PIDFD_STALE
unsigned int pidfd_flags = PIDFD_STALE;
PIDFD_STALE | PIDFD_AUTOKILL) != 4);
flags &= ~PIDFD_STALE;
if (!(flags & PIDFD_STALE)) {
unsigned flags = PIDFD_STALE;
pidfd = pidfd_prepare(scm->pid, PIDFD_STALE, &pidfd_file);
flags = PIDFD_STALE;