[RFC PATCH 3/3] selftests: memfd: error out test process when child test fails

[Aleksa Sarai <cyphar@cyphar.com>]

Before this change, a test runner using this self test would see a
return code of 0 when the tests using a child process (namely the
MFD_NOEXEC_SEAL and MFD_EXEC tests) failed, masking test failures.

Fixes: 11f75a01448f ("selftests/memfd: add tests for MFD_NOEXEC_SEAL MFD_EXEC")
Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>
---
 tools/testing/selftests/memfd/memfd_test.c | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/memfd/memfd_test.c b/tools/testing/selftests/memfd/memfd_test.c
index d8342989c547..8b7390ad81d1 100644
--- a/tools/testing/selftests/memfd/memfd_test.c
+++ b/tools/testing/selftests/memfd/memfd_test.c
@@ -1219,7 +1219,24 @@ static pid_t spawn_newpid_thread(unsigned int flags, int (*fn)(void *))
 
 static void join_newpid_thread(pid_t pid)
 {
-	waitpid(pid, NULL, 0);
+	int wstatus;
+
+	if (waitpid(pid, &wstatus, 0) < 0) {
+		printf("newpid thread: waitpid() failed: %m\n");
+		abort();
+	}
+
+	if (WIFEXITED(wstatus) && WEXITSTATUS(wstatus) != 0) {
+		printf("newpid thread: exited with non-zero error code %d\n",
+		       WEXITSTATUS(wstatus));
+		abort();
+	}
+
+	if (WIFSIGNALED(wstatus)) {
+		printf("newpid thread: killed by signal %d\n",
+		       WTERMSIG(wstatus));
+		abort();
+	}
 }
 
 /*
-- 
2.41.0