* Set the NIX_STORE and NIX_BUILD_TOP environment variables in

  builders to point to the store and the temporary build directory,
  respectively.  Useful for purity checking.
* Also set TEMPDIR, TMPDIR, TEMP, and TEMP to NIX_BUILD_TOP to make
  sure that tools in the builder store temporary files in the right
  location.

1 files changed, 6 insertions, 0 deletions

diff --git a/src/libstore/normalise.cc b/src/libstore/normalise.cc
index 5c13f04ec..e287914a1 100644
--- a/src/libstore/normalise.cc
+++ b/src/libstore/normalise.cc
@@ -124,6 +124,12 @@ Path normaliseStoreExpr(const Path & _nePath, PathSet pending)
        non-existing path. */
     env["HOME"] = "/homeless-shelter";
 
+    /* Tell the builder where the Nix store is.  Usually they
+       shouldn't care, but this is useful for purity checking (e.g.,
+       the compiler or linker might only want to accept paths to files
+       in the store or in the build directory). */
+    env["NIX_STORE"] = nixStore;
+
     /* Build the environment. */
     for (StringPairs::iterator i = ne.derivation.env.begin();
          i != ne.derivation.env.end(); i++)