4 files changed, 36 insertions, 6 deletions

diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index ed0a97757..08a1adf3b 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -1021,7 +1021,9 @@ static void prim_toFile(EvalState & state, const Pos & pos, Value * * args, Valu
 
     for (auto path : context) {
         if (path.at(0) != '/')
-            throw EvalError(format("in 'toFile': the file '%1%' cannot refer to derivation outputs, at %2%") % name % pos);
+            throw EvalError(format(
+                "in 'toFile': the file named '%1%' must not contain a reference "
+                "to a derivation but contains (%2%), at %3%") % name % path % pos);
         refs.insert(state.store->parseStorePath(path));
     }
 
diff --git a/src/libmain/shared.cc b/src/libmain/shared.cc
index d41e772e9..72ba717e5 100644
--- a/src/libmain/shared.cc
+++ b/src/libmain/shared.cc
@@ -155,7 +155,7 @@ void initNix()
        sshd). This breaks build users because they don't have access
        to the TMPDIR, in particular in ‘nix-store --serve’. */
 #if __APPLE__
-    if (getuid() == 0 && hasPrefix(getEnv("TMPDIR").value_or("/tmp"), "/var/folders/"))
+    if (hasPrefix(getEnv("TMPDIR").value_or("/tmp"), "/var/folders/"))
         unsetenv("TMPDIR");
 #endif
 }
diff --git a/src/libstore/build.cc b/src/libstore/build.cc
index 0febb8dfb..b4207e1b8 100644
--- a/src/libstore/build.cc
+++ b/src/libstore/build.cc
@@ -1680,6 +1680,7 @@ void DerivationGoal::buildDone()
         }
 
         if (buildMode == bmCheck) {
+            deleteTmpDir(true);
             done(BuildResult::Built);
             return;
         }
@@ -3536,6 +3537,29 @@ StorePathSet parseReferenceSpecifiers(Store & store, const BasicDerivation & drv
 }
 
 
+static void moveCheckToStore(const Path & src, const Path & dst)
+{
+    /* For the rename of directory to succeed, we must be running as root or
+       the directory must be made temporarily writable (to update the
+       directory's parent link ".."). */
+    struct stat st;
+    if (lstat(src.c_str(), &st) == -1) {
+        throw SysError(format("getting attributes of path '%1%'") % src);
+    }
+
+    bool changePerm = (geteuid() && S_ISDIR(st.st_mode) && !(st.st_mode & S_IWUSR));
+
+    if (changePerm)
+        chmod_(src, st.st_mode | S_IWUSR);
+
+    if (rename(src.c_str(), dst.c_str()))
+        throw SysError(format("renaming '%1%' to '%2%'") % src % dst);
+
+    if (changePerm)
+        chmod_(dst, st.st_mode);
+}
+
+
 void DerivationGoal::registerOutputs()
 {
     /* When using a build hook, the build hook can register the output
@@ -3714,8 +3738,7 @@ void DerivationGoal::registerOutputs()
                 if (settings.runDiffHook || settings.keepFailed) {
                     Path dst = worker.store.toRealPath(path + checkSuffix);
                     deletePath(dst);
-                    if (rename(actualPath.c_str(), dst.c_str()))
-                        throw SysError(format("renaming '%1%' to '%2%'") % actualPath % dst);
+                    moveCheckToStore(actualPath, dst);
 
                     handleDiffHook(
                         buildUser ? buildUser->getUID() : getuid(),
@@ -3723,10 +3746,10 @@ void DerivationGoal::registerOutputs()
                         path, dst, worker.store.printStorePath(drvPath), tmpDir);
 
                     throw NotDeterministic("derivation '%s' may not be deterministic: output '%s' differs from '%s'",
-                        worker.store.printStorePath(drvPath), path, dst);
+                        worker.store.printStorePath(drvPath), worker.store.toRealPath(path), dst);
                 } else
                     throw NotDeterministic("derivation '%s' may not be deterministic: output '%s' differs",
-                        worker.store.printStorePath(drvPath), path);
+                        worker.store.printStorePath(drvPath), worker.store.toRealPath(path));
             }
 
             /* Since we verified the build, it's now ultimately trusted. */
diff --git a/src/libstore/gc.cc b/src/libstore/gc.cc
index 0c3d89611..6bab1e37c 100644
--- a/src/libstore/gc.cc
+++ b/src/libstore/gc.cc
@@ -202,6 +202,11 @@ void LocalStore::findTempRoots(FDs & fds, Roots & tempRoots, bool censor)
     /* Read the `temproots' directory for per-process temporary root
        files. */
     for (auto & i : readDirectory(tempRootsDir)) {
+        if (i.name[0] == '.') {
+            // Ignore hidden files. Some package managers (notably portage) create
+            // those to keep the directory alive.
+            continue;
+        }
         Path path = tempRootsDir + "/" + i.name;
 
         pid_t pid = std::stoi(i.name);