Allow $NIX_BUILD_HOOK to be relative to Nix libexec directory

1 files changed, 4 insertions, 2 deletions

diff --git a/src/libstore/build.cc b/src/libstore/build.cc
index 1870abead491..d59470603295 100644
--- a/src/libstore/build.cc
+++ b/src/libstore/build.cc
@@ -590,7 +590,9 @@ HookInstance::HookInstance()
 {
     debug("starting build hook");
 
-    Path buildHook = absPath(getEnv("NIX_BUILD_HOOK"));
+    Path buildHook = getEnv("NIX_BUILD_HOOK");
+    if (string(buildHook, 0, 1) != "/") buildHook = settings.nixLibexecDir + "/nix/" + buildHook;
+    buildHook = canonPath(buildHook);
 
     /* Create a pipe to get the output of the child. */
     fromHook.create();
@@ -1503,7 +1505,7 @@ void DerivationGoal::buildDone()
 
 HookReply DerivationGoal::tryBuildHook()
 {
-    if (!settings.useBuildHook || getEnv("NIX_BUILD_HOOK") == "") return rpDecline;
+    if (!settings.useBuildHook) return rpDecline;
 
     if (!worker.hook)
         worker.hook = std::shared_ptr<HookInstance>(new HookInstance);