Function pgsigio

freebsd/kern/kern_sig.c:3904–3940

* Send a SIGIO or SIGURG signal to a process or process group using stored * credentials rather than those of the current process. */

 * credentials rather than those of the current process.
 */
void
pgsigio(struct sigio **sigiop, int sig, int checkctty)
{
	ksiginfo_t ksi;
	struct sigio *sigio;

	ksiginfo_init(&ksi);
	ksi.ksi_signo = sig;
	ksi.ksi_code = SI_KERNEL;

	SIGIO_LOCK();
	sigio = *sigiop;
	if (sigio == NULL) {
		SIGIO_UNLOCK();
		return;
	}
	if (sigio->sio_pgid > 0) {
		PROC_LOCK(sigio->sio_proc);
		if (CANSIGIO(sigio->sio_ucred, sigio->sio_proc->p_ucred))
			kern_psignal(sigio->sio_proc, sig);
		PROC_UNLOCK(sigio->sio_proc);
	} else if (sigio->sio_pgid < 0) {
		struct proc *p;

		PGRP_LOCK(sigio->sio_pgrp);
		LIST_FOREACH(p, &sigio->sio_pgrp->pg_members, p_pglist) {
			PROC_LOCK(p);
			if (p->p_state == PRS_NORMAL &&
			    CANSIGIO(sigio->sio_ucred, p->p_ucred) &&
			    (checkctty == 0 || (p->p_flag & P_CONTROLT)))
				kern_psignal(p, sig);
			PROC_UNLOCK(p);
		}
		PGRP_UNLOCK(sigio->sio_pgrp);
	}
	SIGIO_UNLOCK();
}

static int
filt_sigattach(struct knote *kn)