Merge pull request #8735 from obsidiansystems/defexpr

Factor out `nix-defexpr` path computation

src/libexpr/eval-settings.cc

@@ -63,7 +63,7 @@ Strings EvalSettings::getDefaultNixPath()
     };
 
     if (!evalSettings.restrictEval && !evalSettings.pureEval) {
-        add(settings.useXDGBaseDirectories ? getStateDir() + "/nix/defexpr/channels" : getHome() + "/.nix-defexpr/channels");
+        add(getNixDefExpr() + "/channels");
         add(rootChannelsDir() + "/nixpkgs", "nixpkgs");
         add(rootChannelsDir());
     }
@@ -92,4 +92,11 @@ EvalSettings evalSettings;
 
 static GlobalConfig::Register rEvalSettings(&evalSettings);
 
+Path getNixDefExpr()
+{
+    return settings.useXDGBaseDirectories
+        ? getStateDir() + "/nix/defexpr"
+        : getHome() + "/.nix-defexpr";
+}
+
 }

src/libexpr/eval-settings.hh

@@ -95,4 +95,9 @@ struct EvalSettings : Config
 
 extern EvalSettings evalSettings;
 
+/**
+ * Conventionally part of the default nix path in impure mode.
+ */
+Path getNixDefExpr();
+
 }

src/nix-channel/nix-channel.cc

@@ -5,6 +5,7 @@
 #include "store-api.hh"
 #include "legacy.hh"
 #include "fetchers.hh"
+#include "eval-settings.hh" // for defexpr
 #include "util.hh"
 
 #include <fcntl.h>
@@ -165,7 +166,7 @@ static int main_nix_channel(int argc, char ** argv)
         // Figure out the name of the `.nix-channels' file to use
         auto home = getHome();
         channelsList = settings.useXDGBaseDirectories ? createNixStateDir() + "/channels" : home + "/.nix-channels";
-        nixDefExpr = settings.useXDGBaseDirectories ? createNixStateDir() + "/defexpr" : home + "/.nix-defexpr";
+        nixDefExpr = getNixDefExpr();
 
         // Figure out the name of the channels profile.
         profile = profilesDir() +  "/channels";

src/nix-env/nix-env.cc

@@ -15,6 +15,7 @@
 #include "value-to-json.hh"
 #include "xml-writer.hh"
 #include "legacy.hh"
+#include "eval-settings.hh" // for defexpr
 
 #include <cerrno>
 #include <ctime>
@@ -1399,7 +1400,7 @@ static int main_nix_env(int argc, char * * argv)
         globals.instSource.type = srcUnknown;
         globals.instSource.systemFilter = "*";
 
-        Path nixExprPath = settings.useXDGBaseDirectories ? createNixStateDir() + "/defexpr" : getHome() + "/.nix-defexpr";
+        Path nixExprPath = getNixDefExpr();
 
         if (!pathExists(nixExprPath)) {
             try {