =~ $xzpat ]]; then
+        ${xz} -d < $src | ${tar} xf - ${tarFlags}
+      elif [[ "$src" =~ $gzpat ]]; then
+        ${gzip} -d < $src | ${tar} xf - ${tarFlags}
+      else
+        ${bzip2} -d < $src | ${tar} xf - ${tarFlags}
+      fi
+      mv * $out/$channelName
+      if [ -n "$binaryCacheURL" ]; then
+        mkdir $out/binary-caches
+        echo -n "$binaryCacheURL" > $out/binary-caches/$channelName
+      fi
+    '';
+
+in
+
+{ name, channelName, src, binaryCacheURL ? "" }:

 derivation {
  system = builtins.currentSystem;
  builder = shell;
-  args = [ "-e" ./unpack-channel.sh ];
-  inherit name channelName src bzip2 tar tr;
+  args = [ "-e" builder ];
+  inherit name channelName src binaryCacheURL;
+
  PATH = "${nixBinDir}:${coreutils}";
-  
+
  # No point in doing this remotely.
  preferLocalBuild = true;

@@ -1,4 +0,0 @@
-mkdir $out
-cd $out
-$bzip2 -d < $src | $tar xf -
-mv * $out/$channelName
@@ -0,0 +1,17 @@
+#! /bin/sh
+if [ -e tests/test-tmp ]; then
+    chmod -R u+w tests/test-tmp
+    rm -rf tests/test-tmp
+fi
+
+s=$(type -p nix-shell)
+exec $s release.nix -A tarball --command "
+    export NIX_REMOTE=daemon
+    export NIX_PATH='$NIX_PATH'
+    export NIX_BUILD_SHELL=$(type -p bash)
+    export c=\$configureFlags
+    exec $s release.nix -A build.x86_64-linux --exclude tarball --command '
+        configureFlags+=\" \$c --prefix=$(pwd)/inst --sysconfdir=$(pwd)/inst/etc\"
+        return
+    '" \
+    "$@"
@@ -1,33 +0,0 @@
-To produce a `stable' release from the trunk:
-
-1. Update the release notes; make sure that the release date is
-    correct.
-
-0. Make sure that the trunk builds in the release supervisor.
-
-1. Branch the trunk, e.g., `svn cp .../trunk
-   .../branches/0.5-release'.
-
-2. Switch to the branch, e.g., `svn switch .../branches/0.5-release'.
-
-3. In `configure.ac', change `STABLE=0' into `STABLE=1' and commit.
-
-4. In the release supervisor, add a one-time job to build
-   `.../branches/0.5-release'.
-
-5. Make sure that the release succeeds.
-
-6. Move the branch to a tag, e.g., `svn mv .../branches/0.5-release
-   .../tags/0.5'.
-
-   Note that the branch should not be used for maintenance; it should
-   be deleted after the release has been created.  A maintenance
-   branch (e.g., `.../branches/0.5') should be created from the
-   original revision of the trunk (since maintenance releases should
-   also be tested first; hence, we cannot have `STABLE=1').  The same
-   procedure can then be followed to produce maintenance releases;
-   just substitute `.../branches/VERSION' for the trunk.
-
-7. Switch back to the trunk.
-
-8. Bump the version number in `configure.ac' (in AC_INIT).
@@ -16,14 +16,14 @@ dblatex_opts = \
 # Note: we use GIF for now, since the PNGs shipped with Docbook aren't
 # transparent.

-man1_MANS = nix-env.1 nix-build.1 nix-store.1 nix-instantiate.1 \
+man1_MANS = nix-env.1 nix-build.1 nix-shell.1 nix-store.1 nix-instantiate.1 \
 nix-collect-garbage.1 nix-push.1 nix-pull.1 \
 nix-prefetch-url.1 nix-channel.1 \
 nix-install-package.1 nix-hash.1 nix-copy-closure.1

 man5_MANS = nix.conf.5

-man8_MANS = nix-worker.8
+man8_MANS = nix-daemon.8

 FIGURES = figures/user-environments.png

@@ -19,7 +19,7 @@ is also available as <function>builtins.derivation</function>.</para>

 <variablelist>

-  
+
  <varlistentry><term><function>abort</function> <replaceable>s</replaceable></term>

    <listitem><para>Abort Nix expression evaluation, print error
@@ -27,7 +27,7 @@ is also available as <function>builtins.derivation</function>.</para>

  </varlistentry>

-  
+
  <varlistentry><term><function>builtins.add</function>
  <replaceable>e1</replaceable> <replaceable>e2</replaceable></term>

@@ -37,7 +37,7 @@ is also available as <function>builtins.derivation</function>.</para>

  </varlistentry>

-  
+
  <varlistentry><term><function>builtins.attrNames</function>
  <replaceable>attrs</replaceable></term>

@@ -55,7 +55,7 @@ attrValues = attrs: map (name: builtins.getAttr name attrs) (builtins.attrNames

  </varlistentry>

-  
+
  <varlistentry><term><function>baseNameOf</function> <replaceable>s</replaceable></term>

    <listitem><para>Return the <emphasis>base name</emphasis> of the
@@ -65,7 +65,7 @@ attrValues = attrs: map (name: builtins.getAttr name attrs) (builtins.attrNames

  </varlistentry>

-  
+
  <varlistentry><term><varname>builtins</varname></term>

    <listitem><para>The attribute set <varname>builtins</varname>
@@ -82,7 +82,7 @@ if builtins ? getEnv then builtins.getEnv "PATH" else ""</programlisting>

  </varlistentry>

-  
+
  <varlistentry><term><function>builtins.compareVersions</function>
  <replaceable>s1</replaceable> <replaceable>s2</replaceable></term>

@@ -99,7 +99,16 @@ if builtins ? getEnv then builtins.getEnv "PATH" else ""</programlisting>

  </varlistentry>

-  
+
+  <varlistentry><term><function>builtins.concatLists</function>
+  <replaceable>lists</replaceable></term>
+
+    <listitem><para>Concatenate a list of lists into a single
+    list.</para></listitem>
+
+  </varlistentry>
+
+
  <varlistentry
  xml:id='builtin-currentSystem'><term><varname>builtins.currentSystem</varname></term>

@@ -124,7 +133,7 @@ if builtins ? getEnv then builtins.getEnv "PATH" else ""</programlisting>
  </varlistentry>
  -->

-  
+
  <!--
  <varlistentry><term><function>dependencyClosure</function></term>

@@ -133,7 +142,7 @@ if builtins ? getEnv then builtins.getEnv "PATH" else ""</programlisting>
  </varlistentry>
  -->

-  
+
  <varlistentry><term><function>derivation</function>
  <replaceable>attrs</replaceable></term>

@@ -152,7 +161,7 @@ if builtins ? getEnv then builtins.getEnv "PATH" else ""</programlisting>

  </varlistentry>

-  
+
  <varlistentry><term><function>builtins.div</function>
  <replaceable>e1</replaceable> <replaceable>e2</replaceable></term>

@@ -162,7 +171,40 @@ if builtins ? getEnv then builtins.getEnv "PATH" else ""</programlisting>

  </varlistentry>

-  
+
+  <varlistentry><term><function>builtins.elem</function>
+  <replaceable>x</replaceable> <replaceable>xs</replaceable></term>
+
+    <listitem><para>Return <literal>true</literal> if a value equal to
+    <replaceable>x</replaceable> occurs in the list
+    <replaceable>xs</replaceable>, and <literal>false</literal>
+    otherwise.</para></listitem>
+
+  </varlistentry>
+
+
+  <varlistentry><term><function>builtins.elemAt</function>
+  <replaceable>xs</replaceable> <replaceable>n</replaceable></term>
+
+    <listitem><para>Return element <replaceable>n</replaceable> from
+    the list <replaceable>xs</replaceable>.  Elements are counted
+    starting from 0.  A fatal error occurs in the index is out of
+    bounds.</para></listitem>
+
+  </varlistentry>
+
+
+  <varlistentry><term><function>builtins.filter</function>
+  <replaceable>f</replaceable> <replaceable>xs</replaceable></term>
+
+    <listitem><para>Return a list consisting of the elements of
+    <replaceable>xs</replaceable> for which the function
+    <replaceable>f</replaceable> returns
+    <literal>true</literal>.</para></listitem>
+
+  </varlistentry>
+
+
  <varlistentry><term><function>builtins.filterSource</function>
  <replaceable>e1</replaceable> <replaceable>e2</replaceable></term>

@@ -214,7 +256,7 @@ stdenv.mkDerivation {

  </varlistentry>

-  
+
  <varlistentry><term><function>builtins.getAttr</function>
  <replaceable>s</replaceable> <replaceable>attrs</replaceable></term>

@@ -227,7 +269,7 @@ stdenv.mkDerivation {

  </varlistentry>

-  
+
  <varlistentry><term><function>builtins.getEnv</function>
  <replaceable>s</replaceable></term>

@@ -245,7 +287,7 @@ stdenv.mkDerivation {

  </varlistentry>

-  
+
  <varlistentry><term><function>builtins.hasAttr</function>
  <replaceable>s</replaceable> <replaceable>attrs</replaceable></term>

@@ -259,7 +301,19 @@ stdenv.mkDerivation {

  </varlistentry>

-  
+
+  <varlistentry><term><function>builtins.hashString</function>
+  <replaceable>type</replaceable> <replaceable>s</replaceable></term>
+
+    <listitem><para>Return a base-16 representation of the
+    cryptographic hash of string <replaceable>s</replaceable>.  The
+    hash algorithm specified by <replaceable>type</replaceable> must
+    be one of <literal>"md5"</literal>, <literal>"sha1"</literal> or
+    <literal>"sha256"</literal>.</para></listitem>
+
+  </varlistentry>
+
+
  <varlistentry><term><function>builtins.head</function>
  <replaceable>list</replaceable></term>

@@ -270,13 +324,15 @@ stdenv.mkDerivation {

  </varlistentry>

-  
+
  <varlistentry><term><function>import</function>
  <replaceable>path</replaceable></term>

    <listitem><para>Load, parse and return the Nix expression in the
-    file <replaceable>path</replaceable>.  Evaluation aborts if the
-    file doesn’t exist or contains an incorrect Nix
+    file <replaceable>path</replaceable>.  If <replaceable>path
+    </replaceable> is a directory, the file <filename>default.nix
+    </filename> in that directory is loaded.  Evaluation aborts if
+    the file doesn’t exist or contains an incorrect Nix
    expression.  <function>import</function> implements Nix’s module
    system: you can put any Nix expression (such as an attribute set
    or a function) in a separate file, and use it from Nix expressions
@@ -288,7 +344,7 @@ stdenv.mkDerivation {
    built-in).  Therefore, it cannot refer to variables that are in
    scope at the call site.  For instance, if you have a calling
    expression
-    
+
 <programlisting>
 rec {
  x = 123;
@@ -323,7 +379,7 @@ x: x + 456</programlisting>

  </varlistentry>

-  
+
  <varlistentry><term><function>builtins.intersectAttrs</function>
  <replaceable>e1</replaceable> <replaceable>e2</replaceable></term>

@@ -332,8 +388,8 @@ x: x + 456</programlisting>
    exist in the set <replaceable>e1</replaceable>.</para></listitem>

  </varlistentry>
-        
-    
+
+
  <varlistentry><term><function>builtins.isAttrs</function>
  <replaceable>e</replaceable></term>

@@ -343,7 +399,7 @@ x: x + 456</programlisting>

  </varlistentry>

-  
+
  <varlistentry><term><function>builtins.isList</function>
  <replaceable>e</replaceable></term>

@@ -353,7 +409,7 @@ x: x + 456</programlisting>

  </varlistentry>

-  
+
  <varlistentry><term><function>builtins.isFunction</function>
  <replaceable>e</replaceable></term>

@@ -363,7 +419,7 @@ x: x + 456</programlisting>

  </varlistentry>

-  
+
  <varlistentry><term><function>builtins.isString</function>
  <replaceable>e</replaceable></term>

@@ -373,17 +429,17 @@ x: x + 456</programlisting>

  </varlistentry>

-  
+
  <varlistentry><term><function>builtins.isInt</function>
  <replaceable>e</replaceable></term>

    <listitem><para>Return <literal>true</literal> if
-    <replaceable>e</replaceable> evaluates to a int, and
+    <replaceable>e</replaceable> evaluates to an int, and
    <literal>false</literal> otherwise.</para></listitem>

  </varlistentry>

-  
+
  <varlistentry><term><function>builtins.isBool</function>
  <replaceable>e</replaceable></term>

@@ -393,7 +449,7 @@ x: x + 456</programlisting>

  </varlistentry>

-  
+
  <varlistentry><term><function>isNull</function>
  <replaceable>e</replaceable></term>

@@ -403,12 +459,12 @@ x: x + 456</programlisting>

    <warning><para>This function is <emphasis>deprecated</emphasis>;
    just write <literal>e == null</literal> instead.</para></warning>
-    
+
    </listitem>

  </varlistentry>

-  
+
  <varlistentry><term><function>builtins.length</function>
  <replaceable>e</replaceable></term>

@@ -417,7 +473,7 @@ x: x + 456</programlisting>

  </varlistentry>

-  
+
  <varlistentry><term><function>builtins.lessThan</function>
  <replaceable>e1</replaceable> <replaceable>e2</replaceable></term>

@@ -430,7 +486,7 @@ x: x + 456</programlisting>

  </varlistentry>

-  
+
  <varlistentry><term><function>builtins.listToAttrs</function>
  <replaceable>e</replaceable></term>

@@ -457,7 +513,7 @@ builtins.listToAttrs
    </para></listitem>

  </varlistentry>
-  
+
  <varlistentry><term><function>map</function>
  <replaceable>f</replaceable> <replaceable>list</replaceable></term>

@@ -470,10 +526,10 @@ map (x: "foo" + x) [ "bar" "bla" "abc" ]</programlisting>

    evaluates to <literal>[ "foobar" "foobla" "fooabc"
    ]</literal>.</para></listitem>
-    
+
  </varlistentry>

-  
+
  <varlistentry><term><function>builtins.mul</function>
  <replaceable>e1</replaceable> <replaceable>e2</replaceable></term>

@@ -483,7 +539,7 @@ map (x: "foo" + x) [ "bar" "bla" "abc" ]</programlisting>

  </varlistentry>

-  
+
  <varlistentry><term><function>builtins.parseDrvName</function>
  <replaceable>s</replaceable></term>

@@ -498,7 +554,7 @@ map (x: "foo" + x) [ "bar" "bla" "abc" ]</programlisting>

  </varlistentry>

-  
+
  <varlistentry><term><function>builtins.pathExists</function>
  <replaceable>path</replaceable></term>

@@ -531,7 +587,7 @@ in config.someSetting</programlisting>
  </varlistentry>
  -->

-  
+
  <varlistentry><term><function>builtins.readFile</function>
  <replaceable>path</replaceable></term>

@@ -539,8 +595,8 @@ in config.someSetting</programlisting>
    <replaceable>path</replaceable> as a string.</para></listitem>

  </varlistentry>
-  
-  
+
+
  <varlistentry><term><function>removeAttrs</function>
  <replaceable>attrs</replaceable> <replaceable>list</replaceable></term>

@@ -556,7 +612,7 @@ removeAttrs { x = 1; y = 2; z = 3; } [ "a" "x" "z" ]</screen>

  </varlistentry>

-  
+
  <varlistentry><term><function>builtins.stringLength</function>
  <replaceable>e</replaceable></term>

@@ -566,7 +622,7 @@ removeAttrs { x = 1; y = 2; z = 3; } [ "a" "x" "z" ]</screen>

  </varlistentry>

-  
+
  <varlistentry><term><function>builtins.sub</function>
  <replaceable>e1</replaceable> <replaceable>e2</replaceable></term>

@@ -576,7 +632,7 @@ removeAttrs { x = 1; y = 2; z = 3; } [ "a" "x" "z" ]</screen>

  </varlistentry>

-  
+
  <varlistentry><term><function>builtins.substring</function>
  <replaceable>start</replaceable> <replaceable>len</replaceable>
  <replaceable>s</replaceable></term>
@@ -594,7 +650,7 @@ removeAttrs { x = 1; y = 2; z = 3; } [ "a" "x" "z" ]</screen>

  </varlistentry>

-  
+
  <varlistentry><term><function>builtins.tail</function>
  <replaceable>list</replaceable></term>

@@ -604,7 +660,7 @@ removeAttrs { x = 1; y = 2; z = 3; } [ "a" "x" "z" ]</screen>

  </varlistentry>

-  
+
  <varlistentry><term><function>throw</function>
  <replaceable>s</replaceable></term>

@@ -618,7 +674,7 @@ removeAttrs { x = 1; y = 2; z = 3; } [ "a" "x" "z" ]</screen>

  </varlistentry>

-  
+
  <varlistentry
  xml:id='builtin-toFile'><term><function>builtins.toFile</function>
  <replaceable>name</replaceable> <replaceable>s</replaceable></term>
@@ -636,7 +692,7 @@ removeAttrs { x = 1; y = 2; z = 3; } [ "a" "x" "z" ]</screen>

 stdenv.mkDerivation {
  name = "hello-2.1.1";
-  
+
  builder = builtins.toFile "builder.sh" "
    source $stdenv/setup

@@ -655,7 +711,7 @@ stdenv.mkDerivation {
  };
  inherit perl;
 }</programlisting>
-  
+
    </para>

    <para>It is even possible for one file to refer to another, e.g.,
@@ -693,7 +749,7 @@ in foo</programlisting>

  </varlistentry>

-  
+
  <varlistentry><term><function>builtins.toPath</function> <replaceable>s</replaceable></term>

    <listitem><para>Convert the string value
@@ -706,7 +762,7 @@ in foo</programlisting>

  </varlistentry>

-  
+
  <varlistentry><term><function>toString</function> <replaceable>e</replaceable></term>

    <listitem><para>Convert the expression
@@ -718,7 +774,7 @@ in foo</programlisting>

  </varlistentry>

-  
+
  <varlistentry xml:id='builtin-toXML'><term><function>builtins.toXML</function> <replaceable>e</replaceable></term>

    <listitem><para>Return a string containing an XML representation
@@ -763,7 +819,7 @@ in foo</programlisting>

    <example xml:id='ex-toxml'><title>Passing information to a builder
    using <function>toXML</function></title>
-    
+
 <programlisting><![CDATA[
 { stdenv, fetchurl, libxslt, jira, uberwiki }:

@@ -771,7 +827,7 @@ stdenv.mkDerivation (rec {
  name = "web-server";

  buildInputs = [ libxslt ];
-  
+
  builder = builtins.toFile "builder.sh" "
    source $stdenv/setup
    mkdir $out
@@ -804,7 +860,7 @@ stdenv.mkDerivation (rec {

    <example xml:id='ex-toxml-result'><title>XML representation produced by
    <function>toXML</function></title>
-    
+
 <programlisting><![CDATA[<?xml version='1.0' encoding='utf-8'?>
 <expr>
  <list>
@@ -833,7 +889,7 @@ stdenv.mkDerivation (rec {

  </varlistentry>

-  
+
  <varlistentry><term><function>builtins.trace</function>
  <replaceable>e1</replaceable> <replaceable>e2</replaceable></term>

@@ -844,7 +900,7 @@ stdenv.mkDerivation (rec {

  </varlistentry>

-  
+
 </variablelist>


@@ -30,18 +30,21 @@ gc-keep-derivations = true   # Idem
 env-keep-derivations = false
 </programlisting>

-<para>The following settings are currently available: 
+<para>You can override settings using the <option>--option</option>
+flag, e.g. <literal>--option gc-keep-outputs false</literal>.</para>
+
+<para>The following settings are currently available:

 <variablelist>

-  
+
  <varlistentry xml:id="conf-gc-keep-outputs"><term><literal>gc-keep-outputs</literal></term>

    <listitem><para>If <literal>true</literal>, the garbage collector
    will keep the outputs of non-garbage derivations.  If
    <literal>false</literal> (default), outputs will be deleted unless
    they are GC roots themselves (or reachable from other roots).</para>
- 
+
    <para>In general, outputs must be registered as roots separately.
    However, even if the output of a derivation is registered as a
    root, the collector will still delete store paths that are used
@@ -50,7 +53,7 @@ env-keep-derivations = false
    this option to <literal>true</literal>.</para></listitem>

  </varlistentry>
-  
+

  <varlistentry xml:id="conf-gc-keep-derivations"><term><literal>gc-keep-derivations</literal></term>

@@ -68,7 +71,7 @@ env-keep-derivations = false

  </varlistentry>

-  
+
  <varlistentry><term><literal>env-keep-derivations</literal></term>

    <listitem><para>If <literal>false</literal> (default), derivations
@@ -92,14 +95,14 @@ env-keep-derivations = false

  </varlistentry>

-  
+
  <varlistentry xml:id="conf-build-max-jobs"><term><literal>build-max-jobs</literal></term>

    <listitem><para>This option defines the maximum number of jobs
    that Nix will try to build in parallel.  The default is
    <literal>1</literal>.  You should generally set it to the number
-    of CPUs in your system (e.g., <literal>2</literal> on a Athlon 64
-    X2).  It can be overriden using the <option
+    of CPUs in your system (e.g., <literal>2</literal> on an Athlon 64
+    X2).  It can be overridden using the <option
    linkend='opt-max-jobs'>--max-jobs</option> (<option>-j</option>)
    command line switch.</para></listitem>

@@ -116,7 +119,7 @@ env-keep-derivations = false
    <varname>enableParallelBuilding</varname> is set to
    <literal>true</literal>, the builder passes the
    <option>-j<replaceable>N</replaceable></option> flag to GNU Make.
-    It can be overriden using the <option
+    It can be overridden using the <option
    linkend='opt-cores'>--cores</option> command line switch and
    defaults to <literal>1</literal>.  The value <literal>0</literal>
    means that the builder should use all available CPU cores in the
@@ -131,10 +134,10 @@ env-keep-derivations = false

      <para>This option defines the maximum number of seconds that a
      builder can go without producing any data on standard output or
-      standard error.  This is useful (for instance in a automated
+      standard error.  This is useful (for instance in an automated
      build system) to catch builds that are stuck in an infinite
      loop, or to catch remote builds that are hanging due to network
-      problems.  It can be overriden using the <option
+      problems.  It can be overridden using the <option
      linkend="opt-max-silent-time">--max-silent-time</option> command
      line switch.</para>

@@ -145,15 +148,16 @@ env-keep-derivations = false

  </varlistentry>

+
  <varlistentry xml:id="conf-build-timeout"><term><literal>build-timeout</literal></term>

    <listitem>

      <para>This option defines the maximum number of seconds that a
-      builder can run.  This is useful (for instance in a automated
+      builder can run.  This is useful (for instance in an automated
      build system) to catch builds that are stuck in an infinite loop
      but keep writing to their standard output or standard error.  It
-      can be overriden using the <option
+      can be overridden using the <option
      linkend="opt-timeout">--timeout</option> command line
      switch.</para>

@@ -165,6 +169,20 @@ env-keep-derivations = false
  </varlistentry>


+  <varlistentry xml:id="conf-build-max-log-size"><term><literal>build-max-log-size</literal></term>
+
+    <listitem>
+
+      <para>This option defines the maximum number of bytes that a
+      builder can write to its stdout/stderr.  If the builder exceeds
+      this limit, it’s killed.  A value of <literal>0</literal> (the
+      default) means that there is no limit.</para>
+
+    </listitem>
+
+  </varlistentry>
+
+
  <varlistentry xml:id="conf-build-users-group"><term><literal>build-users-group</literal></term>

    <listitem><para>This options specifies the Unix group containing
@@ -198,10 +216,8 @@ env-keep-derivations = false
    under the uid of the Nix process (that is, the uid of the caller
    if <envar>NIX_REMOTE</envar> is empty, the uid under which the Nix
    daemon runs if <envar>NIX_REMOTE</envar> is
-    <literal>daemon</literal>, or the uid that owns the setuid
-    <command>nix-worker</command> program if <envar>NIX_REMOTE</envar>
-    is <literal>slave</literal>).  Obviously, this should not be used
-    in multi-user settings with untrusted users.</para>
+    <literal>daemon</literal>).  Obviously, this should not be used in
+    multi-user settings with untrusted users.</para>

    </listitem>

@@ -233,7 +249,27 @@ env-keep-derivations = false

  </varlistentry>

-  
+
+  <varlistentry xml:id="conf-build-chroot-dirs"><term><literal>build-chroot-dirs</literal></term>
+
+    <listitem><para>When builds are performed in a chroot environment,
+    Nix will mount some directories from the normal file system
+    hierarchy inside the chroot.  These are the Nix store, the
+    temporary build directory (usually
+    <filename>/tmp/nix-build-<replaceable>drvname</replaceable>-<replaceable>number</replaceable></filename>),
+    the <literal>/proc</literal> filesystem, and the directories
+    listed here.  The default is <literal>/dev /dev/pts</literal>,
+    since these contain files needed by many builds (such as
+    <filename>/dev/null</filename>).  You can use the syntax
+    <literal><replaceable>target</replaceable>=<replaceable>source</replaceable></literal>
+    to mount a path in a different location in the chroot; for
+    instance, <literal>/bin=/nix-bin</literal> will mount the
+    directory <literal>/nix-bin</literal> as <literal>/bin</literal>
+    inside the chroot.</para></listitem>
+
+  </varlistentry>
+
+
  <varlistentry><term><literal>build-use-substitutes</literal></term>

    <listitem><para>If set to <literal>true</literal> (default), Nix
@@ -242,34 +278,17 @@ env-keep-derivations = false

  </varlistentry>

-    
-  <varlistentry xml:id="conf-build-chroot-dirs"><term><literal>build-chroot-dirs</literal></term>

-    <listitem><para>When builds are performed in a chroot environment,
-    Nix will mount (using <command>mount --bind</command> on Linux)
-    some directories from the normal file system hierarchy inside the
-    chroot.  These are the Nix store, the temporary build directory
-    (usually
-    <filename>/tmp/nix-<replaceable>pid</replaceable>-<replaceable>number</replaceable></filename>)
-    and the directories listed here.  The default is <literal>dev
-    /proc</literal>.  Files in <filename>/dev</filename> (such as
-    <filename>/dev/null</filename>) are needed by many builds, and
-    some files in <filename>/proc</filename> may also be needed
-    occasionally.</para>
+  <varlistentry><term><literal>build-fallback</literal></term>

-    <para>The value used on NixOS is
-    
-<programlisting>
-build-use-chroot = /dev /proc /bin</programlisting>
-
-    to make the <filename>/bin/sh</filename> symlink available (which
-    is still needed by many builders).</para>
-
-    </listitem>
+    <listitem><para>If set to <literal>true</literal>, Nix will fall
+    back to building from source if a binary substitute fails.  This
+    is equivalent to the <option>--fallback</option> flag.  The
+    default is <literal>false</literal>.</para></listitem>

  </varlistentry>

-  
+
  <varlistentry><term><literal>build-cache-failures</literal></term>

    <listitem><para>If set to <literal>true</literal>, Nix will
@@ -307,6 +326,86 @@ build-use-chroot = /dev /proc /bin</programlisting>
  </varlistentry>


+  <varlistentry><term><literal>use-binary-caches</literal></term>
+
+    <listitem><para>If set to <literal>true</literal> (the default),
+    Nix will check the binary caches specified by
+    <option>binary-caches</option> and related options to obtain
+    binary substitutes.</para></listitem>
+
+  </varlistentry>
+
+
+  <varlistentry><term><literal>binary-caches</literal></term>
+
+    <listitem><para>A list of URLs of binary caches, separated by
+    whitespace.  The default is
+    <literal>http://cache.nixos.org</literal>.</para></listitem>
+
+  </varlistentry>
+
+
+  <varlistentry><term><literal>binary-caches-files</literal></term>
+
+    <listitem><para>A list of names of files that will be read to
+    obtain additional binary cache URLs.  The default is
+    <literal>/nix/var/nix/profiles/per-user/<replaceable>username</replaceable>/channels/binary-caches/*</literal>.
+    Note that when you’re using the Nix daemon,
+    <replaceable>username</replaceable> is always equal to
+    <literal>root</literal>, so Nix will only use the binary caches
+    provided by the channels installed by root.  Do not set this
+    option to read files created by untrusted users!</para></listitem>
+
+  </varlistentry>
+
+
+  <varlistentry><term><literal>trusted-binary-caches</literal></term>
+
+    <listitem><para>A list of URLs of binary caches, separated by
+    whitespace.  These are not used by default, but can be enabled by
+    users of the Nix daemon by specifying <literal>--option
+    binary-caches <replaceable>urls</replaceable></literal> on the
+    command line.  Unprivileged users are only allowed to pass a
+    subset of the URLs listed in <literal>binary-caches</literal> and
+    <literal>trusted-binary-caches</literal>.</para></listitem>
+
+  </varlistentry>
+
+
+  <varlistentry><term><literal>extra-binary-caches</literal></term>
+
+    <listitem><para>Additional binary caches appended to those
+    specified in <option>binary-caches</option> and
+    <option>binary-caches-files</option>.  When used by unprivileged
+    users, untrusted binary caches (i.e. those not listed in
+    <option>trusted-binary-caches</option>) are silently
+    ignored.</para></listitem>
+
+  </varlistentry>
+
+
+  <varlistentry><term><literal>binary-caches-parallel-connections</literal></term>
+
+    <listitem><para>The maximum number of parallel HTTP connections
+    used by the binary cache substituter to get NAR info files.  This
+    number should be high to minimise latency.  It defaults to
+    150.</para></listitem>
+
+  </varlistentry>
+
+
+  <varlistentry><term><literal>force-manifest</literal></term>
+
+    <listitem><para>If this option is set to <literal>false</literal>
+    (default) and a Nix channel provides both a manifest and a binary
+    cache, only the binary cache will be used.  If set to
+    <literal>true</literal>, the manifest will be fetched as well.
+    This is useful if you want to use binary patches (which are
+    currently not supported by binary caches).</para></listitem>
+
+  </varlistentry>
+
+
  <varlistentry><term><literal>system</literal></term>

    <listitem><para>This option specifies the canonical Nix system
@@ -337,7 +436,21 @@ build-use-chroot = /dev /proc /bin</programlisting>
    <literal>true</literal>.</para></listitem>

  </varlistentry>
-    
+
+
+  <varlistentry><term><literal>auto-optimise-store</literal></term>
+
+    <listitem><para>If set to <literal>true</literal>, Nix
+    automatically detects files in the store that have identical
+    contents, and replaces them with hard links to a single copy.
+    This saves disk space.  If set to <literal>false</literal> (the
+    default), you can still run <command>nix-store
+    --optimise</command> to get rid of duplicate
+    files.</para></listitem>
+
+  </varlistentry>
+
+
 </variablelist>

 </para>
@@ -283,7 +283,7 @@ $ mount -o bind /mnt/otherdisk/nix /nix</screen>

  <listitem><para>This variable should be set to
  <literal>daemon</literal> if you want to use the Nix daemon to
-  executed Nix operations, which is necessary in <link
+  execute Nix operations. This is necessary in <link
  linkend="ssec-multi-user">multi-user Nix installations</link>.
  Otherwise, it should be left unset.</para></listitem>

@@ -293,7 +293,7 @@ $ mount -o bind /mnt/otherdisk/nix /nix</screen>
 <varlistentry xml:id="envar-other-stores"><term><envar>NIX_OTHER_STORES</envar></term>

  <listitem><para>This variable contains the paths of remote Nix
-  installations from whichs paths can be copied, separated by colons.
+  installations from which packages can be copied, separated by colons.
  <phrase condition="manual">See <xref linkend="sec-sharing-packages"
  /> for details.</phrase>  Each path should be the
  <filename>/nix</filename> directory of a remote Nix installation
@@ -304,9 +304,9 @@ $ mount -o bind /mnt/otherdisk/nix /nix</screen>
  <literal>/var/run/nix/remote-stores</literal>.</para>

  <para>Note that if you’re building through the <link
-  linkend="sec-nix-worker">Nix daemon</link>, the only setting for
+  linkend="sec-nix-daemon">Nix daemon</link>, the only setting for
  this variable that matters is the one that the
-  <command>nix-worker</command> process uses.  So if you want to
+  <command>nix-daemon</command> process uses.  So if you want to
  change it, you have to restart the daemon.</para></listitem>

 </varlistentry>
@@ -160,6 +160,18 @@
 </glossentry>


+<glossentry xml:id="gloss-nar"><glossterm>NAR</glossterm>
+
+  <glossdef><para>A <emphasis>N</emphasis>ix
+  <emphasis>AR</emphasis>chive.  This is a serialisation of a path in
+  the Nix store.  It can contain regular files, directories and
+  symbolic links.  NARs are generated and unpacked using
+  <command>nix-store --dump</command> and <command>nix-store
+  --restore</command>.</para></glossdef>
+
+</glossentry>
+
+

 </glosslist>

@@ -0,0 +1,41 @@
+<appendix xmlns="http://docbook.org/ns/docbook"
+          xmlns:xlink="http://www.w3.org/1999/xlink"
+          xml:id="chap-hacking">
+
+<title>Hacking</title>
+
+<para>This section provides some notes on how to hack on Nix.  To get
+the latest version of Nix from GitHub:
+<screen>
+$ git clone git://github.com/NixOS/nix.git
+$ cd hydra
+</screen>
+</para>
+
+<para>To build it and its dependencies:
+<screen>
+$ nix-build release.nix -A build.x86_64-linux
+</screen>
+</para>
+
+<para>To build all dependencies and start a shell in which all
+environment variables are set up so that those dependencies can be
+found:
+<screen>
+$ ./dev-shell
+</screen>
+To build Nix itself in this shell:
+<screen>
+[nix-shell]$ ./bootstrap
+[nix-shell]$ configurePhase
+[nix-shell]$ make
+</screen>
+To test it:
+<screen>
+[nix-shell]$ make install
+[nix-shell]$ make installcheck
+</screen>
+
+</para>
+
+</appendix>
@@ -116,6 +116,8 @@ a source distribution.</para>

 <itemizedlist>

+  <listitem><para>GNU Make.</para></listitem>
+
  <listitem><para>A fairly recent version of GCC/G++.  Version 2.95
  and higher should work.  Clang will also work.</para></listitem>

@@ -164,11 +166,10 @@ a source distribution.</para>

  <listitem><para>Recent versions of Bison and Flex to build the
  parser.  (This is because Nix needs GLR support in Bison and
-  reentrancy support in Flex.)  For Bison, you need version 2.3 or
-  higher (1.875 does <emphasis>not</emphasis> work), which can be
-  obtained from the <link
+  reentrancy support in Flex.)  For Bison, you need version 2.6, which
+  can be obtained from the <link
  xlink:href="ftp://alpha.gnu.org/pub/gnu/bison">GNU FTP
-  server</link>.  For Flex, you need version 2.5.33, which is
+  server</link>.  For Flex, you need version 2.5.35, which is
  available on <link
  xlink:href="http://lex.sourceforge.net/">SourceForge</link>.
  Slightly older versions may also work, but ancient versions like the
@@ -217,7 +218,8 @@ $ ./configure <replaceable>options...</replaceable>
 $ make
 $ make install</screen>

-</para>
+Nix requires GNU Make so you may need to invoke
+<command>gmake</command> instead.</para>

 <para>When building from the Git repository, these should be preceded
 by the command:
@@ -409,11 +411,11 @@ $ chown -R root /nix/store /nix/var/nix</screen>

 </para>

-<para>The <link linkend="sec-nix-worker">Nix daemon</link> should be
+<para>The <link linkend="sec-nix-daemon">Nix daemon</link> should be
 started as follows (as <literal>root</literal>):

 <screen>
-$ nix-worker --daemon</screen>
+$ nix-daemon</screen>

 You’ll want to put that line somewhere in your system’s boot
 scripts.</para>
@@ -447,11 +449,11 @@ named anything.  It should own the Nix store and database:
 <screen>
 $ chown -R nix /nix/store /nix/var/nix</screen>

-and of course <command>nix-worker --daemon</command> should be started
-under that user, e.g.,
+and of course <command>nix-daemon</command> should be started under
+that user, e.g.,

 <screen>
-$ su - nix -c "exec /nix/bin/nix-worker --daemon"</screen>
+$ su - nix -c "exec /nix/bin/nix-daemon"</screen>

 </para>

@@ -536,7 +538,7 @@ a symbolic link to the current <emphasis>user environment</emphasis>
 installed packages).  The simplest way to set the required environment
 variables is to include the file
 <filename><replaceable>prefix</replaceable>/etc/profile.d/nix.sh</filename>
-in your <filename>~/.bashrc</filename> (or similar), like this:</para>
+in your <filename>~/.profile</filename> (or similar), like this:</para>

 <screen>
 source <replaceable>prefix</replaceable>/etc/profile.d/nix.sh</screen>
@@ -19,15 +19,15 @@
    </author>

    <copyright>
-      <year>2004-2012</year>
+      <year>2004-2013</year>
      <holder>Eelco Dolstra</holder>
    </copyright>

-    <date>May 2012</date>
-    
+    <date>July 2013</date>
+
  </info>

-  
+
  <xi:include href="introduction.xml" />
  <xi:include href="quick-start.xml" />
  <xi:include href="installation.xml" />
@@ -40,17 +40,18 @@
    <title>Command Reference</title>
    <xi:include href="opt-common.xml" />
    <xi:include href="env-common.xml" />
-    
+
    <section>
      <title>Main commands</title>
      <xi:include href="nix-env.xml" />
      <xi:include href="nix-instantiate.xml" />
      <xi:include href="nix-store.xml" />
    </section>
-    
+
    <section>
      <title>Utilities</title>
      <xi:include href="nix-build.xml" />
+      <xi:include href="nix-shell.xml" />
      <xi:include href="nix-channel.xml" />
      <xi:include href="nix-collect-garbage.xml" />
      <xi:include href="nix-copy-closure.xml" />
@@ -59,24 +60,25 @@
      <xi:include href="nix-prefetch-url.xml" />
      <xi:include href="nix-pull.xml" />
      <xi:include href="nix-push.xml" />
-      <xi:include href="nix-worker.xml" />
+      <xi:include href="nix-daemon.xml" />
    </section>

    <section>
      <title>Files</title>
      <xi:include href="conf-file.xml" />
    </section>
-    
+
  </appendix>

  <xi:include href="troubleshooting.xml" />
  <!-- <xi:include href="bugs.xml" /> -->
  <xi:include href="glossary.xml" />
+  <xi:include href="hacking.xml" />

  <appendix>
    <title>Nix Release Notes</title>
    <xi:include href="release-notes.xml"
                xpointer="xmlns(x=http://docbook.org/ns/docbook)xpointer(x:article/x:section)" />
  </appendix>
-    
+
 </book>
@@ -38,11 +38,6 @@
      </group>
      <replaceable>outlink</replaceable>
    </arg>
-    <arg>
-      <option>--run-env</option>
-      <arg><option>--command</option> <replaceable>cmd</replaceable></arg>
-      <arg><option>--exclude</option> <replaceable>regexp</replaceable></arg>
-    </arg>
    <arg choice='plain' rep='repeat'><replaceable>paths</replaceable></arg>
  </cmdsynopsis>
 </refsynopsisdiv>
@@ -75,13 +70,6 @@ a root of the Nix garbage collector.  This root disappears
 automatically when the <filename>result</filename> symlink is deleted
 or renamed.  So don’t rename the symlink.</para></warning>

-<para>The subcommand <command>nix-build --run-env</command> will build
-the dependencies of the derivation, but not the derivation itself.  It
-will then start an interactive shell in which all environment
-variables defined by the derivation have been set to their
-corresponding values.  This is useful for reproducing the environment
-of a derivation for development.</para>
-
 </refsection>


@@ -96,7 +84,7 @@ also <xref linkend="sec-common-options" />.</phrase></para>
 <variablelist>

  <varlistentry><term><option>--drv-link</option> <replaceable>drvlink</replaceable></term>
-  
+
    <listitem><para>Add a symlink named
    <replaceable>drvlink</replaceable> to the store derivation
    produced by <command>nix-instantiate</command>.  The derivation is
@@ -108,14 +96,14 @@ also <xref linkend="sec-common-options" />.</phrase></para>
  </varlistentry>

  <varlistentry><term><option>--add-drv-link</option></term>
-  
+
    <listitem><para>Shorthand for <option>--drv-link</option>
    <filename>./derivation</filename>.</para></listitem>
-    
+
  </varlistentry>

  <varlistentry><term><option>--no-out-link</option></term>
-  
+
    <listitem><para>Do not create a symlink to the output path.  Note
    that as a result the output does not become a root of the garbage
    collector, and so might be deleted by <command>nix-store
@@ -125,7 +113,7 @@ also <xref linkend="sec-common-options" />.</phrase></para>

  <varlistentry xml:id='opt-out-link'><term><option>--out-link</option> /
  <option>-o</option> <replaceable>outlink</replaceable></term>
-  
+
    <listitem><para>Change the name of the symlink to the output path
    created from <filename>result</filename> to
    <replaceable>outlink</replaceable>.</para></listitem>
@@ -134,32 +122,12 @@ also <xref linkend="sec-common-options" />.</phrase></para>

 </variablelist>

+<para>The following common options are supported:</para>
+
 <variablelist condition="manpage">
  <xi:include href="opt-common.xml#xmlns(db=http://docbook.org/ns/docbook)xpointer(//db:variablelist[@xml:id='opt-common']/*)" />
 </variablelist>

-<para>The following options apply to <command>nix-build --run-env</command>.</para>
-
-<variablelist>
-
-  <varlistentry><term><option>--command</option> <replaceable>cmd</replaceable></term>
-  
-    <listitem><para>In the environment of the derivation, executeq the
-    command <replaceable>cmd</replaceable> instead of the default
-    interactive shell.</para></listitem>
-
-  </varlistentry>
-
-  <varlistentry><term><option>--exclude</option> <replaceable>regexp</replaceable></term>
-  
-    <listitem><para>Do not build any dependencies whose store path
-    matches the regular expression <replaceable>regexp</replaceable>.
-    This option may be specified multiple times.</para></listitem>
-
-  </varlistentry>
-
-</variablelist>
-
 </refsection>


@@ -176,20 +144,25 @@ lrwxrwxrwx  <replaceable>...</replaceable>  result -> /nix/store/d18hyl92g30l...
 $ ls ./result/bin/
 firefox  firefox-config</screen>

-<para>To build the dependencies of the package Pan, and start an
-interactive shell in which to build it:
-
+<para>If a derivation has multiple outputs,
+<command>nix-build</command> will build the default (first) output.
+You can also build all outputs:
 <screen>
-$ nix-build '&lt;nixpkgs>' --run-env -A pan
-$ tar xf $src
-$ cd pan-*
-$ ./configure
-$ make
-$ ./pan/gui/pan
+$ nix-build '&lt;nixpkgs>' -A openssl.all
 </screen>
-
-</para>
-
+This will create a symlink for each output named
+<filename>result-<replaceable>outputname</replaceable></filename>.
+The suffix is omitted if the output name is <literal>out</literal>.
+So if <literal>openssl</literal> has outputs <literal>out</literal>,
+<literal>bin</literal> and <literal>man</literal>,
+<command>nix-build</command> will create symlinks
+<literal>result</literal>, <literal>result-bin</literal> and
+<literal>result-man</literal>.  It’s also possible to build a specific
+output:
+<screen>
+$ nix-build '&lt;nixpkgs>' -A openssl.man
+</screen>
+This will create a symlink <literal>result-man</literal>.</para>

 </refsection>

@@ -201,6 +174,6 @@ $ ./pan/gui/pan
 </variablelist>

 </refsection>
-  
+

 </refentry>
@@ -103,7 +103,7 @@ respectively.</para>
 <para>To subscribe to the Nixpkgs channel and install the GNU Hello package:</para>

 <screen>
-$ nix-channel --add http://nixos.org/releases/nixpkgs/channels/nixpkgs-unstable
+$ nix-channel --add http://nixos.org/channels/nixpkgs-unstable
 $ nix-channel --update
 $ nix-env -iA nixpkgs.hello</screen>

@@ -26,6 +26,7 @@
      <arg choice='plain'><option>--print-dead</option></arg>
      <arg choice='plain'><option>--delete</option></arg>
    </group>
+    <arg><option>--dry-run</option></arg>
  </cmdsynopsis>
 </refsynopsisdiv>

@@ -28,6 +28,8 @@
    <arg><option>--xz</option></arg>
    <arg><option>--show-progress</option></arg>
    <arg><option>--include-outputs</option></arg>
+    <arg><option>--use-substitutes</option></arg>
+    <arg><option>-s</option></arg>
    <arg choice='plain'>
      <replaceable>user@</replaceable><replaceable>machine</replaceable>
    </arg>
@@ -65,7 +67,7 @@ those paths.  If this bothers you, use
 <refsection><title>Options</title>

 <variablelist>
-  
+
  <varlistentry><term><option>--to</option></term>

    <listitem><para>Copy the closure of
@@ -119,10 +121,22 @@ those paths.  If this bothers you, use
  </varlistentry>

  <varlistentry><term><option>--include-outputs</option></term>
-  
-  <listitem><para>Also copy the outputs of store derivations included
-  in the closure.</para></listitem>
-  
+
+    <listitem><para>Also copy the outputs of store derivations
+    included in the closure.</para></listitem>
+
+  </varlistentry>
+
+  <varlistentry><term><option>--use-substitutes</option> / <option>-s</option></term>
+
+    <listitem><para>Attempt to download missing paths on the target
+    machine using Nix’s substitute mechanism.  Any paths that cannot
+    be substituted on the target are still copied normally from the
+    source.  This is useful, for instance, if the connection between
+    the source and target machine is slow, but the connection between
+    the target machine and <literal>nixos.org</literal> (the default
+    binary cache server) is fast.</para></listitem>
+
  </varlistentry>

 </variablelist>
@@ -140,7 +154,7 @@ those paths.  If this bothers you, use
    <command>ssh</command> on the command line.</para></listitem>

  </varlistentry>
-  
+
 </variablelist>

 </refsection>
@@ -1,24 +1,23 @@
 <refentry xmlns="http://docbook.org/ns/docbook"
          xmlns:xlink="http://www.w3.org/1999/xlink"
          xmlns:xi="http://www.w3.org/2001/XInclude"
-          xml:id="sec-nix-worker">
+          xml:id="sec-nix-daemon">

 <refmeta>
-  <refentrytitle>nix-worker</refentrytitle>
+  <refentrytitle>nix-daemon</refentrytitle>
  <manvolnum>8</manvolnum>
  <refmiscinfo class="source">Nix</refmiscinfo>
  <refmiscinfo class="version"><xi:include href="version.txt" parse="text"/></refmiscinfo>
 </refmeta>

 <refnamediv>
-  <refname>nix-worker</refname>
+  <refname>nix-daemon</refname>
  <refpurpose>Nix multi-user support daemon</refpurpose>
 </refnamediv>

 <refsynopsisdiv>
  <cmdsynopsis>
-    <command>nix-worker</command>
-    <arg choice="plain"><option>--daemon</option></arg>
+    <command>nix-daemon</command>
  </cmdsynopsis>
 </refsynopsisdiv>

@@ -93,11 +93,10 @@ also <xref linkend="sec-common-options" />.</phrase></para>

    <listitem><para>Specifies the profile to be used by those
    operations that operate on a profile (designated below as the
-    <emphasis>active profile</emphasis>).  A profile is sequence of
+    <emphasis>active profile</emphasis>).  A profile is a sequence of
    user environments called <emphasis>generations</emphasis>, one of
-    which is the <emphasis>current generation</emphasis>.  The default
-    profile is the target of the symbolic link
-    <filename>~/.nix-profile</filename> (see below).</para></listitem>
+    which is the <emphasis>current
+    generation</emphasis>.</para></listitem>

  </varlistentry>

@@ -105,7 +104,8 @@ also <xref linkend="sec-common-options" />.</phrase></para>

    <listitem><para>For the <option>--install</option>,
    <option>--upgrade</option>, <option>--uninstall</option>,
-    <option>--switch-generation</option> and
+    <option>--switch-generation</option>,
+    <option>--delete-generations</option> and
    <option>--rollback</option> operations, this flag will cause
    <command>nix-env</command> to print what
    <emphasis>would</emphasis> be done if this flag had not been
@@ -209,6 +209,10 @@ also <xref linkend="sec-common-options" />.</phrase></para>
    <arg choice='plain'><option>--preserve-installed</option></arg>
    <arg choice='plain'><option>-P</option></arg>
  </group>
+  <group choice='opt'>
+    <arg choice='plain'><option>--remove-all</option></arg>
+    <arg choice='plain'><option>-r</option></arg>
+  </group>
  <arg choice='plain' rep='repeat'><replaceable>args</replaceable></arg>
 </cmdsynopsis>

@@ -272,7 +276,7 @@ number of possible ways:
  linkend="ss-functions">functions</link> that are called with the
  active Nix expression as their single argument.  The derivations
  returned by those function calls are installed.  This allows
-  derivations to be specified in a unambiguous way, which is necessary
+  derivations to be specified in an unambiguous way, which is necessary
  if there are multiple derivations with the same
  name.</para></listitem>

@@ -318,6 +322,16 @@ number of possible ways:

  </varlistentry>

+  <varlistentry><term><option>--remove-all</option></term>
+    <term><option>-r</option></term>
+
+    <listitem><para>Remove all previously installed packages first.
+    This is equivalent to running <literal>nix-env -e '*'</literal>
+    first, except that everything happens in a single
+    transaction.</para></listitem>
+
+  </varlistentry>
+
 </variablelist>

 </refsection>
@@ -692,7 +706,7 @@ firefox-2.0.0.9 <lineannotation>(the current one)</lineannotation>
 $ nix-env --preserve-installed -i firefox-2.0.0.11
 installing `firefox-2.0.0.11'
 building path(s) `/nix/store/myy0y59q3ig70dgq37jqwg1j0rsapzsl-user-environment'
-Collission between `/nix/store/<replaceable>...</replaceable>-firefox-2.0.0.11/bin/firefox'
+collision between `/nix/store/<replaceable>...</replaceable>-firefox-2.0.0.11/bin/firefox'
  and `/nix/store/<replaceable>...</replaceable>-firefox-2.0.0.9/bin/firefox'.
 <lineannotation>(i.e., can’t have two active at the same time)</lineannotation>

@@ -1244,7 +1258,7 @@ wrapper around <option>--list-generations</option> and
 $ nix-env --rollback
 switching from generation 92 to 91

-$ nix-env --rolback
+$ nix-env --rollback
 error: no generation older than the current (91) exists</screen>

 </refsection>
@@ -1255,6 +1269,16 @@ error: no generation older than the current (91) exists</screen>
 <refsection condition="manpage"><title>Environment variables</title>

 <variablelist>
+  
+  <varlistentry><term><envar>NIX_PROFILE</envar></term>
+
+    <listitem><para>Location of the Nix profile.  Defaults to the
+    target of the symlink <filename>~/.nix-profile</filename>, if it
+    exists, or <filename>/nix/var/nix/profiles/default</filename>
+    otherwise.</para></listitem>
+
+  </varlistentry>
+
  <xi:include href="env-common.xml#xmlns(db=http://docbook.org/ns/docbook)xpointer(//db:variablelist[@xml:id='env-common']/*)" />
 </variablelist>

@@ -91,8 +91,9 @@ cryptographic hash as <literal>nix-store --dump

  <varlistentry><term><option>--type</option> <replaceable>hashAlgo</replaceable></term>

-    <listitem><para>Specify a cryptographic hash, which can be one of
-    <literal>md5</literal>, <literal>sha1</literal>, and
+    <listitem><para>Use the specified cryptographic hash algorithm,
+    which can be one of <literal>md5</literal>,
+    <literal>sha1</literal>, and
    <literal>sha256</literal>.</para></listitem>

  </varlistentry>
@@ -18,6 +18,7 @@
 <refsynopsisdiv>
  <cmdsynopsis>
    <command>nix-prefetch-url</command>
+    <arg><option>--type</option> <replaceable>hashAlgo</replaceable></arg>
    <arg choice='plain'><replaceable>url</replaceable></arg>
    <arg><replaceable>hash</replaceable></arg>
  </cmdsynopsis>
@@ -45,11 +46,6 @@ download it again when you build your Nix expression.  Since
 as <command>nix-prefetch-url</command>, the redundant download can be
 avoided.</para>

-<para>The environment variable <envar>NIX_HASH_ALGO</envar> specifies
-which hash algorithm to use.  It can be either <literal>md5</literal>,
-<literal>sha1</literal>, or <literal>sha256</literal>.  The default is
-<literal>sha256</literal>.</para>
-
 <para>If <replaceable>hash</replaceable> is specified, then a download
 is not performed if the Nix store already contains a file with the
 same hash and base name.  Otherwise, the file is downloaded, and an
@@ -63,6 +59,24 @@ of the downloaded file in the Nix store is also printed.</para>
 </refsection>


+<refsection><title>Options</title>
+
+<variablelist>
+  
+  <varlistentry><term><option>--type</option> <replaceable>hashAlgo</replaceable></term>
+
+    <listitem><para>Use the specified cryptographic hash algorithm,
+    which can be one of <literal>md5</literal>,
+    <literal>sha1</literal>, and
+    <literal>sha256</literal>.</para></listitem>
+
+  </varlistentry>
+
+</variablelist>
+
+</refsection>
+
+
 <refsection><title>Examples</title>

 <screen>
@@ -12,24 +12,20 @@

 <refnamediv>
  <refname>nix-push</refname>
-  <refpurpose>push store paths onto a network cache</refpurpose>
+  <refpurpose>generate a binary cache</refpurpose>
 </refnamediv>

 <refsynopsisdiv>
  <cmdsynopsis>
    <command>nix-push</command>
-    <group choice='req'>
-      <arg choice='req'>
-        <arg choice='plain'><replaceable>archivesPutURL</replaceable></arg>
-        <arg choice='plain'><replaceable>archivesGetURL</replaceable></arg>
-        <arg choice='plain'><replaceable>manifestPutURL</replaceable></arg>
-      </arg>
-      <arg choice='req'>
-        <arg choice='plain'><option>--copy</option></arg>
-        <arg choice='plain'><replaceable>archivesDir</replaceable></arg>
-        <arg choice='plain'><replaceable>manifestFile</replaceable></arg>
-      </arg>
-    </group>
+    <arg choice='plain'><option>--dest</option> <replaceable>dest-dir</replaceable></arg>
+    <arg><option>--bzip2</option></arg>
+    <arg><option>--none</option></arg>
+    <arg><option>--force</option></arg>
+    <arg><option>--link</option></arg>
+    <arg><option>--manifest</option></arg>
+    <arg><option>--manifest-path</option> <replaceable>filename</replaceable></arg>
+    <arg><option>--url-prefix</option> <replaceable>url</replaceable></arg>
    <arg choice='plain' rep='repeat'><replaceable>paths</replaceable></arg>
  </cmdsynopsis>
 </refsynopsisdiv>
@@ -37,93 +33,366 @@

 <refsection><title>Description</title>

-<para>The command <command>nix-push</command> builds a set of store
-paths (if necessary), and then packages and uploads all store paths in
-the resulting closures to a server.  A network cache thus populated
-can subsequently be used to speed up software deployment on other
-machines using the <command>nix-pull</command> command.</para>
+<para>The command <command>nix-push</command> produces a
+<emphasis>binary cache</emphasis>, a directory containing compressed
+Nix archives (NARs) plus some metadata of the closure of the specified
+store paths.  This directory can then be made available through a web
+server to other Nix installations, allowing them to skip building from
+source and instead download binaries from the cache
+automatically.</para>

 <para><command>nix-push</command> performs the following actions.
      
 <orderedlist>

  <listitem><para>Each path in <replaceable>paths</replaceable> is
-  realised (using <link
-  linkend='rsec-nix-store-realise'><literal>nix-store
-  --realise</literal></link>).</para></listitem>
+  built (using <link
+  linkend='rsec-nix-store-realise'><command>nix-store
+  --realise</command></link>).</para></listitem>

-  <listitem><para>All paths in the closure of the store expressions
-  stored in <replaceable>paths</replaceable> are determined (using
-  <literal>nix-store --query --requisites
-  --include-outputs</literal>).  It should be noted that since the
-  <option>--include-outputs</option> flag is used, you get a combined
-  source/binary distribution.</para></listitem>
+  <listitem><para>All paths in the closure of
+  <replaceable>paths</replaceable> are determined (using
+  <command>nix-store --query --requisites
+  --include-outputs</command>).  Note that since the
+  <option>--include-outputs</option> flag is used, if
+  <replaceable>paths</replaceable> includes a store derivation, you
+  get a combined source/binary distribution (e.g., source tarballs
+  will be included).</para></listitem>

  <listitem><para>All store paths determined in the previous step are
-  packaged and compressed into a <command>bzip</command>ped NAR
-  archive (extension <filename>.nar.bz2</filename>).</para></listitem>
+  packaged into a NAR (using <command>nix-store --dump</command>) and
+  compressed using <command>xz</command> or <command>bzip2</command>.
+  The resulting files have the extension <filename>.nar.xz</filename>
+  or <filename>.nar.bz2</filename>.  Also for each store path, Nix
+  generates a file with extension <filename>.narinfo</filename>
+  containing metadata such as the references, cryptographic hash and
+  size of each path.</para></listitem>

-  <listitem><para>A <emphasis>manifest</emphasis> is created that
-  contains information on the store paths, their eventual URLs in the
-  cache, and cryptographic hashes of the contents of the NAR
-  archives.</para></listitem>
+  <listitem><para>Optionally, a single <emphasis>manifest</emphasis>
+  file is created that contains the same metadata as the
+  <filename>.narinfo</filename> files.  This is for compatibility with
+  Nix versions prior to 1.2 (see <command>nix-pull</command> for
+  details).</para></listitem>

-  <listitem><para>Each store path is uploaded to the remote directory
-  specified by <replaceable>archivesPutURL</replaceable>.  HTTP PUT
-  requests are used to do this.  However, before a file
-  <varname>x</varname> is uploaded to
-  <literal><replaceable>archivesPutURL</replaceable>/</literal><varname>x</varname>,
-  <command>nix-push</command> first determines whether this upload is
-  unnecessary by issuing a HTTP HEAD request on
-  <literal><replaceable>archivesGetURL</replaceable>/</literal><varname>x</varname>.
-  This allows a cache to be shared between many partially overlapping
-  <command>nix-push</command> invocations.  (We use two URLs because
-  the upload URL typically refers to a CGI script, while the download
-  URL just refers to a file system directory on the
-  server.)</para></listitem>
+  <listitem><para>A file named <option>nix-cache-info</option> is
+  placed in the destination directory.  The existence of this file
+  marks the directory as a binary cache.</para></listitem>

-  <listitem><para>The manifest is uploaded using an HTTP PUT request
-  to <replaceable>manifestPutURL</replaceable>.  The corresponding
-  URL to download the manifest can then be used by
-  <command>nix-pull</command>.</para></listitem>
-        
 </orderedlist>

 </para>

-<!--
-<para>TODO:  <option>- -copy</option></para>
-->
-            
+</refsection>
+
+
+<refsection><title>Options</title>
+
+<variablelist>
+
+  <varlistentry><term><option>--dest</option> <replaceable>dest-dir</replaceable></term>
+
+    <listitem><para>Set the destination directory to
+    <replaceable>dir</replaceable>, which is created if it does not
+    exist.  This flag is required.</para></listitem>
+
+  </varlistentry>
+
+  <varlistentry><term><option>--bzip2</option></term>
+
+    <listitem><para>Compress NARs using <command>bzip2</command>
+    instead of <command>xz -9</command>.  The latter compresses about
+    30% better on typical archives, decompresses about twice as fast,
+    but compresses a lot slower and is not supported by Nix prior to
+    version 1.2.</para></listitem>
+
+  </varlistentry>
+
+  <varlistentry><term><option>--none</option></term>
+
+    <listitem><para>Do not compress NARs.</para></listitem>
+
+  </varlistentry>
+
+  <varlistentry><term><option>--force</option></term>
+
+    <listitem><para>Overwrite <filename>.narinfo</filename> files if
+    they already exist.</para></listitem>
+
+  </varlistentry>
+
+  <varlistentry><term><option>--link</option></term>
+
+    <listitem><para>By default, NARs are generated in the Nix store
+    and then copied to <replaceable>dest-dir</replaceable>.  If this
+    option is given, hard links are used instead.  This only works if
+    <replaceable>dest-dir</replaceable> is on the same filesystem as
+    the Nix store.</para></listitem>
+
+  </varlistentry>
+
+  <varlistentry><term><option>--manifest</option></term>
+
+    <listitem><para>Force the generation of a manifest suitable for
+    use by <command>nix-pull</command>.  The manifest is stored as
+    <filename><replaceable>dest-dir</replaceable>/MANIFEST</filename>.</para></listitem>
+
+  </varlistentry>
+
+  <varlistentry><term><option>--manifest-path</option> <replaceable>filename</replaceable></term>
+
+    <listitem><para>Like <option>--manifest</option>, but store the
+    manifest in <replaceable>filename</replaceable>.</para></listitem>
+
+  </varlistentry>
+
+  <varlistentry><term><option>--url-prefix</option> <replaceable>url</replaceable></term>
+
+    <listitem><para>Manifests are expected to contain the absolute
+    URLs of NARs.  For generating these URLs, the prefix
+    <replaceable>url</replaceable> is used.  It defaults to
+    <uri>file://<replaceable>dest-dir</replaceable></uri>.</para></listitem>
+
+  </varlistentry>
+
+</variablelist>
+
 </refsection>


 <refsection><title>Examples</title>

-<para>To upload files there typically is some CGI script on the server
-side.  This script should be be protected with a password.  The
-following example uploads the store paths resulting from building the
-Nix expressions in <filename>foo.nix</filename>, passing appropriate
-authentication information:
-    
-<screen>
-$ nix-push \
-    http://foo@bar:server.domain/cgi-bin/upload.pl/cache \
-    http://server.domain/cache \
-    http://foo@bar:server.domain/cgi-bin/upload.pl/MANIFEST \
-    $(nix-instantiate foo.nix)</screen>
+<para>To add the closure of Thunderbird to a binary cache:

-This will push both sources and binaries (and any build-time
-dependencies used in the build, such as compilers).</para>
-
-<para>If we just want to push binaries, not sources and build-time
-dependencies, we can do:
-      
 <screen>
-$ nix-push <replaceable>urls</replaceable> $(nix-store -r $(nix-instantiate foo.nix))</screen>
-    
+$ nix-push --dest /tmp/cache $(nix-build -A thunderbird)
+</screen>
+
+Assuming that <filename>/tmp/cache</filename> is exported by a web
+server as <uri>http://example.org/cache</uri>, you can then use this
+cache on another machine to speed up the installation of Thunderbird:
+
+<screen>
+$ nix-build -A thunderbird --option binary-caches http://example.org/cache
+</screen>
+
+Alternatively, you could add <literal>binary-caches =
+http://example.org/cache</literal> to
+<filename>nix.conf</filename>.</para>
+
+<para>To also include build-time dependencies (such as source
+tarballs):
+
+<screen>
+$ nix-push --dest /tmp/cache $(nix-instantiate -A thunderbird)
+</screen>
+
 </para>

+<para>To generate a manifest suitable for <command>nix-pull</command>:
+
+<screen>
+$ nix-push --dest /tmp/cache $(nix-build -A thunderbird) --manifest
+</screen>
+
+On another machine you can then do:
+
+<screen>
+$ nix-pull http://example.org/cache
+</screen>
+
+to cause the binaries to be used by subsequent Nix operations.</para>
+
 </refsection>
-    
+
+
+<refsection><title>Binary cache format and operation</title>
+
+<para>A binary cache with URL <replaceable>url</replaceable> only
+denotes a valid binary cache if the file
+<uri><replaceable>url</replaceable>/nix-cache-info</uri> exists.  If
+this file does not exist (or cannot be downloaded), the cache is
+ignored.  If it does exist, it must be a text file containing cache
+properties.  Here’s an example:
+
+<screen>
+StoreDir: /nix/store
+WantMassQuery: 1
+Priority: 10
+</screen>
+
+The properties that are currently supported are:
+
+<variablelist>
+  
+  <varlistentry><term><literal>StoreDir</literal></term>
+
+    <listitem><para>The path of the Nix store to which this binary
+    cache applies.  Binaries are not relocatable — a binary built for
+    <filename>/nix/store</filename> won’t generally work in
+    <filename>/home/alice/store</filename> — so to prevent binaries
+    from being used in a wrong store, a binary cache is only used if
+    its <literal>StoreDir</literal> matches the local Nix
+    configuration.  The default is
+    <filename>/nix/store</filename>.</para></listitem>
+
+  </varlistentry>
+
+  <varlistentry><term><literal>WantMassQuery</literal></term>
+
+    <listitem><para>Query operations such as <command>nix-env
+    -qas</command> can cause thousands of cache queries, and thus
+    thousands of HTTP requests, to determine which packages are
+    available in binary form.  While these requests are small, not
+    every server may appreciate a potential onslaught of queries.  If
+    <literal>WantMassQuery</literal> is set to <literal>0</literal>
+    (default), “mass queries” such as <command>nix-env -qas</command>
+    will skip this cache.  Thus a package may appear not to have a
+    binary substitute.  However, the binary will still be used when
+    you actually install the package.  If
+    <literal>WantMassQuery</literal> is set to <literal>1</literal>,
+    mass queries will use this cache.</para></listitem>
+
+  </varlistentry>
+
+  <varlistentry><term><literal>Priority</literal></term>
+
+    <listitem><para>Each binary cache has a priority (defaulting to
+    50).  Binary caches are checked for binaries in order of ascending
+    priority; thus a higher number denotes a lower priority.  The
+    binary cache <uri>http://cache.nixos.org</uri> has priority
+    40.</para></listitem>
+
+  </varlistentry>
+
+</variablelist>
+
+</para>
+
+<para>Every time Nix needs to build some store path
+<replaceable>p</replaceable>, it will check each configured binary
+cache to see if it has a NAR file for <replaceable>p</replaceable>,
+until it finds one.  If no cache has a NAR, Nix will fall back to
+building the path from source (if applicable).  To see if a cache with
+URL <replaceable>url</replaceable> has a binary for
+<replaceable>p</replaceable>, Nix fetches
+<replaceable>url/h</replaceable>, where <replaceable>h</replaceable>
+is the hash part of <replaceable>p</replaceable>.  Thus, if we have a
+cache <uri>http://cache.nixos.org</uri> and we want to obtain
+the store path
+<screen>
+/nix/store/a8922c0h87iilxzzvwn2hmv8x210aqb9-glibc-2.7
+</screen>
+then Nix will attempt to fetch
+<screen>
+http://cache.nixos.org/a8922c0h87iilxzzvwn2hmv8x210aqb9.narinfo
+</screen>
+(Commands such as <command>nix-env -qas</command> will issue an HTTP
+HEAD request, since it only needs to know if the
+<filename>.narinfo</filename> file exists.)  The
+<filename>.narinfo</filename> file is a simple text file that looks
+like this:
+
+<screen>
+StorePath: /nix/store/a8922c0h87iilxzzvwn2hmv8x210aqb9-glibc-2.7
+URL: nar/0zzjpdz46mdn74v09m053yczlz4am038g8r74iy8w43gx8801h70.nar.bz2
+Compression: bzip2
+FileHash: sha256:0zzjpdz46mdn74v09m053yczlz4am038g8r74iy8w43gx8801h70
+FileSize: 24473768
+NarHash: sha256:0s491y1h9hxj5ghiizlxk7ax6jwbha00zwn7lpyd5xg5bhf60vzg
+NarSize: 109521136
+References: 2ma2k0ys8knh4an48n28vigcmc2z8773-linux-headers-2.6.23.16 ...
+Deriver: 7akyyc87ka32xwmqza9dvyg5pwx3j212-glibc-2.7.drv
+</screen>
+
+The fields are as follows:
+
+<variablelist>
+  
+  <varlistentry><term><literal>StorePath</literal></term>
+
+    <listitem><para>The full store path, including the name part
+    (e.g., <literal>glibc-2.7</literal>).  It must match the
+    requested store path.</para></listitem>
+
+  </varlistentry>
+
+  <varlistentry><term><literal>URL</literal></term>
+
+    <listitem><para>The URL of the NAR, relative to the binary cache
+    URL.</para></listitem>
+
+  </varlistentry>
+
+  <varlistentry><term><literal>Compression</literal></term>
+
+    <listitem><para>The compression method; either
+    <literal>xz</literal> or
+    <literal>bzip2</literal>.</para></listitem>
+
+  </varlistentry>
+
+  <varlistentry><term><literal>FileHash</literal></term>
+
+    <listitem><para>The SHA-256 hash of the compressed
+    NAR.</para></listitem>
+
+  </varlistentry>
+
+  <varlistentry><term><literal>FileSize</literal></term>
+
+    <listitem><para>The size of the compressed NAR.</para></listitem>
+
+  </varlistentry>
+
+  <varlistentry><term><literal>NarHash</literal></term>
+
+    <listitem><para>The SHA-256 hash of the uncompressed NAR.  This is
+    equal to the hash of the store path as returned by
+    <command>nix-store -q --hash
+    <replaceable>p</replaceable></command>.</para></listitem>
+
+  </varlistentry>
+
+  <varlistentry><term><literal>NarSize</literal></term>
+
+    <listitem><para>The size of the uncompressed NAR.</para></listitem>
+
+  </varlistentry>
+
+  <varlistentry><term><literal>References</literal></term>
+
+    <listitem><para>The references of the store path, without the Nix
+    store prefix.</para></listitem>
+
+  </varlistentry>
+
+  <varlistentry><term><literal>Deriver</literal></term>
+
+    <listitem><para>The deriver of the store path, without the Nix
+    store prefix.  This field is optional.</para></listitem>
+
+  </varlistentry>
+
+  <varlistentry><term><literal>System</literal></term>
+
+    <listitem><para>The Nix platform type of this binary, if known.
+    This field is optional.</para></listitem>
+
+  </varlistentry>
+
+</variablelist>
+
+</para>
+
+<para>Thus, in our example, after recursively ensuring that the
+references exist (e.g.,
+<filename>/nix/store/2ma2k0ys8knh4an48n28vigcmc2z8773-linux-headers-2.6.23.16</filename>),
+Nix will fetch <screen>
+http://cache.nixos.org/nar/0zzjpdz46mdn74v09m053yczlz4am038g8r74iy8w43gx8801h70.nar.bz2
+</screen> and decompress and unpack it to
+<filename>/nix/store/a8922c0h87iilxzzvwn2hmv8x210aqb9-glibc-2.7</filename>.</para>
+
+</refsection>
+
+
 </refentry>
@@ -0,0 +1,142 @@
+<refentry xmlns="http://docbook.org/ns/docbook"
+          xmlns:xlink="http://www.w3.org/1999/xlink"
+          xmlns:xi="http://www.w3.org/2001/XInclude"
+          xml:id="sec-nix-shell">
+
+<refmeta>
+  <refentrytitle>nix-shell</refentrytitle>
+  <manvolnum>1</manvolnum>
+  <refmiscinfo class="source">Nix</refmiscinfo>
+  <refmiscinfo class="version"><xi:include href="version.txt" parse="text"/></refmiscinfo>
+</refmeta>
+
+<refnamediv>
+  <refname>nix-shell</refname>
+  <refpurpose>start an interactive shell based on a Nix expression</refpurpose>
+</refnamediv>
+
+<refsynopsisdiv>
+  <cmdsynopsis>
+    <command>nix-shell</command>
+    <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="opt-common-syn.xml#xmlns(db=http://docbook.org/ns/docbook)xpointer(/db:nop/*)" />
+    <arg><option>--arg</option> <replaceable>name</replaceable> <replaceable>value</replaceable></arg>
+    <arg><option>--argstr</option> <replaceable>name</replaceable> <replaceable>value</replaceable></arg>
+    <arg>
+      <group choice='req'>
+        <arg choice='plain'><option>--attr</option></arg>
+        <arg choice='plain'><option>-A</option></arg>
+      </group>
+      <replaceable>attrPath</replaceable>
+    </arg>
+    <arg><option>--command</option> <replaceable>cmd</replaceable></arg>
+    <arg><option>--exclude</option> <replaceable>regexp</replaceable></arg>
+    <arg><option>--pure</option></arg>
+    <arg choice='plain' rep='repeat'><replaceable>paths</replaceable></arg>
+  </cmdsynopsis>
+</refsynopsisdiv>
+
+<refsection><title>Description</title>
+
+<para>The command <command>nix-shell</command> will build
+the dependencies of the specified derivation, but not the derivation
+itself.  It will then start an interactive shell in which all
+environment variables defined by the derivation have been set to their
+corresponding values, and the script <literal>$stdenv/setup</literal>
+has been sourced.  This is useful for reproducing the environment of a
+derivation for development.</para>
+
+</refsection>
+
+
+<refsection><title>Options</title>
+
+<para>All options not listed here are passed to <command>nix-store
+--realise</command>, except for <option>--arg</option> and
+<option>--attr</option> / <option>-A</option> which are passed to
+<command>nix-instantiate</command>.  <phrase condition="manual">See
+also <xref linkend="sec-common-options" />.</phrase></para>
+
+<variablelist>
+
+  <varlistentry><term><option>--command</option> <replaceable>cmd</replaceable></term>
+
+    <listitem><para>In the environment of the derivation, run the
+    shell command <replaceable>cmd</replaceable> instead of starting
+    an interactive shell.  However, if you end the shell command with
+    <literal>return</literal>, you still get an interactive shell.
+    This can be useful for doing any additional
+    initialisation.</para></listitem>
+
+  </varlistentry>
+
+  <varlistentry><term><option>--exclude</option> <replaceable>regexp</replaceable></term>
+
+    <listitem><para>Do not build any dependencies whose store path
+    matches the regular expression <replaceable>regexp</replaceable>.
+    This option may be specified multiple times.</para></listitem>
+
+  </varlistentry>
+
+  <varlistentry><term><option>--pure</option></term>
+
+    <listitem><para>If this flag is specified, the environment is
+    almost entirely cleared before the interactive shell is started,
+    so you get an environment that more closely corresponds to the
+    “real” Nix build.  A few variables, in particular
+    <envar>HOME</envar>, <envar>USER</envar> and
+    <envar>DISPLAY</envar>, are retained.  Note that
+    <filename>~/.bashrc</filename> and (depending on your Bash
+    installation) <filename>/etc/bashrc</filename> are still sourced,
+    so any variables set there will affect the interactive
+    shell.</para></listitem>
+
+  </varlistentry>
+
+</variablelist>
+
+<para>The following common options are supported:</para>
+
+<variablelist condition="manpage">
+  <xi:include href="opt-common.xml#xmlns(db=http://docbook.org/ns/docbook)xpointer(//db:variablelist[@xml:id='opt-common']/*)" />
+</variablelist>
+
+</refsection>
+
+
+<refsection><title>Examples</title>
+
+<para>To build the dependencies of the package Pan, and start an
+interactive shell in which to build it:
+
+<screen>
+$ nix-shell '&lt;nixpkgs>' -A pan
+$ unpackPhase
+$ cd pan-*
+$ configurePhase
+$ buildPhase
+$ ./pan/gui/pan
+</screen>
+
+To clear the environment first, and do some additional automatic
+initialisation of the interactive shell:
+
+<screen>
+$ nix-shell '&lt;nixpkgs>' -A pan --pure \
+    --command 'export NIX_DEBUG=1; export NIX_CORES=8; return'
+</screen>
+
+</para>
+
+</refsection>
+
+
+<refsection condition="manpage"><title>Environment variables</title>
+
+<variablelist>
+  <xi:include href="env-common.xml#xmlns(db=http://docbook.org/ns/docbook)xpointer(//db:variablelist[@xml:id='env-common']/*)" />
+</variablelist>
+
+</refsection>
+
+
+</refentry>
@@ -164,7 +164,7 @@ the specified store paths.  Realisation is a somewhat overloaded term:
  exist in the file system).  If the path is already valid, we are
  done immediately.  Otherwise, the path and any missing paths in its
  closure may be produced through substitutes.  If there are no
-  (succesful) subsitutes, realisation fails.</para></listitem>
+  (successful) subsitutes, realisation fails.</para></listitem>

 </itemizedlist>

@@ -174,10 +174,26 @@ the specified store paths.  Realisation is a somewhat overloaded term:
 output.  (For non-derivations argument, the argument itself is
 printed.)</para>

-<para>If the <option>--dry-run</option> option is used, then
-<command>nix-store</command> will print on standard error a
-description of what packages would be built or downloaded, and then
-quit.</para>
+<para>The following flags are available:</para>
+
+<variablelist>
+
+  <varlistentry><term><option>--dry-run</option></term>
+
+    <listitem><para>Print on standard error a description of what
+    packages would be built or downloaded, without actually performing
+    the operation.</para></listitem>
+
+  </varlistentry>
+
+  <varlistentry><term><option>--ignore-unknown</option></term>
+
+    <listitem><para>If a non-derivation path does not have a
+    substitute, then silently ignore it.</para></listitem>
+
+  </varlistentry>
+
+</variablelist>

 </refsection>
            
@@ -773,6 +789,7 @@ $ nix-store --add ./foo.c
    <command>nix-store</command>
    <arg choice='plain'><option>--verify</option></arg>
    <arg><option>--check-contents</option></arg>
+    <arg><option>--repair</option></arg>
  </cmdsynopsis>
 </refsection>

@@ -785,7 +802,7 @@ automatically repaired.  Inconsistencies are generally the result of
 the Nix store or database being modified by non-Nix tools, or of bugs
 in Nix itself.</para>

-<para>There is one option:
+<para>This operation has the following options:

 <variablelist>

@@ -800,6 +817,16 @@ in Nix itself.</para>
    
  </varlistentry>
  
+  <varlistentry><term><option>--repair</option></term>
+  
+    <listitem><para>If any valid path is missing from the store, or
+    (if <option>--check-contents</option> is given) the contents of a
+    valid path has been modified, then try to repair the path by
+    redownloading it.  See <command>nix-store --repair-path</command>
+    for details.</para></listitem>
+    
+  </varlistentry>
+  
 </variablelist>

 </para>
@@ -825,7 +852,7 @@ in Nix itself.</para>

 <refsection><title>Description</title>
            
-<para>The operation <option>--verify-paths</option> compares the
+<para>The operation <option>--verify-path</option> compares the
 contents of the given store paths to their cryptographic hashes stored
 in Nix’s database.  For every changed path, it prints a warning
 message.  The exit status is 0 if no path has changed, and 1
@@ -848,6 +875,52 @@ $ nix-store --verify-path $(nix-store -qR $(which svn))
 </refsection>


+<!--######################################################################-->
+
+<refsection><title>Operation <option>--repair-path</option></title>
+
+<refsection>
+  <title>Synopsis</title>
+  <cmdsynopsis>
+    <command>nix-store</command>
+    <arg choice='plain'><option>--repair-path</option></arg>
+    <arg choice='plain' rep='repeat'><replaceable>paths</replaceable></arg>
+  </cmdsynopsis>
+</refsection>
+
+<refsection><title>Description</title>
+            
+<para>The operation <option>--repair-path</option> attempts to
+“repair” the specified paths by redownloading them using the available
+substituters.  If no substitutes are available, then repair is not
+possible.</para>
+
+<warning><para>During repair, there is a very small time window during
+which the old path (if it exists) is moved out of the way and replaced
+with the new path.  If repair is interrupted in between, then the
+system may be left in a broken state (e.g., if the path contains a
+critical system component like the GNU C Library).</para></warning>
+
+</refsection>
+            
+<refsection><title>Example</title>
+
+<screen>
+$ nix-store --verify-path /nix/store/dj7a81wsm1ijwwpkks3725661h3263p5-glibc-2.13
+path `/nix/store/dj7a81wsm1ijwwpkks3725661h3263p5-glibc-2.13' was modified!
+  expected hash `2db57715ae90b7e31ff1f2ecb8c12ec1cc43da920efcbe3b22763f36a1861588',
+  got `481c5aa5483ebc97c20457bb8bca24deea56550d3985cda0027f67fe54b808e4'
+
+$ nix-store --repair-path /nix/store/dj7a81wsm1ijwwpkks3725661h3263p5-glibc-2.13
+fetching path `/nix/store/d7a81wsm1ijwwpkks3725661h3263p5-glibc-2.13'...
+…
+</screen>
+
+</refsection>
+            
+</refsection>
+
+
 <!--######################################################################-->

 <refsection xml:id='refsec-nix-store-dump'><title>Operation <option>--dump</option></title>
@@ -1169,9 +1242,9 @@ variable <envar>_args</envar>.</para>
 $ nix-store --print-env $(nix-instantiate '&lt;nixpkgs>' -A firefox)
 <replaceable>…</replaceable>
 export src; src='/nix/store/plpj7qrwcz94z2psh6fchsi7s8yihc7k-firefox-12.0.source.tar.bz2'
-export stdenv; stdenv='/nix/store/7c8asx3yfrg5dg1gzhzyq2236zfgibnm-stdenv'
+export stdenv; stdenv='/nix/store/7c8asx3yfrg5dg1gzhzyq2236zfgibnn-stdenv'
 export system; system='x86_64-linux'
-export _args; _args='-e /nix/store/9krlzvny65gdc8s7kpb6lkx8cd02c25b-default-builder.sh'
+export _args; _args='-e /nix/store/9krlzvny65gdc8s7kpb6lkx8cd02c25c-default-builder.sh'
 </screen>

 </refsection>
@@ -1246,8 +1319,8 @@ paths.</para>
 <refsection><title>Example</title>

 <screen>
-$ nix-store --clear-failed-path /nix/store/000zi5dcla86l92jn1g997jb06sidm7x-perl-PerlMagick-6.59
-$ nix-store --clear-failed-path *
+$ nix-store --clear-failed-paths /nix/store/000zi5dcla86l92jn1g997jb06sidm7x-perl-PerlMagick-6.59
+$ nix-store --clear-failed-paths *
 </screen>

 </refsection>
@@ -37,6 +37,11 @@
  <option>-I</option>
  <replaceable>path</replaceable>
 </arg>
+<arg>
+  <option>--option</option>
+  <replaceable>name</replaceable>
+  <replaceable>value</replaceable>
+</arg>
 <sbr />

 </nop>
@@ -181,7 +181,7 @@
  from, say, a network repository.  If the repository is down, the
  realisation of the derivation will fail.  When this option is
  specified, Nix will build the derivation instead.  Thus,
-  installation from binaries falls back on nstallation from source.
+  installation from binaries falls back on installation from source.
  This option is not the default since it is generally not desirable
  for a transient failure in obtaining the substitutes to lead to a
  full build from source (with the related consumption of
@@ -236,7 +236,7 @@
      interpreted by the <command>nix-log2xml</command> tool in the
      Nix source distribution.  The resulting XML file can be fed into
      the <command>log2html.xsl</command> stylesheet to create an HTML
-      file that can be browsed interactively, using Javascript to
+      file that can be browsed interactively, using JavaScript to
      expand and collapse parts of the output.</para></listitem>

    </varlistentry>
@@ -337,20 +337,42 @@
  
  <listitem><para>Causes Nix to print out a stack trace in case of Nix
  expression evaluation errors.</para></listitem>
-  
+
 </varlistentry>


 <varlistentry><term><option>-I</option> <replaceable>path</replaceable></term>
  
-  <listitem><para>Add a path to the Nix expression search path.  See
-  the <envar>NIX_PATH</envar> environment variable for details.  Paths
-  added through <option>-I</option> take precedence over
-  <envar>NIX_PATH</envar>.</para></listitem>
+  <listitem><para>Add a path to the Nix expression search path.  This
+  option may be given multiple times.  See the <envar>NIX_PATH</envar>
+  environment variable for information on the semantics of the Nix
+  search path.  Paths added through <option>-I</option> take
+  precedence over <envar>NIX_PATH</envar>.</para></listitem>
  
 </varlistentry>


+<varlistentry><term><option>--option</option> <replaceable>name</replaceable> <replaceable>value</replaceable></term>
+  
+  <listitem><para>Set the Nix configuration option
+  <replaceable>name</replaceable> to <replaceable>value</replaceable>.
+  This overrides settings in the Nix configuration file (see
+  <citerefentry><refentrytitle>nix.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>).</para></listitem>
+  
+</varlistentry>
+
+
+<varlistentry><term><option>--repair</option></term>
+
+  <listitem><para>Fix corrupted or missing store paths by
+  redownloading or rebuilding them.  Note that this is slow because it
+  requires computing a cryptographic hash of the contents of every
+  path in the closure of the build.  Also note the warning under
+  <command>nix-store --repair-path</command>.</para></listitem>
+
+</varlistentry>
+
+
 </variablelist>


@@ -129,7 +129,7 @@ downloading binaries from <systemitem
 class='fqdomainname'>nixos.org</systemitem>, instead of building
 them from source.  This might still take a while since all
 dependencies must be downloaded, but on a reasonably fast connection
-such as an DSL line it’s on the order of a few minutes.</para>
+such as a DSL line it’s on the order of a few minutes.</para>

 <para>Naturally, packages can also be uninstalled:

@@ -175,21 +175,6 @@ upgrading `coreutils-5.0' to `coreutils-5.2.1'</screen>

 </para>

-<para>If you grow bored of specifying the Nix expressions using
-<parameter>-f</parameter> all the time, you can set a default
-location:
-
-<screen>
-$ nix-env -I nixpkgs-<replaceable>version</replaceable></screen>
-
-After this you can just say, for instance, <literal>nix-env -u
-'*'</literal>.<footnote><para>Setting a default using
-<parameter>-I</parameter> currently clashes with using Nix channels,
-since <literal>nix-channel --update</literal> calls <literal>nix-env
-I</literal> to set the default to the Nix expressions it downloaded
-from the channel, replacing whatever default you had
-set.</para></footnote></para>
-
 </section>


@@ -240,7 +225,7 @@ uses is to create directory trees of symlinks to
 themselves (though automatically generated by
 <command>nix-env</command>), so they too reside in the Nix store.  For
 instance, in <xref linkend='fig-user-environments' /> the user
-environment <filename>/nix/store/5mq2jcn36ldl...-user-env</filename>
+environment <filename>/nix/store/0c1p5z4kda11...-user-env</filename>
 contains a symlink to just Subversion 1.1.2 (arrows in the figure
 indicate symlinks).  This would be what we would obtain if we had done

@@ -458,7 +443,7 @@ URL.</para>
 <command>nix-channel --add</command>, e.g.,

 <screen>
-$ nix-channel --add http://nixos.org/releases/nixpkgs/channels/nixpkgs-unstable</screen>
+$ nix-channel --add http://nixos.org/channels/nixpkgs-unstable</screen>

 subscribes you to a channel that always contains that latest version
 of the Nix Packages collection.  (Instead of
@@ -553,7 +538,7 @@ dependencies) to a file, and then unpack that file into another Nix
 store.  For example,

 <screen>
-$ nix-store --export $(type -p firefox) > firefox.closure</screen>
+$ nix-store --export $(nix-store -qR $(type -p firefox)) > firefox.closure</screen>

 writes the closure of Firefox to a file.  You can then copy this file
 to another machine and install the closure:
@@ -567,7 +552,7 @@ another command, e.g. to copy and install a closure directly to/on
 another machine:

 <screen>
-$ nix-store --export $(type -p firefox) | bzip2 | \
+$ nix-store --export $(nix-store -qR $(type -p firefox)) | bzip2 | \
    ssh alice@itchy.example.org "bunzip2 | nix-store --import"</screen>

 But note that <command>nix-copy-closure</command> is generally more
@@ -598,7 +583,7 @@ $ nix-env -i firefox</screen>
 and Nix has to build a path that it sees is already present in
 <filename>/mnt/nix</filename>, then it will just copy from there
 instead of building it from source.</para>
- 
+

 </section>

@@ -14,9 +14,10 @@ to the following chapters.</para>
 <listitem><para>Download a source tarball or RPM or Debian/Ubuntu
 package from <link xlink:href='http://nixos.org/'/>.  Build source
 distributions using the regular sequence:
-        
+
 <screen>
 $ tar xvfj nix-<replaceable>version</replaceable>.tar.bz2
+$ cd nix-<replaceable>version</replaceable>
 $ ./configure
 $ make
 $ make install <lineannotation>(as root)</lineannotation></screen>
@@ -35,13 +36,13 @@ changed using

 <listitem><para>You should add
 <filename><replaceable>prefix</replaceable>/etc/profile.d/nix.sh</filename>
-to your <filename>~/.bashrc</filename> (or some other login
+to your <filename>~/.profile</filename> (or some other login
 file).</para></listitem>

 <listitem><para>Subscribe to the Nix Packages channel.

 <screen>
-$ nix-channel --add http://nixos.org/releases/nixpkgs/channels/nixpkgs-unstable</screen>
+$ nix-channel --add http://nixos.org/channels/nixpkgs-unstable</screen>

 </para></listitem>

@@ -69,7 +70,7 @@ libxslt-1.1.0
 </para></listitem>

 <listitem><para>Install some packages from the channel:
-        
+
 <screen>
 $ nix-env -i hello firefox <replaceable>...</replaceable> </screen>

@@ -87,7 +88,7 @@ $ firefox
 <lineannotation>(read Slashdot or something)</lineannotation></screen>

 </para></listitem>
-    
+
 <listitem><para>Uninstall a package:

 <screen>
@@ -6,6 +6,418 @@



+<!--==================================================================-->
+
+<section xml:id="ssec-relnotes-1.6.0"><title>Release 1.6.0 (September 10, 2013)</title>
+
+<para>In addition to the usual bug fixes, this release has several new
+features:</para>
+
+<itemizedlist>
+
+  <listitem>
+    <para>The command <command>nix-build --run-env</command> has been
+    renamed to <command>nix-shell</command>.</para>
+  </listitem>
+
+  <listitem>
+    <para><command>nix-shell</command> now sources
+    <filename>$stdenv/setup</filename> <emphasis>inside</emphasis> the
+    interactive shell, rather than in a parent shell.  This ensures
+    that shell functions defined by <literal>stdenv</literal> can be
+    used in the interactive shell.</para>
+  </listitem>
+
+  <listitem>
+    <para><command>nix-shell</command> has a new flag
+    <option>--pure</option> to clear the environment, so you get an
+    environment that more closely corresponds to the “real” Nix build.
+    </para>
+  </listitem>
+
+  <listitem>
+    <para><command>nix-shell</command> now sets the shell prompt
+    (<envar>PS1</envar>) to ensure that Nix shells are distinguishable
+    from your regular shells.</para>
+  </listitem>
+
+  <listitem>
+    <para><command>nix-env</command> no longer requires a
+    <literal>*</literal> argument to match all packages, so
+    <literal>nix-env -qa</literal> is equivalent to <literal>nix-env
+    -qa '*'</literal>.</para>
+  </listitem>
+
+  <listitem>
+    <para><command>nix-env -i</command> has a new flag
+    <option>--remove-all</option> (<option>-r</option>) to remove all
+    previous packages from the profile.  This makes it easier to do
+    declarative package management similar to NixOS’s
+    <option>environment.systemPackages</option>.  For instance, if you
+    have a specification <filename>my-packages.nix</filename> like this:
+
+<programlisting>
+with import &lt;nixpkgs> {};
+[ thunderbird
+  geeqie
+  ...
+]
+</programlisting>
+
+    then after any change to this file, you can run:
+
+<screen>
+$ nix-env -f my-packages.nix -ir
+</screen>
+
+    to update your profile to match the specification.</para>
+  </listitem>
+
+  <listitem>
+    <para>The ‘<literal>with</literal>’ language construct is now more
+    lazy.  It only evaluates its argument if a variable might actually
+    refer to an attribute in the argument.  For instance, this now
+    works:
+
+<programlisting>
+let
+  pkgs = with pkgs; { foo = "old"; bar = foo; } // overrides;
+  overrides = { foo = "new"; };
+in pkgs.bar
+</programlisting>
+
+    This evaluates to <literal>"new"</literal>, while previously it
+    gave an “infinite recursion” error.</para>
+  </listitem>
+
+  <listitem>
+    <para>Nix now has proper integer arithmetic operators. For
+    instance, you can write <literal>x + y</literal> instead of
+    <literal>builtins.add x y</literal>, or <literal>x &lt;
+    y</literal> instead of <literal>builtins.lessThan x y</literal>.
+    The comparison operators also work on strings.</para>
+  </listitem>
+
+  <listitem>
+    <para>On 64-bit systems, Nix integers are now 64 bits rather than
+    32 bits.</para>
+  </listitem>
+
+  <listitem>
+    <para>When using the Nix daemon, the <command>nix-daemon</command>
+    worker process now runs on the same CPU as the client, on systems
+    that support setting CPU affinity.  This gives a significant speedup
+    on some systems.</para>
+  </listitem>
+
+  <listitem>
+    <para>If a stack overflow occurs in the Nix evaluator, you now get
+    a proper error message (rather than “Segmentation fault”) on some
+    systems.</para>
+  </listitem>
+
+  <listitem>
+    <para>In addition to directories, you can now bind-mount regular
+    files in chroots through the (now misnamed) option
+    <option>build-chroot-dirs</option>.</para>
+  </listitem>
+
+</itemizedlist>
+
+<para>This release has contributions from Domen Kožar, Eelco Dolstra,
+Florian Friesdorf, Gergely Risko, Ivan Kozik, Ludovic Courtès and Shea
+Levy.</para>
+
+</section>
+
+
+<!--==================================================================-->
+
+<section xml:id="ssec-relnotes-1.5.3"><title>Release 1.5.3 (June 17, 2013)</title>
+
+<para>This is primarily a bug fix release.  The following changes are
+noteworthy:</para>
+
+<itemizedlist>
+
+  <listitem>
+    <para>Yet another security bug involving hard links to files
+    outside the store was fixed.  This bug only affected multi-user
+    installations that do not have hard link restrictions
+    enabled.  (NixOS is thus not vulnerable.)</para>
+  </listitem>
+
+  <listitem>
+    <para>The default binary cache URL has changed from
+    <uri>http://nixos.org/binary-cache</uri> to
+    <uri>http://cache.nixos.org</uri>.  The latter is hosted on Amazon
+    CloudFront (courtesy of <link
+    xlink:href="http://www.logicblox.com/">LogicBlox</link>) and
+    should provide better performance for users in both Europe and
+    North America.</para>
+  </listitem>
+
+  <listitem>
+    <para>The binary cache substituter now prints a warning message if
+    fetching information from the cache takes more than five seconds.
+    Thus network or server problems no longer make Nix appear to just
+    hang.</para>
+  </listitem>
+
+  <listitem>
+    <para>Stack traces now show function names, e.g.
+<screen>
+while evaluating `concatMapStrings' at `<replaceable>...</replaceable>/nixpkgs/pkgs/lib/strings.nix:18:25':
+</screen>
+      Also, if a function is called with an unexpected argument, Nix
+      now shows the name of the argument.
+    </para>
+  </listitem>
+
+</itemizedlist>
+
+</section>
+
+
+<!--==================================================================-->
+
+<section xml:id="ssec-relnotes-1.5.2"><title>Release 1.5.2 (May 13, 2013)</title>
+
+<para>This is primarily a bug fix release.  It has contributions from
+Eelco Dolstra, Lluís Batlle i Rossell and Shea Levy.</para>
+
+</section>
+
+
+<!--==================================================================-->
+
+<section xml:id="ssec-relnotes-1.5.1"><title>Release 1.5.1 (February 28, 2013)</title>
+
+<para>The bug fix to the bug fix had a bug itself, of course.  But
+this time it will work for sure!</para>
+
+</section>
+
+
+<!--==================================================================-->
+
+<section xml:id="ssec-relnotes-1.5"><title>Release 1.5 (February 27, 2013)</title>
+
+<para>This is a brown paper bag release to fix a regression introduced
+by the hard link security fix in 1.4.</para>
+
+</section>
+
+
+<!--==================================================================-->
+
+<section xml:id="ssec-relnotes-1.4"><title>Release 1.4 (February 26, 2013)</title>
+
+<para>This release fixes a security bug in multi-user operation.  It
+was possible for derivations to cause the mode of files outside of the
+Nix store to be changed to 444 (read-only but world-readable) by
+creating hard links to those files (<link
+xlink:href="https://github.com/NixOS/nix/commit/5526a282b5b44e9296e61e07d7d2626a79141ac4">details</link>).</para>
+
+<para>There are also the following improvements:</para>
+
+<itemizedlist>
+
+  <listitem><para>New built-in function:
+  <function>builtins.hashString</function>.</para></listitem>
+
+  <listitem><para>Build logs are now stored in
+  <filename>/nix/var/log/nix/drvs/<replaceable>XX</replaceable>/</filename>,
+  where <replaceable>XX</replaceable> is the first two characters of
+  the derivation.  This is useful on machines that keep a lot of build
+  logs (such as Hydra servers).</para></listitem>
+
+  <listitem><para>The function <function>corepkgs/fetchurl</function>
+  can now make the downloaded file executable.  This will allow
+  getting rid of all bootstrap binaries in the Nixpkgs source
+  tree.</para></listitem>
+
+  <listitem><para>Language change: The expression <literal>"${./path}
+  ..."</literal> now evaluates to a string instead of a
+  path.</para></listitem>
+
+</itemizedlist>
+
+</section>
+
+
+<!--==================================================================-->
+
+<section xml:id="ssec-relnotes-1.3"><title>Release 1.3 (January 4, 2013)</title>
+
+<para>This is primarily a bug fix release.  When this version is first
+run on Linux, it removes any immutable bits from the Nix store and
+increases the schema version of the Nix store.  (The previous release
+removed support for setting the immutable bit; this release clears any
+remaining immutable bits to make certain operations more
+efficient.)</para>
+
+<para>This release has contributions from Eelco Dolstra and Stuart
+Pernsteiner.</para>
+
+</section>
+
+
+<!--==================================================================-->
+
+<section xml:id="ssec-relnotes-1.2"><title>Release 1.2 (December 6, 2012)</title>
+
+<para>This release has the following improvements and changes:</para>
+
+<itemizedlist>
+
+  <listitem>
+    <para>Nix has a new binary substituter mechanism: the
+    <emphasis>binary cache</emphasis>.  A binary cache contains
+    pre-built binaries of Nix packages.  Whenever Nix wants to build a
+    missing Nix store path, it will check a set of binary caches to
+    see if any of them has a pre-built binary of that path.  The
+    configuration setting <option>binary-caches</option> contains a
+    list of URLs of binary caches.  For instance, doing
+<screen>
+$ nix-env -i thunderbird --option binary-caches http://cache.nixos.org
+</screen>
+    will install Thunderbird and its dependencies, using the available
+    pre-built binaries in <uri>http://cache.nixos.org</uri>.
+    The main advantage over the old “manifest”-based method of getting
+    pre-built binaries is that you don’t have to worry about your
+    manifest being in sync with the Nix expressions you’re installing
+    from; i.e., you don’t need to run <command>nix-pull</command> to
+    update your manifest.  It’s also more scalable because you don’t
+    need to redownload a giant manifest file every time.
+    </para>
+
+    <para>A Nix channel can provide a binary cache URL that will be
+    used automatically if you subscribe to that channel.  If you use
+    the Nixpkgs or NixOS channels
+    (<uri>http://nixos.org/channels</uri>) you automatically get the
+    cache <uri>http://cache.nixos.org</uri>.</para>
+
+    <para>Binary caches are created using <command>nix-push</command>.
+    For details on the operation and format of binary caches, see the
+    <command>nix-push</command> manpage.  More details are provided in
+    <link xlink:href="http://lists.science.uu.nl/pipermail/nix-dev/2012-September/009826.html">this
+    nix-dev posting</link>.</para>
+  </listitem>
+
+  <listitem>
+    <para>Multiple output support should now be usable.  A derivation
+    can declare that it wants to produce multiple store paths by
+    saying something like
+<programlisting>
+outputs = [ "lib" "headers" "doc" ];
+</programlisting>
+    This will cause Nix to pass the intended store path of each output
+    to the builder through the environment variables
+    <literal>lib</literal>, <literal>headers</literal> and
+    <literal>doc</literal>.  Other packages can refer to a specific
+    output by referring to
+    <literal><replaceable>pkg</replaceable>.<replaceable>output</replaceable></literal>,
+    e.g.
+<programlisting>
+buildInputs = [ pkg.lib pkg.headers ];
+</programlisting>
+    If you install a package with multiple outputs using
+    <command>nix-env</command>, each output path will be symlinked
+    into the user environment.</para>
+  </listitem>
+
+  <listitem>
+    <para>Dashes are now valid as part of identifiers and attribute
+    names.</para>
+  </listitem>
+
+  <listitem>
+    <para>The new operation <command>nix-store --repair-path</command>
+    allows corrupted or missing store paths to be repaired by
+    redownloading them.  <command>nix-store --verify --check-contents
+    --repair</command> will scan and repair all paths in the Nix
+    store.  Similarly, <command>nix-env</command>,
+    <command>nix-build</command>, <command>nix-instantiate</command>
+    and <command>nix-store --realise</command> have a
+    <option>--repair</option> flag to detect and fix bad paths by
+    rebuilding or redownloading them.</para>
+  </listitem>
+
+  <listitem>
+    <para>Nix no longer sets the immutable bit on files in the Nix
+    store.  Instead, the recommended way to guard the Nix store
+    against accidental modification on Linux is to make it a read-only
+    bind mount, like this:
+
+<screen>
+$ mount --bind /nix/store /nix/store
+$ mount -o remount,ro,bind /nix/store
+</screen>
+
+    Nix will automatically make <filename>/nix/store</filename>
+    writable as needed (using a private mount namespace) to allow
+    modifications.</para>
+  </listitem>
+
+  <listitem>
+    <para>Store optimisation (replacing identical files in the store
+    with hard links) can now be done automatically every time a path
+    is added to the store.  This is enabled by setting the
+    configuration option <literal>auto-optimise-store</literal> to
+    <literal>true</literal> (disabled by default).</para>
+  </listitem>
+
+  <listitem>
+    <para>Nix now supports <command>xz</command> compression for NARs
+    in addition to <command>bzip2</command>.  It compresses about 30%
+    better on typical archives and decompresses about twice as
+    fast.</para>
+  </listitem>
+
+  <listitem>
+    <para>Basic Nix expression evaluation profiling: setting the
+    environment variable <envar>NIX_COUNT_CALLS</envar> to
+    <literal>1</literal> will cause Nix to print how many times each
+    primop or function was executed.</para>
+  </listitem>
+
+  <listitem>
+    <para>New primops: <varname>concatLists</varname>,
+    <varname>elem</varname>, <varname>elemAt</varname> and
+    <varname>filter</varname>.</para>
+  </listitem>
+
+  <listitem>
+    <para>The command <command>nix-copy-closure</command> has a new
+    flag <option>--use-substitutes</option> (<option>-s</option>) to
+    download missing paths on the target machine using the substitute
+    mechanism.</para>
+  </listitem>
+
+  <listitem>
+    <para>The command <command>nix-worker</command> has been renamed
+    to <command>nix-daemon</command>.  Support for running the Nix
+    worker in “slave” mode has been removed.</para>
+  </listitem>
+
+  <listitem>
+    <para>The <option>--help</option> flag of every Nix command now
+    invokes <command>man</command>.</para>
+  </listitem>
+
+  <listitem>
+    <para>Chroot builds are now supported on systemd machines.</para>
+  </listitem>
+
+</itemizedlist>
+
+<para>This release has contributions from Eelco Dolstra, Florian
+Friesdorf, Mats Erik Andersson and Shea Levy.</para>
+
+</section>
+
+
 <!--==================================================================-->

 <section xml:id="ssec-relnotes-1.1"><title>Release 1.1 (July 18, 2012)</title>
@@ -94,6 +506,11 @@
    <citerefentry><refentrytitle>nix.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
  </listitem>

+  <listitem>
+    <para>When using the Nix daemon, the <option>-s</option> flag in
+    <command>nix-env -qa</command> is now much faster.</para>
+  </listitem>
+    
 </itemizedlist>

 </section>
@@ -1029,7 +1446,7 @@ irreversible.</para></warning>
  </para></listitem>
  

-  <listitem><para>You can now unambigously specify which derivation to
+  <listitem><para>You can now unambiguously specify which derivation to
  build or install in <command>nix-env</command>,
  <command>nix-instantiate</command> and <command>nix-build</command>
  using the <option>--attr</option> / <option>-A</option> flags, which
@@ -1169,7 +1586,7 @@ irreversible.</para></warning>
    <itemizedlist>

      <listitem><para>Make sure that the garbage collector can run
-      succesfully when the disk is full
+      successfully when the disk is full
      (<literal>NIX-18</literal>).</para></listitem>

      <listitem><para><command>nix-env</command> now locks the profile
@@ -1524,7 +1941,7 @@ $ nix-env -f .../i686-linux.nix -i -E 'x: x.firefoxWrapper'</screen>
  </itemizedlist></para></listitem>

  <listitem><para>A hash of the contents of a store path is now stored
-  in the database after a succesful build.  This allows you to check
+  in the database after a successful build.  This allows you to check
  whether store paths have been tampered with: <command>nix-store
  --verify --check-contents</command>.</para></listitem>

@@ -1688,7 +2105,7 @@ $ nix-env -f .../i686-linux.nix -i -E 'x: x.firefoxWrapper'</screen>
    <itemizedlist>

      <listitem><para>Derivations for other platforms are filtered out
-      (which can be overriden using
+      (which can be overridden using
      <option>--system-filter</option>).</para></listitem>

      <listitem><para><option>--install</option> by default now
@@ -17,7 +17,7 @@ bug tracker</link> for a list of currently known issues.</para>
 $ nix-env -i docbook-xml
 ...
 adding /nix/store/s5hyxgm62gk2...-docbook-xml-4.2
-collission between `/nix/store/s5hyxgm62gk2...-docbook-xml-4.2/xml/dtd/docbook/calstblx.dtd'
+collision between `/nix/store/s5hyxgm62gk2...-docbook-xml-4.2/xml/dtd/docbook/calstblx.dtd'
  and `/nix/store/06h377hr4b33...-docbook-xml-4.3/xml/dtd/docbook/calstblx.dtd'
  at /nix/store/...-builder.pl line 62.</screen>

@@ -68,7 +68,7 @@ in <filename>/nix/store</filename>, as can be seen using <command>ls
 $ ls -l /nix/store
 drwxrwxrwt 32000 nix nix 4620288 Sep 8 15:08 store</screen>

-The <literal>ext2</literal> file system is limited to a inode link
+The <literal>ext2</literal> file system is limited to an inode link
 count of 32,000 (each subdirectory increasing the count by one).
 Furthermore, the <literal>st_nlink</literal> field of the
 <function>stat</function> system call is a 16-bit value.</para>
@@ -106,7 +106,7 @@ the single Nix expression in that directory
    here, the entire remainder of the file is the body of the
    function; when given the required arguments, the body should
    describe how to build an instance of the Hello package.</para>
-    
+
  </callout>

  <callout arearefs='ex-hello-nix-co-2'>
@@ -190,7 +190,7 @@ perl = perl;</programlisting>
    with the same name happen to be in scope.</para>

  </callout>
-  
+
 </calloutlist>

 </para>
@@ -301,7 +301,7 @@ steps:</para>
    (<literal>make install</literal>).</para>

  </callout>
-  
+
 </calloutlist>

 <para>If you are wondering about the absence of error checking on the
@@ -321,7 +321,7 @@ error check.</para>
 ...

 rec { <co xml:id='ex-hello-composition-co-1' />
-  
+
  hello = import ../applications/misc/hello/ex-1 <co xml:id='ex-hello-composition-co-2' /> { <co xml:id='ex-hello-composition-co-3' />
    inherit fetchurl stdenv perl;
  };
@@ -330,10 +330,10 @@ rec { <co xml:id='ex-hello-composition-co-1' />
    inherit fetchurl stdenv;
  };

-  fetchurl = import ../build-support/fetchurl { 
+  fetchurl = import ../build-support/fetchurl {
    inherit stdenv; ...
  };
-  
+
  stdenv = ...;

 }
@@ -476,8 +476,8 @@ that the path denoted by <envar>out</envar> is now
 will see that the path is already valid and finish immediately.  If a
 build fails, either because it returns a non-zero exit code, because
 Nix or the builder are killed, or because the machine crashes, then
-the output path will not be registered as valid.  If you try to build
-the derivation again, Nix will remove the output path if it exists
+the output paths will not be registered as valid.  If you try to build
+the derivation again, Nix will remove the output paths if they exist
 (e.g., because the builder died half-way through <literal>make
 install</literal>) and try again.  Note that there is no
 <quote>negative caching</quote>: Nix doesn't remember that a build
@@ -543,7 +543,7 @@ genericBuild <co xml:id='ex-hello-builder2-co-3' /></programlisting>
 <calloutlist>

  <callout arearefs='ex-hello-builder2-co-1'>
-    
+
    <para>The <envar>buildInputs</envar> variable tells
    <filename>setup</filename> to use the indicated packages as
    <quote>inputs</quote>.  This means that if a package provides a
@@ -568,7 +568,7 @@ genericBuild <co xml:id='ex-hello-builder2-co-3' /></programlisting>
    the file <literal>$stdenv/setup</literal>.</para>

  </callout>
-  
+
  <callout arearefs='ex-hello-builder2-co-3'>

    <para>The final step calls the shell function
@@ -580,7 +580,7 @@ genericBuild <co xml:id='ex-hello-builder2-co-3' /></programlisting>
    see <xref linkend='sec-standard-environment' />.</para>

  </callout>
-  
+
 </calloutlist>

 <para>Discerning readers will note that the
@@ -617,7 +617,7 @@ Laziness means that arguments to functions are evaluated only when
 they are needed.  Functional means that functions are
 <quote>normal</quote> values that can be passed around and manipulated
 in interesting ways.  The language is not a full-featured, general
-purpose language.  It's main job is to describe packages,
+purpose language.  Its main job is to describe packages,
 compositions of packages, and the variability within
 packages.</para>

@@ -704,7 +704,7 @@ configureFlags = "
    the third line is indented three spaces.  Thus, two spaces are
    stripped from each line, so the resulting string is

-<programlisting>    
+<programlisting>
 "This is the first line.\nThis is the second line.\n  This is the third line.\n"</programlisting>

    </para>
@@ -714,19 +714,19 @@ configureFlags = "
    text on the initial line.</para>

    <para>Antiquotation
-    (<literal>${<replaceable>expr</replaceable>}}</literal>) is
+    (<literal>${<replaceable>expr</replaceable>}</literal>) is
    supported in indented strings.</para>

    <para>Since <literal>${</literal> and <literal>''</literal> have
    special meaning in indented strings, you need a way to quote them.
    <literal>${</literal> can be escaped by prefixing it with
-    <literal>''</literal>, i.e., <literal>''${</literal>.
-    <literal>''</literal> can be escaped by prefixing it with
-    <literal>'</literal>, i.e., <literal>'''</literal>.  Finally,
-    linefeed, carriage-return and tab characters can be writted as
-    <literal>''\n</literal>, <literal>''\r</literal>,
-    <literal>''\t</literal>.</para>
-    
+    <literal>''</literal> (that is, two single quotes), i.e.,
+    <literal>''${</literal>.  <literal>''</literal> can be escaped by
+    prefixing it with <literal>'</literal>, i.e.,
+    <literal>'''</literal>.  Finally, linefeed, carriage-return and
+    tab characters can be written as <literal>''\n</literal>,
+    <literal>''\r</literal>, <literal>''\t</literal>.</para>
+
    <para>Indented strings are primarily useful in that they allow
    multi-line string literals to follow the indentation of the
    enclosing Nix expression, and that less escaping is typically
@@ -745,7 +745,7 @@ stdenv.mkDerivation {
      ${if enableBar then "cp bar $out/bin" else ""}
    '';
  <replaceable>...</replaceable>
-}    
+}
 </programlisting>

    </para>
@@ -775,13 +775,13 @@ stdenv.mkDerivation {
  absolute at parse time relative to the directory of the Nix
  expression that contained it.  For instance, if a Nix expression in
  <filename>/foo/bar/bla.nix</filename> refers to
-  <filename>../xyzzy/fnord.nix</filename>, the absolutised path is
+  <filename>../xyzzy/fnord.nix</filename>, the absolute path is
  <filename>/foo/xyzzy/fnord.nix</filename>.</para></listitem>

  <listitem><para><emphasis>Booleans</emphasis> with values
  <literal>true</literal> and
  <literal>false</literal>.</para></listitem>
-  
+
 </itemizedlist>

 </para>
@@ -931,7 +931,7 @@ propagate attributes).  This can be shortened using the
 <literal>inherit</literal> keyword.  For instance,

 <programlisting>
-let x = 123; in 
+let x = 123; in
 { inherit x;
  y = 456;
 }</programlisting>
@@ -982,7 +982,7 @@ argument.  There are three kinds of patterns:</para>

 <itemizedlist>

-  
+
  <listitem><para>If a pattern is a single identifier, then the
  function matches any argument.  Example:

@@ -1002,7 +1002,7 @@ map (concat "foo") [ "bar" "bla" "abc" ]</programlisting>
  evaluates to <literal>[ "foobar" "foobla"
  "fooabc" ]</literal>.</para></listitem>

-  
+
  <listitem><para>An <emphasis>attribute set pattern</emphasis> of the
  form <literal>{ name1, name2, …, nameN }</literal>
  matches an attribute set containing the listed attributes, and binds
@@ -1016,7 +1016,7 @@ map (concat "foo") [ "bar" "bla" "abc" ]</programlisting>
  <varname>x</varname>, <varname>y</varname> and
  <varname>z</varname>.  No other attributes are allowed.  If you want
  to allow additional arguments, you can use an ellipsis
-  (<literal>...</literal>): 
+  (<literal>...</literal>):

 <programlisting>
 { x, y, z, ... }: z + y + x</programlisting>
@@ -1164,7 +1164,7 @@ used in the Nix expression for Subversion.</para>
 </calloutlist>

 </simplesect>
-  
+


 <simplesect><title>With-expressions</title>
@@ -1343,7 +1343,7 @@ set, the attributes of which specify the inputs of the build.</para>
  <listitem><para>There must be an attribute named
  <varname>name</varname> whose value must be a string.  This is used
  as a symbolic name for the package by <command>nix-env</command>,
-  and it is appended to the hash in the output path of the
+  and it is appended to the output paths of the
  derivation.</para></listitem>

  <listitem><para>There must be an attribute named
@@ -1358,7 +1358,7 @@ set, the attributes of which specify the inputs of the build.</para>

    <itemizedlist>

-      <listitem><para>Strings, URIs, and integers are just passed
+      <listitem><para>Strings and integers are just passed
      verbatim.</para></listitem>

      <listitem><para>A <emphasis>path</emphasis> (e.g.,
@@ -1369,8 +1369,8 @@ set, the attributes of which specify the inputs of the build.</para>
      should reside in the Nix store.</para></listitem>

      <listitem><para>A <emphasis>derivation</emphasis> causes that
-      derivation to be built prior to the present derivation; the
-      output path is put in the environment
+      derivation to be built prior to the present derivation; its
+      default output path is put in the environment
      variable.</para></listitem>

      <listitem><para>Lists of the previous types are also allowed.
@@ -1389,14 +1389,48 @@ set, the attributes of which specify the inputs of the build.</para>
  specifies command-line arguments to be passed to the builder.  It
  should be a list.</para></listitem>

+  <listitem><para>The optional attribute <varname>outputs</varname>
+  specifies a list of symbolic outputs of the derivation.  By default,
+  a derivation produces a single output path, denoted as
+  <literal>out</literal>.  However, derivations can produce multiple
+  output paths.  This is useful because it allows outputs to be
+  downloaded or garbage-collected separately.  For instance, imagine a
+  library package that provides a dynamic library, header files, and
+  documentation.  A program that links against the library doesn’t
+  need the header files and documentation at runtime, and it doesn’t
+  need the documentation at build time.  Thus, the library package
+  could specify:
+<programlisting>
+outputs = [ "lib" "headers" "doc" ];
+</programlisting>
+  This will cause Nix to pass environment variables
+  <literal>lib</literal>, <literal>headers</literal> and
+  <literal>doc</literal> to the builder containing the intended store
+  paths of each output.  The builder would typically do something like
+<programlisting>
+./configure --libdir=$lib/lib --includedir=$headers/include --docdir=$doc/share/doc
+</programlisting>
+  for an Autoconf-style package.  You can refer to each output of a
+  derivation by selecting it as an attribute, e.g.
+<programlisting>
+buildInputs = [ pkg.lib pkg.headers ];
+</programlisting>
+  The first element of <varname>output</varname> determines the
+  <emphasis>default output</emphasis>.  Thus, you could also write
+<programlisting>
+buildInputs = [ pkg pkg.headers ];
+</programlisting>
+  since <literal>pkg</literal> is equivalent to
+  <literal>pkg.lib</literal>.</para></listitem>
+
 </itemizedlist>

-<para>(Note that <function>mkDerivation</function> in the standard
+<para>The function <function>mkDerivation</function> in the standard
 environment is a wrapper around <function>derivation</function> that
 adds a default value for <varname>system</varname> and always uses
 Bash as the builder, to which the supplied builder is passed as a
 command-line argument.  See <xref linkend='sec-standard-environment'
-/>.)</para>
+/>.</para>

 <para>The builder is executed as follows:

@@ -1440,17 +1474,19 @@ command-line argument.  See <xref linkend='sec-standard-environment'
    top-level Nix store directory (typically,
    <filename>/nix/store</filename>).</para></listitem>

-    <listitem><para><envar>out</envar> is set to point to the output
-    path of the derivation, which is a subdirectory of the Nix store.
-    The output path is a concatenation of the cryptographic hash of
-    all build inputs, and the <varname>name</varname>
-    attribute.</para></listitem>
-    
+    <listitem><para>For each output declared in
+    <varname>outputs</varname>, the corresponding environment variable
+    is set to point to the intended path in the Nix store for that
+    output.  Each output path is a concatenation of the cryptographic
+    hash of all build inputs, the <varname>name</varname> attribute
+    and the output name.  (The output name is omitted if it’s
+    <literal>out</literal>.)</para></listitem>
+
  </itemizedlist>

  </para></listitem>

-  <listitem><para>If the output path already exists, it is removed.
+  <listitem><para>If an output path already exists, it is removed.
  Also, locks are acquired to prevent multiple Nix instances from
  performing the same build at the same time.</para></listitem>

@@ -1464,14 +1500,11 @@ command-line argument.  See <xref linkend='sec-standard-environment'
  <listitem><para>The temporary directory is removed (unless the
  <option>-K</option> option was specified).</para></listitem>

-  <listitem><para>If the build was successful, Nix scans the output
-  for references to the paths of the inputs.  These so-called
-  <emphasis>retained dependencies</emphasis> could be used when the
-  output of the derivation is used (e.g., when it's executed or used
-  as input to another derivation), so if we deploy the derivation, we
-  should copy the retained dependencies as well.  The scan is
-  performed by looking for the hash parts of file names of the
-  inputs.</para></listitem>
+  <listitem><para>If the build was successful, Nix scans each output
+  path for references to input paths by looking for the hash parts of
+  the input paths.  Since these are potential runtime dependencies,
+  Nix registers them as dependencies of the output
+  paths.</para></listitem>

  <listitem><para>After the build, Nix sets the last-modified
  timestamp on all files in the build result to 1 (00:00:01 1/1/1970
@@ -1497,7 +1530,7 @@ attributes.</para>
 <variablelist>

  <varlistentry><term><varname>allowedReferences</varname></term>
-  
+
    <listitem><para>The optional attribute
    <varname>allowedReferences</varname> specifies a list of legal
    references (dependencies) of the output of the builder.  For
@@ -1515,7 +1548,7 @@ allowedReferences = [];

  </varlistentry>

-  
+
  <varlistentry><term><varname>exportReferencesGraph</varname></term>

    <listitem><para>This attribute allows builders access to the
@@ -1626,7 +1659,7 @@ stdenv.mkDerivation {
  outputHashMode = "flat";
  outputHashAlgo = "md5";
  outputHash = md5;
-  
+
  inherit url;
 }
 </programlisting>
@@ -1655,7 +1688,7 @@ stdenv.mkDerivation {
        <para>This is the default.</para></listitem>

      </varlistentry>
-    
+
      <varlistentry><term><literal>"recursive"</literal></term>

        <listitem><para>The hash is computed over the NAR archive dump
@@ -1676,10 +1709,10 @@ stdenv.mkDerivation {
    linkend="sec-nix-hash"><command>nix-hash</command> command</link>
    for information about converting to and from base-32
    notation.)</para></listitem>
-    
+
  </varlistentry>

-  
+
  <varlistentry><term><varname>impureEnvVars</varname></term>

    <listitem><para>This attribute allows you to specify a list of
@@ -1706,7 +1739,7 @@ impureEnvVars = [ "http_proxy" "https_proxy" <replaceable>...</replaceable> ];

  </varlistentry>

-  
+
  <varlistentry><term><varname>preferLocalBuild</varname></term>

    <listitem><para>If this attribute is set to
@@ -78,7 +78,7 @@ The hook `nix-mode-hook' is run when Nix mode is started.
    ("\\<isNull\\>" . font-lock-builtin-face)
    ("[a-zA-Z][a-zA-Z0-9\\+-\\.]*:[a-zA-Z0-9%/\\?:@&=\\+\\$,_\\.!~\\*'-]+"
     . font-lock-constant-face)
-    ("\\<\\([a-zA-Z_][a-zA-Z0-9_'\.]*\\)[ \t]*="
+    ("\\<\\([a-zA-Z_][a-zA-Z0-9_'\-\.]*\\)[ \t]*="
     (1 font-lock-variable-name-face nil nil))
    ("<[a-zA-Z0-9._\\+-]+\\(/[a-zA-Z0-9._\\+-]+\\)*>"
     . font-lock-constant-face)
@@ -4,7 +4,7 @@ After=syslog.target

 [Service]
 Type=simple
-ExecStart=/usr/bin/nix-worker --daemon
+ExecStart=/usr/bin/nix-daemon

 [Install]
 WantedBy=multi-user.target
@@ -10,17 +10,20 @@ License: LGPLv2+
 Group: Applications/System
 %endif
 URL: http://nixos.org/
-Source0: %{name}-%{version}.tar.bz2
+Source0: %{name}-%{version}.tar.gz
 %if 0%{?el5}
 BuildRoot: %(mktemp -ud %{_tmppath}/%{name}-%{version}-%{release}-XXXXXX)
 %endif
 BuildRequires: perl(DBD::SQLite)
 BuildRequires: perl(DBI)
+BuildRequires: perl(WWW::Curl)
 BuildRequires: perl(ExtUtils::ParseXS)
 Requires: /usr/bin/perl
 Requires: curl
 Requires: perl-DBD-SQLite
 Requires: bzip2
+Requires: gzip
+Requires: xz
 BuildRequires: bzip2-devel
 BuildRequires: sqlite-devel

@@ -138,7 +141,7 @@ chmod -x $RPM_BUILD_ROOT%{_sysconfdir}/profile.d/nix.sh
 %if ! 0%{?rhel} 
 # install systemd service descriptor
 mkdir -p $RPM_BUILD_ROOT%{_prefix}/lib/systemd/system
-cp -p misc/systemd/nix-worker.service \
+cp -p misc/systemd/nix-daemon.service \
  $RPM_BUILD_ROOT%{_prefix}/lib/systemd/system/
 %endif

@@ -172,8 +175,8 @@ chgrp %{nixbld_group} /nix/store
 chmod 1775 /nix/store
 %if ! 0%{?rhel}
 # Enable and start Nix worker
-systemctl enable nix-worker.service
-systemctl start  nix-worker.service
+systemctl enable nix-daemon.service
+systemctl start  nix-daemon.service
 %endif

 %files
@@ -185,7 +188,7 @@ systemctl start  nix-worker.service
 %exclude %dir %{perl_vendorarch}/auto/
 %{_prefix}/libexec/*
 %if ! 0%{?rhel}
-%{_prefix}/lib/systemd/system/nix-worker.service
+%{_prefix}/lib/systemd/system/nix-daemon.service
 %endif
 %{_datadir}/emacs/site-lisp/nix-mode.el
 %{_datadir}/nix
@@ -1,4 +1,4 @@
-PERL_MODULES = lib/Nix/Store.pm lib/Nix/Manifest.pm lib/Nix/GeneratePatches.pm lib/Nix/SSH.pm lib/Nix/CopyClosure.pm lib/Nix/Config.pm.in
+PERL_MODULES = lib/Nix/Store.pm lib/Nix/Manifest.pm lib/Nix/GeneratePatches.pm lib/Nix/SSH.pm lib/Nix/CopyClosure.pm lib/Nix/Config.pm.in lib/Nix/Utils.pm

 all: $(PERL_MODULES:.in=)

@@ -26,6 +26,7 @@ AM_CXXFLAGS = \
  -D_FILE_OFFSET_BITS=64

 lib/Nix/Store.cc: lib/Nix/Store.xs
+	$(INSTALL) -d lib/Nix
 	xsubpp $^ -output $@

 else
@@ -1,27 +1,39 @@
 package Nix::Config;

+$version = "@version@";
+
 $binDir = $ENV{"NIX_BIN_DIR"} || "@bindir@";
 $libexecDir = $ENV{"NIX_LIBEXEC_DIR"} || "@libexecdir@";
 $stateDir = $ENV{"NIX_STATE_DIR"} || "@localstatedir@/nix";
 $manifestDir = $ENV{"NIX_MANIFESTS_DIR"} || "@localstatedir@/nix/manifests";
 $logDir = $ENV{"NIX_LOG_DIR"} || "@localstatedir@/log/nix";
 $confDir = $ENV{"NIX_CONF_DIR"} || "@sysconfdir@/nix";
+$storeDir = $ENV{"NIX_STORE_DIR"} || "@storedir@";

-$bzip2 = $ENV{"NIX_BZIP2"} || "@bzip2@";
+$bzip2 = "@bzip2@";
+$xz = "@xz@";
 $curl = "@curl@";

 $useBindings = "@perlbindings@" eq "yes";

+%config = ();
+
 sub readConfig {
-    my %config;
-    my $config = "@sysconfdir@/nix/nix.conf";
+    if (defined $ENV{'_NIX_OPTIONS'}) {
+        foreach my $s (split '\n', $ENV{'_NIX_OPTIONS'}) {
+            my ($n, $v) = split '=', $s, 2;
+            $config{$n} = $v;
+        }
+        return;
+    }
+
+    my $config = "$confDir/nix.conf";
    return unless -f $config;
-    
+
    open CONFIG, "<$config" or die "cannot open `$config'";
    while (<CONFIG>) {
        /^\s*([\w|-]+)\s*=\s*(.*)$/ or next;
        $config{$1} = $2;
-        print "|$1| -> |$2|\n";
    }
    close CONFIG;
 }
@@ -3,39 +3,50 @@ package Nix::CopyClosure;
 use strict;
 use Nix::Config;
 use Nix::Store;
+use List::Util qw(sum);


 sub copyTo {
-    my ($sshHost, $sshOpts, $storePaths, $compressor, $decompressor, $includeOutputs, $dryRun, $sign, $progressViewer) = @_;
-
-    $compressor = "$compressor |" if $compressor ne "";
-    $decompressor = "$decompressor |" if $decompressor ne "";
-    $progressViewer = "$progressViewer |" if $progressViewer ne "";
+    my ($sshHost, $sshOpts, $storePaths, $compressor, $decompressor,
+        $includeOutputs, $dryRun, $sign, $progressViewer, $useSubstitutes) = @_;

    # Get the closure of this path.
    my @closure = reverse(topoSortPaths(computeFSClosure(0, $includeOutputs,
        map { followLinksToStorePath $_ } @{$storePaths})));

+    # Optionally use substitutes on the remote host.
+    if (!$dryRun && $useSubstitutes) {
+        system "ssh $sshHost @{$sshOpts} nix-store -r --ignore-unknown @closure";
+        # Ignore exit status because this is just an optimisation.
+    }
+
    # Ask the remote host which paths are invalid.  Because of limits
    # to the command line length, do this in chunks.  Eventually,
    # we'll want to use ‘--from-stdin’, but we can't rely on the
    # target having this option yet.
    my @missing = ();
+    my $missingSize = 0;
    while (scalar(@closure) > 0) {
        my @ps = splice(@closure, 0, 1500);
        open(READ, "set -f; ssh $sshHost @{$sshOpts} nix-store --check-validity --print-invalid @ps|");
        while (<READ>) {
            chomp;
            push @missing, $_;
+            my ($deriver, $narHash, $time, $narSize, $refs) = queryPathInfo($_, 1);
+            $missingSize += $narSize;
        }
        close READ or die;
    }

+    $compressor = "$compressor |" if $compressor ne "";
+    $decompressor = "$decompressor |" if $decompressor ne "";
+    $progressViewer = "$progressViewer -s $missingSize |" if $progressViewer ne "";
+
    # Export the store paths and import them on the remote machine.
    if (scalar @missing > 0) {
        print STDERR "copying ", scalar @missing, " missing paths to ‘$sshHost’...\n";
        unless ($dryRun) {
-            open SSH, "| $compressor $progressViewer ssh $sshHost @{$sshOpts} '$decompressor nix-store --import' > /dev/null" or die;
+            open SSH, "| $progressViewer $compressor ssh $sshHost @{$sshOpts} '$decompressor nix-store --import' > /dev/null" or die;
            exportPaths(fileno(SSH), $sign, @missing);
            close SSH or die "copying store paths to remote machine `$sshHost' failed: $?";
        }
@@ -9,12 +9,12 @@ use Fcntl ':flock';
 use Nix::Config;

 our @ISA = qw(Exporter);
-our @EXPORT = qw(readManifest writeManifest updateManifestDB addPatch);
+our @EXPORT = qw(readManifest writeManifest updateManifestDB addPatch deleteOldManifests parseNARInfo);


 sub addNAR {
    my ($narFiles, $storePath, $info) = @_;
-    
+
    $$narFiles{$storePath} = []
        unless defined $$narFiles{$storePath};

@@ -24,7 +24,7 @@ sub addNAR {
    foreach my $narFile (@{$narFileList}) {
        $found = 1 if $narFile->{url} eq $info->{url};
    }
-    
+
    push @{$narFileList}, $info if !$found;
 }

@@ -43,7 +43,7 @@ sub addPatch {
            $patch2->{url} eq $patch->{url} &&
            $patch2->{basePath} eq $patch->{basePath};
    }
-    
+
    push @{$patchList}, $patch if !$found;

    return !$found;
@@ -68,7 +68,7 @@ sub readManifest_ {
    my $manifestVersion = 2;

    my ($storePath, $url, $hash, $size, $basePath, $baseHash, $patchType);
-    my ($narHash, $narSize, $references, $deriver, $copyFrom, $system);
+    my ($narHash, $narSize, $references, $deriver, $copyFrom, $system, $compressionType);

    while (<MANIFEST>) {
        chomp;
@@ -93,10 +93,11 @@ sub readManifest_ {
                undef $system;
                $references = "";
                $deriver = "";
-	    }
+                $compressionType = "bzip2";
+            }

        } else {
-            
+
            if (/^\}$/) {
                $inside = 0;

@@ -107,6 +108,7 @@ sub readManifest_ {
                        , references => $references
                        , deriver => $deriver
                        , system => $system
+                        , compressionType => $compressionType
                        });
                }

@@ -120,11 +122,12 @@ sub readManifest_ {
                }

            }
-            
+
            elsif (/^\s*StorePath:\s*(\/\S+)\s*$/) { $storePath = $1; }
            elsif (/^\s*CopyFrom:\s*(\/\S+)\s*$/) { $copyFrom = $1; }
            elsif (/^\s*Hash:\s*(\S+)\s*$/) { $hash = $1; }
            elsif (/^\s*URL:\s*(\S+)\s*$/) { $url = $1; }
+            elsif (/^\s*Compression:\s*(\S+)\s*$/) { $compressionType = $1; }
            elsif (/^\s*Size:\s*(\d+)\s*$/) { $size = $1; }
            elsif (/^\s*BasePath:\s*(\/\S+)\s*$/) { $basePath = $1; }
            elsif (/^\s*BaseHash:\s*(\S+)\s*$/) { $baseHash = $1; }
@@ -172,6 +175,7 @@ sub writeManifest {
            print MANIFEST "{\n";
            print MANIFEST "  StorePath: $storePath\n";
            print MANIFEST "  NarURL: $narFile->{url}\n";
+            print MANIFEST "  Compression: $narFile->{compressionType}\n";
            print MANIFEST "  Hash: $narFile->{hash}\n" if defined $narFile->{hash};
            print MANIFEST "  Size: $narFile->{size}\n" if defined $narFile->{size};
            print MANIFEST "  NarHash: $narFile->{narHash}\n";
@@ -184,7 +188,7 @@ sub writeManifest {
            print MANIFEST "}\n";
        }
    }
-    
+
    foreach my $storePath (sort (keys %{$patches})) {
        my $patchList = $$patches{$storePath};
        foreach my $patch (@{$patchList}) {
@@ -201,8 +205,8 @@ sub writeManifest {
            print MANIFEST "}\n";
        }
    }
-    
-    
+
+
    close MANIFEST;

    rename("$manifest.tmp", $manifest)
@@ -211,11 +215,11 @@ sub writeManifest {

    # Create a bzipped manifest.
    unless (defined $noCompress) {
-	system("$Nix::Config::bzip2 < $manifest > $manifest.bz2.tmp") == 0
-	    or die "cannot compress manifest";
+        system("$Nix::Config::bzip2 < $manifest > $manifest.bz2.tmp") == 0
+            or die "cannot compress manifest";

-	rename("$manifest.bz2.tmp", "$manifest.bz2")
-	    or die "cannot rename $manifest.bz2.tmp: $!";
+        rename("$manifest.bz2.tmp", "$manifest.bz2")
+            or die "cannot rename $manifest.bz2.tmp: $!";
    }
 }

@@ -223,9 +227,13 @@ sub writeManifest {
 sub updateManifestDB {
    my $manifestDir = $Nix::Config::manifestDir;

+    my @manifests = glob "$manifestDir/*.nixmanifest";
+    return undef if scalar @manifests == 0;
+
    mkpath($manifestDir);
-    
-    my $dbPath = "$manifestDir/cache.sqlite";
+
+    unlink "$manifestDir/cache.sqlite"; # remove obsolete cache
+    my $dbPath = "$manifestDir/cache-v2.sqlite";

    # Open/create the database.
    our $dbh = DBI->connect("dbi:SQLite:dbname=$dbPath", "", "")
@@ -245,13 +253,14 @@ sub updateManifestDB {
            timestamp integer not null
        );
 EOF
-    
+
    $dbh->do(<<EOF);
        create table if not exists NARs (
            id               integer primary key autoincrement not null,
            manifest         integer not null,
            storePath        text not null,
            url              text not null,
+            compressionType  text not null,
            hash             text,
            size             integer,
            narHash          text,
@@ -292,8 +301,8 @@ EOF
    flock(MAINLOCK, LOCK_EX) or die;

    our $insertNAR = $dbh->prepare(
-        "insert into NARs(manifest, storePath, url, hash, size, narHash, " .
-        "narSize, refs, deriver, system) values (?, ?, ?, ?, ?, ?, ?, ?, ?, ?)") or die;
+        "insert into NARs(manifest, storePath, url, compressionType, hash, size, narHash, " .
+        "narSize, refs, deriver, system) values (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)") or die;

    our $insertPatch = $dbh->prepare(
        "insert into Patches(manifest, storePath, basePath, baseHash, url, hash, " .
@@ -304,8 +313,8 @@ EOF
    # Read each manifest in $manifestDir and add it to the database,
    # unless we've already done so on a previous run.
    my %seen;
-    
-    for my $manifestLink (glob "$manifestDir/*.nixmanifest") {
+
+    for my $manifestLink (@manifests) {
        my $manifest = Cwd::abs_path($manifestLink);
        next unless -f $manifest;
        my $timestamp = lstat($manifest)->mtime;
@@ -316,9 +325,9 @@ EOF
            {}, $manifest, $timestamp)} == 1;

        print STDERR "caching $manifest...\n";
-        
+
        $dbh->do("delete from Manifests where path = ?", {}, $manifest);
-                 
+
        $dbh->do("insert into Manifests(path, timestamp) values (?, ?)",
                 {}, $manifest, $timestamp);

@@ -327,11 +336,11 @@ EOF
        sub addNARToDB {
            my ($storePath, $narFile) = @_;
            $insertNAR->execute(
-                $id, $storePath, $narFile->{url}, $narFile->{hash}, $narFile->{size},
-                $narFile->{narHash}, $narFile->{narSize}, $narFile->{references},
+                $id, $storePath, $narFile->{url}, $narFile->{compressionType}, $narFile->{hash},
+                $narFile->{size}, $narFile->{narHash}, $narFile->{narSize}, $narFile->{references},
                $narFile->{deriver}, $narFile->{system});
        };
-        
+
        sub addPatchToDB {
            my ($storePath, $patch) = @_;
            $insertPatch->execute(
@@ -341,7 +350,7 @@ EOF
        };

        my $version = readManifest_($manifest, \&addNARToDB, \&addPatchToDB);
-        
+
        if ($version < 3) {
            die "you have an old-style or corrupt manifest `$manifestLink'; please delete it\n";
        }
@@ -364,4 +373,60 @@ EOF
 }


+
+# Delete all old manifests downloaded from a given URL.
+sub deleteOldManifests {
+    my ($url, $curUrlFile) = @_;
+    for my $urlFile (glob "$Nix::Config::manifestDir/*.url") {
+        next if defined $curUrlFile && $urlFile eq $curUrlFile;
+        open URL, "<$urlFile" or die;
+        my $url2 = <URL>;
+        chomp $url2;
+        close URL;
+        next unless $url eq $url2;
+        my $base = $urlFile; $base =~ s/.url$//;
+        unlink "${base}.url";
+        unlink "${base}.nixmanifest";
+    }
+}
+
+
+# Parse a NAR info file.
+sub parseNARInfo {
+    my ($storePath, $content) = @_;
+
+    my ($storePath2, $url, $fileHash, $fileSize, $narHash, $narSize, $deriver, $system);
+    my $compression = "bzip2";
+    my @refs;
+
+    foreach my $line (split "\n", $content) {
+        return undef unless $line =~ /^(.*): (.*)$/;
+        if ($1 eq "StorePath") { $storePath2 = $2; }
+        elsif ($1 eq "URL") { $url = $2; }
+        elsif ($1 eq "Compression") { $compression = $2; }
+        elsif ($1 eq "FileHash") { $fileHash = $2; }
+        elsif ($1 eq "FileSize") { $fileSize = int($2); }
+        elsif ($1 eq "NarHash") { $narHash = $2; }
+        elsif ($1 eq "NarSize") { $narSize = int($2); }
+        elsif ($1 eq "References") { @refs = split / /, $2; }
+        elsif ($1 eq "Deriver") { $deriver = $2; }
+        elsif ($1 eq "System") { $system = $2; }
+    }
+
+    return undef if $storePath ne $storePath2 || !defined $url || !defined $narHash;
+
+    return
+        { url => $url
+        , compression => $compression
+        , fileHash => $fileHash
+        , fileSize => $fileSize
+        , narHash => $narHash
+        , narSize => $narSize
+        , refs => [ @refs ]
+        , deriver => $deriver
+        , system => $system
+        };
+}
+
+
 return 1;
@@ -44,6 +44,7 @@ sub closeSSHConnection {
    if ($sshStarted) {
        system("ssh $sshHost @sshOpts -O exit 2> /dev/null") == 0
            or warn "unable to stop SSH master: $?";
+        $sshStarted = 0;
    }
 }

@@ -42,50 +42,50 @@ if ($Nix::Config::useBindings) {
    use File::Temp;
    use Fcntl qw/F_SETFD/;

-    sub hashFile {
+    *hashFile = sub {
        my ($algo, $base32, $path) = @_;
        my $res = backtick("$Nix::Config::binDir/nix-hash", "--flat", $path, "--type", $algo, $base32 ? "--base32" : ());
        chomp $res;
        return $res;
-    }
-    
-    sub hashPath {
+    };
+
+    *hashPath = sub {
        my ($algo, $base32, $path) = @_;
        my $res = backtick("$Nix::Config::binDir/nix-hash", $path, "--type", $algo, $base32 ? "--base32" : ());
        chomp $res;
        return $res;
-    }
-    
-    sub hashString {
+    };
+
+    *hashString = sub {
        my ($algo, $base32, $s) = @_;
        my $fh = File::Temp->new();
        print $fh $s;
        my $res = backtick("$Nix::Config::binDir/nix-hash", $fh->filename, "--type", $algo, $base32 ? "--base32" : ());
        chomp $res;
        return $res;
-    }
-    
-    sub addToStore {
+    };
+
+    *addToStore = sub {
        my ($srcPath, $recursive, $algo) = @_;
        die "not implemented" if $recursive || $algo ne "sha256";
        my $res = backtick("$Nix::Config::binDir/nix-store", "--add", $srcPath);
        chomp $res;
        return $res;
-    }
-    
-    sub isValidPath {
+    };
+
+    *isValidPath = sub {
        my ($path) = @_;
        my $res = backtick("$Nix::Config::binDir/nix-store", "--check-validity", "--print-invalid", $path);
        chomp $res;
        return $res ne $path;
-    }
-    
-    sub queryPathHash {
+    };
+
+    *queryPathHash = sub {
        my ($path) = @_;
        my $res = backtick("$Nix::Config::binDir/nix-store", "--query", "--hash", $path);
        chomp $res;
        return $res;
-    }
+    };
 }

 1;
@@ -15,11 +15,12 @@
 using namespace nix;


-void doInit() 
+void doInit()
 {
    if (!store) {
        try {
-            setDefaultsFromEnvironment();
+            settings.processEnvironment();
+            settings.lockCPU = false;
            store = openStore();
        } catch (Error & e) {
            croak(e.what());
@@ -237,32 +238,35 @@ SV * derivationFromPath(char * drvPath)
            doInit();
            Derivation drv = derivationFromPath(*store, drvPath);
            hash = newHV();
-            
-            /* TODO: handle drv.outputs */
-            
+
+            HV * outputs = newHV();
+            for (DerivationOutputs::iterator i = drv.outputs.begin(); i != drv.outputs.end(); ++i)
+                hv_store(outputs, i->first.c_str(), i->first.size(), newSVpv(i->second.path.c_str(), 0), 0);
+            hv_stores(hash, "outputs", newRV((SV *) outputs));
+
            AV * inputDrvs = newAV();
            for (DerivationInputs::iterator i = drv.inputDrvs.begin(); i != drv.inputDrvs.end(); ++i)
                av_push(inputDrvs, newSVpv(i->first.c_str(), 0)); // !!! ignores i->second
            hv_stores(hash, "inputDrvs", newRV((SV *) inputDrvs));
-            
+
            AV * inputSrcs = newAV();
            for (PathSet::iterator i = drv.inputSrcs.begin(); i != drv.inputSrcs.end(); ++i)
                av_push(inputSrcs, newSVpv(i->c_str(), 0));
            hv_stores(hash, "inputSrcs", newRV((SV *) inputSrcs));
-            
+
            hv_stores(hash, "platform", newSVpv(drv.platform.c_str(), 0));
            hv_stores(hash, "builder", newSVpv(drv.builder.c_str(), 0));
-            
+
            AV * args = newAV();
            for (Strings::iterator i = drv.args.begin(); i != drv.args.end(); ++i)
                av_push(args, newSVpv(i->c_str(), 0));
            hv_stores(hash, "args", newRV((SV *) args));
-            
+
            HV * env = newHV();
            for (StringPairs::iterator i = drv.env.begin(); i != drv.env.end(); ++i)
                hv_store(env, i->first.c_str(), i->first.size(), newSVpv(i->second.c_str(), 0), 0);
            hv_stores(hash, "env", newRV((SV *) env));
-            
+
            RETVAL = newRV_noinc((SV *)hash);
        } catch (Error & e) {
            croak(e.what());
@@ -0,0 +1,38 @@
+package Nix::Utils;
+
+our @ISA = qw(Exporter);
+our @EXPORT = qw(checkURL uniq writeFile readFile);
+
+$urlRE = "(?: [a-zA-Z][a-zA-Z0-9\+\-\.]*\:[a-zA-Z0-9\%\/\?\:\@\&\=\+\$\,\-\_\.\!\~\*]+ )";
+
+sub checkURL {
+    my ($url) = @_;
+    die "invalid URL ‘$url’\n" unless $url =~ /^ $urlRE $ /x;
+}
+
+sub uniq {
+    my %seen;
+    my @res;
+    foreach my $name (@_) {
+        next if $seen{$name};
+        $seen{$name} = 1;
+        push @res, $name;
+    }
+    return @res;
+}
+
+sub writeFile {
+    my ($fn, $s) = @_;
+    open TMP, ">$fn" or die "cannot create file `$fn': $!";
+    print TMP "$s" or die;
+    close TMP or die;
+}
+
+sub readFile {
+    local $/ = undef;
+    my ($fn) = @_;
+    open TMP, "<$fn" or die "cannot open file `$fn': $!";
+    my $s = <TMP>;
+    close TMP or die;
+    return $s;
+}
@@ -1,15 +1,19 @@
-{ nixpkgs ? <nixpkgs>
-, nix ? { outPath = ./.; revCount = 1234; shortRev = "abcdef"; }
+{ nix ? { outPath = ./.; revCount = 1234; shortRev = "abcdef"; }
 , officialRelease ? false
 }:

 let

+  pkgs = import <nixpkgs> {};
+
+  systems = [ "x86_64-linux" "i686-linux" "x86_64-darwin" "x86_64-freebsd" "i686-freebsd" "i686-cygwin" "i686-solaris" ];
+
+
  jobs = rec {


    tarball =
-      with import nixpkgs {};
+      with pkgs;

      releaseTools.sourceTarball {
        name = "nix-tarball";
@@ -19,7 +23,7 @@ let
        inherit officialRelease;

        buildInputs =
-          [ curl bison25 flex2535 perl libxml2 libxslt w3m bzip2
+          [ curl bison flex2535 perl libxml2 libxslt w3m bzip2
            tetex dblatex nukeReferences pkgconfig sqlite git
          ];

@@ -29,6 +33,7 @@ let
          --with-xml-flags=--nonet
          --with-dbi=${perlPackages.DBI}/${perl.libPrefix}
          --with-dbd-sqlite=${perlPackages.DBDSQLite}/${perl.libPrefix}
+          --with-www-curl=${perlPackages.WWWCurl}/${perl.libPrefix}
        '';

        postUnpack = ''
@@ -41,9 +46,18 @@ let
          export VARTEXFONTS=$TMPDIR/texfonts
        '';

+        distPhase =
+          ''
+            runHook preDist
+            make dist-gzip
+            make dist-xz
+            mkdir -p $out/tarballs
+            cp *.tar.* $out/tarballs
+          '';
+
        preDist = ''
          make -C doc/manual install prefix=$out
-          
+
          make -C doc/manual manual.pdf prefix=$out
          cp doc/manual/manual.pdf $out/manual.pdf

@@ -54,7 +68,7 @@ let
          # to Windows and Macs, so there should be no Linux binaries
          # in the closure).
          nuke-refs $out/manual.pdf
-          
+
          echo "doc manual $out/share/doc/nix/manual" >> $out/nix-support/hydra-build-products
          echo "doc-pdf manual $out/manual.pdf" >> $out/nix-support/hydra-build-products
          echo "doc release-notes $out/share/doc/nix/release-notes" >> $out/nix-support/hydra-build-products
@@ -62,10 +76,9 @@ let
      };


-    build =
-      { system ? "x86_64-linux" }:
+    build = pkgs.lib.genAttrs systems (system:

-      with import nixpkgs { inherit system; };
+      with import <nixpkgs> { inherit system; };

      releaseTools.nixBuild {
        name = "nix";
@@ -77,21 +90,27 @@ let
          --disable-init-state
          --with-dbi=${perlPackages.DBI}/${perl.libPrefix}
          --with-dbd-sqlite=${perlPackages.DBDSQLite}/${perl.libPrefix}
+          --with-www-curl=${perlPackages.WWWCurl}/${perl.libPrefix}
          --enable-gc
+          --sysconfdir=/etc
        '';

        enableParallelBuilding = true;

+        makeFlags = "profiledir=$(out)/etc/profile.d";
+
+        installFlags = "sysconfdir=$(out)/etc";
+
        doInstallCheck = true;
-      };
+      });

-    binaryTarball =
-      { system ? "x86_64-linux" }:

-      with import nixpkgs { inherit system; };
+    binaryTarball = pkgs.lib.genAttrs systems (system:
+
+      with import <nixpkgs> { inherit system; };

      let
-        toplevel = build { inherit system; };
+        toplevel = builtins.getAttr system jobs.build;
        version = toplevel.src.version;
      in

@@ -114,11 +133,11 @@ let
            --transform "s,$TMPDIR/install,/usr/bin/nix-finish-install," \
            --transform "s,$TMPDIR/reginfo,/nix/store/reginfo," \
            $TMPDIR/install $TMPDIR/reginfo $storePaths
-        '';
+        '');


    coverage =
-      with import nixpkgs { system = "x86_64-linux"; };
+      with import <nixpkgs> { system = "x86_64-linux"; };

      releaseTools.coverageAnalysis {
        name = "nix-build";
@@ -134,12 +153,13 @@ let
          --disable-init-state
          --with-dbi=${perlPackages.DBI}/${perl.libPrefix}
          --with-dbd-sqlite=${perlPackages.DBDSQLite}/${perl.libPrefix}
+          --with-www-curl=${perlPackages.WWWCurl}/${perl.libPrefix}
        '';

        dontInstall = false;

        doInstallCheck = true;
-        
+
        lcovFilter = [ "*/boost/*" "*-tab.*" ];

        # We call `dot', and even though we just use it to
@@ -148,16 +168,18 @@ let
        FONTCONFIG_FILE = texFunctions.fontsConf;
      };

-      
-    rpm_fedora13i386 = makeRPM_i686 (diskImageFuns: diskImageFuns.fedora13i386) 50;
-    rpm_fedora13x86_64 = makeRPM_x86_64 (diskImageFunsFun: diskImageFunsFun.fedora13x86_64) 50;
+
    rpm_fedora16i386 = makeRPM_i686 (diskImageFuns: diskImageFuns.fedora16i386) 50;
    rpm_fedora16x86_64 = makeRPM_x86_64 (diskImageFunsFun: diskImageFunsFun.fedora16x86_64) 50;
+    rpm_fedora18i386 = makeRPM_i686 (diskImageFuns: diskImageFuns.fedora18i386) 60;
+    rpm_fedora18x86_64 = makeRPM_x86_64 (diskImageFunsFun: diskImageFunsFun.fedora18x86_64) 60;
+

-    
    deb_debian60i386 = makeDeb_i686 (diskImageFuns: diskImageFuns.debian60i386) 50;
    deb_debian60x86_64 = makeDeb_x86_64 (diskImageFunsFun: diskImageFunsFun.debian60x86_64) 50;
-    
+    deb_debian70i386 = makeDeb_i686 (diskImageFuns: diskImageFuns.debian70i386) 60;
+    deb_debian70x86_64 = makeDeb_x86_64 (diskImageFunsFun: diskImageFunsFun.debian70x86_64) 60;
+
    deb_ubuntu1004i386 = makeDeb_i686 (diskImageFuns: diskImageFuns.ubuntu1004i386) 50;
    deb_ubuntu1004x86_64 = makeDeb_x86_64 (diskImageFuns: diskImageFuns.ubuntu1004x86_64) 50;
    deb_ubuntu1010i386 = makeDeb_i686 (diskImageFuns: diskImageFuns.ubuntu1010i386) 50;
@@ -166,15 +188,19 @@ let
    deb_ubuntu1110x86_64 = makeDeb_x86_64 (diskImageFuns: diskImageFuns.ubuntu1110x86_64) 60;
    deb_ubuntu1204i386 = makeDeb_i686 (diskImageFuns: diskImageFuns.ubuntu1204i386) 60;
    deb_ubuntu1204x86_64 = makeDeb_x86_64 (diskImageFuns: diskImageFuns.ubuntu1204x86_64) 60;
+    deb_ubuntu1210i386 = makeDeb_i686 (diskImageFuns: diskImageFuns.ubuntu1210i386) 70;
+    deb_ubuntu1210x86_64 = makeDeb_x86_64 (diskImageFuns: diskImageFuns.ubuntu1210x86_64) 70;
+    deb_ubuntu1304i386 = makeDeb_i686 (diskImageFuns: diskImageFuns.ubuntu1304i386) 80;
+    deb_ubuntu1304x86_64 = makeDeb_x86_64 (diskImageFuns: diskImageFuns.ubuntu1304x86_64) 80;


    # System tests.
    tests.remote_builds = (import ./tests/remote-builds.nix rec {
-      nix = build { inherit system; }; system = "x86_64-linux";
+      nix = build.x86_64-linux; system = "x86_64-linux";
    }).test;

    tests.nix_copy_closure = (import ./tests/nix-copy-closure.nix rec {
-      nix = build { inherit system; }; system = "x86_64-linux";
+      nix = build.x86_64-linux; system = "x86_64-linux";
    }).test;

  };
@@ -183,16 +209,16 @@ let
  makeRPM_i686 = makeRPM "i686-linux";
  makeRPM_x86_64 = makeRPM "x86_64-linux";

-  makeRPM = 
+  makeRPM =
    system: diskImageFun: prio:

-    with import nixpkgs { inherit system; };
+    with import <nixpkgs> { inherit system; };

    releaseTools.rpmBuild rec {
-      name = "nix-rpm-${diskImage.name}";
+      name = "nix-rpm";
      src = jobs.tarball;
      diskImage = (diskImageFun vmTools.diskImageFuns)
-        { extraPackages = [ "perl-DBD-SQLite" "perl-devel" "sqlite" "sqlite-devel" "bzip2-devel" "emacs" ]; };
+        { extraPackages = [ "perl-DBD-SQLite" "perl-devel" "sqlite" "sqlite-devel" "bzip2-devel" "emacs" "perl-WWW-Curl" ]; };
      memSize = 1024;
      meta.schedulingPriority = prio;
      postRPMInstall = "cd /tmp/rpmout/BUILD/nix-* && make installcheck";
@@ -201,21 +227,21 @@ let

  makeDeb_i686 = makeDeb "i686-linux";
  makeDeb_x86_64 = makeDeb "x86_64-linux";
-  
+
  makeDeb =
    system: diskImageFun: prio:

-    with import nixpkgs { inherit system; };
+    with import <nixpkgs> { inherit system; };

    releaseTools.debBuild {
      name = "nix-deb";
      src = jobs.tarball;
      diskImage = (diskImageFun vmTools.diskImageFuns)
-        { extraPackages = [ "libdbd-sqlite3-perl" "libsqlite3-dev" "libbz2-dev" ]; };
+        { extraPackages = [ "libdbd-sqlite3-perl" "libsqlite3-dev" "libbz2-dev" "libwww-curl-perl" ]; };
      memSize = 1024;
      meta.schedulingPriority = prio;
      configureFlags = "--sysconfdir=/etc";
-      debRequires = [ "curl" "libdbd-sqlite3-perl" "libsqlite3-0" "libbz2-1.0" ];
+      debRequires = [ "curl" "libdbd-sqlite3-perl" "libsqlite3-0" "libbz2-1.0" "bzip2" "xz-utils" "libwww-curl-perl" ];
      doInstallCheck = true;
    };

@@ -7,18 +7,18 @@ noinst_SCRIPTS = nix-profile.sh \
  find-runtime-roots.pl build-remote.pl nix-reduce-build \
  copy-from-other-stores.pl nix-http-export.cgi

-nix-pull nix-push: download-using-manifests.pl
+profiledir = $(sysconfdir)/profile.d

-install-exec-local: download-using-manifests.pl copy-from-other-stores.pl find-runtime-roots.pl
-	$(INSTALL) -d $(DESTDIR)$(sysconfdir)/profile.d
-	$(INSTALL_DATA) nix-profile.sh $(DESTDIR)$(sysconfdir)/profile.d/nix.sh
+install-exec-local: download-using-manifests.pl copy-from-other-stores.pl download-from-binary-cache.pl find-runtime-roots.pl
+	$(INSTALL) -d $(DESTDIR)$(profiledir)
+	$(INSTALL_DATA) nix-profile.sh $(DESTDIR)$(profiledir)/nix.sh
 	$(INSTALL) -d $(DESTDIR)$(libexecdir)/nix
 	$(INSTALL_PROGRAM) find-runtime-roots.pl $(DESTDIR)$(libexecdir)/nix 
 	$(INSTALL_PROGRAM) build-remote.pl $(DESTDIR)$(libexecdir)/nix 
 	$(INSTALL) -d $(DESTDIR)$(libexecdir)/nix/substituters
-	$(INSTALL_PROGRAM) download-using-manifests.pl $(DESTDIR)$(libexecdir)/nix/substituters
-	$(INSTALL_PROGRAM) copy-from-other-stores.pl $(DESTDIR)$(libexecdir)/nix/substituters
+	$(INSTALL_PROGRAM) download-using-manifests.pl copy-from-other-stores.pl download-from-binary-cache.pl $(DESTDIR)$(libexecdir)/nix/substituters
 	$(INSTALL) -d $(DESTDIR)$(sysconfdir)/nix
+	ln -sf nix-build $(DESTDIR)$(bindir)/nix-shell

 include ../substitute.mk

@@ -29,6 +29,7 @@ EXTRA_DIST = nix-collect-garbage.in \
  nix-build.in \
  download-using-manifests.pl.in \
  copy-from-other-stores.pl.in \
+  download-from-binary-cache.pl.in \
  nix-copy-closure.in \
  find-runtime-roots.pl.in \
  build-remote.pl.in \
@@ -6,6 +6,7 @@ use IO::Handle;
 use Nix::Config;
 use Nix::SSH qw/sshOpts openSSHConnection/;
 use Nix::CopyClosure;
+use Nix::Store;
 no warnings('once');


@@ -18,7 +19,7 @@ no warnings('once');
 #   less than the maximum load for that machine, we try to get an
 #   exclusive lock on $currentLoad/$machine-$slot (without blocking).
 #   If we get such a lock, we send "accept" to the caller.  Otherwise,
-#   we send "postpone" and exit. 
+#   we send "postpone" and exit.
 # - We release the exclusive lock on $currentLoad/main-lock.
 # - We perform the build on $neededSystem.
 # - We release the exclusive lock on $currentLoad/$machine-$slot.
@@ -45,8 +46,7 @@ sub all { $_ || return 0 for @_; 1 }
 # Initialisation.
 my $loadIncreased = 0;

-my ($localSystem, $maxSilentTime, $printBuildTrace) = @ARGV;
-$maxSilentTime = 0 unless defined $maxSilentTime;
+my ($localSystem, $maxSilentTime, $printBuildTrace, $buildTimeout) = @ARGV;

 my $currentLoad = $ENV{"NIX_CURRENT_LOAD"};
 my $conf = $ENV{"NIX_REMOTE_SYSTEMS"};
@@ -102,14 +102,14 @@ REQ: while (1) {
        sendReply "decline";
        next;
    }
-    
+
    # Acquire the exclusive lock on $currentLoad/main-lock.
    mkdir $currentLoad, 0777 or die unless -d $currentLoad;
    my $mainLock = "$currentLoad/main-lock";
    sysopen MAINLOCK, "$mainLock", O_RDWR|O_CREAT, 0600 or die;
    flock(MAINLOCK, LOCK_EX) or die;
-    
-    
+
+
    while (1) {
        # Find all machine that can execute this build, i.e., that
        # support builds for the given platform and features, and are
@@ -141,7 +141,7 @@ REQ: while (1) {
                    close $slotLock;
                    $slot++;
                }
-                
+
                push @available, { machine => $cur, load => $load, free => $free }
                if $load < $cur->{maxJobs};
            }
@@ -160,7 +160,7 @@ REQ: while (1) {
            if ($rightType && !$canBuildLocally) {
                sendReply "postpone";
            } else {
-                sendReply "decline";                
+                sendReply "decline";
            }
            close MAINLOCK;
            next REQ;
@@ -182,9 +182,9 @@ REQ: while (1) {


        # Select the best available machine and lock a free slot.
-        my $selected = $available[0]; 
+        my $selected = $available[0];
        my $machine = $selected->{machine};
-        
+
        $slotLock = openSlotLock($machine, $selected->{free});
        flock($slotLock, LOCK_EX | LOCK_NB) or die;
        utime undef, undef, $slotLock;
@@ -195,9 +195,13 @@ REQ: while (1) {
        # Connect to the selected machine.
        @sshOpts = ("-i", $machine->{sshKeys}, "-x");
        $hostName = $machine->{hostName};
-        last REQ if openSSHConnection $hostName;
-    
-        warn "unable to open SSH connection to $hostName, trying other available machines...\n";
+        if (openSSHConnection($hostName)) {
+            last REQ if system("ssh $hostName @sshOpts nix-builds-inhibited < /dev/null > /dev/null 2>&1") != 0;
+            warn "machine `$hostName' is refusing builds, trying other available machines...\n";
+            closeSSHConnection;
+        } else {
+            warn "unable to open SSH connection to `$hostName', trying other available machines...\n";
+        }
        $machine->{enabled} = 0;
    }
 }
@@ -209,7 +213,6 @@ my @inputs = split /\s/, readline(STDIN);
 my @outputs = split /\s/, readline(STDIN);


-print STDERR "building `$drvPath' on `$hostName'\n";
 print STDERR "@ build-remote $drvPath $hostName\n" if $printBuildTrace;


@@ -257,7 +260,10 @@ close UPLOADLOCK;


 # Perform the build.
-my $buildFlags = "--max-silent-time $maxSilentTime --fallback --add-root $rootsDir/\$PPID.out --option verbosity 0";
+my $buildFlags =
+    "--max-silent-time $maxSilentTime --option build-timeout $buildTimeout"
+    . " --fallback --add-root $rootsDir/\$PPID.out --quiet"
+    . " --option build-keep-log false";

 # We let the remote side kill its process group when the connection is
 # closed unexpectedly.  This is necessary to ensure that no processes
@@ -266,8 +272,9 @@ my $buildFlags = "--max-silent-time $maxSilentTime --fallback --add-root $rootsD
 # is interrupted unless the `-tt' flag is used to force a pseudo-tty,
 # in which case every child receives SIGHUP; however, `-tt' doesn't
 # work on some platforms when connection sharing is used.)
+print STDERR "building `$drvPath' on `$hostName'\n";
 pipe STDIN, DUMMY; # make sure we have a readable STDIN
-if (system("exec ssh $hostName @sshOpts '(read; kill -INT -\$\$) <&0 & nix-store -r $drvPath $buildFlags > /dev/null' 2>&4") != 0) {
+if (system("exec ssh $hostName @sshOpts '(read; kill -INT -\$\$) <&0 & exec nix-store -r $drvPath $buildFlags > /dev/null' 2>&4") != 0) {
    # Note that if we get exit code 100 from `nix-store -r', it
    # denotes a permanent build failure (as opposed to an SSH problem
    # or a temporary Nix problem).  We propagate this to the caller to
@@ -283,13 +290,11 @@ if (system("exec ssh $hostName @sshOpts '(read; kill -INT -\$\$) <&0 & nix-store


 # Copy the output from the build machine.
-foreach my $output (@outputs) {
-    my $maybeSignRemote = "";
-    $maybeSignRemote = "--sign" if $UID != 0;
-    
-    system("exec ssh $hostName @sshOpts 'nix-store --export $maybeSignRemote $output'" .
-           "| NIX_HELD_LOCKS=$output @bindir@/nix-store --import > /dev/null") == 0
-	or die "cannot copy $output from $hostName: $?";
+my @outputs2 = grep { !isValidPath($_) } @outputs;
+if (scalar @outputs2 > 0) {
+    system("exec ssh $hostName @sshOpts 'nix-store --export @outputs2'" .
+           "| NIX_HELD_LOCKS='@outputs2' @bindir@/nix-store --import > /dev/null") == 0
+        or die("cannot copy paths " . join(", ", @outputs) . " from `$hostName': $?");
 }


@@ -16,6 +16,9 @@ foreach my $dir (@remoteStoresAll) {
    push @remoteStores, glob($dir);
 }

+exit if scalar @remoteStores == 0;
+print "\n";
+

 $ENV{"NIX_REMOTE"} = "";

@@ -27,7 +30,7 @@ sub findStorePath {
        next unless -e $sourcePath || -l $sourcePath;
        $ENV{"NIX_DB_DIR"} = "$store/var/nix/db";
        return ($store, $sourcePath) if
-            system("@bindir@/nix-store --check-validity $storePath") == 0;
+            system("$binDir/nix-store --check-validity $storePath") == 0;
    }
    return undef;
 }
@@ -36,42 +39,45 @@ sub findStorePath {
 if ($ARGV[0] eq "--query") {

    while (<STDIN>) {
-        my $cmd = $_; chomp $cmd;
+        chomp;
+        my ($cmd, @args) = split " ", $_;

        if ($cmd eq "have") {
-            my $storePath = <STDIN>; chomp $storePath;
-            print STDOUT (defined findStorePath($storePath) ? "1\n" : "0\n");
+            foreach my $storePath (@args) {
+                print "$storePath\n" if defined findStorePath($storePath);
+            }
+            print "\n";
        }

        elsif ($cmd eq "info") {
-            my $storePath = <STDIN>; chomp $storePath;
-            my ($store, $sourcePath) = findStorePath($storePath);
-            if (!defined $store) {
+            foreach my $storePath (@args) {
+                my ($store, $sourcePath) = findStorePath($storePath);
+                next unless defined $store;
+
+                $ENV{"NIX_DB_DIR"} = "$store/var/nix/db";
+
+                my $deriver = `$binDir/nix-store --query --deriver $storePath`;
+                die "cannot query deriver of `$storePath'" if $? != 0;
+                chomp $deriver;
+                $deriver = "" if $deriver eq "unknown-deriver";
+
+                my @references = split "\n",
+                    `$binDir/nix-store --query --references $storePath`;
+                die "cannot query references of `$storePath'" if $? != 0;
+
+                my $narSize = `$binDir/nix-store --query --size $storePath`;
+                die "cannot query size of `$storePath'" if $? != 0;
+                chomp $narSize;
+
+                print "$storePath\n";
+                print "$deriver\n";
+                print scalar @references, "\n";
+                print "$_\n" foreach @references;
                print "0\n";
-                next; # not an error
+                print "$narSize\n";
            }
-            print "1\n";

-            $ENV{"NIX_DB_DIR"} = "$store/var/nix/db";
-            
-            my $deriver = `@bindir@/nix-store --query --deriver $storePath`;
-            die "cannot query deriver of `$storePath'" if $? != 0;
-            chomp $deriver;
-            $deriver = "" if $deriver eq "unknown-deriver";
-
-            my @references = split "\n",
-                `@bindir@/nix-store --query --references $storePath`;
-            die "cannot query references of `$storePath'" if $? != 0;
-
-            my $narSize = `@bindir@/nix-store --query --size $storePath`;
-            die "cannot query size of `$storePath'" if $? != 0;
-            chomp $narSize;
-
-            print "$deriver\n";
-            print scalar @references, "\n";
-            print "$_\n" foreach @references;
-            print "$narSize\n";
-            print "$narSize\n";
+            print "\n";
        }

        else { die "unknown command `$cmd'"; }
@@ -80,13 +86,15 @@ if ($ARGV[0] eq "--query") {


 elsif ($ARGV[0] eq "--substitute") {
-    die unless scalar @ARGV == 2;
+    die unless scalar @ARGV == 3;
    my $storePath = $ARGV[1];
+    my $destPath = $ARGV[2];
    my ($store, $sourcePath) = findStorePath $storePath;
    die unless $store;
-    print "\n*** Copying `$storePath' from `$sourcePath'\n\n";
-    system("$binDir/nix-store --dump $sourcePath | $binDir/nix-store --restore $storePath") == 0
+    print STDERR "\n*** Copying `$storePath' from `$sourcePath'\n\n";
+    system("$binDir/nix-store --dump $sourcePath | $binDir/nix-store --restore $destPath") == 0
        or die "cannot copy `$sourcePath' to `$storePath'";
+    print "\n"; # no hash to verify
 }


@@ -0,0 +1,588 @@
+#! @perl@ -w @perlFlags@
+
+use DBI;
+use File::Basename;
+use IO::Select;
+use Nix::Config;
+use Nix::Store;
+use Nix::Utils;
+use Nix::Manifest;
+use WWW::Curl::Easy;
+use WWW::Curl::Multi;
+use strict;
+
+
+Nix::Config::readConfig;
+
+my @caches;
+my $gotCaches = 0;
+
+my $maxParallelRequests = int($Nix::Config::config{"binary-caches-parallel-connections"} // 150);
+$maxParallelRequests = 1 if $maxParallelRequests < 1;
+
+my $ttlNegative = 24 * 3600; # when to purge negative lookups from the database
+my $ttlNegativeUse = 3600; # how long negative lookups are valid for non-"have" lookups
+my $didExpiration = 0;
+
+my $showAfter = 5; # show that we're waiting for a request after this many seconds
+
+my $debug = ($Nix::Config::config{"debug-subst"} // "") eq 1 || ($Nix::Config::config{"untrusted-debug-subst"} // "") eq 1;
+
+my $cacheFileURLs = ($ENV{"_NIX_CACHE_FILE_URLS"} // "") eq 1; # for testing
+
+my ($dbh, $queryCache, $insertNAR, $queryNAR, $insertNARExistence, $queryNARExistence, $expireNARExistence);
+
+my $curlm = WWW::Curl::Multi->new;
+my $activeRequests = 0;
+my $curlIdCount = 1;
+my %requests;
+my %scheduled;
+my $caBundle = $ENV{"CURL_CA_BUNDLE"} // $ENV{"OPENSSL_X509_CERT_FILE"};
+
+my $userName = getpwuid($<) or die "cannot figure out user name";
+
+
+sub addRequest {
+    my ($storePath, $url, $head) = @_;
+
+    my $curl = WWW::Curl::Easy->new;
+    my $curlId = $curlIdCount++;
+    $requests{$curlId} = { storePath => $storePath, url => $url, handle => $curl, content => "", type => $head ? "HEAD" : "GET"
+                         , shown => 0, started => time() };
+
+    $curl->setopt(CURLOPT_PRIVATE, $curlId);
+    $curl->setopt(CURLOPT_URL, $url);
+    open (my $fh, ">", \$requests{$curlId}->{content});
+    $curl->setopt(CURLOPT_WRITEDATA, $fh);
+    $curl->setopt(CURLOPT_FOLLOWLOCATION, 1);
+    $curl->setopt(CURLOPT_CAINFO, $caBundle) if defined $caBundle;
+    $curl->setopt(CURLOPT_USERAGENT, "Nix/$Nix::Config::version");
+    $curl->setopt(CURLOPT_NOBODY, 1) if $head;
+    $curl->setopt(CURLOPT_FAILONERROR, 1);
+    $curl->setopt(CURLOPT_TIMEOUT, int($ENV{"NIX_CONNECT_TIMEOUT"} // 0));
+
+    if ($activeRequests >= $maxParallelRequests) {
+        $scheduled{$curlId} = 1;
+    } else {
+        $curlm->add_handle($curl);
+        $activeRequests++;
+    }
+
+    return $requests{$curlId};
+}
+
+
+sub processRequests {
+    while ($activeRequests) {
+        my ($rfds, $wfds, $efds) = $curlm->fdset();
+        #print STDERR "R = @{$rfds}, W = @{$wfds}, E = @{$efds}\n";
+
+        # Sleep until we can read or write some data.
+        if (scalar @{$rfds} + scalar @{$wfds} + scalar @{$efds} > 0) {
+            IO::Select->select(IO::Select->new(@{$rfds}), IO::Select->new(@{$wfds}), IO::Select->new(@{$efds}), 1.0);
+        }
+
+        if ($curlm->perform() != $activeRequests) {
+            while (my ($id, $result) = $curlm->info_read) {
+                if ($id) {
+                    my $request = $requests{$id} or die;
+                    my $handle = $request->{handle};
+                    $request->{result} = $result;
+                    $request->{httpStatus} = $handle->getinfo(CURLINFO_RESPONSE_CODE);
+
+                    print STDERR "$request->{type} on $request->{url} [$request->{result}, $request->{httpStatus}]\n" if $debug;
+
+                    $activeRequests--;
+                    delete $request->{handle};
+
+                    if (scalar(keys %scheduled) > 0) {
+                        my $id2 = (keys %scheduled)[0];
+                        $curlm->add_handle($requests{$id2}->{handle});
+                        $activeRequests++;
+                        delete $scheduled{$id2};
+                    }
+                }
+            }
+        }
+
+        my $time = time();
+        while (my ($key, $request) = each %requests) {
+            next unless defined $request->{handle};
+            next if $request->{shown};
+            if ($time > $request->{started} + $showAfter) {
+                print STDERR "still waiting for ‘$request->{url}’ after $showAfter seconds...\n";
+                $request->{shown} = 1;
+            }
+        }
+    }
+}
+
+
+sub initCache {
+    my $dbPath = "$Nix::Config::stateDir/binary-cache-v2.sqlite";
+
+    unlink "$Nix::Config::stateDir/binary-cache-v1.sqlite";
+
+    # Open/create the database.
+    $dbh = DBI->connect("dbi:SQLite:dbname=$dbPath", "", "")
+        or die "cannot open database `$dbPath'";
+    $dbh->{RaiseError} = 1;
+    $dbh->{PrintError} = 0;
+
+    $dbh->sqlite_busy_timeout(60 * 60 * 1000);
+
+    $dbh->do("pragma synchronous = off"); # we can always reproduce the cache
+    $dbh->do("pragma journal_mode = truncate");
+
+    # Initialise the database schema, if necessary.
+    $dbh->do(<<EOF);
+        create table if not exists BinaryCaches (
+            id        integer primary key autoincrement not null,
+            url       text unique not null,
+            timestamp integer not null,
+            storeDir  text not null,
+            wantMassQuery integer not null,
+            priority  integer not null
+        );
+EOF
+
+    $dbh->do(<<EOF);
+        create table if not exists NARs (
+            cache            integer not null,
+            storePath        text not null,
+            url              text not null,
+            compression      text not null,
+            fileHash         text,
+            fileSize         integer,
+            narHash          text,
+            narSize          integer,
+            refs             text,
+            deriver          text,
+            system           text,
+            timestamp        integer not null,
+            primary key (cache, storePath),
+            foreign key (cache) references BinaryCaches(id) on delete cascade
+        );
+EOF
+
+    $dbh->do(<<EOF);
+        create table if not exists NARExistence (
+            cache            integer not null,
+            storePath        text not null,
+            exist            integer not null,
+            timestamp        integer not null,
+            primary key (cache, storePath),
+            foreign key (cache) references BinaryCaches(id) on delete cascade
+        );
+EOF
+
+    $dbh->do("create index if not exists NARExistenceByExistTimestamp on NARExistence (exist, timestamp)");
+
+    $queryCache = $dbh->prepare("select id, storeDir, wantMassQuery, priority from BinaryCaches where url = ?") or die;
+
+    $insertNAR = $dbh->prepare(
+        "insert or replace into NARs(cache, storePath, url, compression, fileHash, fileSize, narHash, " .
+        "narSize, refs, deriver, system, timestamp) values (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)") or die;
+
+    $queryNAR = $dbh->prepare("select * from NARs where cache = ? and storePath = ?") or die;
+
+    $insertNARExistence = $dbh->prepare(
+        "insert or replace into NARExistence(cache, storePath, exist, timestamp) values (?, ?, ?, ?)") or die;
+
+    $queryNARExistence = $dbh->prepare("select exist, timestamp from NARExistence where cache = ? and storePath = ?") or die;
+
+    $expireNARExistence = $dbh->prepare("delete from NARExistence where exist = ? and timestamp < ?") or die;
+}
+
+
+sub getAvailableCaches {
+    return if $gotCaches;
+    $gotCaches = 1;
+
+    sub strToList {
+        my ($s) = @_;
+        return map { s/\/+$//; $_ } split(/ /, $s);
+    }
+
+    my @urls = strToList($Nix::Config::config{"binary-caches"} //
+        ($Nix::Config::storeDir eq "/nix/store" ? "http://cache.nixos.org" : ""));
+
+    my $urlsFiles = $Nix::Config::config{"binary-cache-files"}
+        // "$Nix::Config::stateDir/profiles/per-user/$userName/channels/binary-caches/*";
+    foreach my $urlFile (glob $urlsFiles) {
+        next unless -f $urlFile;
+        open FILE, "<$urlFile" or die "cannot open ‘$urlFile’\n";
+        my $url = <FILE>; chomp $url;
+        close FILE;
+        push @urls, strToList($url);
+    }
+
+    push @urls, strToList($Nix::Config::config{"extra-binary-caches"} // "");
+
+    # Allow Nix daemon users to override the binary caches to a subset
+    # of those listed in the config file.  Note that ‘untrusted-*’
+    # denotes options passed by the client.
+    my @trustedUrls = uniq(@urls, strToList($Nix::Config::config{"trusted-binary-caches"} // ""));
+
+    if (defined $Nix::Config::config{"untrusted-binary-caches"}) {
+        my @untrustedUrls = strToList $Nix::Config::config{"untrusted-binary-caches"};
+        @urls = ();
+        foreach my $url (@untrustedUrls) {
+            die "binary cache ‘$url’ is not trusted (please add it to ‘trusted-binary-caches’ [@trustedUrls] in $Nix::Config::confDir/nix.conf)\n"
+                unless scalar(grep { $url eq $_ } @trustedUrls) > 0;
+            push @urls, $url;
+        }
+    }
+
+    my @untrustedUrls = strToList $Nix::Config::config{"untrusted-extra-binary-caches"} // "";
+    foreach my $url (@untrustedUrls) {
+        next unless scalar(grep { $url eq $_ } @trustedUrls) > 0;
+        push @urls, $url;
+    }
+
+    foreach my $url (uniq @urls) {
+
+        # FIXME: not atomic.
+        $queryCache->execute($url);
+        my $res = $queryCache->fetchrow_hashref();
+        if (defined $res) {
+            next if $res->{storeDir} ne $Nix::Config::storeDir;
+            push @caches, { id => $res->{id}, url => $url, wantMassQuery => $res->{wantMassQuery}, priority => $res->{priority} };
+            next;
+        }
+
+        # Get the cache info file.
+        my $request = addRequest(undef, $url . "/nix-cache-info");
+        processRequests;
+
+        if ($request->{result} != 0) {
+            print STDERR "could not download ‘$request->{url}’ (" .
+                ($request->{result} != 0 ? "Curl error $request->{result}" : "HTTP status $request->{httpStatus}") . ")\n";
+            next;
+        }
+
+        my $storeDir = "/nix/store";
+        my $wantMassQuery = 0;
+        my $priority = 50;
+        foreach my $line (split "\n", $request->{content}) {
+            unless ($line =~ /^(.*): (.*)$/) {
+                print STDERR "bad cache info file ‘$request->{url}’\n";
+                return undef;
+            }
+            if ($1 eq "StoreDir") { $storeDir = $2; }
+            elsif ($1 eq "WantMassQuery") { $wantMassQuery = int($2); }
+            elsif ($1 eq "Priority") { $priority = int($2); }
+        }
+
+        $dbh->do("insert or replace into BinaryCaches(url, timestamp, storeDir, wantMassQuery, priority) values (?, ?, ?, ?, ?)",
+                 {}, $url, time(), $storeDir, $wantMassQuery, $priority);
+        $queryCache->execute($url);
+        $res = $queryCache->fetchrow_hashref() or die;
+        next if $storeDir ne $Nix::Config::storeDir;
+        push @caches, { id => $res->{id}, url => $url, wantMassQuery => $wantMassQuery, priority => $priority };
+    }
+
+    @caches = sort { $a->{priority} <=> $b->{priority} } @caches;
+
+    expireNegative();
+}
+
+
+sub shouldCache {
+    my ($url) = @_;
+    return $cacheFileURLs || $url !~ /^file:/;
+}
+
+
+sub processNARInfo {
+    my ($storePath, $cache, $request) = @_;
+
+    if ($request->{result} != 0) {
+        if ($request->{result} != 37 && $request->{httpStatus} != 404 && $request->{httpStatus} != 403) {
+            print STDERR "could not download ‘$request->{url}’ (" .
+                ($request->{result} != 0 ? "Curl error $request->{result}" : "HTTP status $request->{httpStatus}") . ")\n";
+        } else {
+            $insertNARExistence->execute($cache->{id}, basename($storePath), 0, time())
+                if shouldCache $request->{url};
+        }
+        return undef;
+    }
+
+    my $narInfo = parseNARInfo($storePath, $request->{content});
+    return undef unless defined $narInfo;
+
+    # Cache the result.
+    $insertNAR->execute(
+        $cache->{id}, basename($storePath), $narInfo->{url}, $narInfo->{compression},
+        $narInfo->{fileHash}, $narInfo->{fileSize}, $narInfo->{narHash}, $narInfo->{narSize},
+        join(" ", @{$narInfo->{refs}}), $narInfo->{deriver}, $narInfo->{system}, time())
+        if shouldCache $request->{url};
+
+    return $narInfo;
+}
+
+
+sub getCachedInfoFrom {
+    my ($storePath, $cache) = @_;
+
+    $queryNAR->execute($cache->{id}, basename($storePath));
+    my $res = $queryNAR->fetchrow_hashref();
+    return undef unless defined $res;
+
+    return
+        { url => $res->{url}
+        , compression => $res->{compression}
+        , fileHash => $res->{fileHash}
+        , fileSize => $res->{fileSize}
+        , narHash => $res->{narHash}
+        , narSize => $res->{narSize}
+        , refs => [ split " ", $res->{refs} ]
+        , deriver => $res->{deriver}
+        } if defined $res;
+}
+
+
+sub negativeHit {
+    my ($storePath, $cache) = @_;
+    $queryNARExistence->execute($cache->{id}, basename($storePath));
+    my $res = $queryNARExistence->fetchrow_hashref();
+    return defined $res && $res->{exist} == 0 && time() - $res->{timestamp} < $ttlNegativeUse;
+}
+
+
+sub positiveHit {
+    my ($storePath, $cache) = @_;
+    return 1 if defined getCachedInfoFrom($storePath, $cache);
+    $queryNARExistence->execute($cache->{id}, basename($storePath));
+    my $res = $queryNARExistence->fetchrow_hashref();
+    return defined $res && $res->{exist} == 1;
+}
+
+
+sub expireNegative {
+    return if $didExpiration;
+    $didExpiration = 1;
+    my $time = time();
+    # Round up to the next multiple of the TTL to ensure that we do
+    # expiration only once per time interval.  E.g. if $ttlNegative ==
+    # 3600, we expire entries at most once per hour.  This is
+    # presumably faster than expiring a few entries per request (and
+    # thus doing a transaction).
+    my $limit = (int($time / $ttlNegative) - 1) * $ttlNegative;
+    $expireNARExistence->execute($limit, 0);
+    print STDERR "expired ", $expireNARExistence->rows, " negative entries\n" if $debug;
+}
+
+
+sub printInfo {
+    my ($storePath, $info) = @_;
+    print "$storePath\n";
+    print $info->{deriver} ? "$Nix::Config::storeDir/$info->{deriver}" : "", "\n";
+    print scalar @{$info->{refs}}, "\n";
+    print "$Nix::Config::storeDir/$_\n" foreach @{$info->{refs}};
+    print $info->{fileSize} || 0, "\n";
+    print $info->{narSize} || 0, "\n";
+}
+
+
+sub infoUrl {
+    my ($binaryCacheUrl, $storePath) = @_;
+    my $pathHash = substr(basename($storePath), 0, 32);
+    my $infoUrl = "$binaryCacheUrl/$pathHash.narinfo";
+}
+
+
+sub printInfoParallel {
+    my @paths = @_;
+
+    # First print all paths for which we have cached info.
+    my @left;
+    foreach my $storePath (@paths) {
+        my $found = 0;
+        foreach my $cache (@caches) {
+            my $info = getCachedInfoFrom($storePath, $cache);
+            if (defined $info) {
+                printInfo($storePath, $info);
+                $found = 1;
+                last;
+            }
+        }
+        push @left, $storePath if !$found;
+    }
+
+    return if scalar @left == 0;
+
+    foreach my $cache (@caches) {
+
+        my @left2;
+        %requests = ();
+        foreach my $storePath (@left) {
+            if (negativeHit($storePath, $cache)) {
+                push @left2, $storePath;
+                next;
+            }
+            addRequest($storePath, infoUrl($cache->{url}, $storePath));
+        }
+
+        processRequests;
+
+        foreach my $request (values %requests) {
+            my $info = processNARInfo($request->{storePath}, $cache, $request);
+            if (defined $info) {
+                printInfo($request->{storePath}, $info);
+            } else {
+                push @left2, $request->{storePath};
+            }
+        }
+
+        @left = @left2;
+    }
+}
+
+
+sub printSubstitutablePaths {
+    my @paths = @_;
+
+    # First look for paths that have cached info.
+    my @left;
+    foreach my $storePath (@paths) {
+        my $found = 0;
+        foreach my $cache (@caches) {
+            next unless $cache->{wantMassQuery};
+            if (positiveHit($storePath, $cache)) {
+                print "$storePath\n";
+                $found = 1;
+                last;
+            }
+        }
+        push @left, $storePath if !$found;
+    }
+
+    return if scalar @left == 0;
+
+    # For remaining paths, do HEAD requests.
+    foreach my $cache (@caches) {
+        next unless $cache->{wantMassQuery};
+        my @left2;
+        %requests = ();
+        foreach my $storePath (@left) {
+            if (negativeHit($storePath, $cache)) {
+                push @left2, $storePath;
+                next;
+            }
+            addRequest($storePath, infoUrl($cache->{url}, $storePath), 1);
+        }
+
+        processRequests;
+
+        foreach my $request (values %requests) {
+            if ($request->{result} != 0) {
+                if ($request->{result} != 37 && $request->{httpStatus} != 404 && $request->{httpStatus} != 403) {
+                    print STDERR "could not check ‘$request->{url}’ (" .
+                        ($request->{result} != 0 ? "Curl error $request->{result}" : "HTTP status $request->{httpStatus}") . ")\n";
+                } else {
+                    $insertNARExistence->execute($cache->{id}, basename($request->{storePath}), 0, time())
+                        if shouldCache $request->{url};
+                }
+                push @left2, $request->{storePath};
+            } else {
+                $insertNARExistence->execute($cache->{id}, basename($request->{storePath}), 1, time())
+                    if shouldCache $request->{url};
+                print "$request->{storePath}\n";
+            }
+        }
+
+        @left = @left2;
+    }
+}
+
+
+sub downloadBinary {
+    my ($storePath, $destPath) = @_;
+
+    foreach my $cache (@caches) {
+        my $info = getCachedInfoFrom($storePath, $cache);
+
+        unless (defined $info) {
+            next if negativeHit($storePath, $cache);
+            my $request = addRequest($storePath, infoUrl($cache->{url}, $storePath));
+            processRequests;
+            $info = processNARInfo($storePath, $cache, $request);
+        }
+
+        next unless defined $info;
+
+        my $decompressor;
+        if ($info->{compression} eq "bzip2") { $decompressor = "| $Nix::Config::bzip2 -d"; }
+        elsif ($info->{compression} eq "xz") { $decompressor = "| $Nix::Config::xz -d"; }
+        elsif ($info->{compression} eq "none") { $decompressor = ""; }
+        else {
+            print STDERR "unknown compression method ‘$info->{compression}’\n";
+            next;
+        }
+        my $url = "$cache->{url}/$info->{url}"; # FIXME: handle non-relative URLs
+        print STDERR "\n*** Downloading ‘$url’ to ‘$storePath’...\n";
+        checkURL $url;
+        if (system("$Nix::Config::curl --fail --location --insecure '$url' $decompressor | $Nix::Config::binDir/nix-store --restore $destPath") != 0) {
+            warn "download of `$url' failed" . ($! ? ": $!" : "") . "\n";
+            next;
+        }
+
+        # Tell Nix about the expected hash so it can verify it.
+        print "$info->{narHash}\n";
+
+        print STDERR "\n";
+        return;
+    }
+
+    print STDERR "could not download ‘$storePath’ from any binary cache\n";
+    exit 1;
+}
+
+
+# Bail out right away if binary caches are disabled.
+exit 0 if
+    ($Nix::Config::config{"use-binary-caches"} // "true") eq "false" ||
+    ($Nix::Config::config{"untrusted-use-binary-caches"} // "true") eq "false";
+print "\n";
+flush STDOUT;
+
+initCache();
+
+
+if ($ARGV[0] eq "--query") {
+
+    while (<STDIN>) {
+        getAvailableCaches;
+        chomp;
+        my ($cmd, @args) = split " ", $_;
+
+        if ($cmd eq "have") {
+            print STDERR "checking binary caches for existence of @args\n" if $debug;
+            printSubstitutablePaths(@args);
+            print "\n";
+        }
+
+        elsif ($cmd eq "info") {
+            print STDERR "checking binary caches for info on @args\n" if $debug;
+            printInfoParallel(@args);
+            print "\n";
+        }
+
+        else { die "unknown command `$cmd'"; }
+
+        flush STDOUT;
+    }
+
+}
+
+elsif ($ARGV[0] eq "--substitute") {
+    my $storePath = $ARGV[1] or die;
+    my $destPath = $ARGV[2] or die;
+    getAvailableCaches;
+    downloadBinary($storePath, $destPath);
+}
+
+else {
+    die;
+}
@@ -4,6 +4,7 @@ use strict;
 use Nix::Config;
 use Nix::Manifest;
 use Nix::Store;
+use Nix::Utils;
 use POSIX qw(strftime);
 use File::Temp qw(tempdir);

@@ -15,9 +16,14 @@ my $logFile = "$Nix::Config::logDir/downloads";
 # estimating the expected download size.
 my $fast = 1;

+# ‘--insecure’ is fine because Nix verifies the hash of the result.
+my $curl = "$Nix::Config::curl --fail --location --insecure";
+

 # Open the manifest cache and update it if necessary.
 my $dbh = updateManifestDB();
+exit 0 unless defined $dbh; # exit if there are no manifests
+print "\n";


 # $hashCache->{$algo}->{$path} yields the $algo-hash of $path.
@@ -38,7 +44,7 @@ sub parseHash {
 # given path.
 sub computeSmallestDownload {
    my $targetPath = shift;
-    
+
    # Build a graph of all store paths that might contribute to the
    # construction of $targetPath, and the special node "start".  The
    # edges are either patch operations, or downloads of full NAR
@@ -93,7 +99,7 @@ sub computeSmallestDownload {
            my $patchList = $dbh->selectall_arrayref(
                "select * from Patches where storePath = ?",
                { Slice => {} }, $u);
-            
+
            foreach my $patch (@{$patchList}) {
                if (isValidPath($patch->{basePath})) {
                    my ($baseHashAlgo, $baseHash) = parseHash $patch->{baseHash};
@@ -106,7 +112,7 @@ sub computeSmallestDownload {
                        $hash =~ s/.*://;
                        $hashCache->{$baseHashAlgo}->{$patch->{basePath}} = $hash;
                    }
-                    
+
                    next if $hash ne $baseHash;
                }
                push @queue, $patch->{basePath};
@@ -117,7 +123,7 @@ sub computeSmallestDownload {
            my $narFileList = $dbh->selectall_arrayref(
                "select * from NARs where storePath = ?",
                { Slice => {} }, $u);
-                
+
            foreach my $narFile (@{$narFileList}) {
                # !!! how to handle files whose size is not known in advance?
                # For now, assume some arbitrary size (1 GB).
@@ -173,58 +179,56 @@ sub computeSmallestDownload {
 if ($ARGV[0] eq "--query") {

    while (<STDIN>) {
-        my $cmd = $_; chomp $cmd;
+        chomp;
+        my ($cmd, @args) = split " ", $_;

        if ($cmd eq "have") {
-            my $storePath = <STDIN>; chomp $storePath;
-            print STDOUT (
-                scalar @{$dbh->selectcol_arrayref("select 1 from NARs where storePath = ?", {}, $storePath)} > 0
-                ? "1\n" : "0\n");
+            foreach my $storePath (@args) {
+                print "$storePath\n" if scalar @{$dbh->selectcol_arrayref("select 1 from NARs where storePath = ?", {}, $storePath)} > 0;
+            }
+            print "\n";
        }

        elsif ($cmd eq "info") {
-            my $storePath = <STDIN>; chomp $storePath;
+            foreach my $storePath (@args) {

-            my $infos = $dbh->selectall_arrayref(
-                "select * from NARs where storePath = ?",
-                { Slice => {} }, $storePath);
-            
-            my $info;
-            if (scalar @{$infos} > 0) {
-                $info = @{$infos}[0];
-            }
-            else {
-                print "0\n";
-                next; # not an error
-            }
+                my $infos = $dbh->selectall_arrayref(
+                    "select * from NARs where storePath = ?",
+                    { Slice => {} }, $storePath);

-            print "1\n";
-            print "$info->{deriver}\n";
-            my @references = split " ", $info->{refs};
-            print scalar @references, "\n";
-            print "$_\n" foreach @references;
+                next unless scalar @{$infos} > 0;
+                my $info = @{$infos}[0];

-            my @path = computeSmallestDownload $storePath;
+                print "$storePath\n";
+                print "$info->{deriver}\n";
+                my @references = split " ", $info->{refs};
+                print scalar @references, "\n";
+                print "$_\n" foreach @references;

-            my $downloadSize = 0;
-            while (scalar @path > 0) {
-                my $edge = pop @path;
-                my $u = $edge->{start};
-                my $v = $edge->{end};
-                if ($edge->{type} eq "patch") {
-                    $downloadSize += $edge->{info}->{size} || 0;
-                }
-                elsif ($edge->{type} eq "narfile") {
-                    $downloadSize += $edge->{info}->{size} || 0;
+                my @path = computeSmallestDownload $storePath;
+
+                my $downloadSize = 0;
+                while (scalar @path > 0) {
+                    my $edge = pop @path;
+                    my $u = $edge->{start};
+                    my $v = $edge->{end};
+                    if ($edge->{type} eq "patch") {
+                        $downloadSize += $edge->{info}->{size} || 0;
+                    }
+                    elsif ($edge->{type} eq "narfile") {
+                        $downloadSize += $edge->{info}->{size} || 0;
+                    }
                }
+
+                print "$downloadSize\n";
+
+                my $narSize = $info->{narSize} || 0;
+                print "$narSize\n";
            }

-            print "$downloadSize\n";
-            
-            my $narSize = $info->{narSize} || 0;
-            print "$narSize\n";
+            print "\n";
        }
-        
+
        else { die "unknown command `$cmd'"; }
    }

@@ -236,8 +240,9 @@ elsif ($ARGV[0] ne "--substitute") {
 }


-die unless scalar @ARGV == 2;
+die unless scalar @ARGV == 3;
 my $targetPath = $ARGV[1];
+my $destPath = $ARGV[2];
 $fast = 0;


@@ -273,16 +278,6 @@ $dbh->disconnect;
 my $curStep = 1;
 my $maxStep = scalar @path;

-sub downloadFile { 
-    my $url = shift; 
-    $ENV{"PRINT_PATH"} = 1;
-    $ENV{"QUIET"} = 1;
-    my ($hash, $path) = `$Nix::Config::binDir/nix-prefetch-url '$url'`;
-    die "download of `$url' failed" . ($! ? ": $!" : "") . "\n" unless $? == 0;
-    chomp $path;
-    return $path;
-}
-
 my $finalNarHash;

 while (scalar @path > 0) {
@@ -314,13 +309,16 @@ while (scalar @path > 0) {

        # Download the patch.
        print STDERR "  downloading patch...\n";
-        my $patchPath = downloadFile "$patch->{url}";
+        my $patchPath = "$tmpDir/patch";
+        checkURL $patch->{url};
+        system("$curl '$patch->{url}' -o $patchPath") == 0
+            or die "cannot download patch `$patch->{url}'\n";

        # Apply the patch to the NAR archive produced in step 1 (for
        # the already present path) or a later step (for patch sequences).
        print STDERR "  applying patch...\n";
        system("$Nix::Config::libexecDir/bspatch $tmpNar $tmpNar2 $patchPath") == 0
-            or die "cannot apply patch `$patchPath' to $tmpNar";
+            or die "cannot apply patch `$patchPath' to $tmpNar\n";

        if ($curStep < $maxStep) {
            # The archive will be used as the base of the next patch.
@@ -329,8 +327,8 @@ while (scalar @path > 0) {
            # This was the last patch.  Unpack the final NAR archive
            # into the target path.
            print STDERR "  unpacking patched archive...\n";
-            system("$Nix::Config::binDir/nix-store --restore $v < $tmpNar2") == 0
-                or die "cannot unpack $tmpNar2 into `$v'";
+            system("$Nix::Config::binDir/nix-store --restore $destPath < $tmpNar2") == 0
+                or die "cannot unpack $tmpNar2 to `$v'\n";
        }

        $finalNarHash = $patch->{narHash};
@@ -338,24 +336,27 @@ while (scalar @path > 0) {

    elsif ($edge->{type} eq "narfile") {
        my $narFile = $edge->{info};
-        print STDERR "downloading `$narFile->{url}' into `$v'\n";
+        print STDERR "downloading `$narFile->{url}' to `$v'\n";

        my $size = $narFile->{size} || -1;
        print LOGFILE "$$ narfile $narFile->{url} $size $v\n";
-        
-        # Download the archive.
-        print STDERR "  downloading archive...\n";
-        my $narFilePath = downloadFile "$narFile->{url}";
+
+        checkURL $narFile->{url};
+
+        my $decompressor =
+            $narFile->{compressionType} eq "bzip2" ? "| $Nix::Config::bzip2 -d" :
+            $narFile->{compressionType} eq "xz" ? "| $Nix::Config::xz -d" :
+            $narFile->{compressionType} eq "none" ? "" :
+            die "unknown compression type `$narFile->{compressionType}'";

        if ($curStep < $maxStep) {
            # The archive will be used a base to a patch.
-            system("$Nix::Config::bzip2 -d < '$narFilePath' > $tmpNar") == 0
-                or die "cannot unpack `$narFilePath' into `$v'";
+            system("$curl '$narFile->{url}' $decompressor > $tmpNar") == 0
+                or die "cannot download and unpack `$narFile->{url}' to `$v'\n";
        } else {
-            # Unpack the archive into the target path.
-            print STDERR "  unpacking archive...\n";
-            system("$Nix::Config::bzip2 -d < '$narFilePath' | $Nix::Config::binDir/nix-store --restore '$v'") == 0
-                or die "cannot unpack `$narFilePath' into `$v'";
+            # Unpack the archive to the target path.
+            system("$curl '$narFile->{url}' $decompressor | $Nix::Config::binDir/nix-store --restore '$destPath'") == 0
+                or die "cannot download and unpack `$narFile->{url}' to `$v'\n";
        }

        $finalNarHash = $narFile->{narHash};
@@ -365,21 +366,10 @@ while (scalar @path > 0) {
 }


-# Make sure that the hash declared in the manifest matches what we
-# downloaded and unpacked.
-
-if (defined $finalNarHash) {
-    my ($hashAlgo, $hash) = parseHash $finalNarHash;
-
-    # The hash in the manifest can be either in base-16 or base-32.
-    # Handle both.
-    my $hash2 = hashPath($hashAlgo, $hashAlgo eq "sha256" && length($hash) != 64, $targetPath);
-    
-    die "hash mismatch in downloaded path $targetPath; expected $hash, got $hash2\n"
-        if $hash ne $hash2;
-} else {
-    die "cannot check integrity of the downloaded path since its hash is not known\n";
-}
+# Tell Nix about the expected hash so it can verify it.
+die "cannot check integrity of the downloaded path since its hash is not known\n"
+    unless defined $finalNarHash;
+print "$finalNarHash\n";


 print STDERR "\n";
@@ -1,22 +1,22 @@
-#! @perl@ -w
+#! @perl@ -w @perlFlags@

 use strict;
-
-my $procDir = "/proc";
+use Nix::Utils;
+use Nix::Config;


 sub readProc {
-    return unless -d $procDir;
+    return unless -d "/proc";
+
+    opendir DIR, "/proc" or return;

-    opendir DIR, $procDir or return;
-    
    foreach my $name (readdir DIR) {
        next unless $name =~ /^\d+$/;

-        my $process = "$procDir/$name";
+        my $process = "/proc/$name";

        #print STDERR "=== $process\n";
-        
+
        my $target;
        print "$target\n" if $target = readlink "$process/exe";
        print "$target\n" if $target = readlink "$process/cwd";
@@ -36,6 +36,13 @@ sub readProc {
            }
            close MAP;
        }
+
+        # Get all store paths that appear in the environment of this process.
+        eval {
+            my $env = Nix::Utils::readFile "$process/environ";
+            my @matches = $env =~ /\Q$Nix::Config::storeDir\E\/[0-9a-z]+[0-9a-zA-Z\+\-\._\?=]*/g;
+            print "$_\n" foreach @matches;
+        }
    }

    closedir DIR;
@@ -58,18 +65,15 @@ readProc;
 lsof;


-sub readFile {
-    my $path = shift;
-    if (-e $path) {
-        if (open FILE, "$path") {
-            while (<FILE>) {
-                print;
-            }
-            close FILE;
-        }
+sub printFile {
+    my ($fn) = @_;
+    if (-e $fn) {
+        print Nix::Utils::readFile($fn), "\n";
    }
 }

+
 # This is rather NixOS-specific, so it probably shouldn't be here.
-readFile "/proc/sys/kernel/modprobe";
-readFile "/proc/sys/kernel/fbsplash";
+printFile "/proc/sys/kernel/modprobe";
+printFile "/proc/sys/kernel/fbsplash";
+printFile "/proc/sys/kernel/poweroff_cmd";
@@ -3,23 +3,27 @@
 use strict;
 use Nix::Config;
 use Nix::Store;
+use Nix::Utils;
 use File::Temp qw(tempdir);


 my $dryRun = 0;
 my $verbose = 0;
-my $runEnv = 0;
+my $runEnv = $0 =~ /nix-shell$/;
+my $pure = 0;

 my @instArgs = ();
 my @buildArgs = ();
 my @exprs = ();

 my $shell = $ENV{SHELL} || "/bin/sh";
-my $envCommand = "p=\$PATH; source \$stdenv/setup; PATH=\$PATH:\$p; exec $shell";
+my $envCommand = ""; # interactive shell
 my @envExclude = ();

+my $myName = $runEnv ? "nix-shell" : "nix-build";

-my $tmpDir = tempdir("nix-build.XXXXXX", CLEANUP => 1, TMPDIR => 1)
+
+my $tmpDir = tempdir("$myName.XXXXXX", CLEANUP => 1, TMPDIR => 1)
    or die "cannot create a temporary directory";

 my $outLink = "./result";
@@ -33,29 +37,12 @@ for (my $n = 0; $n < scalar @ARGV; $n++) {
    my $arg = $ARGV[$n];

    if ($arg eq "--help") {
-        print STDERR <<EOF;
-Usage: nix-build [OPTION]... [FILE]...
+        exec "man $myName" or die;
+    }

-`nix-build' builds the given Nix expressions (which
-default to ./default.nix if none are given).  A symlink called
-`result' is placed in the current directory.
-
-Flags:
-  --add-drv-link: create a symlink `derivation' to the store derivation
-  --drv-link NAME: create symlink NAME instead of `derivation'
-  --no-out-link: do not create the `result' symlink
-  --out-link / -o NAME: create symlink NAME instead of `result'
-  --attr / -A ATTR: select a specific attribute from the Nix expression
-  
-  --run-env: build dependencies of the specified derivation, then start a
-      shell with the environment of the derivation
-  --command: command to run with `--run-env'
-  --exclude: regexp specifying dependencies to be excluded by `--run-env'
-
-Any additional flags are passed to `nix-store'.
-EOF
+    elsif ($arg eq "--version") {
+        print "$myName (Nix) $Nix::Config::version\n";
        exit 0;
-        # '` hack
    }

    elsif ($arg eq "--add-drv-link") {
@@ -104,7 +91,7 @@ EOF
        $n += 2;
    }

-    elsif ($arg eq "--max-jobs" or $arg eq "-j" or $arg eq "--max-silent-time" or $arg eq "--log-type" or $arg eq "--cores") {
+    elsif ($arg eq "--max-jobs" or $arg eq "-j" or $arg eq "--max-silent-time" or $arg eq "--log-type" or $arg eq "--cores" or $arg eq "--timeout") {
        $n++;
        die "$0: `$arg' requires an argument\n" unless $n < scalar @ARGV;
        push @buildArgs, ($arg, $ARGV[$n]);
@@ -114,30 +101,34 @@ EOF
        push @buildArgs, "--dry-run";
        $dryRun = 1;
    }
-    
+
    elsif ($arg eq "--show-trace") {
        push @instArgs, $arg;
    }
-    
+
+    elsif ($arg eq "-") {
+        @exprs = ("-");
+    }
+
    elsif ($arg eq "--verbose" or substr($arg, 0, 2) eq "-v") {
        push @buildArgs, $arg;
        push @instArgs, $arg;
        $verbose = 1;
    }
-    
-    elsif ($arg eq "--quiet") {
+
+    elsif ($arg eq "--quiet" || $arg eq "--repair") {
        push @buildArgs, $arg;
        push @instArgs, $arg;
    }
-    
-    elsif ($arg eq "--run-env") {
+
+    elsif ($arg eq "--run-env") { # obsolete
        $runEnv = 1;
    }
-    
+
    elsif ($arg eq "--command") {
        $n++;
        die "$0: `$arg' requires an argument\n" unless $n < scalar @ARGV;
-        $envCommand = $ARGV[$n];
+        $envCommand = "$ARGV[$n]\nexit $!";
    }

    elsif ($arg eq "--exclude") {
@@ -146,6 +137,10 @@ EOF
        push @envExclude, $ARGV[$n];
    }

+    elsif ($arg eq "--pure") {
+        $pure = 1;
+    }
+
    elsif (substr($arg, 0, 1) eq "-") {
        push @buildArgs, $arg;
    }
@@ -162,17 +157,22 @@ foreach my $expr (@exprs) {

    # Instantiate.
    my @drvPaths;
-    # !!! would prefer the perl 5.8.0 pipe open feature here.
-    my $pid = open(DRVPATHS, "-|") || exec "$Nix::Config::binDir/nix-instantiate", "--add-root", $drvLink, "--indirect", @instArgs, $expr;
-    while (<DRVPATHS>) {chomp; push @drvPaths, $_;}
-    if (!close DRVPATHS) {
-        die "nix-instantiate killed by signal " . ($? & 127) . "\n" if ($? & 127);
-        exit 1;
+    if ($expr !~ /^\/.*\.drv$/) {
+        # !!! would prefer the perl 5.8.0 pipe open feature here.
+        my $pid = open(DRVPATHS, "-|") || exec "$Nix::Config::binDir/nix-instantiate", "--add-root", $drvLink, "--indirect", @instArgs, $expr;
+        while (<DRVPATHS>) {chomp; push @drvPaths, $_;}
+        if (!close DRVPATHS) {
+            die "nix-instantiate killed by signal " . ($? & 127) . "\n" if ($? & 127);
+            exit 1;
+        }
+    } else {
+        push @drvPaths, $expr;
    }

    if ($runEnv) {
-        die "$0: ‘--run-env’ requires a single derivation\n" if scalar @drvPaths != 1;
-        my $drvPath = readlink $drvPaths[0] or die "cannot read symlink `$drvPaths[0]'";
+        die "$0: a single derivation is required\n" if scalar @drvPaths != 1;
+        my $drvPath = $drvPaths[0];
+        $drvPath = readlink $drvPath or die "cannot read symlink `$drvPath'" if -l $drvPath;
        my $drv = derivationFromPath($drvPath);

        # Build or fetch all dependencies of the derivation.
@@ -181,28 +181,67 @@ foreach my $expr (@exprs) {
            or die "$0: failed to build all dependencies\n";

        # Set the environment.
-        $ENV{'NIX_BUILD_TOP'} = $ENV{'TMPDIR'} || "/tmp";
-        foreach (keys %{$drv->{env}}) {
-            $ENV{$_} = $drv->{env}->{$_};
+        if ($pure) {
+            foreach my $name (keys %ENV) {
+                next if $name eq "HOME" || $name eq "USER" || $name eq "LOGNAME" || $name eq "DISPLAY" || $name eq "PATH";
+                delete $ENV{$name};
+            }
+            # NixOS hack: prevent /etc/bashrc from sourcing /etc/profile.
+            $ENV{'__ETC_PROFILE_SOURCED'} = 1;
        }
+        $ENV{'NIX_BUILD_TOP'} = $ENV{'TMPDIR'} = $ENV{'TEMPDIR'} = $ENV{'TMP'} = $ENV{'TEMP'} = $ENV{'TMPDIR'} // "/tmp";
+        $ENV{'NIX_STORE'} = $Nix::Config::storeDir;
+        $ENV{$_} = $drv->{env}->{$_} foreach keys %{$drv->{env}};
+
+        $ENV{'IN_NIX_SHELL'} = 1;

        # Run a shell using the derivation's environment.  For
        # convenience, source $stdenv/setup to setup additional
-        # environment variables.  Also don't lose the current $PATH
-        # directories.
-        exec($ENV{SHELL}, "-c", $envCommand);
+        # environment variables and shell functions.  Also don't lose
+        # the current $PATH directories.
+        my $rcfile = "$tmpDir/rc";
+        writeFile(
+            $rcfile,
+            '[ -e ~/.bashrc ] && source ~/.bashrc; ' .
+            ($pure ? '' : 'p=$PATH; ' ) .
+            'dontAddDisableDepTrack=1; ' .
+            '[ -e $stdenv/setup ] && source $stdenv/setup; ' .
+            ($pure ? '' : 'PATH=$PATH:$p; ') .
+            'set +e; ' .
+            'PS1="\n\[\033[1;32m\][nix-shell:\w]$\[\033[0m\] "; ' .
+            'unset NIX_ENFORCE_PURITY; ' .
+            $envCommand);
+        exec($ENV{NIX_BUILD_SHELL} // "bash", "--rcfile", $rcfile);
        die;
    }

+    # Ugly hackery to make "nix-build -A foo.all" produce symlinks
+    # ./result, ./result-dev, and so on, rather than ./result,
+    # ./result-2-dev, and so on.  This combines multiple derivation
+    # paths into one "/nix/store/drv-path!out1,out2,..." argument.
+    my $prevDrvPath = "";
+    my @drvPaths2;
    foreach my $drvPath (@drvPaths) {
-        my $target = readlink $drvPath or die "cannot read symlink `$drvPath'";
+        my $p = $drvPath; my $output = "out";
+        if ($drvPath =~ /(.*)!(.*)/) {
+            $p = $1; $output = $2;
+        } else {
+            $p = $drvPath;
+        }
+        my $target = readlink $p or die "cannot read symlink `$p'";
        print STDERR "derivation is $target\n" if $verbose;
+        if ($target eq $prevDrvPath) {
+            push @drvPaths2, (pop @drvPaths2) . "," . $output;
+        } else {
+            push @drvPaths2, $target . "!" . $output;
+            $prevDrvPath = $target;
+        }
    }

    # Build.
    my @outPaths;
-    $pid = open(OUTPATHS, "-|") || exec "$Nix::Config::binDir/nix-store", "--add-root", $outLink, "--indirect", "-r",
-        @buildArgs, @drvPaths;
+    my $pid = open(OUTPATHS, "-|") || exec "$Nix::Config::binDir/nix-store", "--add-root", $outLink, "--indirect", "-r",
+        @buildArgs, @drvPaths2;
    while (<OUTPATHS>) {chomp; push @outPaths, $_;}
    if (!close OUTPATHS) {
        die "nix-store killed by signal " . ($? & 127) . "\n" if ($? & 127);
@@ -4,6 +4,9 @@ use strict;
 use File::Basename;
 use File::Path qw(mkpath);
 use Nix::Config;
+use Nix::Manifest;
+
+Nix::Config::readConfig;

 my $manifestDir = $Nix::Config::manifestDir;

@@ -22,7 +25,7 @@ my $nixDefExpr = "$home/.nix-defexpr";
 my $userName = getpwuid($<) or die "cannot figure out user name";
 my $profile = "$Nix::Config::stateDir/profiles/per-user/$userName/channels";
 mkpath(dirname $profile, 0, 0755);
-    
+
 my %channels;


@@ -65,11 +68,13 @@ sub addChannel {
 sub removeChannel {
    my ($name) = @_;
    readChannels;
+    my $url = $channels{$name};
+    deleteOldManifests($url . "/MANIFEST", undef) if defined $url;
    delete $channels{$name};
    writeChannels;

    system("$Nix::Config::binDir/nix-env --profile '$profile' -e '$name'") == 0
-        or die "cannot remove channel `$name'";
+        or die "cannot remove channel `$name'\n";
 }


@@ -77,20 +82,14 @@ sub removeChannel {
 # channels.
 sub update {
    my @channelNames = @_;
-        
+
    readChannels;

-    # Create the manifests directory if it doesn't exist.
-    mkdir $manifestDir, 0755 unless -e $manifestDir;
-
-    # Do we have write permission to the manifests directory?
-    die "$0: you do not have write permission to `$manifestDir'!\n" unless -W $manifestDir;
-
    # Download each channel.
    my $exprs = "";
    foreach my $name (keys %channels) {
        next if scalar @channelNames > 0 && ! grep { $_ eq $name } @{channelNames};
-        
+
        my $url = $channels{$name};
        my $origUrl = "$url/MANIFEST";

@@ -101,17 +100,34 @@ sub update {
        die "$0: unable to check `$url'\n" if $? != 0;
        $headers =~ s/\r//g;
        $url = $1 if $headers =~ /^Location:\s*(.*)\s*$/m;
-        
-        # Pull the channel manifest.
-        $ENV{'NIX_ORIG_URL'} = $origUrl;
-        system("$Nix::Config::binDir/nix-pull", "--skip-wrong-store", "$url/MANIFEST") == 0
-            or die "cannot pull manifest from `$url'\n";
+
+        # Check if the channel advertises a binary cache.
+        my $binaryCacheURL = `$Nix::Config::curl --silent '$url'/binary-cache-url`;
+        my $extraAttrs = "";
+        my $getManifest = ($Nix::Config::config{"force-manifest"} // "false") eq "true";
+        if ($? == 0 && $binaryCacheURL ne "") {
+            $extraAttrs .= "binaryCacheURL = \"$binaryCacheURL\"; ";
+            deleteOldManifests($origUrl, undef);
+        } else {
+            $getManifest = 1;
+        }
+
+        if ($getManifest) {
+            # No binary cache, so pull the channel manifest.
+            mkdir $manifestDir, 0755 unless -e $manifestDir;
+            die "$0: you do not have write permission to `$manifestDir'!\n" unless -W $manifestDir;
+            $ENV{'NIX_ORIG_URL'} = $origUrl;
+            system("$Nix::Config::binDir/nix-pull", "--skip-wrong-store", "$url/MANIFEST") == 0
+                or die "cannot pull manifest from `$url'\n";
+        }

        # Download the channel tarball.
-        my $fullURL = "$url/nixexprs.tar.bz2";
+        my $fullURL = "$url/nixexprs.tar.xz";
+        system("$Nix::Config::curl --fail --silent --head '$fullURL' > /dev/null") == 0 or
+            $fullURL = "$url/nixexprs.tar.bz2";
        print STDERR "downloading Nix expressions from `$fullURL'...\n";
        my ($hash, $path) = `PRINT_PATH=1 QUIET=1 $Nix::Config::binDir/nix-prefetch-url '$fullURL'`;
-        die "cannot fetch `$fullURL'" if $? != 0;
+        die "cannot fetch `$fullURL'\n" if $? != 0;
        chomp $path;

        # If the URL contains a version number, append it to the name
@@ -120,7 +136,7 @@ sub update {
        my $cname = $name;
        $cname .= $1 if basename($url) =~ /(-\d.*)$/;

-        $exprs .= "'f: f { name = \"$cname\"; channelName = \"$name\"; src = builtins.storePath \"$path\"; }' ";
+        $exprs .= "'f: f { name = \"$cname\"; channelName = \"$name\"; src = builtins.storePath \"$path\"; $extraAttrs }' ";
    }

    # Unpack the channel tarballs into the Nix store and install them
@@ -139,26 +155,14 @@ sub update {
 }


-sub usageError {
-    print STDERR <<EOF;
-Usage:
-  nix-channel --add URL [CHANNEL-NAME]
-  nix-channel --remove CHANNEL-NAME
-  nix-channel --list
-  nix-channel --update [CHANNEL-NAME...]
-EOF
-    exit 1;
-}
-
-
-usageError if scalar @ARGV == 0;
+die "$0: argument expected\n" if scalar @ARGV == 0;


 while (scalar @ARGV) {
    my $arg = shift @ARGV;

    if ($arg eq "--add") {
-        usageError if scalar @ARGV < 1 || scalar @ARGV > 2;
+        die "$0: `--add' requires one or two arguments\n" if scalar @ARGV < 1 || scalar @ARGV > 2;
        my $url = shift @ARGV;
        my $name = shift @ARGV;
        unless (defined $name) {
@@ -171,13 +175,13 @@ while (scalar @ARGV) {
    }

    if ($arg eq "--remove") {
-        usageError if scalar @ARGV != 1;
+        die "$0: `--remove' requires one argument\n" if scalar @ARGV != 1;
        removeChannel(shift @ARGV);
        last;
    }

    if ($arg eq "--list") {
-        usageError if scalar @ARGV != 0;
+        die "$0: `--list' requires one argument\n" if scalar @ARGV != 0;
        readChannels;
        foreach my $name (keys %channels) {
            print "$name $channels{$name}\n";
@@ -189,12 +193,17 @@ while (scalar @ARGV) {
        update(@ARGV);
        last;
    }
-    
+
    elsif ($arg eq "--help") {
-        usageError;
+        exec "man nix-channel" or die;
+    }
+
+    elsif ($arg eq "--version") {
+        print "nix-channel (Nix) $Nix::Config::version\n";
+        exit 0;
    }

    else {
-        die "unknown argument `$arg'; try `--help'";
+        die "unknown argument `$arg'; try `--help'\n";
    }
 }
@@ -9,10 +9,15 @@ my $profilesDir = "@localstatedir@/nix/profiles";
 # Process the command line arguments.
 my @args = ();
 my $removeOld = 0;
+my $dryRun = 0;

 for my $arg (@ARGV) {
    if ($arg eq "--delete-old" || $arg eq "-d") {
        $removeOld = 1;
+    } elsif ($arg eq "--dry-run") {
+        $dryRun = 1;
+    } elsif ($arg eq "--help") {
+        exec "man nix-collect-garbage" or die;
    } else {
        push @args, $arg;
    }
@@ -35,13 +40,13 @@ sub removeOldGenerations {
        $name = $dir . "/" . $name;
        if (-l $name && (readlink($name) =~ /link/)) {
            print STDERR "removing old generations of profile $name\n";
-            system("$Nix::Config::binDir/nix-env", "-p", $name, "--delete-generations", "old");
+            system("$Nix::Config::binDir/nix-env", "-p", $name, "--delete-generations", "old", $dryRun ? "--dry-run" : ());
        }
        elsif (! -l $name && -d $name) {
            removeOldGenerations $name;
        }
    }
-    
+
    closedir $dh or die;
 }

@@ -49,4 +54,4 @@ removeOldGenerations $profilesDir if $removeOld;


 # Run the actual garbage collector.
-exec "$Nix::Config::binDir/nix-store", "--gc", @args;
+exec "$Nix::Config::binDir/nix-store", "--gc", @args unless $dryRun;
@@ -4,6 +4,7 @@ use Nix::SSH;
 use Nix::Config;
 use Nix::Store;
 use Nix::CopyClosure;
+use List::Util qw(sum);


 if (scalar @ARGV < 1) {
@@ -17,19 +18,14 @@ EOF

 # Get the target host.
 my $sshHost;
-
 my $sign = 0;
-
 my $compressor = "";
 my $decompressor = "";
-
 my $progressViewer = "";
-
 my $toMode = 1;
-
 my $includeOutputs = 0;
-
 my $dryRun = 0;
+my $useSubstitutes = 0;


 # !!! Copied from nix-pack-closure, should put this in a module.
@@ -37,8 +33,11 @@ my @storePaths = ();

 while (@ARGV) {
    my $arg = shift @ARGV;
-    
-    if ($arg eq "--sign") {
+
+    if ($arg eq "--help") {
+        exec "man nix-copy-closure" or die;
+    }
+    elsif ($arg eq "--sign") {
        $sign = 1;
    }
    elsif ($arg eq "--gzip") {
@@ -68,6 +67,9 @@ while (@ARGV) {
    elsif ($arg eq "--dry-run") {
        $dryRun = 1;
    }
+    elsif ($arg eq "--use-substitutes" || $arg eq "-s") {
+        $useSubstitutes = 1;
+    }
    elsif (!defined $sshHost) {
        $sshHost = $arg;
    }
@@ -76,12 +78,16 @@ while (@ARGV) {
    }
 }

+die "$0: you did not specify a host name\n" unless defined $sshHost;
+

 openSSHConnection $sshHost or die "$0: unable to start SSH\n";


 if ($toMode) { # Copy TO the remote machine.
-    Nix::CopyClosure::copyTo($sshHost, [ @sshOpts ], [ @storePaths ], $compressor, $decompressor, $includeOutputs, $dryRun, $sign, $progressViewer);
+    Nix::CopyClosure::copyTo(
+        $sshHost, [ @sshOpts ], [ @storePaths ], $compressor, $decompressor,
+        $includeOutputs, $dryRun, $sign, $progressViewer, $useSubstitutes);
 }

 else { # Copy FROM the remote machine.
@@ -92,7 +98,7 @@ else { # Copy FROM the remote machine.
    my $extraOpts = $includeOutputs ? "--include-outputs" : "";
    my $pid = open(READ,
        "set -f; ssh @sshOpts $sshHost nix-store --query --requisites $extraOpts @storePaths|") or die;
-    
+
    while (<READ>) {
        chomp;
        die "bad: $_" unless /^\//;
@@ -101,15 +107,23 @@ else { # Copy FROM the remote machine.

    close READ or die "nix-store on remote machine `$sshHost' failed: $?";

+    my $missingSize = 0;
+    if ($progressViewer ne "") {
+        $missingSize = sum (split ' ', `set -f; ssh @sshOpts $sshHost nix-store -q --size @missing`) or die;
+    }
+
    # Export the store paths on the remote machine and import them locally.
    if (scalar @missing > 0) {
        print STDERR "copying ", scalar @missing, " missing paths from ‘$sshHost’...\n";
-        $compressor = "| $compressor" if $compressor ne "";
-        $decompressor = "$decompressor |" if $decompressor ne "";
-	$progressViewer = "$progressViewer |" if $progressViewer ne "";
        unless ($dryRun) {
+            if ($useSubstitutes) {
+                system "$Nix::Config::binDir/nix-store -r --ignore-unknown @missing";
+            }
+            $compressor = "| $compressor" if $compressor ne "";
+            $decompressor = "$decompressor |" if $decompressor ne "";
+            $progressViewer = "$progressViewer -s $missingSize |" if $progressViewer ne "";
            my $extraOpts = $sign ? "--sign" : "";
-            system("set -f; ssh $sshHost @sshOpts 'nix-store --export $extraOpts @missing $compressor' | $progressViewer $decompressor $Nix::Config::binDir/nix-store --import > /dev/null") == 0
+            system("set -f; ssh $sshHost @sshOpts 'nix-store --export $extraOpts @missing $compressor' | $decompressor $progressViewer $Nix::Config::binDir/nix-store --import > /dev/null") == 0
                or die "copying store paths from remote machine `$sshHost' failed: $?";
        }
    }
@@ -3,27 +3,11 @@
 use strict;
 use File::Temp qw(tempdir);
 use Nix::Config;
-
-
-sub usageError {
-    print STDERR <<EOF;
-Usage: nix-install-package (FILE | --url URL)
-
-Install a Nix Package (.nixpkg) either directly from FILE or by
-downloading it from URL.
-
-Flags:
-  --profile / -p LINK: install into the specified profile
-  --non-interactive: don't run inside a new terminal
-EOF
-    ; # '
-    exit 1;
-}
+use Nix::Utils;


 # Parse the command line arguments.
 my @args = @ARGV;
-usageError if scalar @args == 0;

 my $source;
 my $fromURL = 0;
@@ -33,14 +17,14 @@ my $interactive = 1;
 while (scalar @args) {
    my $arg = shift @args;
    if ($arg eq "--help") {
-        usageError;
+        exec "man nix-install-package" or die;
    }
    elsif ($arg eq "--url") {
        $fromURL = 1;
    }
    elsif ($arg eq "--profile" || $arg eq "-p") {
        my $profile = shift @args;
-        usageError if !defined $profile;
+        die "$0: `--profile' requires an argument\n" if !defined $profile;
        push @extraNixEnvArgs, "-p", $profile;
    }
    elsif ($arg eq "--non-interactive") {
@@ -51,7 +35,7 @@ while (scalar @args) {
    }
 }

-usageError unless defined $source;
+die "$0: please specify a .nixpkg file or URL\n" unless defined $source;


 # Re-execute in a terminal, if necessary, so that if we're executed
@@ -72,7 +56,7 @@ my $tmpDir = tempdir("nix-install-package.XXXXXX", CLEANUP => 1, TMPDIR => 1)

 sub barf {
    my $msg = shift;
-    print "$msg\n";
+    print "\nInstallation failed: $msg\n";
    <STDIN> if $interactive;
    exit 1;
 }
@@ -92,7 +76,6 @@ open PKGFILE, "<$pkgFile" or barf "cannot open `$pkgFile': $!";
 my $contents = <PKGFILE>;
 close PKGFILE;

-my $urlRE = "(?: [a-zA-Z][a-zA-Z0-9\+\-\.]*\:[a-zA-Z0-9\%\/\?\:\@\&\=\+\$\,\-\_\.\!\~\*\']+ )";
 my $nameRE = "(?: [A-Za-z0-9\+\-\.\_\?\=]+ )"; # see checkStoreName()
 my $systemRE = "(?: [A-Za-z0-9\+\-\_]+ )";
 my $pathRE = "(?: \/ [\/A-Za-z0-9\+\-\.\_\?\=]* )";
@@ -101,7 +84,7 @@ my $pathRE = "(?: \/ [\/A-Za-z0-9\+\-\.\_\?\=]* )";
 # store path.  We'll let nix-env do that.

 $contents =~
-    / ^ \s* (\S+) \s+ ($urlRE) \s+ ($nameRE) \s+ ($systemRE) \s+ ($pathRE) \s+ ($pathRE) /x
+    / ^ \s* (\S+) \s+ ($Nix::Utils::urlRE) \s+ ($nameRE) \s+ ($systemRE) \s+ ($pathRE) \s+ ($pathRE) ( \s+ ($Nix::Utils::urlRE) )?  /x
    or barf "invalid package contents";
 my $version = $1;
 my $manifestURL = $2;
@@ -109,6 +92,7 @@ my $drvName = $3;
 my $system = $4;
 my $drvPath = $5;
 my $outPath = $6;
+my $binaryCacheURL = $8;

 barf "invalid package version `$version'" unless $version eq "NIXPKG1";

@@ -122,17 +106,25 @@ if ($interactive) {
 }


-# Store the manifest in the temporary directory so that we don't
-# pollute /nix/var/nix/manifests.  This also requires that we don't
-# use the Nix daemon (because otherwise download-using-manifests won't
-# see our NIX_MANIFESTS_DIRS environment variable).
-$ENV{NIX_MANIFESTS_DIR} = $tmpDir;
-$ENV{NIX_REMOTE} = "";
+if (defined $binaryCacheURL) {

+    push @extraNixEnvArgs, "--option", "binary-caches", $binaryCacheURL;

-print "\nPulling manifests...\n";
-system("$Nix::Config::binDir/nix-pull", $manifestURL) == 0
-    or barf "nix-pull failed: $?";
+} else {
+
+    # Store the manifest in the temporary directory so that we don't
+    # pollute /nix/var/nix/manifests.  This also requires that we
+    # don't use the Nix daemon (because otherwise
+    # download-using-manifests won't see our NIX_MANIFESTS_DIRS
+    # environment variable).
+    $ENV{NIX_MANIFESTS_DIR} = $tmpDir;
+    $ENV{NIX_REMOTE} = "";
+
+    print "\nPulling manifests...\n";
+    system("$Nix::Config::binDir/nix-pull", $manifestURL) == 0
+        or barf "nix-pull failed: $?";
+
+}


 print "\nInstalling package...\n";
@@ -6,12 +6,30 @@ use File::Temp qw(tempdir);
 use File::stat;
 use Nix::Store;
 use Nix::Config;
+use Nix::Utils;

-my $url = shift;
-my $expHash = shift;
-my $hashType = $ENV{'NIX_HASH_ALGO'} || "sha256";
+my $hashType = $ENV{'NIX_HASH_ALGO'} || "sha256"; # obsolete
 my $cacheDir = $ENV{'NIX_DOWNLOAD_CACHE'};

+my @args;
+my $arg;
+while ($arg = shift) {
+    if ($arg eq "--help") {
+        exec "man nix-prefetch-url" or die;
+    } elsif ($arg eq "--type") {
+        $hashType = shift;
+        die "$0: `$arg' requires an argument\n" unless defined $hashType;
+    } elsif (substr($arg, 0, 1) eq "-") {
+        die "$0: unknown flag `$arg'\n";
+    } else {
+        push @args, $arg;
+    }
+}
+
+my $url = $args[0];
+my $expHash = $args[1];
+
+
 if (!defined $url || $url eq "") {
    print STDERR <<EOF
 Usage: nix-prefetch-url URL [EXPECTED-HASH]
@@ -20,22 +38,6 @@ EOF
    exit 1;
 }

-sub writeFile {
-    my ($fn, $s) = @_;
-    open TMP, ">$fn" or die;
-    print TMP "$s" or die;
-    close TMP or die;
-}
-
-sub readFile {
-    local $/ = undef;
-    my ($fn) = @_;
-    open TMP, "<$fn" or die;
-    my $s = <TMP>;
-    close TMP or die;
-    return $s;
-}
-
 my $tmpDir = tempdir("nix-prefetch-url.XXXXXX", CLEANUP => 1, TMPDIR => 1)
    or die "cannot create a temporary directory";

@@ -1,50 +1,17 @@
-export NIX_USER_PROFILE_DIR=@localstatedir@/nix/profiles/per-user/$USER
-export NIX_PROFILES="@localstatedir@/nix/profiles/default $HOME/.nix-profile"
+if test -n "$HOME"; then
+    NIX_LINK="$HOME/.nix-profile"

-# Set up the per-user profile.
-mkdir -m 0755 -p $NIX_USER_PROFILE_DIR
-if test "$(stat --printf '%u' $NIX_USER_PROFILE_DIR)" != "$(id -u)"; then
-    echo "WARNING: bad ownership on $NIX_USER_PROFILE_DIR" >&2
-fi
-
-if ! test -L $HOME/.nix-profile; then
-    echo "creating $HOME/.nix-profile" >&2
-    if test "$USER" != root; then
-        @coreutils@/ln -s $NIX_USER_PROFILE_DIR/profile $HOME/.nix-profile
-    else
-        # Root installs in the system-wide profile by default.
-        @coreutils@/ln -s /nix/var/nix/profiles/default $HOME/.nix-profile
+    # Set the default profile.
+    if ! [ -L "$NIX_LINK" ]; then
+        echo "creating $NIX_LINK" >&2
+        _NIX_DEF_LINK=@localstatedir@/nix/profiles/default
+        @coreutils@/ln -s "$_NIX_DEF_LINK" "$NIX_LINK"
    fi
-fi

-export PATH="$HOME/.nix-profile/bin:$PATH"
-
-# Subscribe the root user to the NixOS channel by default.
-if [ "$USER" = root -a ! -e $HOME/.nix-channels ]; then
-    echo "http://nixos.org/releases/nixos/channels/nixos-unstable nixos" > $HOME/.nix-channels
-fi
-
-# Create the per-user garbage collector roots directory.
-NIX_USER_GCROOTS_DIR=@localstatedir@/nix/gcroots/per-user/$USER
-mkdir -m 0755 -p $NIX_USER_GCROOTS_DIR
-if test "$(stat --printf '%u' $NIX_USER_GCROOTS_DIR)" != "$(id -u)"; then
-    echo "WARNING: bad ownership on $NIX_USER_GCROOTS_DIR" >&2
-fi
-
-# Set up a default Nix expression from which to install stuff.
-if [ ! -e $HOME/.nix-defexpr -o -L $HOME/.nix-defexpr ]; then
-    echo "creating $HOME/.nix-defexpr" >&2
-    rm -f $HOME/.nix-defexpr
-    mkdir $HOME/.nix-defexpr
-    if [ "$USER" != root ]; then
-        @coreutils@/ln -s @localstatedir@/nix/profiles/per-user/root/channels $HOME/.nix-defexpr/channels_root
+    # Subscribe the root user to the Nixpkgs channel by default.
+    if [ ! -e $HOME/.nix-channels ]; then
+        echo "http://nixos.org/channels/nixpkgs-unstable nixpkgs" > $HOME/.nix-channels
    fi
-fi

-# Set up secure multi-user builds: non-root users build through the
-# Nix daemon.
-if test "$USER" != root; then
-    export NIX_REMOTE=daemon
-else
-    unset NIX_REMOTE
+    export PATH=$NIX_LINK/bin:$PATH
 fi
@@ -76,31 +76,22 @@ sub processURL {
    open URL, ">$urlFile" or die "cannot create `$urlFile'";
    print URL $origUrl;
    close URL;
-    
+
    my $finalPath = "$manifestDir/$baseName-$hash.nixmanifest";

    unlink $finalPath if -e $finalPath;
-        
+
    symlink("$manifest", "$finalPath")
        or die "cannot link `$finalPath to `$manifest'";

-    # Delete all old manifests downloaded from this URL.
-    for my $urlFile2 (glob "$manifestDir/*.url") {
-        next if $urlFile eq $urlFile2;
-        open URL, "<$urlFile2" or die;
-        my $url2 = <URL>;
-        chomp $url2;
-        close URL;
-        next unless $origUrl eq $url2;
-        my $base = $urlFile2; $base =~ s/.url$//;
-        unlink "${base}.url";
-        unlink "${base}.nixmanifest";
-    }
+    deleteOldManifests($origUrl, $urlFile);
 }

 while (@ARGV) {
    my $url = shift @ARGV;
-    if ($url eq "--skip-wrong-store") {
+    if ($url eq "--help") {
+        exec "man nix-pull" or die;
+    } elsif ($url eq "--skip-wrong-store") {
        # No-op, no longer supported.
    } else {
        processURL $url;
@@ -1,85 +1,85 @@
 #! @perl@ -w @perlFlags@

 use strict;
+use File::Basename;
 use File::Temp qw(tempdir);
+use File::Path qw(mkpath);
 use File::stat;
+use File::Copy;
 use Nix::Config;
+use Nix::Store;
 use Nix::Manifest;
-
-my $hashAlgo = "sha256";
+use Nix::Utils;

 my $tmpDir = tempdir("nix-push.XXXXXX", CLEANUP => 1, TMPDIR => 1)
    or die "cannot create a temporary directory";

 my $nixExpr = "$tmpDir/create-nars.nix";
-my $manifest = "$tmpDir/MANIFEST";
-
-my $curl = "$Nix::Config::curl --fail --silent";
-my $extraCurlFlags = ${ENV{'CURL_FLAGS'}};
-$curl = "$curl $extraCurlFlags" if defined $extraCurlFlags;


 # Parse the command line.
-my $localCopy;
-my $localArchivesDir;
-my $localManifestFile;
+my $compressionType = "xz";
+my $force = 0;
+my $destDir;
+my $writeManifest = 0;
+my $manifestPath;
+my $archivesURL;
+my $link = 0;
+my @roots;

-my $targetArchivesUrl;
+for (my $n = 0; $n < scalar @ARGV; $n++) {
+    my $arg = $ARGV[$n];

-my $archivesPutURL;
-my $archivesGetURL;
-my $manifestPutURL;
-
-sub showSyntax {
-    print STDERR <<EOF
-Usage: nix-push --copy ARCHIVES_DIR MANIFEST_FILE PATHS...
-   or: nix-push ARCHIVES_PUT_URL ARCHIVES_GET_URL MANIFEST_PUT_URL PATHS...
-
-`nix-push' copies or uploads the closure of PATHS to the given
-destination.
-EOF
-    ; # `
-    exit 1;
-}
-
-showSyntax if scalar @ARGV < 1;
-
-if ($ARGV[0] eq "--copy") {
-    showSyntax if scalar @ARGV < 3;
-    $localCopy = 1;
-    shift @ARGV;
-    $localArchivesDir = shift @ARGV;
-    $localManifestFile = shift @ARGV;
-    if ($ARGV[0] eq "--target") {
-       shift @ARGV;
-       $targetArchivesUrl = shift @ARGV;
-    }
-    else {
-       $targetArchivesUrl = "file://$localArchivesDir";
+    if ($arg eq "--help") {
+        exec "man nix-push" or die;
+    } elsif ($arg eq "--bzip2") {
+        $compressionType = "bzip2";
+    } elsif ($arg eq "--none") {
+        $compressionType = "none";
+    } elsif ($arg eq "--force") {
+        $force = 1;
+    } elsif ($arg eq "--dest") {
+        $n++;
+        die "$0: `$arg' requires an argument\n" unless $n < scalar @ARGV;
+        $destDir = $ARGV[$n];
+        mkpath($destDir, 0, 0755);
+    } elsif ($arg eq "--manifest") {
+        $writeManifest = 1;
+    } elsif ($arg eq "--manifest-path") {
+        $n++;
+        die "$0: `$arg' requires an argument\n" unless $n < scalar @ARGV;
+        $manifestPath = $ARGV[$n];
+        $writeManifest = 1;
+        mkpath(dirname($manifestPath), 0, 0755);
+    } elsif ($arg eq "--url-prefix") {
+        $n++;
+        die "$0: `$arg' requires an argument\n" unless $n < scalar @ARGV;
+        $archivesURL = $ARGV[$n];
+    } elsif ($arg eq "--link") {
+        $link = 1;
+    } elsif (substr($arg, 0, 1) eq "-") {
+        die "$0: unknown flag `$arg'\n";
+    } else {
+        push @roots, $arg;
    }
 }
-else {
-    showSyntax if scalar @ARGV < 3;
-    $localCopy = 0;
-    $archivesPutURL = shift @ARGV;
-    $archivesGetURL = shift @ARGV;
-    $manifestPutURL = shift @ARGV;
-}
+
+die "$0: please specify a destination directory\n" if !defined $destDir;
+
+$archivesURL = "file://$destDir" unless defined $archivesURL;


 # From the given store paths, determine the set of requisite store
 # paths, i.e, the paths required to realise them.
 my %storePaths;

-foreach my $path (@ARGV) {
-    die unless $path =~ /^\//;
-
-    # Get all paths referenced by the normalisation of the given 
+foreach my $path (@roots) {
+    # Get all paths referenced by the normalisation of the given
    # Nix expression.
    my $pid = open(READ,
        "$Nix::Config::binDir/nix-store --query --requisites --force-realise " .
        "--include-outputs '$path'|") or die;
-    
+
    while (<READ>) {
        chomp;
        die "bad: $_" unless /^\//;
@@ -92,19 +92,50 @@ foreach my $path (@ARGV) {
 my @storePaths = keys %storePaths;


-# For each path, create a Nix expression that turns the path into
-# a Nix archive.
+# Don't create archives for files that are already in the binary cache.
+my @storePaths2;
+my %narFiles;
+foreach my $storePath (@storePaths) {
+    my $pathHash = substr(basename($storePath), 0, 32);
+    my $narInfoFile = "$destDir/$pathHash.narinfo";
+    if (-e $narInfoFile) {
+        my $narInfo = parseNARInfo($storePath, readFile($narInfoFile));
+        my $narFile = "$destDir/$narInfo->{url}";
+        if (-e $narFile) {
+            print STDERR "skipping existing $storePath\n";
+            # Add the NAR info to $narFiles if we're writing a
+            # manifest.
+            $narFiles{$storePath} = [
+                { url => ("$archivesURL/" . basename $narInfo->{url})
+                  , hash => $narInfo->{fileHash}
+                  , size => $narInfo->{fileSize}
+                  , compressionType => $narInfo->{compression}
+                  , narHash => $narInfo->{narHash}
+                  , narSize => $narInfo->{narSize}
+                  , references => join(" ", map { "$Nix::Config::storeDir/$_" } @{$narInfo->{refs}})
+                  , deriver => $narInfo->{deriver} ? "$Nix::Config::storeDir/$narInfo->{deriver}" : undef
+                  }
+            ] if $writeManifest;
+            next;
+        }
+    }
+    push @storePaths2, $storePath;
+}
+
+
+# Create a list of Nix derivations that turn each path into a Nix
+# archive.
 open NIX, ">$nixExpr";
 print NIX "[";

-foreach my $storePath (@storePaths) {
+foreach my $storePath (@storePaths2) {
    die unless ($storePath =~ /\/[0-9a-z]{32}[^\"\\\$]*$/);

    # Construct a Nix expression that creates a Nix archive.
-    my $nixexpr = 
+    my $nixexpr =
        "(import <nix/nar.nix> " .
-        "{ storePath = builtins.storePath \"$storePath\"; hashAlgo = \"$hashAlgo\"; }) ";
-    
+        "{ storePath = builtins.storePath \"$storePath\"; hashAlgo = \"sha256\"; compressionType = \"$compressionType\"; }) ";
+
    print NIX $nixexpr;
 }

@@ -112,172 +143,135 @@ print NIX "]";
 close NIX;


-# Instantiate store derivations from the Nix expression.
-my @storeExprs;
-print STDERR "instantiating store derivations...\n";
-my $pid = open(READ, "$Nix::Config::binDir/nix-instantiate $nixExpr|")
-    or die "cannot run nix-instantiate";
+# Build the Nix expression.
+print STDERR "building compressed archives...\n";
+my @narPaths;
+my $pid = open(READ, "$Nix::Config::binDir/nix-build $nixExpr -o $tmpDir/result |")
+    or die "cannot run nix-build";
 while (<READ>) {
    chomp;
    die unless /^\//;
-    push @storeExprs, $_;
+    push @narPaths, $_;
 }
-close READ or die "nix-instantiate failed: $?";
+close READ or die "nix-build failed: $?";


-# Build the derivations.
-print STDERR "creating archives...\n";
-
-my @narPaths;
-
-my @tmp = @storeExprs;
-while (scalar @tmp > 0) {
-    my $n = scalar @tmp;
-    if ($n > 256) { $n = 256 };
-    my @tmp2 = @tmp[0..$n - 1];
-    @tmp = @tmp[$n..scalar @tmp - 1];
-
-    my $pid = open(READ, "$Nix::Config::binDir/nix-store --realise @tmp2|")
-        or die "cannot run nix-store";
-    while (<READ>) {
-        chomp;
-        die unless (/^\//);
-        push @narPaths, "$_";
-    }
-    close READ or die "nix-store failed: $?";
+# Write the cache info file.
+my $cacheInfoFile = "$destDir/nix-cache-info";
+if (! -e $cacheInfoFile) {
+    open FILE, ">$cacheInfoFile" or die "cannot create $cacheInfoFile: $!";
+    print FILE "StoreDir: $Nix::Config::storeDir\n";
+    print FILE "WantMassQuery: 0\n"; # by default, don't hit this cache for "nix-env -qas"
+    close FILE;
 }


-# Create the manifest.
-print STDERR "creating manifest...\n";
+# Copy the archives and the corresponding NAR info files.
+print STDERR "copying archives...\n";

-my %narFiles;
-my %patches;
+my $totalNarSize = 0;
+my $totalCompressedSize = 0;

-my @narArchives;
-for (my $n = 0; $n < scalar @storePaths; $n++) {
-    my $storePath = $storePaths[$n];
+for (my $n = 0; $n < scalar @storePaths2; $n++) {
+    my $storePath = $storePaths2[$n];
    my $narDir = $narPaths[$n];
-    
-    $storePath =~ /\/([^\/]*)$/;
-    my $basename = $1;
-    defined $basename or die;
+    my $baseName = basename $storePath;

-    open HASH, "$narDir/narbz2-hash" or die "cannot open narbz2-hash";
-    my $narbz2Hash = <HASH>;
-    chomp $narbz2Hash;
-    $narbz2Hash =~ /^[0-9a-z]+$/ or die "invalid hash";
-    close HASH;
-
-    my $narName = "$narbz2Hash.nar.bz2";
-
-    my $narFile = "$narDir/$narName";
-    (-f $narFile) or die "narfile for $storePath not found";
-    push @narArchives, $narFile;
-
-    my $narbz2Size = stat($narFile)->size;
-
-    my $references = `$Nix::Config::binDir/nix-store --query --references '$storePath'`;
-    die "cannot query references for `$storePath'" if $? != 0;
-    $references = join(" ", split(" ", $references));
-
-    my $deriver = `$Nix::Config::binDir/nix-store --query --deriver '$storePath'`;
-    die "cannot query deriver for `$storePath'" if $? != 0;
-    chomp $deriver;
-    $deriver = "" if $deriver eq "unknown-deriver";
-
-    my $narHash = `$Nix::Config::binDir/nix-store --query --hash '$storePath'`;
-    die "cannot query hash for `$storePath'" if $? != 0;
-    chomp $narHash;
+    # Get info about the store path.
+    my ($deriver, $narHash, $time, $narSize, $refs) = queryPathInfo($storePath, 1);

    # In some exceptional cases (such as VM tests that use the Nix
    # store of the host), the database doesn't contain the hash.  So
    # compute it.
    if ($narHash =~ /^sha256:0*$/) {
-        $narHash = `$Nix::Config::binDir/nix-hash --type sha256 --base32 '$storePath'`;
-        die "cannot hash `$storePath'" if $? != 0;
+        my $nar = "$tmpDir/nar";
+        system("$Nix::Config::binDir/nix-store --dump $storePath > $nar") == 0
+            or die "cannot dump $storePath\n";
+        $narHash = `$Nix::Config::binDir/nix-hash --type sha256 --base32 --flat $nar`;
+        die "cannot hash `$nar'" if $? != 0;
        chomp $narHash;
        $narHash = "sha256:$narHash";
+        $narSize = stat("$nar")->size;
+        unlink $nar or die;
    }

-    my $narSize = `$Nix::Config::binDir/nix-store --query --size '$storePath'`;
-    die "cannot query size for `$storePath'" if $? != 0;
-    chomp $narSize;
+    $totalNarSize += $narSize;

-    my $url;
-    if ($localCopy) {
-        $url = "$targetArchivesUrl/$narName";
-    } else {
-        $url = "$archivesGetURL/$narName";
+    # Get info about the compressed NAR.
+    open HASH, "$narDir/nar-compressed-hash" or die "cannot open nar-compressed-hash";
+    my $compressedHash = <HASH>;
+    chomp $compressedHash;
+    $compressedHash =~ /^[0-9a-z]+$/ or die "invalid hash";
+    close HASH;
+
+    my $narName = "$compressedHash.nar" . ($compressionType eq "xz" ? ".xz" : $compressionType eq "bzip2" ? ".bz2" : "");
+
+    my $narFile = "$narDir/$narName";
+    (-f $narFile) or die "NAR file for $storePath not found";
+
+    my $compressedSize = stat($narFile)->size;
+    $totalCompressedSize += $compressedSize;
+
+    printf STDERR "%s [%.2f MiB, %.1f%%]\n", $storePath,
+        $compressedSize / (1024 * 1024), $compressedSize / $narSize * 100;
+
+    # Copy the compressed NAR.
+    my $dst = "$destDir/$narName";
+    if (! -f $dst) {
+        my $tmp = "$destDir/.tmp.$$.$narName";
+        if ($link) {
+            link($narFile, $tmp) or die "cannot link $tmp to $narFile: $!\n";
+        } else {
+            copy($narFile, $tmp) or die "cannot copy $narFile to $tmp: $!\n";
+        }
+        rename($tmp, $dst) or die "cannot rename $tmp to $dst: $!\n";
    }
+
+    # Write the info file.
+    my $info;
+    $info .= "StorePath: $storePath\n";
+    $info .= "URL: $narName\n";
+    $info .= "Compression: $compressionType\n";
+    $info .= "FileHash: sha256:$compressedHash\n";
+    $info .= "FileSize: $compressedSize\n";
+    $info .= "NarHash: $narHash\n";
+    $info .= "NarSize: $narSize\n";
+    $info .= "References: " . join(" ", map { basename $_ } @{$refs}) . "\n";
+    if (defined $deriver) {
+        $info .= "Deriver: " . basename $deriver . "\n";
+        if (isValidPath($deriver)) {
+            my $drv = derivationFromPath($deriver);
+            $info .= "System: $drv->{platform}\n";
+        }
+    }
+
+    my $pathHash = substr(basename($storePath), 0, 32);
+
+    $dst = "$destDir/$pathHash.narinfo";
+    if ($force || ! -f $dst) {
+        my $tmp = "$destDir/.tmp.$$.$pathHash.narinfo";
+        open INFO, ">$tmp" or die;
+        print INFO "$info" or die;
+        close INFO or die;
+        rename($tmp, $dst) or die "cannot rename $tmp to $dst: $!\n";
+    }
+
    $narFiles{$storePath} = [
-        { url => $url
-        , hash => "$hashAlgo:$narbz2Hash"
-        , size => $narbz2Size
+        { url => "$archivesURL/$narName"
+        , hash => "sha256:$compressedHash"
+        , size => $compressedSize
+        , compressionType => $compressionType
        , narHash => "$narHash"
        , narSize => $narSize
-        , references => $references
+        , references => join(" ", @{$refs})
        , deriver => $deriver
        }
-    ];
+    ] if $writeManifest;
 }

-writeManifest $manifest, \%narFiles, \%patches;
+printf STDERR "total compressed size %.2f MiB, %.1f%%\n",
+    $totalCompressedSize / (1024 * 1024), $totalCompressedSize / ($totalNarSize || 1) * 100;


-sub copyFile {
-    my $src = shift;
-    my $dst = shift;
-    my $tmp = "$dst.tmp.$$";
-    system("@coreutils@/cp", $src, $tmp) == 0 or die "cannot copy file";
-    rename($tmp, $dst) or die "cannot rename file: $!";
-}
-
-
-# Upload/copy the archives.
-print STDERR "uploading/copying archives...\n";
-
-sub archiveExists {
-    my $name = shift;
-    print STDERR "  HEAD on $archivesGetURL/$name\n";
-    return system("$curl --head $archivesGetURL/$name > /dev/null") == 0;
-}
-
-foreach my $narArchive (@narArchives) {
-
-    $narArchive =~ /\/([^\/]*)$/;
-    my $basename = $1;
-
-    if ($localCopy) {
-        # Since nix-push creates $dst atomically, if it exists we
-        # don't have to copy again.
-        my $dst = "$localArchivesDir/$basename";
-        if (! -f "$localArchivesDir/$basename") {
-            print STDERR "  $narArchive\n";
-            copyFile $narArchive, $dst;
-        }
-    }
-    else {
-        if (!archiveExists("$basename")) {
-            print STDERR "  $narArchive\n";
-            system("$curl --show-error --upload-file " .
-                   "'$narArchive' '$archivesPutURL/$basename' > /dev/null") == 0 or
-                   die "curl failed on $narArchive: $?";
-        }
-    }
-}
-
-
-# Upload the manifest.
-print STDERR "uploading manifest...\n";
-if ($localCopy) {
-    copyFile $manifest, $localManifestFile;
-    copyFile "$manifest.bz2", "$localManifestFile.bz2";
-} else {
-    system("$curl --show-error --upload-file " .
-           "'$manifest' '$manifestPutURL' > /dev/null") == 0 or
-           die "curl failed on $manifest: $?";
-    system("$curl --show-error --upload-file " .
-           "'$manifest'.bz2 '$manifestPutURL'.bz2 > /dev/null") == 0 or
-           die "curl failed on $manifest: $?";
-}
+# Optionally write a manifest.
+writeManifest($manifestPath // "$destDir/MANIFEST", \%narFiles, \()) if $writeManifest;
@@ -1,3 +1,3 @@
-SUBDIRS = bin2c boost libutil libstore libmain nix-store nix-hash \
- libexpr nix-instantiate nix-env nix-worker nix-setuid-helper \
+SUBDIRS = boost libutil libstore libmain nix-store nix-hash \
+ libexpr nix-instantiate nix-env nix-daemon nix-setuid-helper \
 nix-log2xml bsdiff-4.3
@@ -1,6 +0,0 @@
-noinst_PROGRAMS = bin2c
-
-bin2c_SOURCES = bin2c.c
-
-bin2c$(EXEEXT): bin2c.c
-	$(CC_FOR_BUILD) $(CFLAGS_FOR_BUILD) -o bin2c bin2c.c
@@ -1,23 +0,0 @@
-#include <stdlib.h>
-#include <stdio.h>
-#include <stdarg.h>
-
-void print(const char *format, ...)
-{
-    va_list ap;
-    va_start(ap, format);
-    if (vprintf(format, ap) < 0) abort();
-    va_end(ap);
-}
-
-int main(int argc, char * * argv)
-{
-    int c;
-    if (argc != 2) abort();
-    print("static unsigned char %s[] = { ", argv[1]);
-    while ((c = getchar()) != EOF) {
-        print("0x%02x, ", (unsigned char) c);
-    }
-    print("0 };\n");
-    return 0;
-}
@@ -6,19 +6,18 @@
 namespace nix {


-// !!! Shouldn't we return a pointer to a Value?
-void findAlongAttrPath(EvalState & state, const string & attrPath,
-    Bindings & autoArgs, Expr * e, Value & v)
+Value * findAlongAttrPath(EvalState & state, const string & attrPath,
+    Bindings & autoArgs, Value & vIn)
 {
-    Strings tokens = tokenizeString(attrPath, ".");
+    Strings tokens = tokenizeString<Strings>(attrPath, ".");

    Error attrError =
        Error(format("attribute selection path `%1%' does not match expression") % attrPath);

    string curPath;

-    state.mkThunk_(v, e);
-    
+    Value * v = &vIn;
+
    foreach (Strings::iterator, i, tokens) {

        if (!curPath.empty()) curPath += ".";
@@ -27,14 +26,14 @@ void findAlongAttrPath(EvalState & state, const string & attrPath,
        /* Is *i an index (integer) or a normal attribute name? */
        enum { apAttr, apIndex } apType = apAttr;
        string attr = *i;
-        int attrIndex = -1;
+        unsigned int attrIndex;
        if (string2Int(attr, attrIndex)) apType = apIndex;

        /* Evaluate the expression. */
-        Value vTmp;
-        state.autoCallFunction(autoArgs, v, vTmp);
-        v = vTmp;
-        state.forceValue(v);
+        Value * vNew = state.allocValue();
+        state.autoCallFunction(autoArgs, *v, *vNew);
+        v = vNew;
+        state.forceValue(*v);

        /* It should evaluate to either an attribute set or an
           expression, according to what is specified in the
@@ -42,32 +41,34 @@ void findAlongAttrPath(EvalState & state, const string & attrPath,

        if (apType == apAttr) {

-            if (v.type != tAttrs)
+            if (v->type != tAttrs)
                throw TypeError(
                    format("the expression selected by the selection path `%1%' should be an attribute set but is %2%")
-                    % curPath % showType(v));
+                    % curPath % showType(*v));

-            Bindings::iterator a = v.attrs->find(state.symbols.create(attr));
-            if (a == v.attrs->end())
+            Bindings::iterator a = v->attrs->find(state.symbols.create(attr));
+            if (a == v->attrs->end())
                throw Error(format("attribute `%1%' in selection path `%2%' not found") % attr % curPath);
-            v = *a->value;
+            v = &*a->value;
        }

        else if (apType == apIndex) {

-            if (v.type != tList)
+            if (v->type != tList)
                throw TypeError(
                    format("the expression selected by the selection path `%1%' should be a list but is %2%")
-                    % curPath % showType(v));
+                    % curPath % showType(*v));

-            if (attrIndex >= v.list.length)
+            if (attrIndex >= v->list.length)
                throw Error(format("list index %1% in selection path `%2%' is out of range") % attrIndex % curPath);

-            v = *v.list.elems[attrIndex];
+            v = v->list.elems[attrIndex];
        }
-        
+
    }
+
+    return v;
 }

- 
+
 }
@@ -7,7 +7,7 @@

 namespace nix {

-void findAlongAttrPath(EvalState & state, const string & attrPath,
-    Bindings & autoArgs, Expr * e, Value & v);
+Value * findAlongAttrPath(EvalState & state, const string & attrPath,
+    Bindings & autoArgs, Value & vIn);

 }
@@ -21,13 +21,16 @@ LocalNoInlineNoReturn(void throwTypeError(const char * s, const string & s2))
 void EvalState::forceValue(Value & v)
 {
    if (v.type == tThunk) {
-        ValueType saved = v.type;
+        Env * env = v.thunk.env;
+        Expr * expr = v.thunk.expr;
        try {
            v.type = tBlackhole;
            //checkInterrupt();
-            v.thunk.expr->eval(*this, *v.thunk.env, v);
+            expr->eval(*this, *env, v);
        } catch (Error & e) {
-            v.type = saved;
+            v.type = tThunk;
+            v.thunk.env = env;
+            v.thunk.expr = expr;
            throw;
        }
    }
@@ -44,7 +44,7 @@ void Bindings::sort()
 {
    std::sort(begin(), end());
 }
-    
+

 std::ostream & operator << (std::ostream & str, const Value & v)
 {
@@ -138,12 +138,18 @@ EvalState::EvalState()
    , sName(symbols.create("name"))
    , sSystem(symbols.create("system"))
    , sOverrides(symbols.create("__overrides"))
+    , sOutputs(symbols.create("outputs"))
+    , sOutputName(symbols.create("outputName"))
+    , sIgnoreNulls(symbols.create("__ignoreNulls"))
+    , repair(false)
    , baseEnv(allocEnv(128))
-    , baseEnvDispl(0)
    , staticBaseEnv(false, 0)
+    , baseEnvDispl(0)
 {
    nrEnvs = nrValuesInEnvs = nrValues = nrListElems = 0;
    nrAttrsets = nrOpUpdates = nrOpUpdateValuesCopied = 0;
+    nrListConcats = nrPrimOpCalls = nrFunctionCalls = 0;
+    countCalls = getEnv("NIX_COUNT_CALLS", "0") != "0";

 #if HAVE_BOEHMGC
    static bool gcInitialised = true;
@@ -152,7 +158,7 @@ EvalState::EvalState()
           physical RAM, up to a maximum of 384 MiB) so that in most
           cases we don't need to garbage collect at all.  (Collection
           has a fairly significant overhead.)  The heap size can be
-           overriden through libgc's GC_INITIAL_HEAP_SIZE environment
+           overridden through libgc's GC_INITIAL_HEAP_SIZE environment
           variable.  We should probably also provide a nix.conf
           setting for this.  Note that GC_expand_hp() causes a lot of
           virtual, but not physical (resident) memory to be
@@ -177,9 +183,9 @@ EvalState::EvalState()

    /* Initialise the Nix expression search path. */
    searchPathInsertionPoint = searchPath.end();
-    Strings paths = tokenizeString(getEnv("NIX_PATH", ""), ":");
+    Strings paths = tokenizeString<Strings>(getEnv("NIX_PATH", ""), ":");
    foreach (Strings::iterator, i, paths) addToSearchPath(*i);
-    addToSearchPath("nix=" + nixDataDir + "/nix/corepkgs");
+    addToSearchPath("nix=" + settings.nixDataDir + "/nix/corepkgs");
    searchPathInsertionPoint = searchPath.begin();

    createBaseEnv();
@@ -216,6 +222,12 @@ void EvalState::addPrimOp(const string & name,
 }


+void EvalState::getBuiltin(const string & name, Value & v)
+{
+    v = *baseEnv.values[0]->attrs->find(symbols.create(name))->value;
+}
+
+
 /* Every "format" object (even temporary) takes up a few hundred bytes
   of stack space, which is a real killer in the recursive
   evaluator.  So here are some helper functions for throwing
@@ -241,6 +253,11 @@ LocalNoInlineNoReturn(void throwTypeError(const char * s, const Pos & pos, const
    throw TypeError(format(s) % pos % s2);
 }

+LocalNoInlineNoReturn(void throwTypeError(const char * s, const string & s1, const string & s2))
+{
+    throw TypeError(format(s) % s1 % s2);
+}
+
 LocalNoInlineNoReturn(void throwTypeError(const char * s, const Pos & pos))
 {
    throw TypeError(format(s) % pos);
@@ -280,7 +297,7 @@ void mkString(Value & v, const string & s, const PathSet & context)
        unsigned int n = 0;
        v.string.context = (const char * *)
            GC_MALLOC((context.size() + 1) * sizeof(char *));
-        foreach (PathSet::const_iterator, i, context)  
+        foreach (PathSet::const_iterator, i, context)
            v.string.context[n++] = GC_STRDUP(i->c_str());
        v.string.context[n] = 0;
    }
@@ -293,21 +310,29 @@ void mkPath(Value & v, const char * s)
 }


-inline Value * EvalState::lookupVar(Env * env, const VarRef & var)
+inline Value * EvalState::lookupVar(Env * env, const VarRef & var, bool noEval)
 {
    for (unsigned int l = var.level; l; --l, env = env->up) ;
-    
-    if (var.fromWith) {
-        while (1) {
-            Bindings::iterator j = env->values[0]->attrs->find(var.name);
-            if (j != env->values[0]->attrs->end())
-                return j->value;
-            if (env->prevWith == 0)
-                throwEvalError("undefined variable `%1%'", var.name);
-            for (unsigned int l = env->prevWith; l; --l, env = env->up) ;
+
+    if (!var.fromWith) return env->values[var.displ];
+
+    while (1) {
+        if (!env->haveWithAttrs) {
+            if (noEval) return 0;
+            Expr * attrs = (Expr *) env->values[0];
+            env->values[0] = allocValue();
+            evalAttrs(*env->up, attrs, *env->values[0]);
+            env->haveWithAttrs = true;
        }
-    } else
-        return env->values[var.displ];
+        Bindings::iterator j = env->values[0]->attrs->find(var.name);
+        if (j != env->values[0]->attrs->end()) {
+            if (countCalls && j->pos) attrSelects[*j->pos]++;
+            return j->value;
+        }
+        if (!env->prevWith)
+            throwEvalError("undefined variable `%1%'", var.name);
+        for (unsigned int l = env->prevWith; l; --l, env = env->up) ;
+    }
 }


@@ -324,10 +349,10 @@ Env & EvalState::allocEnv(unsigned int size)
    nrValuesInEnvs += size;
    Env * env = (Env *) GC_MALLOC(sizeof(Env) + size * sizeof(Value *));

-    /* Clear the values because maybeThunk() expects this. */
+    /* Clear the values because maybeThunk() and lookupVar fromWith expects this. */
    for (unsigned i = 0; i < size; ++i)
        env->values[i] = 0;
-    
+
    return *env;
 }

@@ -339,12 +364,12 @@ Value * EvalState::allocAttr(Value & vAttrs, const Symbol & name)
    return v;
 }

-    
+
 void EvalState::mkList(Value & v, unsigned int length)
 {
    v.type = tList;
    v.list.length = length;
-    v.list.elems = (Value * *) GC_MALLOC(length * sizeof(Value *));
+    v.list.elems = length ? (Value * *) GC_MALLOC(length * sizeof(Value *)) : 0;
    nrListElems += length;
 }

@@ -392,7 +417,7 @@ unsigned long nrAvoided = 0;

 Value * ExprVar::maybeThunk(EvalState & state, Env & env)
 {
-    Value * v = state.lookupVar(&env, info);
+    Value * v = state.lookupVar(&env, info, true);
    /* The value might not be initialised in the environment yet.
       In that case, ignore it. */
    if (v) { nrAvoided++; return v; }
@@ -421,19 +446,30 @@ Value * ExprPath::maybeThunk(EvalState & state, Env & env)

 void EvalState::evalFile(const Path & path, Value & v)
 {
-    FileEvalCache::iterator i = fileEvalCache.find(path);
-    if (i == fileEvalCache.end()) {
-        startNest(nest, lvlTalkative, format("evaluating file `%1%'") % path);
-        Expr * e = parseExprFromFile(path);
-        try {
-            eval(e, v);
-        } catch (Error & e) {
-            addErrorPrefix(e, "while evaluating the file `%1%':\n", path);
-            throw;
-        }
-        fileEvalCache[path] = v;
-    } else
+    Path path2 = resolveExprPath(path);
+
+    FileEvalCache::iterator i = fileEvalCache.find(path2);
+    if (i != fileEvalCache.end()) {
        v = i->second;
+        return;
+    }
+
+    startNest(nest, lvlTalkative, format("evaluating file `%1%'") % path2);
+    Expr * e = parseExprFromFile(path2);
+    try {
+        eval(e, v);
+    } catch (Error & e) {
+        addErrorPrefix(e, "while evaluating the file `%1%':\n", path2);
+        throw;
+    }
+    fileEvalCache[path2] = v;
+    //if (path != path2) fileEvalCache[path2] = v;
+}
+
+
+void EvalState::resetFileCache()
+{
+    fileEvalCache.clear();
 }


@@ -502,23 +538,17 @@ void ExprAttrs::eval(EvalState & state, Env & env, Value & v)
           environment, while the inherited attributes are evaluated
           in the original environment. */
        unsigned int displ = 0;
-        foreach (AttrDefs::iterator, i, attrs)
-            if (i->second.inherited) {
-                /* !!! handle overrides? */
-                Value * vAttr = state.lookupVar(&env, i->second.var);
-                env2.values[displ++] = vAttr;
-                v.attrs->push_back(Attr(i->first, vAttr, &i->second.pos));
-            } else {
-                Value * vAttr;
-                if (hasOverrides) {
-                    vAttr = state.allocValue();
-                    mkThunk(*vAttr, env2, i->second.e);
-                } else
-                    vAttr = i->second.e->maybeThunk(state, env2);
-                env2.values[displ++] = vAttr;
-                v.attrs->push_back(Attr(i->first, vAttr, &i->second.pos));
-            }
-        
+        foreach (AttrDefs::iterator, i, attrs) {
+            Value * vAttr;
+            if (hasOverrides && !i->second.inherited) {
+                vAttr = state.allocValue();
+                mkThunk(*vAttr, env2, i->second.e);
+            } else
+                vAttr = i->second.e->maybeThunk(state, i->second.inherited ? env : env2);
+            env2.values[displ++] = vAttr;
+            v.attrs->push_back(Attr(i->first, vAttr, &i->second.pos));
+        }
+
        /* If the rec contains an attribute called `__overrides', then
           evaluate it, and add the attributes in that set to the rec.
           This allows overriding of recursive attributes, which is
@@ -544,10 +574,7 @@ void ExprAttrs::eval(EvalState & state, Env & env, Value & v)

    else {
        foreach (AttrDefs::iterator, i, attrs)
-            if (i->second.inherited)
-                v.attrs->push_back(Attr(i->first, state.lookupVar(&env, i->second.var), &i->second.pos));
-            else
-                v.attrs->push_back(Attr(i->first, i->second.e->maybeThunk(state, env), &i->second.pos));
+            v.attrs->push_back(Attr(i->first, i->second.e->maybeThunk(state, env), &i->second.pos));
    }
 }

@@ -564,10 +591,7 @@ void ExprLet::eval(EvalState & state, Env & env, Value & v)
       environment. */
    unsigned int displ = 0;
    foreach (ExprAttrs::AttrDefs::iterator, i, attrs->attrs)
-        if (i->second.inherited)
-            env2.values[displ++] = state.lookupVar(&env, i->second.var);
-        else
-            env2.values[displ++] = i->second.e->maybeThunk(state, env2);
+        env2.values[displ++] = i->second.e->maybeThunk(state, i->second.inherited ? env : env2);

    body->eval(state, env2, v);
 }
@@ -583,7 +607,7 @@ void ExprList::eval(EvalState & state, Env & env, Value & v)

 void ExprVar::eval(EvalState & state, Env & env, Value & v)
 {
-    Value * v2 = state.lookupVar(&env, info);
+    Value * v2 = state.lookupVar(&env, info, false);
    state.forceValue(*v2);
    v = *v2;
 }
@@ -600,7 +624,7 @@ void ExprSelect::eval(EvalState & state, Env & env, Value & v)
    e->eval(state, env, vTmp);

    try {
-        
+
        foreach (AttrPath::const_iterator, i, attrPath) {
            nrLookups++;
            Bindings::iterator j;
@@ -619,17 +643,19 @@ void ExprSelect::eval(EvalState & state, Env & env, Value & v)
            }
            vAttrs = j->value;
            pos = j->pos;
+            if (state.countCalls && pos) state.attrSelects[*pos]++;
        }
-    
+
+
        state.forceValue(*vAttrs);
-        
+
    } catch (Error & e) {
        if (pos)
            addErrorPrefix(e, "while evaluating the attribute `%1%' at %2%:\n",
                showAttrPath(attrPath), *pos);
        throw;
    }
-    
+
    v = *vAttrs;
 }

@@ -653,7 +679,7 @@ void ExprOpHasAttr::eval(EvalState & state, Env & env, Value & v)
            vAttrs = j->value;
        }
    }
-    
+
    mkBool(v, true);
 }

@@ -688,10 +714,10 @@ void EvalState::callFunction(Value & fun, Value & arg, Value & v)
        assert(primOp->type == tPrimOp);
        unsigned int arity = primOp->primOp->arity;
        unsigned int argsLeft = arity - argsDone;
-        
+
        if (argsLeft == 1) {
            /* We have all the arguments, so call the primop. */
-                
+
            /* Put all the arguments in an array. */
            Value * vArgs[arity];
            unsigned int n = arity - 1;
@@ -700,6 +726,8 @@ void EvalState::callFunction(Value & fun, Value & arg, Value & v)
                vArgs[n--] = arg->primOpApp.right;

            /* And call the primop. */
+            nrPrimOpCalls++;
+            if (countCalls) primOpCalls[primOp->primOp->name]++;
            try {
                primOp->primOp->fun(*this, vArgs, v);
            } catch (Error & e) {
@@ -714,9 +742,9 @@ void EvalState::callFunction(Value & fun, Value & arg, Value & v)
        }
        return;
    }
-    
+
    if (fun.type != tLambda)
-        throwTypeError("attempt to call something which is neither a function nor a primop (built-in operation) but %1%",
+        throwTypeError("attempt to call something which is not a function but %1%",
            showType(fun));

    unsigned int size =
@@ -732,7 +760,7 @@ void EvalState::callFunction(Value & fun, Value & arg, Value & v)

    else {
        forceAttrs(arg);
-        
+
        if (!fun.lambda.fun->arg.empty())
            env2.values[displ++] = &arg;

@@ -743,8 +771,8 @@ void EvalState::callFunction(Value & fun, Value & arg, Value & v)
        foreach (Formals::Formals_::iterator, i, fun.lambda.fun->formals->formals) {
            Bindings::iterator j = arg.attrs->find(i->name);
            if (j == arg.attrs->end()) {
-                if (!i->def) throwTypeError("function at %1% called without required argument `%2%'",
-                    fun.lambda.fun->pos, i->name);
+                if (!i->def) throwTypeError("%1% called without required argument `%2%'",
+                    fun.lambda.fun->showNamePos(), i->name);
                env2.values[displ++] = i->def->maybeThunk(*this, env2);
            } else {
                attrsUsed++;
@@ -753,17 +781,24 @@ void EvalState::callFunction(Value & fun, Value & arg, Value & v)
        }

        /* Check that each actual argument is listed as a formal
-           argument (unless the attribute match specifies a `...').
-           TODO: show the names of the expected/unexpected
-           arguments. */
-        if (!fun.lambda.fun->formals->ellipsis && attrsUsed != arg.attrs->size()) 
-            throwTypeError("function at %1% called with unexpected argument", fun.lambda.fun->pos);
+           argument (unless the attribute match specifies a `...'). */
+        if (!fun.lambda.fun->formals->ellipsis && attrsUsed != arg.attrs->size()) {
+            /* Nope, so show the first unexpected argument to the
+               user. */
+            foreach (Bindings::iterator, i, *arg.attrs)
+                if (fun.lambda.fun->formals->argNames.find(i->name) == fun.lambda.fun->formals->argNames.end())
+                    throwTypeError("%1% called with unexpected argument `%2%'", fun.lambda.fun->showNamePos(), i->name);
+            abort(); // can't happen
+        }
    }

+    nrFunctionCalls++;
+    if (countCalls) functionCalls[fun.lambda.fun]++;
+
    try {
        fun.lambda.fun->body->eval(*this, env2, v);
    } catch (Error & e) {
-        addErrorPrefix(e, "while evaluating the function at %1%:\n", fun.lambda.fun->pos);
+        addErrorPrefix(e, "while evaluating %1%:\n", fun.lambda.fun->showNamePos());
        throw;
    }
 }
@@ -778,20 +813,20 @@ void EvalState::autoCallFunction(Bindings & args, Value & fun, Value & res)
        return;
    }

-    Value actualArgs;
-    mkAttrs(actualArgs, fun.lambda.fun->formals->formals.size());
+    Value * actualArgs = allocValue();
+    mkAttrs(*actualArgs, fun.lambda.fun->formals->formals.size());

    foreach (Formals::Formals_::iterator, i, fun.lambda.fun->formals->formals) {
        Bindings::iterator j = args.find(i->name);
        if (j != args.end())
-            actualArgs.attrs->push_back(*j);
+            actualArgs->attrs->push_back(*j);
        else if (!i->def)
            throwTypeError("cannot auto-call a function that has an argument without a default value (`%1%')", i->name);
    }

-    actualArgs.attrs->sort();
+    actualArgs->attrs->sort();

-    callFunction(fun, actualArgs, res);
+    callFunction(fun, *actualArgs, res);
 }


@@ -800,9 +835,8 @@ void ExprWith::eval(EvalState & state, Env & env, Value & v)
    Env & env2(state.allocEnv(1));
    env2.up = &env;
    env2.prevWith = prevWith;
-
-    env2.values[0] = state.allocValue();
-    state.evalAttrs(env, attrs, *env2.values[0]);
+    env2.haveWithAttrs = false;
+    env2.values[0] = (Value *) attrs;

    body->eval(state, env2, v);
 }
@@ -813,7 +847,7 @@ void ExprIf::eval(EvalState & state, Env & env, Value & v)
    (state.evalBool(env, cond) ? then : else_)->eval(state, env, v);
 }

-    
+
 void ExprAssert::eval(EvalState & state, Env & env, Value & v)
 {
    if (!state.evalBool(env, cond))
@@ -821,7 +855,7 @@ void ExprAssert::eval(EvalState & state, Env & env, Value & v)
    body->eval(state, env, v);
 }

-    
+
 void ExprOpNot::eval(EvalState & state, Env & env, Value & v)
 {
    mkBool(v, !state.evalBool(env, e));
@@ -894,7 +928,7 @@ void ExprOpUpdate::eval(EvalState & state, Env & env, Value & v)

    while (i != v1.attrs->end()) v.attrs->push_back(*i++);
    while (j != v2.attrs->end()) v.attrs->push_back(*j++);
-    
+
    state.nrOpUpdateValuesCopied += v.attrs->size();
 }

@@ -902,14 +936,36 @@ void ExprOpUpdate::eval(EvalState & state, Env & env, Value & v)
 void ExprOpConcatLists::eval(EvalState & state, Env & env, Value & v)
 {
    Value v1; e1->eval(state, env, v1);
-    state.forceList(v1);
    Value v2; e2->eval(state, env, v2);
-    state.forceList(v2);
-    state.mkList(v, v1.list.length + v2.list.length);
-    for (unsigned int n = 0; n < v1.list.length; ++n)
-        v.list.elems[n] = v1.list.elems[n];
-    for (unsigned int n = 0; n < v2.list.length; ++n)
-        v.list.elems[n + v1.list.length] = v2.list.elems[n];
+    Value * lists[2] = { &v1, &v2 };
+    state.concatLists(v, 2, lists);
+}
+
+
+void EvalState::concatLists(Value & v, unsigned int nrLists, Value * * lists)
+{
+    nrListConcats++;
+
+    Value * nonEmpty = 0;
+    unsigned int len = 0;
+    for (unsigned int n = 0; n < nrLists; ++n) {
+        forceList(*lists[n]);
+        unsigned int l = lists[n]->list.length;
+        len += l;
+        if (l) nonEmpty = lists[n];
+    }
+
+    if (nonEmpty && len == nonEmpty->list.length) {
+        v = *nonEmpty;
+        return;
+    }
+
+    mkList(v, len);
+    for (unsigned int n = 0, pos = 0; n < nrLists; ++n) {
+        unsigned int l = lists[n]->list.length;
+        memcpy(v.list.elems + pos, lists[n]->list.elems, l * sizeof(Value *));
+        pos += l;
+    }
 }


@@ -917,31 +973,39 @@ void ExprConcatStrings::eval(EvalState & state, Env & env, Value & v)
 {
    PathSet context;
    std::ostringstream s;
-        
-    bool first = true, isPath = false;
-    Value vStr;
+    NixInt n = 0;
+
+    bool first = true;
+    ValueType firstType;

    foreach (vector<Expr *>::iterator, i, *es) {
-        (*i)->eval(state, env, vStr);
+        Value vTmp;
+        (*i)->eval(state, env, vTmp);

        /* If the first element is a path, then the result will also
           be a path, we don't copy anything (yet - that's done later,
           since paths are copied when they are used in a derivation),
           and none of the strings are allowed to have contexts. */
        if (first) {
-            isPath = vStr.type == tPath;
+            firstType = vTmp.type;
            first = false;
        }
-            
-        s << state.coerceToString(vStr, context, false, !isPath);
-    }
-        
-    if (isPath && !context.empty())
-        throwEvalError("a string that refers to a store path cannot be appended to a path, in `%1%'", s.str());

-    if (isPath)
+        if (firstType == tInt && !forceString) {
+            if (vTmp.type != tInt)
+                throwEvalError("cannot add %1% to an integer", showType(vTmp));
+            n += vTmp.integer;
+        } else
+            s << state.coerceToString(vTmp, context, false, firstType != tPath);
+    }
+
+    if (firstType == tInt)
+        mkInt(v, n);
+    else if (firstType == tPath) {
+        if (!context.empty())
+            throwEvalError("a string that refers to a store path cannot be appended to a path, in `%1%'", s.str());
        mkPath(v, s.str().c_str());
-    else
+    } else
        mkString(v, s.str(), context);
 }

@@ -949,12 +1013,12 @@ void ExprConcatStrings::eval(EvalState & state, Env & env, Value & v)
 void EvalState::strictForceValue(Value & v)
 {
    forceValue(v);
-    
+
    if (v.type == tAttrs) {
        foreach (Bindings::iterator, i, *v.attrs)
            strictForceValue(*i->value);
    }
-    
+
    else if (v.type == tList) {
        for (unsigned int n = 0; n < v.list.length; ++n)
            strictForceValue(*v.list.elems[n]);
@@ -962,7 +1026,7 @@ void EvalState::strictForceValue(Value & v)
 }


-int EvalState::forceInt(Value & v)
+NixInt EvalState::forceInt(Value & v)
 {
    forceValue(v);
    if (v.type != tInt)
@@ -1000,7 +1064,7 @@ string EvalState::forceString(Value & v)
 void copyContext(const Value & v, PathSet & context)
 {
    if (v.string.context)
-        for (const char * * p = v.string.context; *p; ++p) 
+        for (const char * * p = v.string.context; *p; ++p)
            context.insert(*p);
 }

@@ -1050,7 +1114,7 @@ string EvalState::coerceToString(Value & v, PathSet & context,
        Path path(canonPath(v.path));

        if (!copyToStore) return path;
-        
+
        if (nix::isDerivation(path))
            throwEvalError("file names are not allowed to end in `%1%'", drvExtension);

@@ -1058,9 +1122,9 @@ string EvalState::coerceToString(Value & v, PathSet & context,
        if (srcToStore[path] != "")
            dstPath = srcToStore[path];
        else {
-            dstPath = readOnlyMode
+            dstPath = settings.readOnlyMode
                ? computeStorePathForPath(path).first
-                : store->addToStore(path);
+                : store->addToStore(path, true, htSHA256, defaultPathFilter, repair);
            srcToStore[path] = dstPath;
            printMsg(lvlChatty, format("copied source `%1%' -> `%2%'")
                % path % dstPath);
@@ -1099,7 +1163,7 @@ string EvalState::coerceToString(Value & v, PathSet & context,
            return result;
        }
    }
-    
+
    throwTypeError("cannot coerce %1% to a string", showType(v));
 }

@@ -1175,7 +1239,7 @@ bool EvalState::eqValues(Value & v1, Value & v2)
            for (i = v1.attrs->begin(), j = v2.attrs->begin(); i != v1.attrs->end(); ++i, ++j)
                if (i->name != j->name || !eqValues(*i->value, *j->value))
                    return false;
-            
+
            return true;
        }

@@ -1207,6 +1271,7 @@ void EvalState::printStats()
        % nrEnvs % (nrEnvs * sizeof(Env) + nrValuesInEnvs * sizeof(Value *)));
    printMsg(v, format("  list elements: %1% (%2% bytes)")
        % nrListElems % (nrListElems * sizeof(Value *)));
+    printMsg(v, format("  list concatenations: %1%") % nrListConcats);
    printMsg(v, format("  values allocated: %1% (%2% bytes)")
        % nrValues % (nrValues * sizeof(Value)));
    printMsg(v, format("  attribute sets allocated: %1%") % nrAttrsets);
@@ -1216,6 +1281,36 @@ void EvalState::printStats()
    printMsg(v, format("  number of thunks: %1%") % nrThunks);
    printMsg(v, format("  number of thunks avoided: %1%") % nrAvoided);
    printMsg(v, format("  number of attr lookups: %1%") % nrLookups);
+    printMsg(v, format("  number of primop calls: %1%") % nrPrimOpCalls);
+    printMsg(v, format("  number of function calls: %1%") % nrFunctionCalls);
+
+    if (countCalls) {
+
+        printMsg(v, format("calls to %1% primops:") % primOpCalls.size());
+        typedef std::multimap<unsigned int, Symbol> PrimOpCalls_;
+        PrimOpCalls_ primOpCalls_;
+        foreach (PrimOpCalls::iterator, i, primOpCalls)
+            primOpCalls_.insert(std::pair<unsigned int, Symbol>(i->second, i->first));
+        foreach_reverse (PrimOpCalls_::reverse_iterator, i, primOpCalls_)
+            printMsg(v, format("%1$10d %2%") % i->first % i->second);
+
+        printMsg(v, format("calls to %1% functions:") % functionCalls.size());
+        typedef std::multimap<unsigned int, ExprLambda *> FunctionCalls_;
+        FunctionCalls_ functionCalls_;
+        foreach (FunctionCalls::iterator, i, functionCalls)
+            functionCalls_.insert(std::pair<unsigned int, ExprLambda *>(i->second, i->first));
+        foreach_reverse (FunctionCalls_::reverse_iterator, i, functionCalls_)
+            printMsg(v, format("%1$10d %2%") % i->first % i->second->showNamePos());
+
+        printMsg(v, format("evaluations of %1% attributes:") % attrSelects.size());
+        typedef std::multimap<unsigned int, Pos> AttrSelects_;
+        AttrSelects_ attrSelects_;
+        foreach (AttrSelects::iterator, i, attrSelects)
+            attrSelects_.insert(std::pair<unsigned int, Pos>(i->second, i->first));
+        foreach_reverse (AttrSelects_::reverse_iterator, i, attrSelects_)
+            printMsg(v, format("%1$10d %2%") % i->first % i->second);
+
+    }
 }


@@ -52,7 +52,8 @@ struct PrimOp
 struct Env
 {
    Env * up;
-    unsigned int prevWith; // nr of levels up to next `with' environment
+    unsigned short prevWith; // nr of levels up to next `with' environment
+    bool haveWithAttrs;
    Value * values[0];
 };

@@ -87,19 +88,20 @@ struct EvalState;
 std::ostream & operator << (std::ostream & str, const Value & v);


-class EvalState 
+class EvalState
 {
 public:
    SymbolTable symbols;

    const Symbol sWith, sOutPath, sDrvPath, sType, sMeta, sName,
-        sSystem, sOverrides;
+        sSystem, sOverrides, sOutputs, sOutputName, sIgnoreNulls;
+
+    /* If set, force copying files to the Nix store even if they
+       already exist there. */
+    bool repair;

 private:
-    SrcToStore srcToStore; 
-
-    /* A cache from path names to parse trees. */
-    std::map<Path, Expr *> parseTrees;
+    SrcToStore srcToStore;

    /* A cache from path names to values. */
 #if HAVE_BOEHMGC
@@ -114,23 +116,25 @@ private:
    SearchPath::iterator searchPathInsertionPoint;

 public:
-    
+
    EvalState();
    ~EvalState();

    void addToSearchPath(const string & s);

-    /* Parse a Nix expression from the specified file.  If `path'
-       refers to a directory, then "/default.nix" is appended. */
-    Expr * parseExprFromFile(Path path);
+    /* Parse a Nix expression from the specified file. */
+    Expr * parseExprFromFile(const Path & path);

    /* Parse a Nix expression from the specified string. */
+    Expr * parseExprFromString(const string & s, const Path & basePath, StaticEnv & staticEnv);
    Expr * parseExprFromString(const string & s, const Path & basePath);
-    
+
    /* Evaluate an expression read from the given file to normal
       form. */
    void evalFile(const Path & path, Value & v);

+    void resetFileCache();
+
    /* Look up a file in the search path. */
    Path findFile(const string & path);

@@ -154,7 +158,7 @@ public:
    void strictForceValue(Value & v);

    /* Force `v', and then verify that it has the expected type. */
-    int forceInt(Value & v);
+    NixInt forceInt(Value & v);
    bool forceBool(Value & v);
    inline void forceAttrs(Value & v);
    inline void forceList(Value & v);
@@ -170,7 +174,7 @@ public:
    /* String coercion.  Converts strings, paths and derivations to a
       string.  If `coerceMore' is set, also converts nulls, integers,
       booleans and lists to a string.  If `copyToStore' is set,
-       referenced paths are copied to the Nix store as a side effect.q */
+       referenced paths are copied to the Nix store as a side effect. */
    string coerceToString(Value & v, PathSet & context,
        bool coerceMore = false, bool copyToStore = true);

@@ -179,39 +183,43 @@ public:
       path.  Nothing is copied to the store. */
    Path coerceToPath(Value & v, PathSet & context);

-private:
+public:

    /* The base environment, containing the builtin functions and
       values. */
    Env & baseEnv;

-    unsigned int baseEnvDispl;
-
-public:
-    
    /* The same, but used during parsing to resolve variables. */
    StaticEnv staticBaseEnv; // !!! should be private

 private:
-    
+
+    unsigned int baseEnvDispl;
+
    void createBaseEnv();
-    
+
    void addConstant(const string & name, Value & v);

    void addPrimOp(const string & name,
        unsigned int arity, PrimOpFun primOp);

-    inline Value * lookupVar(Env * env, const VarRef & var);
-    
+public:
+
+    void getBuiltin(const string & name, Value & v);
+
+private:
+
+    inline Value * lookupVar(Env * env, const VarRef & var, bool noEval);
+
    friend class ExprVar;
    friend class ExprAttrs;
    friend class ExprLet;

-    Expr * parse(const char * text,
-        const Path & path, const Path & basePath);
+    Expr * parse(const char * text, const Path & path,
+        const Path & basePath, StaticEnv & staticEnv);

 public:
-    
+
    /* Do a deep equality test between two values.  That is, list
       elements and attributes are compared recursively. */
    bool eqValues(Value & v1, Value & v2);
@@ -221,7 +229,7 @@ public:
    /* Automatically call a function for which each argument has a
       default value or has a binding in the `args' map. */
    void autoCallFunction(Bindings & args, Value & fun, Value & res);
-    
+
    /* Allocation primitives. */
    Value * allocValue();
    Env & allocEnv(unsigned int size);
@@ -232,11 +240,13 @@ public:
    void mkAttrs(Value & v, unsigned int expected);
    void mkThunk_(Value & v, Expr * expr);

+    void concatLists(Value & v, unsigned int nrLists, Value * * lists);
+
    /* Print statistics. */
    void printStats();

 private:
-    
+
    unsigned long nrEnvs;
    unsigned long nrValuesInEnvs;
    unsigned long nrValues;
@@ -244,9 +254,25 @@ private:
    unsigned long nrAttrsets;
    unsigned long nrOpUpdates;
    unsigned long nrOpUpdateValuesCopied;
-    
-    friend class RecursionCounter;
+    unsigned long nrListConcats;
+    unsigned long nrPrimOpCalls;
+    unsigned long nrFunctionCalls;
+
+    bool countCalls;
+
+    typedef std::map<Symbol, unsigned int> PrimOpCalls;
+    PrimOpCalls primOpCalls;
+
+    typedef std::map<ExprLambda *, unsigned int> FunctionCalls;
+    FunctionCalls functionCalls;
+
+    typedef std::map<Pos, unsigned int> AttrSelects;
+    AttrSelects attrSelects;
+
    friend class ExprOpUpdate;
+    friend class ExprOpConcatLists;
+    friend class ExprSelect;
+    friend void prim_getAttr(EvalState & state, Value * * args, Value & v);
 };


@@ -254,4 +280,8 @@ private:
 string showType(const Value & v);


+/* If `path' refers to a directory, then append "/default.nix". */
+Path resolveExprPath(Path path);
+
+
 }
@@ -28,12 +28,53 @@ string DrvInfo::queryOutPath(EvalState & state) const
 }


+DrvInfo::Outputs DrvInfo::queryOutputs(EvalState & state)
+{
+    if (outputs.empty()) {
+        /* Get the ‘outputs’ list. */
+        Bindings::iterator i = attrs->find(state.sOutputs);
+
+        if (i == attrs->end())
+            outputs["out"] = queryOutPath(state);
+        else {
+            state.forceList(*i->value);
+
+            /* For each output... */
+            for (unsigned int j = 0; j < i->value->list.length; ++j) {
+                /* Evaluate the corresponding attribute set. */
+                string name = state.forceStringNoCtx(*i->value->list.elems[j]);
+                Bindings::iterator out = attrs->find(state.symbols.create(name));
+                if (out == attrs->end()) continue; // FIXME: throw error?
+                state.forceAttrs(*out->value);
+
+                /* And evaluate its ‘outPath’ attribute. */
+                Bindings::iterator outPath = out->value->attrs->find(state.sOutPath);
+                if (outPath == out->value->attrs->end()) continue; // FIXME: throw error?
+                PathSet context;
+                outputs[name] = state.coerceToPath(*outPath->value, context);
+            }
+        }
+    }
+    return outputs;
+}
+
+
+string DrvInfo::queryOutputName(EvalState & state) const
+{
+    if (outputName == "" && attrs) {
+        Bindings::iterator i = attrs->find(state.sOutputName);
+        (string &) outputName = i != attrs->end() ? state.forceStringNoCtx(*i->value) : "";
+    }
+    return outputName;
+}
+
+
 MetaInfo DrvInfo::queryMetaInfo(EvalState & state) const
 {
    if (metaInfoRead) return meta;
-    
+
    (bool &) metaInfoRead = true;
-    
+
    Bindings::iterator a = attrs->find(state.sMeta);
    if (a == attrs->end()) return meta; /* fine, empty meta information */

@@ -84,7 +125,8 @@ typedef set<Bindings *> Done;
   makes sense for the caller to recursively search for derivations in
   `v'. */
 static bool getDerivation(EvalState & state, Value & v,
-    const string & attrPath, DrvInfos & drvs, Done & done)
+    const string & attrPath, DrvInfos & drvs, Done & done,
+    bool ignoreAssertionFailures)
 {
    try {
        state.forceValue(v);
@@ -96,7 +138,7 @@ static bool getDerivation(EvalState & state, Value & v,
        done.insert(v.attrs);

        DrvInfo drv;
-    
+
        Bindings::iterator i = v.attrs->find(state.sName);
        /* !!! We really would like to have a decent back trace here. */
        if (i == v.attrs->end()) throw TypeError("derivation name missing");
@@ -114,18 +156,20 @@ static bool getDerivation(EvalState & state, Value & v,

        drvs.push_back(drv);
        return false;
-    
+
    } catch (AssertionError & e) {
-        return false;
+        if (ignoreAssertionFailures) return false;
+        throw;
    }
 }


-bool getDerivation(EvalState & state, Value & v, DrvInfo & drv)
+bool getDerivation(EvalState & state, Value & v, DrvInfo & drv,
+    bool ignoreAssertionFailures)
 {
    Done done;
    DrvInfos drvs;
-    getDerivation(state, v, "", drvs, done);
+    getDerivation(state, v, "", drvs, done, ignoreAssertionFailures);
    if (drvs.size() != 1) return false;
    drv = drvs.front();
    return true;
@@ -140,15 +184,16 @@ static string addToPath(const string & s1, const string & s2)

 static void getDerivations(EvalState & state, Value & vIn,
    const string & pathPrefix, Bindings & autoArgs,
-    DrvInfos & drvs, Done & done)
+    DrvInfos & drvs, Done & done,
+    bool ignoreAssertionFailures)
 {
    Value v;
    state.autoCallFunction(autoArgs, vIn, v);
-    
+
    /* Process the expression. */
    DrvInfo drv;

-    if (!getDerivation(state, v, pathPrefix, drvs, done)) ;
+    if (!getDerivation(state, v, pathPrefix, drvs, done, ignoreAssertionFailures)) ;

    else if (v.type == tAttrs) {

@@ -171,8 +216,8 @@ static void getDerivations(EvalState & state, Value & vIn,
            string pathPrefix2 = addToPath(pathPrefix, i->first);
            Value & v2(*v.attrs->find(i->second)->value);
            if (combineChannels)
-                getDerivations(state, v2, pathPrefix2, autoArgs, drvs, done);
-            else if (getDerivation(state, v2, pathPrefix2, drvs, done)) {
+                getDerivations(state, v2, pathPrefix2, autoArgs, drvs, done, ignoreAssertionFailures);
+            else if (getDerivation(state, v2, pathPrefix2, drvs, done, ignoreAssertionFailures)) {
                /* If the value of this attribute is itself an
                   attribute set, should we recurse into it?  => Only
                   if it has a `recurseForDerivations = true'
@@ -180,7 +225,7 @@ static void getDerivations(EvalState & state, Value & vIn,
                if (v2.type == tAttrs) {
                    Bindings::iterator j = v2.attrs->find(state.symbols.create("recurseForDerivations"));
                    if (j != v2.attrs->end() && state.forceBool(*j->value))
-                        getDerivations(state, v2, pathPrefix2, autoArgs, drvs, done);
+                        getDerivations(state, v2, pathPrefix2, autoArgs, drvs, done, ignoreAssertionFailures);
                }
            }
        }
@@ -191,8 +236,8 @@ static void getDerivations(EvalState & state, Value & vIn,
            startNest(nest, lvlDebug,
                format("evaluating list element"));
            string pathPrefix2 = addToPath(pathPrefix, (format("%1%") % n).str());
-            if (getDerivation(state, *v.list.elems[n], pathPrefix2, drvs, done))
-                getDerivations(state, *v.list.elems[n], pathPrefix2, autoArgs, drvs, done);
+            if (getDerivation(state, *v.list.elems[n], pathPrefix2, drvs, done, ignoreAssertionFailures))
+                getDerivations(state, *v.list.elems[n], pathPrefix2, autoArgs, drvs, done, ignoreAssertionFailures);
        }
    }

@@ -201,11 +246,11 @@ static void getDerivations(EvalState & state, Value & vIn,


 void getDerivations(EvalState & state, Value & v, const string & pathPrefix,
-    Bindings & autoArgs, DrvInfos & drvs)
+    Bindings & autoArgs, DrvInfos & drvs, bool ignoreAssertionFailures)
 {
    Done done;
-    getDerivations(state, v, pathPrefix, autoArgs, drvs, done);
+    getDerivations(state, v, pathPrefix, autoArgs, drvs, done, ignoreAssertionFailures);
 }

- 
+
 }
@@ -25,13 +25,20 @@ typedef std::map<string, MetaValue> MetaInfo;

 struct DrvInfo
 {
+public:
+    typedef std::map<string, Path> Outputs;
+
 private:
    string drvPath;
    string outPath;
+    string outputName;
+    Outputs outputs;

    bool metaInfoRead;
    MetaInfo meta;
-    
+
+    bool failed; // set if we get an AssertionError
+
 public:
    string name;
    string attrPath; /* path towards the derivation */
@@ -40,10 +47,12 @@ public:
    /* !!! make this private */
    Bindings * attrs;

-    DrvInfo() : metaInfoRead(false), attrs(0) { };
+    DrvInfo() : metaInfoRead(false), failed(false), attrs(0) { };

    string queryDrvPath(EvalState & state) const;
    string queryOutPath(EvalState & state) const;
+    string queryOutputName(EvalState & state) const;
+    Outputs queryOutputs(EvalState & state);
    MetaInfo queryMetaInfo(EvalState & state) const;
    MetaValue queryMetaInfo(EvalState & state, const string & name) const;

@@ -51,13 +60,16 @@ public:
    {
        drvPath = s;
    }
-    
+
    void setOutPath(const string & s)
    {
        outPath = s;
    }

    void setMetaInfo(const MetaInfo & meta);
+
+    void setFailed() { failed = true; };
+    bool hasFailed() { return failed; };
 };


@@ -70,10 +82,12 @@ typedef list<DrvInfo> DrvInfos;

 /* If value `v' denotes a derivation, store information about the
   derivation in `drv' and return true.  Otherwise, return false. */
-bool getDerivation(EvalState & state, Value & v, DrvInfo & drv);
+bool getDerivation(EvalState & state, Value & v, DrvInfo & drv,
+    bool ignoreAssertionFailures);

 void getDerivations(EvalState & state, Value & v, const string & pathPrefix,
-    Bindings & autoArgs, DrvInfos & drvs);
+    Bindings & autoArgs, DrvInfos & drvs,
+    bool ignoreAssertionFailures);
+

- 
 }
@@ -9,21 +9,20 @@

 %{
 #include "nixexpr.hh"
-#define BISON_HEADER_HACK
 #include "parser-tab.hh"

 using namespace nix;

 namespace nix {

-    
+
 static void initLoc(YYLTYPE * loc)
 {
    loc->first_line = loc->last_line = 1;
    loc->first_column = loc->last_column = 1;
 }

-    
+
 static void adjustLoc(YYLTYPE * loc, const char * s, size_t len)
 {
    loc->first_line = loc->last_line;
@@ -35,7 +34,7 @@ static void adjustLoc(YYLTYPE * loc, const char * s, size_t len)
           if (*s == '\n') /* cr/lf */
               s++;
           /* fall through */
-       case '\n': 
+       case '\n':
           ++loc->last_line;
           loc->last_column = 1;
           break;
@@ -69,7 +68,7 @@ static Expr * unescapeStr(SymbolTable & symbols, const char * s)
    return new ExprString(symbols.create(t));
 }

- 
+
 }

 #define YY_USER_INIT initLoc(yylloc)
@@ -78,7 +77,7 @@ static Expr * unescapeStr(SymbolTable & symbols, const char * s)
 %}


-ID          [a-zA-Z\_][a-zA-Z0-9\_\']*
+ID          [a-zA-Z\_][a-zA-Z0-9\_\'\-]*
 INT         [0-9]+
 PATH        [a-zA-Z0-9\.\_\-\+]*(\/[a-zA-Z0-9\.\_\-\+]+)+
 SPATH       \<[a-zA-Z0-9\.\_\-\+]+(\/[a-zA-Z0-9\.\_\-\+]+)*\>
@@ -102,6 +101,8 @@ or          { return OR_KW; }

 \=\=        { return EQ; }
 \!\=        { return NEQ; }
+\<\=        { return LEQ; }
+\>\=        { return GEQ; }
 \&\&        { return AND; }
 \|\|        { return OR; }
 \-\>        { return IMPL; }
@@ -109,8 +110,10 @@ or          { return OR_KW; }
 \+\+        { return CONCAT; }

 {ID}        { yylval->id = strdup(yytext); return ID; }
-{INT}       { int n = atoi(yytext); /* !!! overflow */
-              yylval->n = n;
+{INT}       { errno = 0;
+              yylval->n = strtol(yytext, 0, 10);
+              if (errno != 0)
+                  throw ParseError(format("invalid integer `%1%'") % yytext);
              return INT;
            }

@@ -168,7 +171,7 @@ or          { return OR_KW; }


 namespace nix {
-    
+
 /* Horrible, disgusting hack: allow the parser to set the scanner
   start condition back to STRING.  Necessary in interpolations like
   "foo${expr}bar"; after the close brace we have to go back to the
@@ -55,7 +55,7 @@ static string nextComponent(string::const_iterator & p,
    else
        while (p != end && (!isdigit(*p) && *p != '.' && *p != '-'))
            s += *p++;
-    
+
    return s;
 }

@@ -80,7 +80,7 @@ int compareVersions(const string & v1, const string & v2)
 {
    string::const_iterator p1 = v1.begin();
    string::const_iterator p2 = v2.begin();
-    
+
    while (p1 != v1.end() || p2 != v2.end()) {
        string c1 = nextComponent(p1, v1.end());
        string c2 = nextComponent(p2, v2.end());
@@ -95,11 +95,10 @@ int compareVersions(const string & v1, const string & v2)
 DrvNames drvNamesFromArgs(const Strings & opArgs)
 {
    DrvNames result;
-    for (Strings::const_iterator i = opArgs.begin();
-         i != opArgs.end(); ++i)
+    foreach (Strings::const_iterator, i, opArgs)
        result.push_back(DrvName(*i));
    return result;
 }

- 
+
 }
@@ -224,20 +224,18 @@ void ExprAttrs::bindVars(const StaticEnv & env)
 {
    if (recursive) {
        StaticEnv newEnv(false, &env);
-    
+
        unsigned int displ = 0;
        foreach (AttrDefs::iterator, i, attrs)
            newEnv.vars[i->first] = i->second.displ = displ++;
-        
+
        foreach (AttrDefs::iterator, i, attrs)
-            if (i->second.inherited) i->second.var.bind(env);
-            else i->second.e->bindVars(newEnv);
+            i->second.e->bindVars(i->second.inherited ? env : newEnv);
    }

    else
        foreach (AttrDefs::iterator, i, attrs)
-            if (i->second.inherited) i->second.var.bind(env);
-            else i->second.e->bindVars(env);
+            i->second.e->bindVars(env);
 }

 void ExprList::bindVars(const StaticEnv & env)
@@ -249,9 +247,9 @@ void ExprList::bindVars(const StaticEnv & env)
 void ExprLambda::bindVars(const StaticEnv & env)
 {
    StaticEnv newEnv(false, &env);
-    
+
    unsigned int displ = 0;
-    
+
    if (!arg.empty()) newEnv.vars[arg] = displ++;

    if (matchAttrs) {
@@ -268,15 +266,14 @@ void ExprLambda::bindVars(const StaticEnv & env)
 void ExprLet::bindVars(const StaticEnv & env)
 {
    StaticEnv newEnv(false, &env);
-    
+
    unsigned int displ = 0;
    foreach (ExprAttrs::AttrDefs::iterator, i, attrs->attrs)
        newEnv.vars[i->first] = i->second.displ = displ++;
-    
+
    foreach (ExprAttrs::AttrDefs::iterator, i, attrs->attrs)
-        if (i->second.inherited) i->second.var.bind(env);
-        else i->second.e->bindVars(newEnv);
-    
+        i->second.e->bindVars(i->second.inherited ? env : newEnv);
+
    body->bindVars(newEnv);
 }

@@ -293,8 +290,8 @@ void ExprWith::bindVars(const StaticEnv & env)
            prevWith = level;
            break;
        }
-    
-    attrs->bindVars(env);    
+
+    attrs->bindVars(env);
    StaticEnv newEnv(true, &env);
    body->bindVars(newEnv);
 }
@@ -324,4 +321,24 @@ void ExprConcatStrings::bindVars(const StaticEnv & env)
 }


+/* Storing function names. */
+
+void Expr::setName(Symbol & name)
+{
+}
+
+
+void ExprLambda::setName(Symbol & name)
+{
+    this->name = name;
+    body->setName(name);
+}
+
+
+string ExprLambda::showNamePos()
+{
+    return (format("%1% at %2%") % (name.set() ? "`" + (string) name + "'" : "an anonymous function") % pos).str();
+}
+
+
 }
@@ -27,6 +27,15 @@ struct Pos
    Pos() : line(0), column(0) { };
    Pos(const string & file, unsigned int line, unsigned int column)
        : file(file), line(line), column(column) { };
+    bool operator < (const Pos & p2) const
+    {
+        int d = file.compare(p2.file);
+        if (d < 0) return true;
+        if (d > 0) return false;
+        if (line < p2.line) return true;
+        if (line > p2.line) return false;
+        return column < p2.column;
+    }
 };

 extern Pos noPos;
@@ -54,6 +63,7 @@ struct Expr
    virtual void bindVars(const StaticEnv & env);
    virtual void eval(EvalState & state, Env & env, Value & v);
    virtual Value * maybeThunk(EvalState & state, Env & env);
+    virtual void setName(Symbol & name);
 };

 std::ostream & operator << (std::ostream & str, Expr & e);
@@ -65,9 +75,9 @@ std::ostream & operator << (std::ostream & str, Expr & e);

 struct ExprInt : Expr
 {
-    int n;
+    NixInt n;
    Value v;
-    ExprInt(int n) : n(n) { mkInt(v, n); };
+    ExprInt(NixInt n) : n(n) { mkInt(v, n); };
    COMMON_METHODS
    Value * maybeThunk(EvalState & state, Env & env);
 };
@@ -104,7 +114,7 @@ struct VarRef
    /* Whether the variable comes from an environment (e.g. a rec, let
       or function argument) or from a "with". */
    bool fromWith;
-    
+
    /* In the former case, the value is obtained by going `level'
       levels up from the current environment and getting the
       `displ'th value in that environment.  In the latter case, the
@@ -149,12 +159,10 @@ struct ExprAttrs : Expr
    bool recursive;
    struct AttrDef {
        bool inherited;
-        Expr * e; // if not inherited
-        VarRef var; // if inherited
+        Expr * e;
        Pos pos;
        unsigned int displ; // displacement
-        AttrDef(Expr * e, const Pos & pos) : inherited(false), e(e), pos(pos) { };
-        AttrDef(const Symbol & name, const Pos & pos) : inherited(true), var(name), pos(pos) { };
+        AttrDef(Expr * e, const Pos & pos, bool inherited=false) : inherited(inherited), e(e), pos(pos) { };
        AttrDef() { };
    };
    typedef std::map<Symbol, AttrDef> AttrDefs;
@@ -188,6 +196,7 @@ struct Formals
 struct ExprLambda : Expr
 {
    Pos pos;
+    Symbol name;
    Symbol arg;
    bool matchAttrs;
    Formals * formals;
@@ -199,6 +208,8 @@ struct ExprLambda : Expr
            throw ParseError(format("duplicate formal function argument `%1%' at %2%")
                % arg % pos);
    };
+    void setName(Symbol & name);
+    string showNamePos();
    COMMON_METHODS
 };

@@ -268,8 +279,10 @@ MakeBinOp(OpConcatLists, "++")

 struct ExprConcatStrings : Expr
 {
+    bool forceString;
    vector<Expr *> * es;
-    ExprConcatStrings(vector<Expr *> * es) : es(es) { };
+    ExprConcatStrings(bool forceString, vector<Expr *> * es)
+        : forceString(forceString), es(es) { };
    COMMON_METHODS
 };

@@ -4,26 +4,26 @@
 %error-verbose
 %defines
 /* %no-lines */
-%parse-param { yyscan_t scanner }
-%parse-param { ParseData * data }
-%lex-param { yyscan_t scanner }
-%lex-param { ParseData * data }
+%parse-param { void * scanner }
+%parse-param { nix::ParseData * data }
+%lex-param { void * scanner }
+%lex-param { nix::ParseData * data }
 %expect 1
 %expect-rr 1

 %code requires {
-    
+
 #ifndef BISON_HEADER
 #define BISON_HEADER
-    
+
 #include "util.hh"
-    
+
 #include "nixexpr.hh"
 #include "eval.hh"

 namespace nix {

-    struct ParseData 
+    struct ParseData
    {
        EvalState & state;
        SymbolTable & symbols;
@@ -38,7 +38,7 @@ namespace nix {
            , sLetBody(symbols.create("<let-body>"))
            { };
    };
-    
+
 }

 #define YY_DECL int yylex \
@@ -52,7 +52,6 @@ namespace nix {

 #include "parser-tab.hh"
 #include "lexer-tab.hh"
-#define YYSTYPE YYSTYPE // workaround a bug in Bison 2.4

 #include <stdio.h>
 #include <stdlib.h>
@@ -64,14 +63,14 @@ using namespace nix;


 namespace nix {
-    
+

 static void dupAttr(const AttrPath & attrPath, const Pos & pos, const Pos & prevPos)
 {
    throw ParseError(format("attribute `%1%' at %2% already defined at %3%")
        % showAttrPath(attrPath) % pos % prevPos);
 }
- 
+

 static void dupAttr(Symbol attr, const Pos & pos, const Pos & prevPos)
 {
@@ -79,7 +78,7 @@ static void dupAttr(Symbol attr, const Pos & pos, const Pos & prevPos)
    throw ParseError(format("attribute `%1%' at %2% already defined at %3%")
        % showAttrPath(attrPath) % pos % prevPos);
 }
- 
+

 static void addAttr(ExprAttrs * attrs, AttrPath & attrPath,
    Expr * e, const Pos & pos)
@@ -105,6 +104,7 @@ static void addAttr(ExprAttrs * attrs, AttrPath & attrPath,
            }
        }
    }
+    e->setName(attrPath.back());
 }


@@ -121,7 +121,7 @@ static void addFormal(const Pos & pos, Formals * formals, const Formal & formal)
 static Expr * stripIndentation(SymbolTable & symbols, vector<Expr *> & es)
 {
    if (es.empty()) return new ExprString(symbols.create(""));
-    
+
    /* Figure out the minimum indentation.  Note that by design
       whitespace-only final lines are not taken into account.  (So
       the " " in "\n ''" is ignored, but the " " in "\n foo''" is.) */
@@ -170,7 +170,7 @@ static Expr * stripIndentation(SymbolTable & symbols, vector<Expr *> & es)
            es2->push_back(*i);
            continue;
        }
-        
+
        string s2;
        for (unsigned int j = 0; j < e->s.size(); ++j) {
            if (atStartOfLine) {
@@ -203,7 +203,7 @@ static Expr * stripIndentation(SymbolTable & symbols, vector<Expr *> & es)
        es2->push_back(new ExprString(symbols.create(s2)));
    }

-    return new ExprConcatStrings(es2);
+    return es2->size() == 1 ? (*es2)[0] : new ExprConcatStrings(true, es2);
 }


@@ -232,13 +232,13 @@ void yyerror(YYLTYPE * loc, yyscan_t scanner, ParseData * data, const char * err
 %}

 %union {
-  // !!! We're probably leaking stuff here.  
+  // !!! We're probably leaking stuff here.
  nix::Expr * e;
  nix::ExprList * list;
  nix::ExprAttrs * attrs;
  nix::Formals * formals;
  nix::Formal * formal;
-  int n;
+  nix::NixInt n;
  char * id; // !!! -> Symbol
  char * path;
  char * uri;
@@ -269,12 +269,15 @@ void yyerror(YYLTYPE * loc, yyscan_t scanner, ParseData * data, const char * err
 %left OR
 %left AND
 %nonassoc EQ NEQ
+%left '<' '>' LEQ GEQ
 %right UPDATE
-%left NEG
-%left '+'
+%left NOT
+%left '+' '-'
+%left '*' '/'
 %right CONCAT
 %nonassoc '?'
 %nonassoc '~'
+%nonassoc NEGATE

 %%

@@ -306,9 +309,14 @@ expr_if
  ;

 expr_op
-  : '!' expr_op %prec NEG { $$ = new ExprOpNot($2); }
+  : '!' expr_op %prec NOT { $$ = new ExprOpNot($2); }
+  | '-' expr_op %prec NEGATE { $$ = new ExprApp(new ExprApp(new ExprVar(data->symbols.create("__sub")), new ExprInt(0)), $2); }
  | expr_op EQ expr_op { $$ = new ExprOpEq($1, $3); }
  | expr_op NEQ expr_op { $$ = new ExprOpNEq($1, $3); }
+  | expr_op '<' expr_op { $$ = new ExprApp(new ExprApp(new ExprVar(data->symbols.create("__lessThan")), $1), $3); }
+  | expr_op LEQ expr_op { $$ = new ExprOpNot(new ExprApp(new ExprApp(new ExprVar(data->symbols.create("__lessThan")), $3), $1)); }
+  | expr_op '>' expr_op { $$ = new ExprApp(new ExprApp(new ExprVar(data->symbols.create("__lessThan")), $3), $1); }
+  | expr_op GEQ expr_op { $$ = new ExprOpNot(new ExprApp(new ExprApp(new ExprVar(data->symbols.create("__lessThan")), $1), $3)); }
  | expr_op AND expr_op { $$ = new ExprOpAnd($1, $3); }
  | expr_op OR expr_op { $$ = new ExprOpOr($1, $3); }
  | expr_op IMPL expr_op { $$ = new ExprOpImpl($1, $3); }
@@ -318,8 +326,11 @@ expr_op
    { vector<Expr *> * l = new vector<Expr *>;
      l->push_back($1);
      l->push_back($3);
-      $$ = new ExprConcatStrings(l);
+      $$ = new ExprConcatStrings(false, l);
    }
+  | expr_op '-' expr_op { $$ = new ExprApp(new ExprApp(new ExprVar(data->symbols.create("__sub")), $1), $3); }
+  | expr_op '*' expr_op { $$ = new ExprApp(new ExprApp(new ExprVar(data->symbols.create("__mul")), $1), $3); }
+  | expr_op '/' expr_op { $$ = new ExprApp(new ExprApp(new ExprVar(data->symbols.create("__div")), $1), $3); }
  | expr_op CONCAT expr_op { $$ = new ExprOpConcatLists($1, $3); }
  | expr_app
  ;
@@ -349,7 +360,7 @@ expr_simple
      /* For efficiency, and to simplify parse trees a bit. */
      if ($2->empty()) $$ = new ExprString(data->symbols.create(""));
      else if ($2->size() == 1) $$ = $2->front();
-      else $$ = new ExprConcatStrings($2);
+      else $$ = new ExprConcatStrings(true, $2);
  }
  | IND_STRING_OPEN ind_string_parts IND_STRING_CLOSE {
      $$ = stripIndentation(data->symbols, *$2);
@@ -402,7 +413,7 @@ binds
          if ($$->attrs.find(*i) != $$->attrs.end())
              dupAttr(*i, makeCurPos(@3, data), $$->attrs[*i].pos);
          Pos pos = makeCurPos(@3, data);
-          $$->attrs[*i] = ExprAttrs::AttrDef(*i, pos);
+          $$->attrs[*i] = ExprAttrs::AttrDef(new ExprVar(*i), pos, true);
      }
    }
  | binds INHERIT '(' expr ')' attrs ';'
@@ -454,7 +465,7 @@ formal
  : ID { $$ = new Formal(data->symbols.create($1), 0); }
  | ID '?' expr { $$ = new Formal(data->symbols.create($1), $3); }
  ;
-  
+
 %%


@@ -467,10 +478,10 @@ formal


 namespace nix {
-      
+

 Expr * EvalState::parse(const char * text,
-    const Path & path, const Path & basePath)
+    const Path & path, const Path & basePath, StaticEnv & staticEnv)
 {
    yyscan_t scanner;
    ParseData data(*this);
@@ -481,20 +492,20 @@ Expr * EvalState::parse(const char * text,
    yy_scan_string(text, scanner);
    int res = yyparse(scanner, &data);
    yylex_destroy(scanner);
-    
+
    if (res) throw ParseError(data.error);

    try {
-        data.result->bindVars(staticBaseEnv);
+        data.result->bindVars(staticEnv);
    } catch (Error & e) {
        throw ParseError(format("%1%, in `%2%'") % e.msg() % path);
    }
-    
+
    return data.result;
 }


-Expr * EvalState::parseExprFromFile(Path path)
+Path resolveExprPath(Path path)
 {
    assert(path[0] == '/');

@@ -512,21 +523,25 @@ Expr * EvalState::parseExprFromFile(Path path)
    if (S_ISDIR(st.st_mode))
        path = canonPath(path + "/default.nix");

-    /* Read and parse the input file, unless it's already in the parse
-       tree cache. */
-    Expr * e = parseTrees[path];
-    if (!e) {
-        e = parse(readFile(path).c_str(), path, dirOf(path));
-        parseTrees[path] = e;
-    }
+    return path;
+}

-    return e;
+
+Expr * EvalState::parseExprFromFile(const Path & path)
+{
+    return parse(readFile(path).c_str(), path, dirOf(path), staticBaseEnv);
+}
+
+
+Expr * EvalState::parseExprFromString(const string & s, const Path & basePath, StaticEnv & staticEnv)
+{
+    return parse(s.c_str(), "(string)", basePath, staticEnv);
 }


 Expr * EvalState::parseExprFromString(const string & s, const Path & basePath)
 {
-    return parse(s.c_str(), "(string)", basePath);
+    return parseExprFromString(s, basePath, staticBaseEnv);
 }


@@ -541,7 +556,7 @@ void EvalState::addToSearchPath(const string & s)
        prefix = string(s, 0, pos);
        path = string(s, pos + 1);
    }
-    
+
    path = absPath(path);
    if (pathExists(path)) {
        debug(format("adding path `%1%' to the search path") % path);
@@ -554,7 +569,7 @@ Path EvalState::findFile(const string & path)
 {
    foreach (SearchPath::iterator, i, searchPath) {
        Path res;
-        if (i->first.empty()) 
+        if (i->first.empty())
            res = i->second + "/" + path;
        else {
            if (path.compare(0, i->first.size(), i->first) != 0 ||
@@ -37,7 +37,7 @@ std::pair<string, string> decodeContext(const string & s)


 /* Load and evaluate an expression from path specified by the
-   argument. */ 
+   argument. */
 static void prim_import(EvalState & state, Value * * args, Value & v)
 {
    PathSet context;
@@ -51,6 +51,12 @@ static void prim_import(EvalState & state, Value * * args, Value & v)
                % path % ctx);
        if (isDerivation(ctx))
            try {
+                /* For performance, prefetch all substitute info. */
+                PathSet willBuild, willSubstitute, unknown;
+                unsigned long long downloadSize, narSize;
+                queryMissing(*store, singleton<PathSet>(ctx),
+                    willBuild, willSubstitute, unknown, downloadSize, narSize);
+
                /* !!! If using a substitute, we only need to fetch
                   the selected output of this derivation. */
                store->buildPaths(singleton<PathSet>(ctx));
@@ -59,7 +65,30 @@ static void prim_import(EvalState & state, Value * * args, Value & v)
            }
    }

-    state.evalFile(path, v);
+    if (isStorePath(path) && store->isValidPath(path) && isDerivation(path)) {
+        Derivation drv = parseDerivation(readFile(path));
+        Value & w = *state.allocValue();
+        state.mkAttrs(w, 1 + drv.outputs.size());
+        mkString(*state.allocAttr(w, state.sDrvPath), path, singleton<PathSet>("=" + path));
+        state.mkList(*state.allocAttr(w, state.symbols.create("outputs")), drv.outputs.size());
+        unsigned int outputs_index = 0;
+
+        Value * outputsVal = w.attrs->find(state.symbols.create("outputs"))->value;
+        foreach (DerivationOutputs::iterator, i, drv.outputs) {
+            mkString(*state.allocAttr(w, state.symbols.create(i->first)),
+                i->second.path, singleton<PathSet>("!" + i->first + "!" + path));
+            mkString(*(outputsVal->list.elems[outputs_index++] = state.allocValue()),
+                i->first);
+        }
+        w.attrs->sort();
+        Value fun;
+        state.evalFile(state.findFile("nix/imported-drv-to-derivation.nix"), fun);
+        state.forceFunction(fun);
+        mkApp(v, fun, w);
+        state.forceAttrs(v);
+    } else {
+        state.evalFile(path, v);
+    }
 }


@@ -153,8 +182,8 @@ static void prim_genericClosure(EvalState & state, Value * * args, Value & v)
    list<Value> res;
    set<Value, CompareValues> doneKeys; // !!! use Value *?
    while (!workSet.empty()) {
-	Value * e = *(workSet.begin());
-	workSet.pop_front();
+        Value * e = *(workSet.begin());
+        workSet.pop_front();

        state.forceAttrs(*e);

@@ -167,7 +196,7 @@ static void prim_genericClosure(EvalState & state, Value * * args, Value & v)
        if (doneKeys.find(*key->value) != doneKeys.end()) continue;
        doneKeys.insert(*key->value);
        res.push_back(*e);
-        
+
        /* Call the `operator' function with `e' as argument. */
        Value call;
        mkApp(call, *op->value, *e);
@@ -217,7 +246,7 @@ static void prim_addErrorContext(EvalState & state, Value * * args, Value & v)
 }


-/* Try evaluating the argument. Success => {success=true; value=something;}, 
+/* Try evaluating the argument. Success => {success=true; value=something;},
 * else => {success=false; value=false;} */
 static void prim_tryEval(EvalState & state, Value * * args, Value & v)
 {
@@ -280,16 +309,22 @@ static void prim_derivationStrict(EvalState & state, Value * * args, Value & v)
        throw EvalError("required attribute `name' missing");
    string drvName;
    Pos & posDrvName(*attr->pos);
-    try {        
+    try {
        drvName = state.forceStringNoCtx(*attr->value);
    } catch (Error & e) {
        e.addPrefix(format("while evaluating the derivation attribute `name' at %1%:\n") % posDrvName);
        throw;
    }
-    
+
+    /* Check whether null attributes should be ignored. */
+    bool ignoreNulls = false;
+    attr = args[0]->attrs->find(state.sIgnoreNulls);
+    if (attr != args[0]->attrs->end())
+        ignoreNulls = state.forceBool(*attr->value);
+
    /* Build the derivation expression by processing the attributes. */
    Derivation drv;
-    
+
    PathSet context;

    string outputHash, outputHashAlgo;
@@ -299,11 +334,17 @@ static void prim_derivationStrict(EvalState & state, Value * * args, Value & v)
    outputs.insert("out");

    foreach (Bindings::iterator, i, *args[0]->attrs) {
+        if (i->name == state.sIgnoreNulls) continue;
        string key = i->name;
        startNest(nest, lvlVomit, format("processing attribute `%1%'") % key);

        try {

+            if (ignoreNulls) {
+                state.forceValue(*i->value);
+                if (i->value->type == tNull) continue;
+            }
+
            /* The `args' attribute is special: it supplies the
               command-line arguments to the builder. */
            if (key == "args") {
@@ -328,12 +369,12 @@ static void prim_derivationStrict(EvalState & state, Value * * args, Value & v)
                else if (key == "outputHash") outputHash = s;
                else if (key == "outputHashAlgo") outputHashAlgo = s;
                else if (key == "outputHashMode") {
-                    if (s == "recursive") outputHashRecursive = true; 
+                    if (s == "recursive") outputHashRecursive = true;
                    else if (s == "flat") outputHashRecursive = false;
                    else throw EvalError(format("invalid value `%1%' for `outputHashMode' attribute") % s);
                }
                else if (key == "outputs") {
-                    Strings tmp = tokenizeString(s);
+                    Strings tmp = tokenizeString<Strings>(s);
                    outputs.clear();
                    foreach (Strings::iterator, j, tmp) {
                        if (outputs.find(*j) != outputs.end())
@@ -360,13 +401,13 @@ static void prim_derivationStrict(EvalState & state, Value * * args, Value & v)
            throw;
        }
    }
-    
+
    /* Everything in the context of the strings in the derivation
       attributes should be added as dependencies of the resulting
       derivation. */
    foreach (PathSet::iterator, i, context) {
        Path path = *i;
-        
+
        /* Paths marked with `=' denote that the path of a derivation
           is explicitly passed to the builder.  Since that allows the
           builder to gain access to every path in the dependency
@@ -403,7 +444,7 @@ static void prim_derivationStrict(EvalState & state, Value * * args, Value & v)
        else
            drv.inputSrcs.insert(path);
    }
-            
+
    /* Do we have all required attributes? */
    if (drv.builder == "")
        throw EvalError("required attribute `builder' missing");
@@ -420,14 +461,14 @@ static void prim_derivationStrict(EvalState & state, Value * * args, Value & v)
        /* Handle fixed-output derivations. */
        if (outputs.size() != 1 || *(outputs.begin()) != "out")
            throw Error("multiple outputs are not supported in fixed-output derivations");
-        
+
        HashType ht = parseHashType(outputHashAlgo);
        if (ht == htUnknown)
            throw EvalError(format("unknown hash algorithm `%1%'") % outputHashAlgo);
        Hash h = parseHash16or32(ht, outputHash);
        outputHash = printHash(h);
        if (outputHashRecursive) outputHashAlgo = "r:" + outputHashAlgo;
-        
+
        Path outPath = makeFixedOutputPath(outputHashRecursive, ht, h, drvName);
        drv.env["out"] = outPath;
        drv.outputs["out"] = DerivationOutput(outPath, outputHashAlgo, outputHash);
@@ -447,7 +488,7 @@ static void prim_derivationStrict(EvalState & state, Value * * args, Value & v)
        /* Use the masked derivation expression to compute the output
           path. */
        Hash h = hashDerivationModulo(*store, drv);
-        
+
        foreach (DerivationOutputs::iterator, i, drv.outputs)
            if (i->second.path == "") {
                Path outPath = makeOutputPath(i->first, h, drvName);
@@ -457,7 +498,7 @@ static void prim_derivationStrict(EvalState & state, Value * * args, Value & v)
    }

    /* Write the resulting term into the Nix store directory. */
-    Path drvPath = writeDerivation(*store, drv, drvName);
+    Path drvPath = writeDerivation(*store, drv, drvName, state.repair);

    printMsg(lvlChatty, format("instantiated `%1%' -> `%2%'")
        % drvName % drvPath);
@@ -592,10 +633,10 @@ static void prim_toFile(EvalState & state, Value * * args, Value & v)
            throw EvalError(format("in `toFile': the file `%1%' cannot refer to derivation outputs") % name);
        refs.insert(path);
    }
-    
-    Path storePath = readOnlyMode
+
+    Path storePath = settings.readOnlyMode
        ? computeStorePathForText(name, contents, refs)
-        : store->addTextToStore(name, contents, refs);
+        : store->addTextToStore(name, contents, refs, state.repair);

    /* Note: we don't need to add `context' to the context of the
       result, since `storePath' itself has references to the paths
@@ -609,7 +650,7 @@ struct FilterFromExpr : PathFilter
 {
    EvalState & state;
    Value & filter;
-    
+
    FilterFromExpr(EvalState & state, Value & filter)
        : state(state), filter(filter)
    {
@@ -630,12 +671,12 @@ struct FilterFromExpr : PathFilter
        state.callFunction(filter, arg1, fun2);

        Value arg2;
-        mkString(arg2, 
+        mkString(arg2,
            S_ISREG(st.st_mode) ? "regular" :
            S_ISDIR(st.st_mode) ? "directory" :
            S_ISLNK(st.st_mode) ? "symlink" :
            "unknown" /* not supported, will fail! */);
-        
+
        Value res;
        state.callFunction(fun2, arg2, res);

@@ -657,9 +698,9 @@ static void prim_filterSource(EvalState & state, Value * * args, Value & v)

    FilterFromExpr filter(state, *args[0]);

-    Path dstPath = readOnlyMode
+    Path dstPath = settings.readOnlyMode
        ? computeStorePathForPath(path, true, htSHA256, filter).first
-        : store->addToStore(path, true, htSHA256, filter);
+        : store->addToStore(path, true, htSHA256, filter, state.repair);

    mkString(v, dstPath, singleton<PathSet>(dstPath));
 }
@@ -689,7 +730,7 @@ static void prim_attrNames(EvalState & state, Value * * args, Value & v)


 /* Dynamic version of the `.' operator. */
-static void prim_getAttr(EvalState & state, Value * * args, Value & v)
+void prim_getAttr(EvalState & state, Value * * args, Value & v)
 {
    string attr = state.forceStringNoCtx(*args[0]);
    state.forceAttrs(*args[1]);
@@ -698,6 +739,7 @@ static void prim_getAttr(EvalState & state, Value * * args, Value & v)
    if (i == args[1]->attrs->end())
        throw EvalError(format("attribute `%1%' missing") % attr);
    // !!! add to stack trace?
+    if (state.countCalls && i->pos) state.attrSelects[*i->pos]++;
    state.forceValue(*i->value);
    v = *i->value;
 }
@@ -758,12 +800,12 @@ static void prim_listToAttrs(EvalState & state, Value * * args, Value & v)
    for (unsigned int i = 0; i < args[0]->list.length; ++i) {
        Value & v2(*args[0]->list.elems[i]);
        state.forceAttrs(v2);
-        
+
        Bindings::iterator j = v2.attrs->find(state.sName);
        if (j == v2.attrs->end())
            throw TypeError("`name' attribute missing in a call to `listToAttrs'");
        string name = state.forceStringNoCtx(*j->value);
-        
+
        Bindings::iterator j2 = v2.attrs->find(state.symbols.create("value"));
        if (j2 == v2.attrs->end())
            throw TypeError("`value' attribute missing in a call to `listToAttrs'");
@@ -787,7 +829,7 @@ static void prim_intersectAttrs(EvalState & state, Value * * args, Value & v)
 {
    state.forceAttrs(*args[0]);
    state.forceAttrs(*args[1]);
-        
+
    state.mkAttrs(v, std::min(args[0]->attrs->size(), args[1]->attrs->size()));

    foreach (Bindings::iterator, i, *args[0]->attrs) {
@@ -843,19 +885,33 @@ static void prim_isList(EvalState & state, Value * * args, Value & v)
 }


+static void elemAt(EvalState & state, Value & list, int n, Value & v)
+{
+    state.forceList(list);
+    if (n < 0 || n >= list.list.length)
+        throw Error(format("list index %1% is out of bounds") % n);
+    state.forceValue(*list.list.elems[n]);
+    v = *list.list.elems[n];
+}
+
+
+/* Return the n-1'th element of a list. */
+static void prim_elemAt(EvalState & state, Value * * args, Value & v)
+{
+    elemAt(state, *args[0], state.forceInt(*args[1]), v);
+}
+
+
 /* Return the first element of a list. */
 static void prim_head(EvalState & state, Value * * args, Value & v)
 {
-    state.forceList(*args[0]);
-    if (args[0]->list.length == 0)
-        throw Error("`head' called on an empty list");
-    state.forceValue(*args[0]->list.elems[0]);
-    v = *args[0]->list.elems[0];
+    elemAt(state, *args[0], 0, v);
 }


 /* Return a list consisting of everything but the the first element of
-   a list. */
+   a list.  Warning: this function takes O(n) time, so you probably
+   don't want to use it!  */
 static void prim_tail(EvalState & state, Value * * args, Value & v)
 {
    state.forceList(*args[0]);
@@ -876,11 +932,64 @@ static void prim_map(EvalState & state, Value * * args, Value & v)
    state.mkList(v, args[1]->list.length);

    for (unsigned int n = 0; n < v.list.length; ++n)
-        mkApp(*(v.list.elems[n] = state.allocValue()), 
+        mkApp(*(v.list.elems[n] = state.allocValue()),
            *args[0], *args[1]->list.elems[n]);
 }


+/* Filter a list using a predicate; that is, return a list containing
+   every element from the list for which the predicate function
+   returns true. */
+static void prim_filter(EvalState & state, Value * * args, Value & v)
+{
+    state.forceFunction(*args[0]);
+    state.forceList(*args[1]);
+
+    // FIXME: putting this on the stack is risky.
+    Value * vs[args[1]->list.length];
+    unsigned int k = 0;
+
+    bool same = true;
+    for (unsigned int n = 0; n < args[1]->list.length; ++n) {
+        Value res;
+        state.callFunction(*args[0], *args[1]->list.elems[n], res);
+        if (state.forceBool(res))
+            vs[k++] = args[1]->list.elems[n];
+        else
+            same = false;
+    }
+
+    if (same)
+        v = *args[1];
+    else {
+        state.mkList(v, k);
+        for (unsigned int n = 0; n < k; ++n) v.list.elems[n] = vs[n];
+    }
+}
+
+
+/* Return true if a list contains a given element. */
+static void prim_elem(EvalState & state, Value * * args, Value & v)
+{
+    bool res = false;
+    state.forceList(*args[1]);
+    for (unsigned int n = 0; n < args[1]->list.length; ++n)
+        if (state.eqValues(*args[0], *args[1]->list.elems[n])) {
+            res = true;
+            break;
+        }
+    mkBool(v, res);
+}
+
+
+/* Concatenate a list of lists. */
+static void prim_concatLists(EvalState & state, Value * * args, Value & v)
+{
+    state.forceList(*args[0]);
+    state.concatLists(v, args[0]->list.length, args[0]->list.elems);
+}
+
+
 /* Return the length of a list.  This is an O(1) time operation. */
 static void prim_length(EvalState & state, Value * * args, Value & v)
 {
@@ -914,7 +1023,7 @@ static void prim_mul(EvalState & state, Value * * args, Value & v)

 static void prim_div(EvalState & state, Value * * args, Value & v)
 {
-    int i2 = state.forceInt(*args[1]);
+    NixInt i2 = state.forceInt(*args[1]);
    if (i2 == 0) throw EvalError("division by zero");
    mkInt(v, state.forceInt(*args[0]) / i2);
 }
@@ -922,7 +1031,10 @@ static void prim_div(EvalState & state, Value * * args, Value & v)

 static void prim_lessThan(EvalState & state, Value * * args, Value & v)
 {
-    mkBool(v, state.forceInt(*args[0]) < state.forceInt(*args[1]));
+    state.forceValue(*args[0]);
+    state.forceValue(*args[1]);
+    CompareValues comp;
+    mkBool(v, comp(*args[0], *args[1]));
 }


@@ -992,11 +1104,26 @@ static void prim_unsafeDiscardOutputDependency(EvalState & state, Value * * args
        if (p.at(0) == '=') p = "~" + string(p, 1);
        context2.insert(p);
    }
-    
+
    mkString(v, s, context2);
 }


+/* Return the cryptographic hash of a string in base-16. */
+static void prim_hashString(EvalState & state, Value * * args, Value & v)
+{
+    string type = state.forceStringNoCtx(*args[0]);
+    HashType ht = parseHashType(type);
+    if (ht == htUnknown)
+      throw Error(format("unknown hash type `%1%'") % type);
+
+    PathSet context; // discarded
+    string s = state.forceString(*args[1], context);
+
+    mkString(v, printHash(hashString(ht, s)), context);
+};
+
+
 /*************************************************************
 * Versions
 *************************************************************/
@@ -1039,19 +1166,29 @@ void EvalState::createBaseEnv()

    mkBool(v, true);
    addConstant("true", v);
-    
+
    mkBool(v, false);
    addConstant("false", v);
-    
+
    v.type = tNull;
    addConstant("null", v);

    mkInt(v, time(0));
    addConstant("__currentTime", v);

-    mkString(v, thisSystem.c_str());
+    mkString(v, settings.thisSystem.c_str());
    addConstant("__currentSystem", v);

+    mkString(v, nixVersion.c_str());
+    addConstant("__nixVersion", v);
+
+    /* Language version.  This should be increased every time a new
+       language feature gets added.  It's not necessary to increase it
+       when primops get added, because you can just use `builtins ?
+       primOp' to check. */
+    mkInt(v, 1);
+    addConstant("__langVersion", v);
+
    // Miscellaneous
    addPrimOp("import", 1, prim_import);
    addPrimOp("isNull", 1, prim_isNull);
@@ -1092,11 +1229,15 @@ void EvalState::createBaseEnv()

    // Lists
    addPrimOp("__isList", 1, prim_isList);
+    addPrimOp("__elemAt", 2, prim_elemAt);
    addPrimOp("__head", 1, prim_head);
    addPrimOp("__tail", 1, prim_tail);
    addPrimOp("map", 2, prim_map);
+    addPrimOp("__filter", 2, prim_filter);
+    addPrimOp("__elem", 2, prim_elem);
+    addPrimOp("__concatLists", 1, prim_concatLists);
    addPrimOp("__length", 1, prim_length);
-    
+
    // Integer arithmetic
    addPrimOp("__add", 2, prim_add);
    addPrimOp("__sub", 2, prim_sub);
@@ -1110,6 +1251,7 @@ void EvalState::createBaseEnv()
    addPrimOp("__stringLength", 1, prim_stringLength);
    addPrimOp("__unsafeDiscardStringContext", 1, prim_unsafeDiscardStringContext);
    addPrimOp("__unsafeDiscardOutputDependency", 1, prim_unsafeDiscardOutputDependency);
+    addPrimOp("__hashString", 2, prim_hashString);

    // Versions
    addPrimOp("__parseDrvName", 1, prim_parseDrvName);
@@ -1120,7 +1262,7 @@ void EvalState::createBaseEnv()

    /* Add a wrapper around the derivation primop that computes the
       `drvPath' and `outPath' attributes lazily. */
-    mkThunk_(v, parseExprFromFile(findFile("nix/derivation.nix")));
+    evalFile(findFile("nix/derivation.nix"), v);
    addConstant("derivation", v);

    /* Now that we've added all primops, sort the `builtins' attribute
@@ -28,17 +28,17 @@ private:

 public:
    Symbol() : s(0) { };
-    
+
    bool operator == (const Symbol & s2) const
    {
        return s == s2.s;
    }
-    
+
    bool operator != (const Symbol & s2) const
    {
        return s != s2.s;
    }
-    
+
    bool operator < (const Symbol & s2) const
    {
        return s < s2.s;
@@ -49,6 +49,11 @@ public:
        return *s;
    }

+    bool set() const
+    {
+        return s;
+    }
+
    bool empty() const
    {
        return s->empty();
@@ -66,7 +71,7 @@ inline std::ostream & operator << (std::ostream & str, const Symbol & sym)
 class SymbolTable
 {
 private:
-#if HAVE_TR1_UNORDERED_SET 
+#if HAVE_TR1_UNORDERED_SET
    typedef std::tr1::unordered_set<string> Symbols;
 #else
    typedef std::set<string> Symbols;
@@ -31,17 +31,20 @@ struct PrimOp;
 struct Symbol;


+typedef long NixInt;
+
+
 struct Value
 {
    ValueType type;
-    union 
+    union
    {
-        int integer;
+        NixInt integer;
        bool boolean;
-        
-        /* Strings in the evaluator carry a so-called `context' (the
-           ATermList) which is a list of strings representing store
-           paths.  This is to allow users to write things like
+
+        /* Strings in the evaluator carry a so-called `context' which
+           is a list of strings representing store paths.  This is to
+           allow users to write things like

             "--with-freetype2-library=" + freetype + "/lib"

@@ -63,7 +66,7 @@ struct Value
            const char * s;
            const char * * context; // must be in sorted order
        } string;
-        
+
        const char * path;
        Bindings * attrs;
        struct {
@@ -97,7 +100,7 @@ static inline void clearValue(Value & v)
 }


-static inline void mkInt(Value & v, int n)
+static inline void mkInt(Value & v, NixInt n)
 {
    clearValue(v);
    v.type = tInt;
@@ -131,7 +134,7 @@ static inline void mkStringNoCopy(Value & v, const char * s)

 static inline void mkString(Value & v, const Symbol & s)
 {
-    mkStringNoCopy(v, ((string) s).c_str());
+    mkStringNoCopy(v, ((const string &) s).c_str());
 }


@@ -1,12 +1,11 @@
 pkglib_LTLIBRARIES = libmain.la

-libmain_la_SOURCES = shared.cc
+libmain_la_SOURCES = shared.cc stack.cc

 libmain_la_LIBADD = ../libstore/libstore.la @BDW_GC_LIBS@

 pkginclude_HEADERS = shared.hh

 AM_CXXFLAGS = \
- -DNIX_VERSION=\"$(VERSION)\" \
 -I$(srcdir)/.. -I$(srcdir)/../libutil \
 -I$(srcdir)/../libstore
@@ -10,8 +10,10 @@
 #include <cctype>
 #include <exception>

+#include <sys/time.h>
 #include <sys/stat.h>
 #include <unistd.h>
+#include <signal.h>

 #if HAVE_BOEHMGC
 #include <gc/gc.h>
@@ -33,20 +35,10 @@ static void sigintHandler(int signo)
 }


-Path makeRootName(const Path & gcRoot, int & counter)
-{
-    counter++;
-    if (counter == 1)
-        return gcRoot;
-    else
-        return (format("%1%-%2%") % gcRoot % counter).str();
-}
-
-
 void printGCWarning()
 {
    static bool haveWarned = false;
-    warnOnce(haveWarned, 
+    warnOnce(haveWarned,
        "you did not specify `--add-root'; "
        "the result might be removed by the garbage collector");
 }
@@ -57,7 +49,14 @@ void printMissing(StoreAPI & store, const PathSet & paths)
    unsigned long long downloadSize, narSize;
    PathSet willBuild, willSubstitute, unknown;
    queryMissing(store, paths, willBuild, willSubstitute, unknown, downloadSize, narSize);
+    printMissing(willBuild, willSubstitute, unknown, downloadSize, narSize);
+}

+
+void printMissing(const PathSet & willBuild,
+    const PathSet & willSubstitute, const PathSet & unknown,
+    unsigned long long downloadSize, unsigned long long narSize)
+{
    if (!willBuild.empty()) {
        printMsg(lvlInfo, format("these derivations will be built:"));
        foreach (PathSet::iterator, i, willBuild)
@@ -74,7 +73,7 @@ void printMissing(StoreAPI & store, const PathSet & paths)

    if (!unknown.empty()) {
        printMsg(lvlInfo, format("don't know how to build these paths%1%:")
-            % (readOnlyMode ? " (may be caused by read-only store access)" : ""));
+            % (settings.readOnlyMode ? " (may be caused by read-only store access)" : ""));
        foreach (PathSet::iterator, i, unknown)
            printMsg(lvlInfo, format("  %1%") % *i);
    }
@@ -93,12 +92,25 @@ static void setLogType(string lt)
 static bool showTrace = false;


+string getArg(const string & opt,
+    Strings::iterator & i, const Strings::iterator & end)
+{
+    ++i;
+    if (i == end) throw UsageError(format("`%1%' requires an argument") % opt);
+    return *i;
+}
+
+
+void detectStackOverflow();
+
+
 /* Initialize and reorder arguments, then call the actual argument
   processor. */
 static void initAndRun(int argc, char * * argv)
 {
-    setDefaultsFromEnvironment();
-    
+    settings.processEnvironment();
+    settings.loadConfFile();
+
    /* Catch SIGINT. */
    struct sigaction act;
    act.sa_handler = sigintHandler;
@@ -123,12 +135,19 @@ static void initAndRun(int argc, char * * argv)
    if (sigaction(SIGCHLD, &act, 0))
        throw SysError("resetting SIGCHLD");

+    /* Register a SIGSEGV handler to detect stack overflows. */
+    detectStackOverflow();
+
    /* There is no privacy in the Nix system ;-)  At least not for
       now.  In particular, store objects should be readable by
-       everybody.  This prevents nasty surprises when using a shared
-       store (with the setuid() hack). */
+       everybody. */
    umask(0022);

+    /* Initialise the PRNG. */
+    struct timeval tv;
+    gettimeofday(&tv, 0);
+    srandom(tv.tv_usec);
+
    /* Process the NIX_LOG_TYPE environment variable. */
    string lt = getEnv("NIX_LOG_TYPE");
    if (lt != "") setLogType(lt);
@@ -137,7 +156,7 @@ static void initAndRun(int argc, char * * argv)
    Strings args, remaining;
    while (argc--) args.push_back(*argv++);
    args.erase(args.begin());
-    
+
    /* Expand compound dash options (i.e., `-qlf' -> `-q -l -f'), and
       ignore options for the ATerm library. */
    for (Strings::iterator i = args.begin(); i != args.end(); ++i) {
@@ -156,46 +175,44 @@ static void initAndRun(int argc, char * * argv)
    remaining.clear();

    /* Process default options. */
-    int verbosityDelta = 0;
    for (Strings::iterator i = args.begin(); i != args.end(); ++i) {
        string arg = *i;
-        if (arg == "--verbose" || arg == "-v") verbosityDelta++;
-        else if (arg == "--quiet") verbosityDelta--;
+        if (arg == "--verbose" || arg == "-v") verbosity = (Verbosity) (verbosity + 1);
+        else if (arg == "--quiet") verbosity = verbosity > lvlError ? (Verbosity) (verbosity - 1) : lvlError;
        else if (arg == "--log-type") {
-            ++i;
-            if (i == args.end()) throw UsageError("`--log-type' requires an argument");
-            setLogType(*i);
+            string s = getArg(arg, i, args.end());
+            setLogType(s);
        }
        else if (arg == "--no-build-output" || arg == "-Q")
-            buildVerbosity = lvlVomit;
+            settings.buildVerbosity = lvlVomit;
        else if (arg == "--print-build-trace")
-            printBuildTrace = true;
+            settings.printBuildTrace = true;
        else if (arg == "--help") {
            printHelp();
            return;
        }
        else if (arg == "--version") {
-            std::cout << format("%1% (Nix) %2%") % programId % NIX_VERSION << std::endl;
+            std::cout << format("%1% (Nix) %2%") % programId % nixVersion << std::endl;
            return;
        }
        else if (arg == "--keep-failed" || arg == "-K")
-            keepFailed = true;
+            settings.keepFailed = true;
        else if (arg == "--keep-going" || arg == "-k")
-            keepGoing = true;
+            settings.keepGoing = true;
        else if (arg == "--fallback")
-            tryFallback = true;
+            settings.set("build-fallback", "true");
        else if (arg == "--max-jobs" || arg == "-j")
-            maxBuildJobs = getIntArg<unsigned int>(arg, i, args.end());
+            settings.set("build-max-jobs", getArg(arg, i, args.end()));
        else if (arg == "--cores")
-            buildCores = getIntArg<unsigned int>(arg, i, args.end());
+            settings.set("build-cores", getArg(arg, i, args.end()));
        else if (arg == "--readonly-mode")
-            readOnlyMode = true;
+            settings.readOnlyMode = true;
        else if (arg == "--max-silent-time")
-            maxSilentTime = getIntArg<unsigned int>(arg, i, args.end());
+            settings.set("build-max-silent-time", getArg(arg, i, args.end()));
        else if (arg == "--timeout")
-            buildTimeout = getIntArg<unsigned int>(arg, i, args.end());
+            settings.set("build-timeout", getArg(arg, i, args.end()));
        else if (arg == "--no-build-hook")
-            useBuildHook = false;
+            settings.useBuildHook = false;
        else if (arg == "--show-trace")
            showTrace = true;
        else if (arg == "--option") {
@@ -203,14 +220,13 @@ static void initAndRun(int argc, char * * argv)
            string name = *i;
            ++i; if (i == args.end()) throw UsageError("`--option' requires two arguments");
            string value = *i;
-            overrideSetting(name, tokenizeString(value));
+            settings.set(name, value);
        }
        else remaining.push_back(arg);
    }

-    verbosityDelta += queryIntSetting("verbosity", lvlInfo);
-    verbosity = (Verbosity) (verbosityDelta < 0 ? 0 : verbosityDelta);
-    
+    settings.update();
+
    run(remaining);

    /* Close the Nix database. */
@@ -218,56 +234,6 @@ static void initAndRun(int argc, char * * argv)
 }


-bool setuidMode = false;
-
-
-static void setuidInit()
-{
-    /* Don't do anything if this is not a setuid binary. */
-    if (getuid() == geteuid() && getgid() == getegid()) return;
-
-    uid_t nixUid = geteuid();
-    gid_t nixGid = getegid();
-    
-    setuidCleanup();
-
-    /* Don't trust the current directory. */
-    if (chdir("/") == -1) abort();
-
-    /* Set the real (and preferably also the save) uid/gid to the
-       effective uid/gid.  This matters mostly when we're not using
-       build-users (bad!), since some builders (like Perl) complain
-       when real != effective.
-
-       On systems where setresuid is unavailable, we can't drop the
-       saved uid/gid.  This means that we could go back to the
-       original real uid (i.e., the uid of the caller).  That's not
-       really a problem, except maybe when we execute a builder and
-       we're not using build-users.  In that case, the builder may be
-       able to switch to the uid of the caller and possibly do bad
-       stuff.  But note that when not using build-users, the builder
-       could also modify the Nix executables (say, replace them by a
-       Trojan horse), so the problem is already there. */
-
-#if HAVE_SETRESUID
-    if (setresuid(nixUid, nixUid, nixUid)) abort();
-    if (setresgid(nixGid, nixGid, nixGid)) abort();
-#elif HAVE_SETREUID
-    /* Note: doesn't set saved uid/gid! */
-    fprintf(stderr, "warning: cannot set saved uid\n");
-    if (setreuid(nixUid, nixUid)) abort();
-    if (setregid(nixGid, nixGid)) abort();
-#else
-    /* Note: doesn't set real and saved uid/gid! */
-    fprintf(stderr, "warning: cannot set real and saved uids\n");
-    if (setuid(nixUid)) abort();
-    if (setgid(nixGid)) abort();
-#endif
-
-    setuidMode = true;
-}
-
-
 /* Called when the Boehm GC runs out of memory. */
 static void * oomHandler(size_t requested)
 {
@@ -276,6 +242,14 @@ static void * oomHandler(size_t requested)
 }


+void showManPage(const string & name)
+{
+    string cmd = "man " + name;
+    if (system(cmd.c_str()) != 0)
+        throw Error(format("command `%1%' failed") % cmd);
+}
+
+
 int exitCode = 0;
 char * * argvSaved = 0;

@@ -290,11 +264,6 @@ int main(int argc, char * * argv)

    argvSaved = argv;

-    /* If we're setuid, then we need to take some security precautions
-       right away. */
-    if (argc == 0) abort();
-    setuidInit();
-    
    /* Turn on buffering for cerr. */
 #if HAVE_PUBSETBUF
    std::cerr.rdbuf()->pubsetbuf(buf, sizeof(buf));
@@ -323,7 +292,7 @@ int main(int argc, char * * argv)
            throw;
        }
    } catch (UsageError & e) {
-        printMsg(lvlError, 
+        printMsg(lvlError,
            format(
                "error: %1%\n"
                "Try `%2% --help' for more information.")
@@ -26,11 +26,14 @@ MakeError(UsageError, nix::Error);
 class StoreAPI;

 /* Ugh.  No better place to put this. */
-Path makeRootName(const Path & gcRoot, int & counter);
 void printGCWarning();

 void printMissing(StoreAPI & store, const PathSet & paths);

+void printMissing(const PathSet & willBuild,
+    const PathSet & willSubstitute, const PathSet & unknown,
+    unsigned long long downloadSize, unsigned long long narSize);
+
 template<class N> N getIntArg(const string & opt,
    Strings::iterator & i, const Strings::iterator & end)
 {
@@ -42,8 +45,8 @@ template<class N> N getIntArg(const string & opt,
    return n;
 }

-/* Whether we're running setuid. */
-extern bool setuidMode;
+/* Show the manual page for the specified program. */
+void showManPage(const string & name);

 extern volatile ::sig_atomic_t blockInt;

@@ -0,0 +1,72 @@
+#include "config.h"
+
+#include "types.hh"
+
+#include <cstring>
+#include <cstddef>
+#include <cstdlib>
+
+#include <unistd.h>
+#include <signal.h>
+
+namespace nix {
+
+
+static void sigsegvHandler(int signo, siginfo_t * info, void * ctx)
+{
+    /* Detect stack overflows by comparing the faulting address with
+       the stack pointer.  Unfortunately, getting the stack pointer is
+       not portable. */
+    bool haveSP = true;
+    char * sp;
+#if defined(__x86_64__) && defined(REG_RSP)
+    sp = (char *) ((ucontext *) ctx)->uc_mcontext.gregs[REG_RSP];
+#elif defined(REG_ESP)
+    sp = (char *) ((ucontext *) ctx)->uc_mcontext.gregs[REG_ESP];
+#else
+    haveSP = false;
+#endif
+
+    if (haveSP) {
+        ptrdiff_t diff = (char *) info->si_addr - sp;
+        if (diff < 0) diff = -diff;
+        if (diff < 4096) {
+            char msg[] = "error: stack overflow (possible infinite recursion)\n";
+            write(2, msg, strlen(msg));
+            _exit(1); // maybe abort instead?
+        }
+    }
+
+    /* Restore default behaviour (i.e. segfault and dump core). */
+    struct sigaction act;
+    sigfillset(&act.sa_mask);
+    act.sa_handler = SIG_DFL;
+    act.sa_flags = 0;
+    if (sigaction(SIGSEGV, &act, 0)) abort();
+}
+
+
+void detectStackOverflow()
+{
+#if defined(SA_SIGINFO) && defined (SA_ONSTACK)
+    /* Install a SIGSEGV handler to detect stack overflows.  This
+       requires an alternative stack, otherwise the signal cannot be
+       delivered when we're out of stack space. */
+    stack_t stack;
+    stack.ss_size = 4096 * 4 + MINSIGSTKSZ;
+    stack.ss_sp = new char[stack.ss_size];
+    if (!stack.ss_sp) throw Error("cannot allocate alternative stack");
+    stack.ss_flags = 0;
+    if (sigaltstack(&stack, 0) == -1) throw SysError("cannot set alternative stack");
+
+    struct sigaction act;
+    sigfillset(&act.sa_mask);
+    act.sa_sigaction = sigsegvHandler;
+    act.sa_flags = SA_SIGINFO | SA_ONSTACK;
+    if (sigaction(SIGSEGV, &act, 0))
+        throw SysError("resetting SIGCHLD");
+#endif
+}
+
+
+}
@@ -23,10 +23,11 @@ AM_CXXFLAGS = -Wall \
 -DNIX_CONF_DIR=\"$(sysconfdir)/nix\" \
 -DNIX_LIBEXEC_DIR=\"$(libexecdir)\" \
 -DNIX_BIN_DIR=\"$(bindir)\" \
+ -DNIX_VERSION=\"$(VERSION)\" \
 -I$(srcdir)/.. -I$(srcdir)/../libutil \
 -I$(srcdir)/../libstore

 local-store.lo: schema.sql.hh

 %.sql.hh: %.sql
-	../bin2c/bin2c schema < $< > $@ || (rm $@ && exit 1)
+	sed -e 's/"/\\"/g' -e 's/\(.*\)/"\1\\n"/' < $< > $@ || (rm $@ && exit 1)
@@ -12,7 +12,7 @@ void DerivationOutput::parseHashInfo(bool & recursive, HashType & hashType, Hash
 {
    recursive = false;
    string algo = hashAlgo;
-        
+
    if (string(algo, 0, 2) == "r:") {
        recursive = true;
        algo = string(algo, 2);
@@ -21,13 +21,13 @@ void DerivationOutput::parseHashInfo(bool & recursive, HashType & hashType, Hash
    hashType = parseHashType(algo);
    if (hashType == htUnknown)
        throw Error(format("unknown hash algorithm `%1%'") % algo);
-        
+
    hash = parseHash(hashType, this->hash);
 }


 Path writeDerivation(StoreAPI & store,
-    const Derivation & drv, const string & name)
+    const Derivation & drv, const string & name, bool repair)
 {
    PathSet references;
    references.insert(drv.inputSrcs.begin(), drv.inputSrcs.end());
@@ -38,9 +38,9 @@ Path writeDerivation(StoreAPI & store,
       held during a garbage collection). */
    string suffix = name + drvExtension;
    string contents = unparseDerivation(drv);
-    return readOnlyMode
+    return settings.readOnlyMode
        ? computeStorePathForText(suffix, contents, references)
-        : store.addTextToStore(suffix, contents, references);
+        : store.addTextToStore(suffix, contents, references, repair);
 }


@@ -51,7 +51,7 @@ static Path parsePath(std::istream & str)
        throw Error(format("bad path `%1%' in derivation") % s);
    return s;
 }
-    
+

 static StringSet parseStrings(std::istream & str, bool arePaths)
 {
@@ -60,7 +60,7 @@ static StringSet parseStrings(std::istream & str, bool arePaths)
        res.insert(arePaths ? parsePath(str) : parseString(str));
    return res;
 }
-    
+

 Derivation parseDerivation(const string & s)
 {
@@ -106,7 +106,7 @@ Derivation parseDerivation(const string & s)
        expect(str, ")");
        drv.env[name] = value;
    }
-    
+
    expect(str, ")");
    return drv;
 }
@@ -165,7 +165,7 @@ string unparseDerivation(const Derivation & drv)

    s += "],";
    printStrings(s, drv.inputSrcs.begin(), drv.inputSrcs.end());
-    
+
    s += ','; printString(s, drv.platform);
    s += ','; printString(s, drv.builder);
    s += ','; printStrings(s, drv.args.begin(), drv.args.end());
@@ -178,9 +178,9 @@ string unparseDerivation(const Derivation & drv)
        s += ','; printString(s, i->second);
        s += ')';
    }
-    
+
    s += "])";
-    
+
    return s;
 }

@@ -190,7 +190,7 @@ bool isDerivation(const string & fileName)
    return hasSuffix(fileName, drvExtension);
 }

- 
+
 bool isFixedOutputDrv(const Derivation & drv)
 {
    return drv.outputs.size() == 1 &&
@@ -247,9 +247,32 @@ Hash hashDerivationModulo(StoreAPI & store, Derivation drv)
        inputs2[printHash(h)] = i->second;
    }
    drv.inputDrvs = inputs2;
-    
+
    return hashString(htSHA256, unparseDerivation(drv));
 }


+DrvPathWithOutputs parseDrvPathWithOutputs(const string & s)
+{
+    size_t n = s.find("!");
+    return n == s.npos
+        ? DrvPathWithOutputs(s, std::set<string>())
+        : DrvPathWithOutputs(string(s, 0, n), tokenizeString<std::set<string> >(string(s, n + 1), ","));
+}
+
+
+Path makeDrvPathWithOutputs(const Path & drvPath, const std::set<string> & outputs)
+{
+    return outputs.empty()
+        ? drvPath
+        : drvPath + "!" + concatStringsSep(",", outputs);
+}
+
+
+bool wantOutput(const string & output, const std::set<string> & wanted)
+{
+    return wanted.empty() || wanted.find(output) != wanted.end();
+}
+
+
 }
@@ -1,10 +1,10 @@
 #pragma once

-#include <map>
-
 #include "types.hh"
 #include "hash.hh"

+#include <map>
+

 namespace nix {

@@ -57,7 +57,7 @@ class StoreAPI;

 /* Write a derivation to the Nix store, and return its path. */
 Path writeDerivation(StoreAPI & store,
-    const Derivation & drv, const string & name);
+    const Derivation & drv, const string & name, bool repair = false);

 /* Parse a derivation. */
 Derivation parseDerivation(const string & s);
@@ -79,4 +79,15 @@ typedef std::map<Path, Hash> DrvHashes;

 extern DrvHashes drvHashes;

+/* Split a string specifying a derivation and a set of outputs
+   (/nix/store/hash-foo!out1,out2,...) into the derivation path and
+   the outputs. */
+typedef std::pair<string, std::set<string> > DrvPathWithOutputs;
+DrvPathWithOutputs parseDrvPathWithOutputs(const string & s);
+
+Path makeDrvPathWithOutputs(const Path & drvPath, const std::set<string> & outputs);
+
+bool wantOutput(const string & output, const std::set<string> & wanted);
+
+
 }
@@ -1,7 +1,6 @@
 #include "globals.hh"
 #include "misc.hh"
 #include "local-store.hh"
-#include "immutable.hh"

 #include <boost/shared_ptr.hpp>

@@ -34,10 +33,10 @@ static const int defaultGcLevel = 1000;
 int LocalStore::openGCLock(LockType lockType)
 {
    Path fnGCLock = (format("%1%/%2%")
-        % nixStateDir % gcLockName).str();
-         
+        % settings.nixStateDir % gcLockName).str();
+
    debug(format("acquiring global GC lock `%1%'") % fnGCLock);
-    
+
    AutoCloseFD fdGCLock = open(fnGCLock.c_str(), O_RDWR | O_CREAT, 0600);
    if (fdGCLock == -1)
        throw SysError(format("opening global GC lock `%1%'") % fnGCLock);
@@ -51,7 +50,7 @@ int LocalStore::openGCLock(LockType lockType)
    /* !!! Restrict read permission on the GC root.  Otherwise any
       process that can open the file for reading can DoS the
       collector. */
-    
+
    return fdGCLock.borrow();
 }

@@ -85,7 +84,7 @@ void LocalStore::addIndirectRoot(const Path & path)
 {
    string hash = printHash32(hashString(htSHA1, path));
    Path realRoot = canonPath((format("%1%/%2%/auto/%3%")
-        % nixStateDir % gcRootsDir % hash).str());
+        % settings.nixStateDir % gcRootsDir % hash).str());
    createSymlink(realRoot, path);
 }

@@ -113,15 +112,15 @@ Path addPermRoot(StoreAPI & store, const Path & _storePath,

    else {
        if (!allowOutsideRootsDir) {
-            Path rootsDir = canonPath((format("%1%/%2%") % nixStateDir % gcRootsDir).str());
-    
+            Path rootsDir = canonPath((format("%1%/%2%") % settings.nixStateDir % gcRootsDir).str());
+
            if (string(gcRoot, 0, rootsDir.size() + 1) != rootsDir + "/")
                throw Error(format(
                    "path `%1%' is not a valid garbage collector root; "
                    "it's not in the directory `%2%'")
                    % gcRoot % rootsDir);
        }
-            
+
        createSymlink(gcRoot, storePath);
    }

@@ -130,10 +129,10 @@ Path addPermRoot(StoreAPI & store, const Path & _storePath,
       Instead of reading all the roots, it would be more efficient to
       check if the root is in a directory in or linked from the
       gcroots directory. */
-    if (queryBoolSetting("gc-check-reachability", false)) {
+    if (settings.checkRootReachability) {
        Roots roots = store.findRoots();
        if (roots.find(gcRoot) == roots.end())
-            printMsg(lvlError, 
+            printMsg(lvlError,
                format(
                    "warning: `%1%' is not in a directory where the garbage collector looks for roots; "
                    "therefore, `%2%' might be removed by the garbage collector")
@@ -144,7 +143,7 @@ Path addPermRoot(StoreAPI & store, const Path & _storePath,
       progress.  This prevents the set of permanent roots from
       increasing while a GC is in progress. */
    store.syncWithGC();
-    
+
    return gcRoot;
 }

@@ -160,23 +159,23 @@ void LocalStore::addTempRoot(const Path & path)
    if (fdTempRoots == -1) {

        while (1) {
-            Path dir = (format("%1%/%2%") % nixStateDir % tempRootsDir).str();
+            Path dir = (format("%1%/%2%") % settings.nixStateDir % tempRootsDir).str();
            createDirs(dir);
-            
+
            fnTempRoots = (format("%1%/%2%")
                % dir % getpid()).str();

            AutoCloseFD fdGCLock = openGCLock(ltRead);
-            
+
            if (pathExists(fnTempRoots))
                /* It *must* be stale, since there can be no two
                   processes with the same pid. */
                unlink(fnTempRoots.c_str());

-	    fdTempRoots = openLockFile(fnTempRoots, true);
+            fdTempRoots = openLockFile(fnTempRoots, true);

            fdGCLock.close();
-      
+
            debug(format("acquiring read lock on `%1%'") % fnTempRoots);
            lockFile(fdTempRoots, ltRead, true);

@@ -186,7 +185,7 @@ void LocalStore::addTempRoot(const Path & path)
            if (fstat(fdTempRoots, &st) == -1)
                throw SysError(format("statting `%1%'") % fnTempRoots);
            if (st.st_size == 0) break;
-            
+
            /* The garbage collector deleted this file before we could
               get a lock.  (It won't delete the file after we get a
               lock.)  Try again. */
@@ -218,7 +217,7 @@ void removeTempRoots()


 /* Automatically clean up the temporary roots file when we exit. */
-struct RemoveTempRoots 
+struct RemoveTempRoots
 {
    ~RemoveTempRoots()
    {
@@ -238,10 +237,10 @@ static void readTempRoots(PathSet & tempRoots, FDs & fds)
    /* Read the `temproots' directory for per-process temporary root
       files. */
    Strings tempRootFiles = readDirectory(
-        (format("%1%/%2%") % nixStateDir % tempRootsDir).str());
+        (format("%1%/%2%") % settings.nixStateDir % tempRootsDir).str());

    foreach (Strings::iterator, i, tempRootFiles) {
-        Path path = (format("%1%/%2%/%3%") % nixStateDir % tempRootsDir % *i).str();
+        Path path = (format("%1%/%2%/%3%") % settings.nixStateDir % tempRootsDir % *i).str();

        debug(format("reading temporary root file `%1%'") % path);
        FDPtr fd(new AutoCloseFD(open(path.c_str(), O_RDWR, 0666)));
@@ -259,8 +258,7 @@ static void readTempRoots(PathSet & tempRoots, FDs & fds)
           only succeed if the owning process has died.  In that case
           we don't care about its temporary roots. */
        if (lockFile(*fd, ltWrite, false)) {
-            printMsg(lvlError, format("removing stale temporary roots file `%1%'")
-                % path);
+            printMsg(lvlError, format("removing stale temporary roots file `%1%'") % path);
            unlink(path.c_str());
            writeFull(*fd, (const unsigned char *) "d", 1);
            continue;
@@ -291,46 +289,47 @@ static void readTempRoots(PathSet & tempRoots, FDs & fds)
 }


-static void findRoots(StoreAPI & store, const Path & path,
-    bool recurseSymlinks, bool deleteStale, Roots & roots)
+static void foundRoot(StoreAPI & store,
+    const Path & path, const Path & target, Roots & roots)
+{
+    Path storePath = toStorePath(target);
+    if (store.isValidPath(storePath))
+        roots[path] = storePath;
+    else
+        printMsg(lvlInfo, format("skipping invalid root from `%1%' to `%2%'") % path % storePath);
+}
+
+
+static void findRoots(StoreAPI & store, const Path & path, Roots & roots)
 {
    try {
-        
-        struct stat st;
-        if (lstat(path.c_str(), &st) == -1)
-            throw SysError(format("statting `%1%'") % path);

-        printMsg(lvlVomit, format("looking at `%1%'") % path);
+        struct stat st = lstat(path);

        if (S_ISDIR(st.st_mode)) {
            Strings names = readDirectory(path);
            foreach (Strings::iterator, i, names)
-                findRoots(store, path + "/" + *i, recurseSymlinks, deleteStale, roots);
+                findRoots(store, path + "/" + *i, roots);
        }

        else if (S_ISLNK(st.st_mode)) {
-            Path target = absPath(readLink(path), dirOf(path));
+            Path target = readLink(path);
+            if (isInStore(target))
+                foundRoot(store, path, target, roots);

-            if (isInStore(target)) {
-                debug(format("found root `%1%' in `%2%'")
-                    % target % path);
-                Path storePath = toStorePath(target);
-                if (store.isValidPath(storePath)) 
-                    roots[path] = storePath;
-                else
-                    printMsg(lvlInfo, format("skipping invalid root from `%1%' to `%2%'")
-                        % path % storePath);
-            }
-
-            else if (recurseSymlinks) {
-                if (pathExists(target))
-                    findRoots(store, target, false, deleteStale, roots);
-                else if (deleteStale) {
-                    printMsg(lvlInfo, format("removing stale link from `%1%' to `%2%'") % path % target);
-                    /* Note that we only delete when recursing, i.e.,
-                       when we are still in the `gcroots' tree.  We
-                       never delete stuff outside that tree. */
-                    unlink(path.c_str());
+            /* Handle indirect roots. */
+            else {
+                target = absPath(target, dirOf(path));
+                if (!pathExists(target)) {
+                    if (isInDir(path, settings.nixStateDir + "/" + gcRootsDir + "/auto")) {
+                        printMsg(lvlInfo, format("removing stale link from `%1%' to `%2%'") % path % target);
+                        unlink(path.c_str());
+                    }
+                } else {
+                    struct stat st2 = lstat(target);
+                    if (!S_ISLNK(st2.st_mode)) return;
+                    Path target2 = readLink(target);
+                    if (isInStore(target2)) foundRoot(store, path, target2, roots);
                }
            }
        }
@@ -347,35 +346,33 @@ static void findRoots(StoreAPI & store, const Path & path,
 }


-static Roots findRoots(StoreAPI & store, bool deleteStale)
-{
-    Roots roots;
-    Path rootsDir = canonPath((format("%1%/%2%") % nixStateDir % gcRootsDir).str());
-    findRoots(store, rootsDir, true, deleteStale, roots);
-    return roots;
-}
-
-
 Roots LocalStore::findRoots()
 {
-    return nix::findRoots(*this, false);
+    Roots roots;
+
+    /* Process direct roots in {gcroots,manifests,profiles}. */
+    nix::findRoots(*this, settings.nixStateDir + "/" + gcRootsDir, roots);
+    nix::findRoots(*this, settings.nixStateDir + "/manifests", roots);
+    nix::findRoots(*this, settings.nixStateDir + "/profiles", roots);
+
+    return roots;
 }


 static void addAdditionalRoots(StoreAPI & store, PathSet & roots)
 {
    Path rootFinder = getEnv("NIX_ROOT_FINDER",
-        nixLibexecDir + "/nix/find-runtime-roots.pl");
+        settings.nixLibexecDir + "/nix/find-runtime-roots.pl");

    if (rootFinder.empty()) return;
-    
+
    debug(format("executing `%1%' to find additional roots") % rootFinder);

    string result = runProgram(rootFinder);

-    Strings paths = tokenizeString(result, "\n");
-    
-    foreach (Strings::iterator, i, paths) {
+    StringSet paths = tokenizeString<StringSet>(result, "\n");
+
+    foreach (StringSet::iterator, i, paths) {
        if (isInStore(*i)) {
            Path path = toStorePath(*i);
            if (roots.find(path) == roots.end() && store.isValidPath(path)) {
@@ -396,24 +393,17 @@ struct LocalStore::GCState
    GCResults & results;
    PathSet roots;
    PathSet tempRoots;
-    PathSet deleted;
-    PathSet live;
-    PathSet busy;
-    PathSet invalidated;
+    PathSet dead;
+    PathSet alive;
    bool gcKeepOutputs;
    bool gcKeepDerivations;
    unsigned long long bytesInvalidated;
+    Path trashDir;
+    bool shouldDelete;
    GCState(GCResults & results_) : results(results_), bytesInvalidated(0) { }
 };


-static bool shouldDelete(GCOptions::GCAction action)
-{
-    return action == GCOptions::gcDeleteDead
-        || action == GCOptions::gcDeleteSpecific;
-}
-
-
 bool LocalStore::isActiveTempFile(const GCState & state,
    const Path & path, const string & suffix)
 {
@@ -424,158 +414,207 @@ bool LocalStore::isActiveTempFile(const GCState & state,

 void LocalStore::deleteGarbage(GCState & state, const Path & path)
 {
-    printMsg(lvlInfo, format("deleting `%1%'") % path);
-    unsigned long long bytesFreed, blocksFreed;
-    deletePathWrapped(path, bytesFreed, blocksFreed);
+    unsigned long long bytesFreed;
+    deletePathWrapped(path, bytesFreed);
    state.results.bytesFreed += bytesFreed;
-    state.results.blocksFreed += blocksFreed;
 }


-bool LocalStore::tryToDelete(GCState & state, const Path & path)
+void LocalStore::deletePathRecursive(GCState & state, const Path & path)
 {
    checkInterrupt();

-    struct stat st;
-    if (lstat(path.c_str(), &st)) {
-        if (errno == ENOENT) return true;
-        throw SysError(format("getting status of %1%") % path);
-    }
-
-    if (state.deleted.find(path) != state.deleted.end()) return true;
-    if (state.live.find(path) != state.live.end()) return false;
-
-    startNest(nest, lvlDebug, format("considering whether to delete `%1%'") % path);
-
-    if (state.roots.find(path) != state.roots.end()) {
-        printMsg(lvlDebug, format("cannot delete `%1%' because it's a root") % path);
-        goto isLive;
-    }
+    unsigned long long size = 0;

    if (isValidPath(path)) {
-
-        /* Recursively try to delete the referrers of this path.  If
-           any referrer can't be deleted, then this path can't be
-           deleted either. */
        PathSet referrers;
        queryReferrers(path, referrers);
        foreach (PathSet::iterator, i, referrers)
-            if (*i != path && !tryToDelete(state, *i)) {
-                printMsg(lvlDebug, format("cannot delete `%1%' because it has live referrers") % path);
-                goto isLive;
-            }
-
-        /* If gc-keep-derivations is set and this is a derivation,
-           then don't delete the derivation if any of the outputs are
-           live. */
-        if (state.gcKeepDerivations && isDerivation(path)) {
-            PathSet outputs = queryDerivationOutputs(path);
-            foreach (PathSet::iterator, i, outputs)
-                if (!tryToDelete(state, *i)) {
-                    printMsg(lvlDebug, format("cannot delete derivation `%1%' because its output `%2%' is alive") % path % *i);
-                    goto isLive;
-                }
-        }
-
-        /* If gc-keep-derivations and gc-keep-outputs are both set,
-           it's possible that the path has already been deleted (due
-           to the recursion below), so bail out. */
-        if (!pathExists(path)) return true;
-
-        /* If gc-keep-outputs is set, then don't delete this path if
-           there are derivers of this path that are not garbage. */
-        if (state.gcKeepOutputs) {
-            PathSet derivers = queryValidDerivers(path);
-            foreach (PathSet::iterator, deriver, derivers) {
-                /* Break an infinite recursion if gc-keep-derivations
-                   and gc-keep-outputs are both set by tentatively
-                   assuming that this path is garbage.  This is a safe
-                   assumption because at this point, the only thing
-                   that can prevent it from being garbage is the
-                   deriver.  Since tryToDelete() works "upwards"
-                   through the dependency graph, it won't encouter
-                   this path except in the call to tryToDelete() in
-                   the gc-keep-derivation branch. */
-                state.deleted.insert(path);
-                if (!tryToDelete(state, *deriver)) {
-                    state.deleted.erase(path);
-                    printMsg(lvlDebug, format("cannot delete `%1%' because its deriver `%2%' is alive") % path % *deriver);
-                    goto isLive;
-                }
-            }
-        }
+            if (*i != path) deletePathRecursive(state, *i);
+        size = queryPathInfo(path).narSize;
+        invalidatePathChecked(path);
    }

-    else {
+    struct stat st;
+    if (lstat(path.c_str(), &st)) {
+        if (errno == ENOENT) return;
+        throw SysError(format("getting status of %1%") % path);
+    }

+    printMsg(lvlInfo, format("deleting `%1%'") % path);
+
+    state.results.paths.insert(path);
+
+    /* If the path is not a regular file or symlink, move it to the
+       trash directory.  The move is to ensure that later (when we're
+       not holding the global GC lock) we can delete the path without
+       being afraid that the path has become alive again.  Otherwise
+       delete it right away. */
+    if (S_ISDIR(st.st_mode)) {
+        // Estimate the amount freed using the narSize field.  FIXME:
+        // if the path was not valid, need to determine the actual
+        // size.
+        state.bytesInvalidated += size;
+        // Mac OS X cannot rename directories if they are read-only.
+        if (chmod(path.c_str(), st.st_mode | S_IWUSR) == -1)
+            throw SysError(format("making `%1%' writable") % path);
+        Path tmp = state.trashDir + "/" + baseNameOf(path);
+        if (rename(path.c_str(), tmp.c_str()))
+            throw SysError(format("unable to rename `%1%' to `%2%'") % path % tmp);
+    } else
+        deleteGarbage(state, path);
+
+    if (state.results.bytesFreed + state.bytesInvalidated > state.options.maxFreed) {
+        printMsg(lvlInfo, format("deleted or invalidated more than %1% bytes; stopping") % state.options.maxFreed);
+        throw GCLimitReached();
+    }
+}
+
+
+bool LocalStore::canReachRoot(GCState & state, PathSet & visited, const Path & path)
+{
+    if (visited.find(path) != visited.end()) return false;
+
+    if (state.alive.find(path) != state.alive.end()) {
+        return true;
+    }
+
+    if (state.dead.find(path) != state.dead.end()) {
+        return false;
+    }
+
+    if (state.roots.find(path) != state.roots.end()) {
+        printMsg(lvlDebug, format("cannot delete `%1%' because it's a root") % path);
+        state.alive.insert(path);
+        return true;
+    }
+
+    visited.insert(path);
+
+    if (!isValidPath(path)) return false;
+
+    PathSet incoming;
+
+    /* Don't delete this path if any of its referrers are alive. */
+    queryReferrers(path, incoming);
+
+    /* If gc-keep-derivations is set and this is a derivation, then
+       don't delete the derivation if any of the outputs are alive. */
+    if (state.gcKeepDerivations && isDerivation(path)) {
+        PathSet outputs = queryDerivationOutputs(path);
+        foreach (PathSet::iterator, i, outputs)
+            if (isValidPath(*i) && queryDeriver(*i) == path)
+                incoming.insert(*i);
+    }
+
+    /* If gc-keep-outputs is set, then don't delete this path if there
+       are derivers of this path that are not garbage. */
+    if (state.gcKeepOutputs) {
+        PathSet derivers = queryValidDerivers(path);
+        foreach (PathSet::iterator, i, derivers)
+            incoming.insert(*i);
+    }
+
+    foreach (PathSet::iterator, i, incoming)
+        if (*i != path)
+            if (canReachRoot(state, visited, *i)) {
+                state.alive.insert(path);
+                return true;
+            }
+
+    return false;
+}
+
+
+void LocalStore::tryToDelete(GCState & state, const Path & path)
+{
+    checkInterrupt();
+
+    if (path == linksDir || path == state.trashDir) return;
+
+    startNest(nest, lvlDebug, format("considering whether to delete `%1%'") % path);
+
+    if (!isValidPath(path)) {
        /* A lock file belonging to a path that we're building right
           now isn't garbage. */
-        if (isActiveTempFile(state, path, ".lock")) return false;
+        if (isActiveTempFile(state, path, ".lock")) return;

        /* Don't delete .chroot directories for derivations that are
           currently being built. */
-        if (isActiveTempFile(state, path, ".chroot")) return false;
-
+        if (isActiveTempFile(state, path, ".chroot")) return;
    }

-    /* The path is garbage, so delete it. */
-    if (shouldDelete(state.options.action)) {
+    PathSet visited;

-        /* If it's a valid path that's not a regular file or symlink,
-           invalidate it, rename it, and schedule it for deletion.
-           The renaming is to ensure that later (when we're not
-           holding the global GC lock) we can delete the path without
-           being afraid that the path has become alive again.
-           Otherwise delete it right away. */
-        if (isValidPath(path)) {
-            if (S_ISDIR(st.st_mode)) {
-                printMsg(lvlInfo, format("invalidating `%1%'") % path);
-                // Estimate the amount freed using the narSize field.
-                state.bytesInvalidated += queryPathInfo(path).narSize;
-                invalidatePathChecked(path);
-                makeMutable(path.c_str());
-                // Mac OS X cannot rename directories if they are read-only.
-                if (chmod(path.c_str(), st.st_mode | S_IWUSR) == -1)
-                    throw SysError(format("making `%1%' writable") % path);
-                Path tmp = (format("%1%-gc-%2%") % path % getpid()).str();
-                if (rename(path.c_str(), tmp.c_str()))
-                    throw SysError(format("unable to rename `%1%' to `%2%'") % path % tmp);
-                state.invalidated.insert(tmp);
-            } else {
-                invalidatePathChecked(path);
-                deleteGarbage(state, path);
-            }
-        } else
-            deleteGarbage(state, path);
+    if (canReachRoot(state, visited, path)) {
+        printMsg(lvlDebug, format("cannot delete `%1%' because it's still reachable") % path);
+    } else {
+        /* No path we visited was a root, so everything is garbage.
+           But we only delete ‘path’ and its referrers here so that
+           ‘nix-store --delete’ doesn't have the unexpected effect of
+           recursing into derivations and outputs. */
+        state.dead.insert(visited.begin(), visited.end());
+        if (state.shouldDelete)
+            deletePathRecursive(state, path);
+    }
+}

-        if (state.options.maxFreed && state.results.bytesFreed + state.bytesInvalidated > state.options.maxFreed) {
-            printMsg(lvlInfo, format("deleted or invalidated more than %1% bytes; stopping") % state.options.maxFreed);
-            throw GCLimitReached();
+
+/* Unlink all files in /nix/store/.links that have a link count of 1,
+   which indicates that there are no other links and so they can be
+   safely deleted.  FIXME: race condition with optimisePath(): we
+   might see a link count of 1 just before optimisePath() increases
+   the link count. */
+void LocalStore::removeUnusedLinks(const GCState & state)
+{
+    AutoCloseDir dir = opendir(linksDir.c_str());
+    if (!dir) throw SysError(format("opening directory `%1%'") % linksDir);
+
+    long long actualSize = 0, unsharedSize = 0;
+
+    struct dirent * dirent;
+    while (errno = 0, dirent = readdir(dir)) {
+        checkInterrupt();
+        string name = dirent->d_name;
+        if (name == "." || name == "..") continue;
+        Path path = linksDir + "/" + name;
+
+        struct stat st;
+        if (lstat(path.c_str(), &st) == -1)
+            throw SysError(format("statting `%1%'") % path);
+
+        if (st.st_nlink != 1) {
+            unsigned long long size = st.st_blocks * 512ULL;
+            actualSize += size;
+            unsharedSize += (st.st_nlink - 1) * size;
+            continue;
        }

-    } else
-        printMsg(lvlTalkative, format("would delete `%1%'") % path);
-    
-    state.deleted.insert(path);
-    if (state.options.action != GCOptions::gcReturnLive)
-        state.results.paths.insert(path);
-    return true;
+        printMsg(lvlTalkative, format("deleting unused link `%1%'") % path);

- isLive:
-    state.live.insert(path);
-    if (state.options.action == GCOptions::gcReturnLive)
-        state.results.paths.insert(path);
-    return false;
+        if (unlink(path.c_str()) == -1)
+            throw SysError(format("deleting `%1%'") % path);
+
+        state.results.bytesFreed += st.st_blocks * 512;
+    }
+
+    struct stat st;
+    if (stat(linksDir.c_str(), &st) == -1)
+        throw SysError(format("statting `%1%'") % linksDir);
+    long long overhead = st.st_blocks * 512ULL;
+
+    printMsg(lvlInfo, format("note: currently hard linking saves %.2f MiB")
+        % ((unsharedSize - actualSize - overhead) / (1024.0 * 1024.0)));
 }


 void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
 {
    GCState state(results);
-    state.options = options;    
-    
-    state.gcKeepOutputs = queryBoolSetting("gc-keep-outputs", false);
-    state.gcKeepDerivations = queryBoolSetting("gc-keep-derivations", true);
+    state.options = options;
+    state.trashDir = settings.nixStore + "/trash";
+    state.gcKeepOutputs = settings.gcKeepOutputs;
+    state.gcKeepDerivations = settings.gcKeepDerivations;

    /* Using `--ignore-liveness' with `--delete' can have unintended
       consequences if `gc-keep-outputs' or `gc-keep-derivations' are
@@ -585,7 +624,9 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
        state.gcKeepOutputs = false;
        state.gcKeepDerivations = false;
    }
-    
+
+    state.shouldDelete = options.action == GCOptions::gcDeleteDead || options.action == GCOptions::gcDeleteSpecific;
+
    /* Acquire the global GC root.  This prevents
       a) New roots from being added.
       b) Processes from creating new temporary root files. */
@@ -594,7 +635,7 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
    /* Find the roots.  Since we've grabbed the GC lock, the set of
       permanent roots cannot increase now. */
    printMsg(lvlError, format("finding garbage collector roots..."));
-    Roots rootMap = options.ignoreLiveness ? Roots() : nix::findRoots(*this, true);
+    Roots rootMap = options.ignoreLiveness ? Roots() : findRoots();

    foreach (Roots::iterator, i, rootMap) state.roots.insert(i->second);

@@ -616,6 +657,11 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
       increase, since we hold locks on everything.  So everything
       that is not reachable from `roots'. */

+    if (state.shouldDelete) {
+        if (pathExists(state.trashDir)) deleteGarbage(state, state.trashDir);
+        createDirs(state.trashDir);
+    }
+
    /* Now either delete all garbage paths, or just the specified
       paths (for gcDeleteSpecific). */

@@ -623,21 +669,22 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)

        foreach (PathSet::iterator, i, options.pathsToDelete) {
            assertStorePath(*i);
-            if (!tryToDelete(state, *i))
+            tryToDelete(state, *i);
+            if (state.dead.find(*i) == state.dead.end())
                throw Error(format("cannot delete path `%1%' since it is still alive") % *i);
        }
-        
-    } else {
-        
-        if (shouldDelete(state.options.action))
+
+    } else if (options.maxFreed > 0) {
+
+        if (state.shouldDelete)
            printMsg(lvlError, format("deleting garbage..."));
        else
            printMsg(lvlError, format("determining live/dead paths..."));
-    
+
        try {

-            AutoCloseDir dir = opendir(nixStore.c_str());
-            if (!dir) throw SysError(format("opening directory `%1%'") % nixStore);
+            AutoCloseDir dir = opendir(settings.nixStore.c_str());
+            if (!dir) throw SysError(format("opening directory `%1%'") % settings.nixStore);

            /* Read the store and immediately delete all paths that
               aren't valid.  When using --max-freed etc., deleting
@@ -651,14 +698,14 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
                checkInterrupt();
                string name = dirent->d_name;
                if (name == "." || name == "..") continue;
-                Path path = nixStore + "/" + name;
+                Path path = settings.nixStore + "/" + name;
                if (isValidPath(path))
                    entries.push_back(path);
                else
                    tryToDelete(state, path);
            }

-	    dir.close();
+            dir.close();

            /* Now delete the unreachable valid paths.  Randomise the
               order in which we delete entries to make the collector
@@ -675,13 +722,31 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
        }
    }

+    if (state.options.action == GCOptions::gcReturnLive) {
+        state.results.paths = state.alive;
+        return;
+    }
+
+    if (state.options.action == GCOptions::gcReturnDead) {
+        state.results.paths = state.dead;
+        return;
+    }
+
    /* Allow other processes to add to the store from here on. */
    fdGCLock.close();

-    /* Delete the invalidated paths now that the lock has been
-       released. */
-    foreach (PathSet::iterator, i, state.invalidated)
-        deleteGarbage(state, *i);
+    /* Delete the trash directory. */
+    printMsg(lvlInfo, format("deleting `%1%'") % state.trashDir);
+    deleteGarbage(state, state.trashDir);
+
+    /* Clean up the links directory. */
+    if (options.action == GCOptions::gcDeleteDead || options.action == GCOptions::gcDeleteSpecific) {
+        printMsg(lvlError, format("deleting unused links..."));
+        removeUnusedLinks(state);
+    }
+
+    /* While we're at it, vacuum the database. */
+    if (options.action == GCOptions::gcDeleteDead) vacuumDB();
 }


@@ -10,47 +10,80 @@
 namespace nix {


-string nixStore = "/UNINIT";
-string nixDataDir = "/UNINIT";
-string nixLogDir = "/UNINIT";
-string nixStateDir = "/UNINIT";
-string nixDBPath = "/UNINIT";
-string nixConfDir = "/UNINIT";
-string nixLibexecDir = "/UNINIT";
-string nixBinDir = "/UNINIT";
-
-bool keepFailed = false;
-bool keepGoing = false;
-bool tryFallback = false;
-Verbosity buildVerbosity = lvlError;
-unsigned int maxBuildJobs = 1;
-unsigned int buildCores = 1;
-bool readOnlyMode = false;
-string thisSystem = "unset";
-time_t maxSilentTime = 0;
-time_t buildTimeout = 0;
-Paths substituters;
-bool useBuildHook = true;
-bool printBuildTrace = false;
+/* The default location of the daemon socket, relative to nixStateDir.
+   The socket is in a directory to allow you to control access to the
+   Nix daemon by setting the mode/ownership of the directory
+   appropriately.  (This wouldn't work on the socket itself since it
+   must be deleted and recreated on startup.) */
+#define DEFAULT_SOCKET_PATH "/daemon-socket/socket"


-static bool settingsRead = false;
-
-static std::map<string, Strings> settings;
-
-/* Overriden settings. */
-std::map<string, Strings> settingsCmdline;
+Settings settings;


-string & at(Strings & ss, unsigned int n)
+Settings::Settings()
 {
-    Strings::iterator i = ss.begin();
-    advance(i, n);
-    return *i;
+    keepFailed = false;
+    keepGoing = false;
+    tryFallback = false;
+    buildVerbosity = lvlError;
+    maxBuildJobs = 1;
+    buildCores = 1;
+    readOnlyMode = false;
+    thisSystem = SYSTEM;
+    maxSilentTime = 0;
+    buildTimeout = 0;
+    useBuildHook = true;
+    printBuildTrace = false;
+    reservedSize = 1024 * 1024;
+    fsyncMetadata = true;
+    useSQLiteWAL = true;
+    syncBeforeRegistering = false;
+    useSubstitutes = true;
+    useChroot = false;
+    dirsInChroot.insert("/dev");
+    dirsInChroot.insert("/dev/pts");
+    impersonateLinux26 = false;
+    keepLog = true;
+    compressLog = true;
+    maxLogSize = 0;
+    cacheFailure = false;
+    pollInterval = 5;
+    checkRootReachability = false;
+    gcKeepOutputs = false;
+    gcKeepDerivations = true;
+    autoOptimiseStore = false;
+    envKeepDerivations = false;
+    lockCPU = getEnv("NIX_AFFINITY_HACK", "1") == "1";
 }


-static void readSettings()
+void Settings::processEnvironment()
+{
+    nixStore = canonPath(getEnv("NIX_STORE_DIR", getEnv("NIX_STORE", NIX_STORE_DIR)));
+    nixDataDir = canonPath(getEnv("NIX_DATA_DIR", NIX_DATA_DIR));
+    nixLogDir = canonPath(getEnv("NIX_LOG_DIR", NIX_LOG_DIR));
+    nixStateDir = canonPath(getEnv("NIX_STATE_DIR", NIX_STATE_DIR));
+    nixDBPath = getEnv("NIX_DB_DIR", nixStateDir + "/db");
+    nixConfDir = canonPath(getEnv("NIX_CONF_DIR", NIX_CONF_DIR));
+    nixLibexecDir = canonPath(getEnv("NIX_LIBEXEC_DIR", NIX_LIBEXEC_DIR));
+    nixBinDir = canonPath(getEnv("NIX_BIN_DIR", NIX_BIN_DIR));
+    nixDaemonSocketFile = canonPath(nixStateDir + DEFAULT_SOCKET_PATH);
+
+    string subs = getEnv("NIX_SUBSTITUTERS", "default");
+    if (subs == "default") {
+#if 0
+        if (getEnv("NIX_OTHER_STORES") != "")
+            substituters.push_back(nixLibexecDir + "/nix/substituters/copy-from-other-stores.pl");
+#endif
+        substituters.push_back(nixLibexecDir + "/nix/substituters/download-using-manifests.pl");
+        substituters.push_back(nixLibexecDir + "/nix/substituters/download-from-binary-cache.pl");
+    } else
+        substituters = tokenizeString<Strings>(subs, ":");
+}
+
+
+void Settings::loadConfFile()
 {
    Path settingsFile = (format("%1%/%2%") % nixConfDir % "nix.conf").str();
    if (!pathExists(settingsFile)) return;
@@ -68,105 +101,117 @@ static void readSettings()
        if (hash != string::npos)
            line = string(line, 0, hash);

-        Strings tokens = tokenizeString(line);
+        vector<string> tokens = tokenizeString<vector<string> >(line);
        if (tokens.empty()) continue;

-        if (tokens.size() < 2 || at(tokens, 1) != "=")
+        if (tokens.size() < 2 || tokens[1] != "=")
            throw Error(format("illegal configuration line `%1%' in `%2%'") % line % settingsFile);

-        string name = at(tokens, 0);
+        string name = tokens[0];

-        Strings::iterator i = tokens.begin();
+        vector<string>::iterator i = tokens.begin();
        advance(i, 2);
-        settings[name] = Strings(i, tokens.end());
+        settings[name] = concatStringsSep(" ", Strings(i, tokens.end())); // FIXME: slow
    };
-
-    settings.insert(settingsCmdline.begin(), settingsCmdline.end());
-    
-    settingsRead = true;
 }


-Strings querySetting(const string & name, const Strings & def)
+void Settings::set(const string & name, const string & value)
 {
-    if (!settingsRead) readSettings();
-    std::map<string, Strings>::iterator i = settings.find(name);
-    return i == settings.end() ? def : i->second;
+    settings[name] = value;
+    overrides[name] = value;
 }


-string querySetting(const string & name, const string & def)
+void Settings::update()
 {
-    Strings defs;
-    defs.push_back(def);
-
-    Strings value = querySetting(name, defs);
-    if (value.size() != 1)
-        throw Error(format("configuration option `%1%' should not be a list") % name);
-
-    return value.front();
+    get(tryFallback, "build-fallback");
+    get(maxBuildJobs, "build-max-jobs");
+    get(buildCores, "build-cores");
+    get(thisSystem, "system");
+    get(maxSilentTime, "build-max-silent-time");
+    get(buildTimeout, "build-timeout");
+    get(reservedSize, "gc-reserved-space");
+    get(fsyncMetadata, "fsync-metadata");
+    get(useSQLiteWAL, "use-sqlite-wal");
+    get(syncBeforeRegistering, "sync-before-registering");
+    get(useSubstitutes, "build-use-substitutes");
+    get(buildUsersGroup, "build-users-group");
+    get(useChroot, "build-use-chroot");
+    get(dirsInChroot, "build-chroot-dirs");
+    get(impersonateLinux26, "build-impersonate-linux-26");
+    get(keepLog, "build-keep-log");
+    get(compressLog, "build-compress-log");
+    get(maxLogSize, "build-max-log-size");
+    get(cacheFailure, "build-cache-failure");
+    get(pollInterval, "build-poll-interval");
+    get(checkRootReachability, "gc-check-reachability");
+    get(gcKeepOutputs, "gc-keep-outputs");
+    get(gcKeepDerivations, "gc-keep-derivations");
+    get(autoOptimiseStore, "auto-optimise-store");
+    get(envKeepDerivations, "env-keep-derivations");
 }


-bool queryBoolSetting(const string & name, bool def)
+void Settings::get(string & res, const string & name)
 {
-    string v = querySetting(name, def ? "true" : "false");
-    if (v == "true") return true;
-    else if (v == "false") return false;
+    SettingsMap::iterator i = settings.find(name);
+    if (i == settings.end()) return;
+    res = i->second;
+}
+
+
+void Settings::get(bool & res, const string & name)
+{
+    SettingsMap::iterator i = settings.find(name);
+    if (i == settings.end()) return;
+    if (i->second == "true") res = true;
+    else if (i->second == "false") res = false;
    else throw Error(format("configuration option `%1%' should be either `true' or `false', not `%2%'")
-        % name % v);
+        % name % i->second);
 }


-unsigned int queryIntSetting(const string & name, unsigned int def)
+void Settings::get(StringSet & res, const string & name)
 {
-    int n;
-    if (!string2Int(querySetting(name, int2String(def)), n) || n < 0)
+    SettingsMap::iterator i = settings.find(name);
+    if (i == settings.end()) return;
+    res.clear();
+    Strings ss = tokenizeString<Strings>(i->second);
+    res.insert(ss.begin(), ss.end());
+}
+
+
+template<class N> void Settings::get(N & res, const string & name)
+{
+    SettingsMap::iterator i = settings.find(name);
+    if (i == settings.end()) return;
+    if (!string2Int(i->second, res))
        throw Error(format("configuration setting `%1%' should have an integer value") % name);
-    return n;
 }


-void overrideSetting(const string & name, const Strings & value)
+string Settings::pack()
 {
-    if (settingsRead) settings[name] = value;
-    settingsCmdline[name] = value;
+    string s;
+    foreach (SettingsMap::iterator, i, settings) {
+        if (i->first.find('\n') != string::npos ||
+            i->first.find('=') != string::npos ||
+            i->second.find('\n') != string::npos)
+            throw Error("illegal option name/value");
+        s += i->first; s += '='; s += i->second; s += '\n';
+    }
+    return s;
 }


-void reloadSettings()
+Settings::SettingsMap Settings::getOverrides()
 {
-    settingsRead = false;
-    settings.clear();
+    return overrides;
 }


-void setDefaultsFromEnvironment()
-{
-    /* Setup Nix paths. */
-    nixStore = canonPath(getEnv("NIX_STORE_DIR", getEnv("NIX_STORE", NIX_STORE_DIR)));
-    nixDataDir = canonPath(getEnv("NIX_DATA_DIR", NIX_DATA_DIR));
-    nixLogDir = canonPath(getEnv("NIX_LOG_DIR", NIX_LOG_DIR));
-    nixStateDir = canonPath(getEnv("NIX_STATE_DIR", NIX_STATE_DIR));
-    nixDBPath = getEnv("NIX_DB_DIR", nixStateDir + "/db");
-    nixConfDir = canonPath(getEnv("NIX_CONF_DIR", NIX_CONF_DIR));
-    nixLibexecDir = canonPath(getEnv("NIX_LIBEXEC_DIR", NIX_LIBEXEC_DIR));
-    nixBinDir = canonPath(getEnv("NIX_BIN_DIR", NIX_BIN_DIR));
+const string nixVersion = NIX_VERSION;

-    string subs = getEnv("NIX_SUBSTITUTERS", "default");
-    if (subs == "default") {
-        substituters.push_back(nixLibexecDir + "/nix/substituters/copy-from-other-stores.pl");
-        substituters.push_back(nixLibexecDir + "/nix/substituters/download-using-manifests.pl");
-    } else
-        substituters = tokenizeString(subs, ":");

-    /* Get some settings from the configuration file. */
-    thisSystem = querySetting("system", SYSTEM);
-    maxBuildJobs = queryIntSetting("build-max-jobs", 1);
-    buildCores = queryIntSetting("build-cores", 1);
-    maxSilentTime = queryIntSetting("build-max-silent-time", 0);
-    buildTimeout = queryIntSetting("build-timeout", 0);
-}
-
- 
 }
@@ -2,118 +2,205 @@

 #include "types.hh"

+#include <map>
+#include <sys/types.h>
+

 namespace nix {


-/* Path names. */
+struct Settings {

-/* nixStore is the directory where we generally store atomic and
-   derived files. */
-extern string nixStore;
+    typedef std::map<string, string> SettingsMap;

-extern string nixDataDir; /* !!! fix */
+    Settings();

-/* nixLogDir is the directory where we log various operations. */ 
-extern string nixLogDir;
+    void processEnvironment();

-/* nixStateDir is the directory where state is stored. */
-extern string nixStateDir;
+    void loadConfFile();

-/* nixDBPath is the path name of our Berkeley DB environment. */
-extern string nixDBPath;
+    void set(const string & name, const string & value);

-/* nixConfDir is the directory where configuration files are
-   stored. */
-extern string nixConfDir;
+    void update();

-/* nixLibexecDir is the directory where internal helper programs are
-   stored. */
-extern string nixLibexecDir;
+    string pack();

-/* nixBinDir is the directory where the main programs are stored. */
-extern string nixBinDir;
+    SettingsMap getOverrides();
+
+    /* The directory where we store sources and derived files. */
+    Path nixStore;
+
+    Path nixDataDir; /* !!! fix */
+
+    /* The directory where we log various operations. */
+    Path nixLogDir;
+
+    /* The directory where state is stored. */
+    Path nixStateDir;
+
+    /* The directory where we keep the SQLite database. */
+    Path nixDBPath;
+
+    /* The directory where configuration files are stored. */
+    Path nixConfDir;
+
+    /* The directory where internal helper programs are stored. */
+    Path nixLibexecDir;
+
+    /* The directory where the main programs are stored. */
+    Path nixBinDir;
+
+    /* File name of the socket the daemon listens to.  */
+    Path nixDaemonSocketFile;
+
+    /* Whether to keep temporary directories of failed builds. */
+    bool keepFailed;
+
+    /* Whether to keep building subgoals when a sibling (another
+       subgoal of the same goal) fails. */
+    bool keepGoing;
+
+    /* Whether, if we cannot realise the known closure corresponding
+       to a derivation, we should try to normalise the derivation
+       instead. */
+    bool tryFallback;
+
+    /* Verbosity level for build output. */
+    Verbosity buildVerbosity;
+
+    /* Maximum number of parallel build jobs.  0 means unlimited. */
+    unsigned int maxBuildJobs;
+
+    /* Number of CPU cores to utilize in parallel within a build,
+       i.e. by passing this number to Make via '-j'. 0 means that the
+       number of actual CPU cores on the local host ought to be
+       auto-detected. */
+    unsigned int buildCores;
+
+    /* Read-only mode.  Don't copy stuff to the store, don't change
+       the database. */
+    bool readOnlyMode;
+
+    /* The canonical system name, as returned by config.guess. */
+    string thisSystem;
+
+    /* The maximum time in seconds that a builer can go without
+       producing any output on stdout/stderr before it is killed.  0
+       means infinity. */
+    time_t maxSilentTime;
+
+    /* The maximum duration in seconds that a builder can run.  0
+       means infinity.  */
+    time_t buildTimeout;
+
+    /* The substituters.  There are programs that can somehow realise
+       a store path without building, e.g., by downloading it or
+       copying it from a CD. */
+    Paths substituters;
+
+    /* Whether to use build hooks (for distributed builds).  Sometimes
+       users want to disable this from the command-line. */
+    bool useBuildHook;
+
+    /* Whether buildDerivations() should print out lines on stderr in
+       a fixed format to allow its progress to be monitored.  Each
+       line starts with a "@".  The following are defined:
+
+       @ build-started <drvpath> <outpath> <system> <logfile>
+       @ build-failed <drvpath> <outpath> <exitcode> <error text>
+       @ build-succeeded <drvpath> <outpath>
+       @ substituter-started <outpath> <substituter>
+       @ substituter-failed <outpath> <exitcode> <error text>
+       @ substituter-succeeded <outpath>
+
+       Best combined with --no-build-output, otherwise stderr might
+       conceivably contain lines in this format printed by the
+       builders. */
+    bool printBuildTrace;
+
+    /* Amount of reserved space for the garbage collector
+       (/nix/var/nix/db/reserved). */
+    off_t reservedSize;
+
+    /* Whether SQLite should use fsync. */
+    bool fsyncMetadata;
+
+    /* Whether SQLite should use WAL mode. */
+    bool useSQLiteWAL;
+
+    /* Whether to call sync() before registering a path as valid. */
+    bool syncBeforeRegistering;
+
+    /* Whether to use substitutes. */
+    bool useSubstitutes;
+
+    /* The Unix group that contains the build users. */
+    string buildUsersGroup;
+
+    /* Whether to build in chroot. */
+    bool useChroot;
+
+    /* The directories from the host filesystem to be included in the
+       chroot. */
+    StringSet dirsInChroot;
+
+    /* Whether to impersonate a Linux 2.6 machine on newer kernels. */
+    bool impersonateLinux26;
+
+    /* Whether to store build logs. */
+    bool keepLog;
+
+    /* Whether to compress logs. */
+    bool compressLog;
+
+    /* Maximum number of bytes a builder can write to stdout/stderr
+       before being killed (0 means no limit). */
+    unsigned long maxLogSize;
+
+    /* Whether to cache build failures. */
+    bool cacheFailure;
+
+    /* How often (in seconds) to poll for locks. */
+    unsigned int pollInterval;
+
+    /* Whether to check if new GC roots can in fact be found by the
+       garbage collector. */
+    bool checkRootReachability;
+
+    /* Whether the garbage collector should keep outputs of live
+       derivations. */
+    bool gcKeepOutputs;
+
+    /* Whether the garbage collector should keep derivers of live
+       paths. */
+    bool gcKeepDerivations;
+
+    /* Whether to automatically replace files with identical contents
+       with hard links. */
+    bool autoOptimiseStore;
+
+    /* Whether to add derivations as a dependency of user environments
+       (to prevent them from being GCed). */
+    bool envKeepDerivations;
+
+    /* Whether to lock the Nix client and worker to the same CPU. */
+    bool lockCPU;
+
+private:
+    SettingsMap settings, overrides;
+
+    void get(string & res, const string & name);
+    void get(bool & res, const string & name);
+    void get(StringSet & res, const string & name);
+    template<class N> void get(N & res, const string & name);
+};


-/* Misc. global flags. */
-
-/* Whether to keep temporary directories of failed builds. */
-extern bool keepFailed;
-
-/* Whether to keep building subgoals when a sibling (another subgoal
-   of the same goal) fails. */
-extern bool keepGoing;
-
-/* Whether, if we cannot realise the known closure corresponding to a
-   derivation, we should try to normalise the derivation instead. */
-extern bool tryFallback;
-
-/* Verbosity level for build output. */
-extern Verbosity buildVerbosity;
-
-/* Maximum number of parallel build jobs.  0 means unlimited. */
-extern unsigned int maxBuildJobs;
-
-/* Number of CPU cores to utilize in parallel within a build, i.e. by passing
-   this number to Make via '-j'. 0 means that the number of actual CPU cores on
-   the local host ought to be auto-detected. */
-extern unsigned int buildCores;
-
-/* Read-only mode.  Don't copy stuff to the store, don't change the
-   database. */
-extern bool readOnlyMode;
-
-/* The canonical system name, as returned by config.guess. */ 
-extern string thisSystem;
-
-/* The maximum time in seconds that a builer can go without producing
-   any output on stdout/stderr before it is killed.  0 means
-   infinity. */
-extern time_t maxSilentTime;
-
-/* The maximum duration in seconds that a builder can run.  0 means
-   infinity.  */
-extern time_t buildTimeout;
-
-/* The substituters.  There are programs that can somehow realise a
-   store path without building, e.g., by downloading it or copying it
-   from a CD. */
-extern Paths substituters;
-
-/* Whether to use build hooks (for distributed builds).  Sometimes
-   users want to disable this from the command-line. */
-extern bool useBuildHook;
-
-/* Whether buildDerivations() should print out lines on stderr in a
-   fixed format to allow its progress to be monitored.  Each line
-   starts with a "@".  The following are defined:
-
-   @ build-started <drvpath> <outpath> <system> <logfile>
-   @ build-failed <drvpath> <outpath> <exitcode> <error text>
-   @ build-succeeded <drvpath> <outpath>
-   @ substituter-started <outpath> <substituter>
-   @ substituter-failed <outpath> <exitcode> <error text>
-   @ substituter-succeeded <outpath>
-
-   Best combined with --no-build-output, otherwise stderr might
-   conceivably contain lines in this format printed by the builders.
-*/
-extern bool printBuildTrace;
+// FIXME: don't use a global variable.
+extern Settings settings;


-Strings querySetting(const string & name, const Strings & def);
-
-string querySetting(const string & name, const string & def);
-
-bool queryBoolSetting(const string & name, bool def);
-
-unsigned int queryIntSetting(const string & name, unsigned int def);
-
-void overrideSetting(const string & name, const Strings & value);
-
-void reloadSettings();
-
-void setDefaultsFromEnvironment();
+extern const string nixVersion;


 }
@@ -17,8 +17,8 @@ namespace nix {
 /* Nix store and database schema version.  Version 1 (or 0) was Nix <=
   0.7.  Version 2 was Nix 0.8 and 0.9.  Version 3 is Nix 0.10.
   Version 4 is Nix 0.11.  Version 5 is Nix 0.12-0.16.  Version 6 is
-   Nix 1.0. */
-const int nixSchemaVersion = 6;
+   Nix 1.0.  Version 7 is Nix 1.3. */
+const int nixSchemaVersion = 7;


 extern string drvsLogDir;
@@ -44,8 +44,12 @@ struct OptimiseStats

 struct RunningSubstituter
 {
+    Path program;
    Pid pid;
-    AutoCloseFD to, from;
+    AutoCloseFD to, from, error;
+    FdSource fromBuf;
+    bool disabled;
+    RunningSubstituter() : disabled(false) { };
 };


@@ -75,17 +79,16 @@ struct SQLiteStmt
    void bind64(long long value);
    void bind();
 };
-    
+

 class LocalStore : public StoreAPI
 {
 private:
-    bool substitutablePathsLoaded;
-    PathSet substitutablePaths;
-
    typedef std::map<Path, RunningSubstituter> RunningSubstituters;
    RunningSubstituters runningSubstituters;
-    
+
+    Path linksDir;
+
 public:

    /* Initialise the local store, upgrading the schema if
@@ -93,13 +96,15 @@ public:
    LocalStore(bool reserveSpace = true);

    ~LocalStore();
-    
+
    /* Implementations of abstract store API methods. */
-    
+
    bool isValidPath(const Path & path);

-    PathSet queryValidPaths();
-    
+    PathSet queryValidPaths(const PathSet & paths);
+
+    PathSet queryAllValidPaths();
+
    ValidPathInfo queryPathInfo(const Path & path);

    Hash queryPathHash(const Path & path);
@@ -110,55 +115,49 @@ public:

    Path queryDeriver(const Path & path);

-    /* Return all currently valid derivations that have `path' as an
-       output.  (Note that the result of `queryDeriver()' is the
-       derivation that was actually used to produce `path', which may
-       not exist anymore.) */
    PathSet queryValidDerivers(const Path & path);

    PathSet queryDerivationOutputs(const Path & path);

    StringSet queryDerivationOutputNames(const Path & path);
-    
-    Path queryPathFromHashPart(const string & hashPart);
-    
-    PathSet querySubstitutablePaths();
-    
-    bool hasSubstitutes(const Path & path);

-    bool querySubstitutablePathInfo(const Path & path,
-        SubstitutablePathInfo & info);
-    
-    bool querySubstitutablePathInfo(const Path & substituter,
-        const Path & path, SubstitutablePathInfo & info);
-    
+    Path queryPathFromHashPart(const string & hashPart);
+
+    PathSet querySubstitutablePaths(const PathSet & paths);
+
+    void querySubstitutablePathInfos(const Path & substituter,
+        PathSet & paths, SubstitutablePathInfos & infos);
+
+    void querySubstitutablePathInfos(const PathSet & paths,
+        SubstitutablePathInfos & infos);
+
    Path addToStore(const Path & srcPath,
        bool recursive = true, HashType hashAlgo = htSHA256,
-        PathFilter & filter = defaultPathFilter);
+        PathFilter & filter = defaultPathFilter, bool repair = false);

    /* Like addToStore(), but the contents of the path are contained
       in `dump', which is either a NAR serialisation (if recursive ==
       true) or simply the contents of a regular file (if recursive ==
       false). */
    Path addToStoreFromDump(const string & dump, const string & name,
-        bool recursive = true, HashType hashAlgo = htSHA256);
+        bool recursive = true, HashType hashAlgo = htSHA256, bool repair = false);

    Path addTextToStore(const string & name, const string & s,
-        const PathSet & references);
+        const PathSet & references, bool repair = false);

    void exportPath(const Path & path, bool sign,
        Sink & sink);

    Paths importPaths(bool requireSignature, Source & source);
-    
-    void buildPaths(const PathSet & paths);
+
+    void buildPaths(const PathSet & paths, bool repair = false);

    void ensurePath(const Path & path);

    void addTempRoot(const Path & path);

    void addIndirectRoot(const Path & path);
-    
+
    void syncWithGC();

    Roots findRoots();
@@ -167,14 +166,18 @@ public:

    /* Optimise the disk space usage of the Nix store by hard-linking
       files with the same contents. */
-    void optimiseStore(bool dryRun, OptimiseStats & stats);
+    void optimiseStore(OptimiseStats & stats);

-    /* Check the integrity of the Nix store. */
-    void verifyStore(bool checkContents);
+    /* Optimise a single store path. */
+    void optimisePath(const Path & path);
+
+    /* Check the integrity of the Nix store.  Returns true if errors
+       remain. */
+    bool verifyStore(bool checkContents, bool repair);

    /* Register the validity of a path, i.e., that `path' exists, that
       the paths referenced by it exists, and in the case of an output
-       path of a derivation, that it has been produced by a succesful
+       path of a derivation, that it has been produced by a successful
       execution of the derivation (or something equivalent).  Also
       register the hash of the file system contents of the path.  The
       hash must be a SHA-256 hash. */
@@ -193,6 +196,20 @@ public:

    void clearFailedPaths(const PathSet & paths);

+    void vacuumDB();
+
+    /* Repair the contents of the given path by redownloading it using
+       a substituter (if available). */
+    void repairPath(const Path & path);
+
+    /* Check whether the given valid path exists and has the right
+       contents. */
+    bool pathContentsGood(const Path & path);
+
+    void markContentsGood(const Path & path);
+
+    void setSubstituterEnv();
+
 private:

    Path schemaPath;
@@ -220,56 +237,80 @@ private:
    SQLiteStmt stmtQueryDerivationOutputs;
    SQLiteStmt stmtQueryPathFromHashPart;

+    /* Cache for pathContentsGood(). */
+    std::map<Path, bool> pathContentsGoodCache;
+
+    bool didSetSubstituterEnv;
+
    int getSchema();

    void openDB(bool create);

+    void makeStoreWritable();
+
    unsigned long long queryValidPathId(const Path & path);

    unsigned long long addValidPath(const ValidPathInfo & info, bool checkOutputs = true);
-        
+
    void addReference(unsigned long long referrer, unsigned long long reference);
-    
+
    void appendReferrer(const Path & from, const Path & to, bool lock);
-    
+
    void rewriteReferrers(const Path & path, bool purge, PathSet referrers);

    void invalidatePath(const Path & path);

    /* Delete a path from the Nix store. */
    void invalidatePathChecked(const Path & path);
-    
+
    void verifyPath(const Path & path, const PathSet & store,
-        PathSet & done, PathSet & validPaths);
+        PathSet & done, PathSet & validPaths, bool repair, bool & errors);

    void updatePathInfo(const ValidPathInfo & info);

    void upgradeStore6();
+    void upgradeStore7();
    PathSet queryValidPathsOld();
    ValidPathInfo queryPathInfoOld(const Path & path);

    struct GCState;

    void deleteGarbage(GCState & state, const Path & path);
-    
-    bool tryToDelete(GCState & state, const Path & path);
-    
+
+    void tryToDelete(GCState & state, const Path & path);
+
+    bool canReachRoot(GCState & state, PathSet & visited, const Path & path);
+
+    void deletePathRecursive(GCState & state, const Path & path);
+
    bool isActiveTempFile(const GCState & state,
        const Path & path, const string & suffix);
-        
+
    int openGCLock(LockType lockType);
-    
+
+    void removeUnusedLinks(const GCState & state);
+
    void startSubstituter(const Path & substituter,
        RunningSubstituter & runningSubstituter);

+    string getLineFromSubstituter(RunningSubstituter & run);
+
+    template<class T> T getIntLineFromSubstituter(RunningSubstituter & run);
+
    Path createTempDirInStore();

    Path importPath(bool requireSignature, Source & source);
-    
+
    void checkDerivationOutputs(const Path & drvPath, const Derivation & drv);
+
+    void optimisePath_(OptimiseStats & stats, const Path & path);
 };


+typedef std::pair<dev_t, ino_t> Inode;
+typedef set<Inode> InodesSeen;
+
+
 /* "Fix", or canonicalise, the meta-data of the files in a store path
   after it has been built.  In particular:
   - the last modification date on each file is set to 1 (i.e.,
@@ -278,15 +319,13 @@ private:
     without execute permission; setuid bits etc. are cleared)
   - the owner and group are set to the Nix user and group, if we're
     in a setuid Nix installation. */
-void canonicalisePathMetaData(const Path & path);
+void canonicalisePathMetaData(const Path & path, uid_t fromUid, InodesSeen & inodesSeen);
+void canonicalisePathMetaData(const Path & path, uid_t fromUid);

-void canonicalisePathMetaData(const Path & path, bool recurse);
+void canonicaliseTimestampAndPermissions(const Path & path);

 MakeError(PathInUse, Error);

-/* Whether we are in build users mode. */
-bool haveBuildUsers();
-
 /* Whether we are root. */
 bool amPrivileged();

@@ -295,9 +334,8 @@ void getOwnership(const Path & path);

 /* Like deletePath(), but changes the ownership of `path' using the
   setuid wrapper if necessary (and possible). */
-void deletePathWrapped(const Path & path,
-    unsigned long long & bytesFreed, unsigned long long & blocksFreed);
+void deletePathWrapped(const Path & path, unsigned long long & bytesFreed);

 void deletePathWrapped(const Path & path);
- 
+
 }
--- a/Show More
+++ b/Show More