From bee19cd8f241ab3cd1bf79e03884e5371f9ef514 Mon Sep 17 00:00:00 2001 From: "Dmitry V. Levin" Date: Sun, 23 Jun 2019 14:28:00 +0300 Subject: samples: make pidfd-metadata fail gracefully on older kernels Initialize pidfd to an invalid descriptor, to fail gracefully on those kernels that do not implement CLONE_PIDFD and leave pidfd unchanged. Signed-off-by: Dmitry V. Levin Signed-off-by: Christian Brauner --- samples/pidfd/pidfd-metadata.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) (limited to 'samples') diff --git a/samples/pidfd/pidfd-metadata.c b/samples/pidfd/pidfd-metadata.c index 14b454448429..c459155daf9a 100644 --- a/samples/pidfd/pidfd-metadata.c +++ b/samples/pidfd/pidfd-metadata.c @@ -83,7 +83,7 @@ static int pidfd_metadata_fd(pid_t pid, int pidfd) int main(int argc, char *argv[]) { - int pidfd = 0, ret = EXIT_FAILURE; + int pidfd = -1, ret = EXIT_FAILURE; char buf[4096] = { 0 }; pid_t pid; int procfd, statusfd; @@ -91,7 +91,11 @@ int main(int argc, char *argv[]) pid = pidfd_clone(CLONE_PIDFD, &pidfd); if (pid < 0) - exit(ret); + err(ret, "CLONE_PIDFD"); + if (pidfd == -1) { + warnx("CLONE_PIDFD is not supported by the kernel"); + goto out; + } procfd = pidfd_metadata_fd(pid, pidfd); close(pidfd); -- cgit