Function ttydisc_read_raw_read_timer

freebsd/kern/tty_ttydisc.c:222–274

}

static int
ttydisc_read_raw_read_timer(struct tty *tp, struct uio *uio, int ioflag,
    int oresid)
{
	size_t vmin = MAX(tp->t_termios.c_cc[VMIN], 1);
	unsigned int vtime = tp->t_termios.c_cc[VTIME];
	struct timeval end, now, left;
	int error, hz;

	MPASS(tp->t_termios.c_cc[VTIME] != 0);

	/* Determine when the read should be expired. */
	end.tv_sec = vtime / 10;
	end.tv_usec = (vtime % 10) * 100000;
	getmicrotime(&now);
	timevaladd(&end, &now);

	for (;;) {
		error = tty_wait_background(tp, curthread, SIGTTIN);
		if (error)
			return (error);

		error = ttyinq_read_uio(&tp->t_inq, tp, uio,
		    uio->uio_resid, 0);
		if (error)
			return (error);
		if (uio->uio_resid == 0 || (oresid - uio->uio_resid) >= vmin)
			return (0);

		/* Calculate how long we should wait. */
		getmicrotime(&now);
		if (timevalcmp(&now, &end, >))
			return (0);
		left = end;
		timevalsub(&left, &now);
		hz = tvtohz(&left);

		/*
		 * We have to wait for more. If the timer expires, we
		 * should return a 0-byte read.
		 */
		if (tp->t_flags & TF_ZOMBIE)
			return (0);
		else if (ioflag & IO_NDELAY)
			return (EWOULDBLOCK);

		error = tty_timedwait(tp, &tp->t_inwait, hz);
		if (error)
			return (error == EWOULDBLOCK ? 0 : error);
	}

	return (0);
}

static int
ttydisc_read_raw_interbyte_timer(struct tty *tp, struct uio *uio, int ioflag)