[PATCH v5 1/3] idmapped-mounts: Reset errno to zero before run_test

[Yang Xu <xuyang2018.jy@fujitsu.com>]

If we run case on old kernel that doesn't support mount_setattr and
then fail on our own function before call is_setgid/is_setuid function
to reset errno, run_test will print "Function not implement" error.

We also check whether system support user namespace, so reset errno to
zero after userns check.

Acked-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Signed-off-by: Yang Xu <xuyang2018.jy@fujitsu.com>
---
 src/idmapped-mounts/idmapped-mounts.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/idmapped-mounts/idmapped-mounts.c b/src/idmapped-mounts/idmapped-mounts.c
index ce3f73be..2e94bf71 100644
--- a/src/idmapped-mounts/idmapped-mounts.c
+++ b/src/idmapped-mounts/idmapped-mounts.c
@@ -14232,6 +14232,8 @@ int main(int argc, char *argv[])
 		exit(EXIT_SUCCESS);
 	}
 	t_has_userns = sys_has_userns();
+	/* don't copy ENOSYS errno to child process on older kernel */
+	errno = 0;
 
 	stash_overflowuid();
 	stash_overflowgid();
-- 
2.27.0