On Sun, Jun 23, 2019 at 02:28:00PM +0300, Dmitry V. Levin wrote:
> 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 <ldv@xxxxxxxxxxxx>
Reviewed-by: Christian Brauner <christian@xxxxxxxxxx>
Thank you Dmitry, queueing this up for rc7.
> ---
> samples/pidfd/pidfd-metadata.c | 8 ++++++--
> 1 file changed, 6 insertions(+), 2 deletions(-)
>
> 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);
> --
> ldv
