[LTP] [PATCH v2 08/13] sigwaitinfo01: catch SEGV and report success for bad_address2 testcase

[Punit Agrawal]

The bad_address2 testcase passes (void *)1 as a sigset pointer to the
sigwaitinfo syscall. Unsurprisingly, this segfaults in libc rather than
returning -1 (errno = EFAULT) as LTP expects.

Instead, fork a child process which registers a SIGSEGV handler to catch
any SEGV's generated by the sigwaitinfo syscall. The signal handler
exits the child process with a return code which is checked by the
parent to evaluate test outcome.

Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
---
 .../kernel/syscalls/sigwaitinfo/sigwaitinfo01.c    | 29 ++++++++++++++++++++--
 1 file changed, 27 insertions(+), 2 deletions(-)

diff --git a/testcases/kernel/syscalls/sigwaitinfo/sigwaitinfo01.c b/testcases/kernel/syscalls/sigwaitinfo/sigwaitinfo01.c
index 16b5096b8..8f517e918 100644
--- a/testcases/kernel/syscalls/sigwaitinfo/sigwaitinfo01.c
+++ b/testcases/kernel/syscalls/sigwaitinfo/sigwaitinfo01.c
@@ -361,10 +361,35 @@ void test_bad_address(swi_func sigwaitinfo, int signo)
 	kill(child, SIGTERM);
 }
 
+static void segv_handler(int signo)
+{
+	/* SIGSEGV is expected, exit with 0xff */
+	_exit(0xff);
+}
+
 void test_bad_address2(swi_func sigwaitinfo, int signo)
 {
-	TEST(sigwaitinfo((void *)1, NULL, NULL));
-	REPORT_SUCCESS(-1, EFAULT);
+	pid_t pid;
+	int status;
+
+	switch (pid = FORK_OR_VFORK()) {
+	case -1:
+		tst_brkm(TBROK | TERRNO, NULL, "fork() failed");
+	case 0:
+		signal(SIGSEGV, segv_handler);
+		TEST(sigwaitinfo((void *)1, NULL, NULL));
+
+		_exit(0);
+		break;
+	default:
+		break;
+	}
+
+	SUCCEED_OR_DIE(waitpid, "waitpid failed", pid, &status, 0);
+	if (WIFEXITED(status) && WEXITSTATUS(status) == 0xff)
+		tst_resm(TPASS, "Test passed");
+	else
+		tst_resm(TFAIL, "Unrecognised child exit code");
 }
 
 void test_bad_address3(swi_func sigwaitinfo, int signo)
-- 
2.14.2