* A very dirty hack to make setuid installations a bit nicer to use.

  Previously there was the problem that all files read by nix-env
  etc. should be reachable and readable by the Nix user.  So for
  instance building a Nix expression in your home directory meant that
  the home directory should have at least g+x or o+x permission so
  that the Nix user could reach the Nix expression.  Now we just
  switch back to the original user just prior to reading sources and
  the like.  The places where this happens are somewhat arbitrary,
  however.  Any scope that has a live SwitchToOriginalUser object in
  it is executed as the original user.

* Back out r1385.  setreuid() sets the saved uid to the new
  real/effective uid, which prevents us from switching back to the
  original uid.  setresuid() doesn't have this problem (although the
  manpage has a bug: specifying -1 for the saved uid doesn't leave it
  unchanged; an explicit value must be specified).

1 files changed, 9 insertions, 2 deletions

diff --git a/src/libstore/store.cc b/src/libstore/store.cc
index 110ec2b48556..5b471a1d9cd8 100644
--- a/src/libstore/store.cc
+++ b/src/libstore/store.cc
@@ -157,7 +157,10 @@ void copyPath(const Path & src, const Path & dst)
     
     CopySink sink;
     sink.fd = pipe.writeSide;
-    dumpPath(src, sink);
+    {
+        SwitchToOriginalUser sw;
+        dumpPath(src, sink);
+    }
 
     /* Wait for the child to finish. */
     int status = pid.wait(true);
@@ -421,7 +424,11 @@ Path addToStore(const Path & _srcPath)
     Path srcPath(absPath(_srcPath));
     debug(format("adding `%1%' to the store") % srcPath);
 
-    Hash h = hashPath(srcPath);
+    Hash h;
+    {
+        SwitchToOriginalUser sw;
+        h = hashPath(srcPath);
+    }
 
     string baseName = baseNameOf(srcPath);
     Path dstPath = canonPath(nixStore + "/" + (string) h + "-" + baseName);