3 files changed, 28 insertions, 6 deletions
diff --git a/src/libstore/gc.cc b/src/libstore/gc.cc
index ed1b1a84a44c..3a626dedae98 100644
--- a/src/libstore/gc.cc
+++ b/src/libstore/gc.cc
@@ -528,12 +528,8 @@ void collectGarbage(GCAction action, const PathSet & pathsToDelete,
 
         /* If just returning the set of dead paths, we also return the
            space that would be freed if we deleted them. */
-        if (action == gcReturnDead) {
-            struct stat st;
-            if (lstat(i->c_str(), &st) == -1)
-                st.st_size = 0;
-            bytesFreed += st.st_size;
-        }
+        if (action == gcReturnDead)
+            bytesFreed += computePathSize(*i);
 
         if (action == gcDeleteDead || action == gcDeleteSpecific) {
 
diff --git a/src/libutil/util.cc b/src/libutil/util.cc
index 38e32bfa9b58..f80fb7dbf766 100644
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@@ -238,6 +238,29 @@ void writeFile(const Path & path, const string & s)
 }
 
 
+unsigned long long computePathSize(const Path & path)
+{
+    unsigned long long size = 0;
+    
+    checkInterrupt();
+
+    struct stat st;
+    if (lstat(path.c_str(), &st))
+	throw SysError(format("getting attributes of path `%1%'") % path);
+
+    size += st.st_size;
+
+    if (S_ISDIR(st.st_mode)) {
+	Strings names = readDirectory(path);
+
+	for (Strings::iterator i = names.begin(); i != names.end(); ++i)
+            size += computePathSize(path + "/" + *i);
+    }
+
+    return size;
+}
+
+
 static void _deletePath(const Path & path, unsigned long long & bytesFreed)
 {
     checkInterrupt();
diff --git a/src/libutil/util.hh b/src/libutil/util.hh
index 52ef2c6eb20e..7f3d41e76ef3 100644
--- a/src/libutil/util.hh
+++ b/src/libutil/util.hh
@@ -56,6 +56,9 @@ string readFile(const Path & path);
 /* Write a string to a file. */
 void writeFile(const Path & path, const string & s);
 
+/* Compute the sum of the sizes of all files in `path'. */
+unsigned long long computePathSize(const Path & path);
+
 /* Delete a path; i.e., in the case of a directory, it is deleted
    recursively.  Don't use this at home, kids.  The second variant
    returns the number of bytes freed. */