PIDFD_NS_PID
if (self->nsfds[PIDFD_NS_USER] >= 0 && self->nsfds[PIDFD_NS_PID] >= 0)
else if (self->nsfds[PIDFD_NS_PID] >= 0)
if (self->nsfds[PIDFD_NS_USER] >= 0 && self->nsfds[PIDFD_NS_PID] >= 0)
else if (self->nsfds[PIDFD_NS_PID] >= 0)
[PIDFD_NS_PID] = { "pid", CLONE_NEWPID, PIDFD_GET_PID_NAMESPACE, },