2 files changed, 16 insertions, 1 deletions
diff --git a/pkgs/build-support/libredirect/libredirect.c b/pkgs/build-support/libredirect/libredirect.c
index 19211a813eb..fdbdcb6ebb8 100644
--- a/pkgs/build-support/libredirect/libredirect.c
+++ b/pkgs/build-support/libredirect/libredirect.c
@@ -70,9 +70,12 @@ static void init()
 
 }
 
-static const char * rewrite(const char * path, char * buf)
+static const char * rewrite(const char * volatile path, char * buf)
 {
+    // Marking the path volatile is needed so the the following check isn't
+    // optimized away by the compiler.
     if (path == NULL) return path;
+
     for (int n = 0; n < nrRedirects; ++n) {
         int len = strlen(from[n]);
         if (strncmp(path, from[n], len) != 0) continue;
diff --git a/pkgs/build-support/libredirect/test.c b/pkgs/build-support/libredirect/test.c
index 7dd384ae3ed..20b27759f01 100644
--- a/pkgs/build-support/libredirect/test.c
+++ b/pkgs/build-support/libredirect/test.c
@@ -45,6 +45,17 @@ void test_subprocess(void) {
     assert(system(SUBTEST) == 0);
 }
 
+void test_stat_with_null_path(void) {
+    // This checks whether the compiler optimizes away the null pointer check
+    // on the path passed to stat(). If that's the case, the following code
+    // should segfault.
+    struct stat buf;
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wnonnull"
+    stat(NULL, &buf);
+#pragma GCC diagnostic pop
+}
+
 void assert_mktemp_path(
     const char * orig_prefix,
     const char * orig_suffix,
@@ -147,6 +158,7 @@ int main(int argc, char *argv[])
 
     test_spawn();
     test_system();
+    test_stat_with_null_path();
 
     // Only run subprocess if no arguments are given
     // as the subprocess will be called without argument