Merge branch 'optional-derivation-output-storepath' into ca-derivation-data-types

src/libutil/serialise.cc

@@ -322,5 +322,18 @@ void StringSink::operator () (const unsigned char * data, size_t len)
     s->append((const char *) data, len);
 }
 
+size_t ChainSource::read(unsigned char * data, size_t len)
+{
+    if (useSecond) {
+        return source2.read(data, len);
+    } else {
+        try {
+            return source1.read(data, len);
+        } catch (EndOfFile &) {
+            useSecond = true;
+            return this->read(data, len);
+        }
+    }
+}
 
 }

src/libutil/serialise.hh

@@ -189,7 +189,7 @@ struct TeeSource : Source
     size_t read(unsigned char * data, size_t len)
     {
         size_t n = orig.read(data, len);
-        sink(data, len);
+        sink(data, n);
         return n;
     }
 };
@@ -256,6 +256,19 @@ struct LambdaSource : Source
     }
 };
 
+/* Chain two sources together so after the first is exhausted, the second is
+   used */
+struct ChainSource : Source
+{
+    Source & source1, & source2;
+    bool useSecond = false;
+    ChainSource(Source & s1, Source & s2)
+        : source1(s1), source2(s2)
+    { }
+
+    size_t read(unsigned char * data, size_t len) override;
+};
+
 
 /* Convert a function that feeds data into a Sink into a Source. The
    Source executes the function as a coroutine. */

src/libutil/util.cc

@@ -1581,7 +1581,7 @@ AutoCloseFD createUnixDomainSocket(const Path & path, mode_t mode)
 
     struct sockaddr_un addr;
     addr.sun_family = AF_UNIX;
-    if (path.size() >= sizeof(addr.sun_path))
+    if (path.size() + 1 >= sizeof(addr.sun_path))
         throw Error("socket path '%1%' is too long", path);
     strcpy(addr.sun_path, path.c_str());