Function pts_alloc

freebsd/kern/tty_pts.c:738–788

!PTS_EXTERNAL */

static
#endif /* !PTS_EXTERNAL */
int
pts_alloc(int fflags, struct thread *td, struct file *fp)
{
	int unit, ok, error;
	struct tty *tp;
	struct pts_softc *psc;
	struct proc *p = td->td_proc;
	struct ucred *cred = td->td_ucred;

	/* Resource limiting. */
	PROC_LOCK(p);
	error = racct_add(p, RACCT_NPTS, 1);
	if (error != 0) {
		PROC_UNLOCK(p);
		return (EAGAIN);
	}
	ok = chgptscnt(cred->cr_ruidinfo, 1, lim_cur(td, RLIMIT_NPTS));
	if (!ok) {
		racct_sub(p, RACCT_NPTS, 1);
		PROC_UNLOCK(p);
		return (EAGAIN);
	}
	PROC_UNLOCK(p);

	/* Try to allocate a new pts unit number. */
	unit = alloc_unr(pts_pool);
	if (unit < 0) {
		racct_sub(p, RACCT_NPTS, 1);
		chgptscnt(cred->cr_ruidinfo, -1, 0);
		return (EAGAIN);
	}

	/* Allocate TTY and softc. */
	psc = malloc(sizeof(struct pts_softc), M_PTS, M_WAITOK|M_ZERO);
	cv_init(&psc->pts_inwait, "ptsin");
	cv_init(&psc->pts_outwait, "ptsout");

	psc->pts_unit = unit;
	psc->pts_cred = crhold(cred);

	tp = tty_alloc(&pts_class, psc);
	knlist_init_mtx(&psc->pts_inpoll.si_note, tp->t_mtx);
	knlist_init_mtx(&psc->pts_outpoll.si_note, tp->t_mtx);

	/* Expose the slave device as well. */
	tty_makedev(tp, td->td_ucred, "pts/%u", psc->pts_unit);

	finit(fp, fflags, DTYPE_PTS, tp, &ptsdev_ops);

	return (0);
}

#ifdef PTS_EXTERNAL
int