[PATCH] selftests/exec: Check if the syscall exists and bail if not

[Michael Ellerman <mpe@ellerman.id.au>]

On systems which don't implement sys_execveat(), this test produces a
lot of output.

Add a check at the beginning to see if the syscall is present, and if
not just note one error and return.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
---
 tools/testing/selftests/exec/execveat.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/tools/testing/selftests/exec/execveat.c b/tools/testing/selftests/exec/execveat.c
index e238c9559caf..b87e4a843bea 100644
--- a/tools/testing/selftests/exec/execveat.c
+++ b/tools/testing/selftests/exec/execveat.c
@@ -234,6 +234,14 @@ static int run_tests(void)
 	int fd_cloexec = open_or_die("execveat", O_RDONLY|O_CLOEXEC);
 	int fd_script_cloexec = open_or_die("script", O_RDONLY|O_CLOEXEC);
 
+	/* Check if we have execveat at all, and bail early if not */
+	errno = 0;
+	execveat_(-1, NULL, NULL, NULL, 0);
+	if (errno == -ENOSYS) {
+		printf("[FAIL] ENOSYS calling execveat - no kernel support?\n");
+		return 1;
+	}
+
 	/* Change file position to confirm it doesn't affect anything */
 	lseek(fd, 10, SEEK_SET);
 
-- 
2.1.0