idmapped-mounts: Reset errno to zero before run_test

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>
Signed-off-by: Zorro Lang <zlang@kernel.org>

diff --git a/src/idmapped-mounts/idmapped-mounts.c b/src/idmapped-mounts/idmapped-mounts.c
index ce3f73be189fc76ed9c8bfeb67d870218425035d..2e94bf712f1203c3556dc0304f3157c78dd65223 100644 (file)
--- 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();