/*	$OpenBSD: tty_pty.c,v 1.16 2003/10/03 16:44:51 miod Exp $	*/
/*	$NetBSD: tty_pty.c,v 1.33.4.1 1996/06/02 09:08:11 mrg Exp $	*/

/*
 * Copyright (c) 1982, 1986, 1989, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	@(#)tty_pty.c	8.4 (Berkeley) 2/20/95
 */

/*
 * Pseudo-teletype Driver
 * (Actually two drivers, requiring two entries in 'cdevsw')
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/ioctl.h>
#include <sys/proc.h>
#include <sys/tty.h>
#include <sys/file.h>
#include <sys/uio.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/vnode.h>
#include <sys/signalvar.h>
#include <sys/uio.h>
#include <sys/conf.h>
#include <sys/poll.h>

#define BUFSIZ 100		/* Chunk size iomoved to/from user */

/*
 * pts == /dev/tty[pqrs]?
 * ptc == /dev/pty[pqrs]?
 */
struct	pt_softc {
	struct	tty *pt_tty;
	int	pt_flags;
	struct	selinfo pt_selr, pt_selw;
	u_char	pt_send;
	u_char	pt_ucntl;
} *pt_softc;
int	npty;

#define	PF_PKT		0x08		/* packet mode */
#define	PF_STOPPED	0x10		/* user told stopped */
#define	PF_REMOTE	0x20		/* remote and flow controlled input */
#define	PF_NOSTOP	0x40
#define PF_UCNTL	0x80		/* user control mode */

void	ptyattach(int);
void	ptcwakeup(struct tty *, int);
struct tty *ptytty(dev_t);
void	ptsstart(struct tty *);

void	filt_ptcrdetach(struct knote *);
int	filt_ptcread(struct knote *, long);
void	filt_ptcwdetach(struct knote *);
int	filt_ptcwrite(struct knote *, long);

/*
 * Establish n (or default if n is 1) ptys in the system.
 */
void
ptyattach(n)
	int n;
{
#define	DEFAULT_NPTY	32

	/* maybe should allow 0 => none? */
	if (n <= 1)
		n = DEFAULT_NPTY;
	pt_softc = malloc(n * sizeof(struct pt_softc), M_DEVBUF, M_WAITOK);
	bzero(pt_softc, n * sizeof(struct pt_softc));
	npty = n;
}

/*ARGSUSED*/
int
ptsopen(dev, flag, devtype, p)
	dev_t dev;
	int flag, devtype;
	struct proc *p;
{
	struct pt_softc *pti;
	register struct tty *tp;
	int error;

	if (minor(dev) >= npty)
		return (ENXIO);
	pti = &pt_softc[minor(dev)];
	if (!pti->pt_tty) {
		tp = pti->pt_tty = ttymalloc();
	} else
		tp = pti->pt_tty;
	if ((tp->t_state & TS_ISOPEN) == 0) {
		tp->t_state |= TS_WOPEN;
		ttychars(tp);		/* Set up default chars */
		tp->t_iflag = TTYDEF_IFLAG;
		tp->t_oflag = TTYDEF_OFLAG;
		tp->t_lflag = TTYDEF_LFLAG;
		tp->t_cflag = TTYDEF_CFLAG;
		tp->t_ispeed = tp->t_ospeed = TTYDEF_SPEED;
		ttsetwater(tp);		/* would be done in xxparam() */
	} else if (tp->t_state&TS_XCLUDE && p->p_ucred->cr_uid != 0)
		return (EBUSY);
	if (tp->t_oproc)			/* Ctrlr still around. */
		tp->t_state |= TS_CARR_ON;
	while ((tp->t_state & TS_CARR_ON) == 0) {
		tp->t_state |= TS_WOPEN;
		if (flag&FNONBLOCK)
			break;
		error = ttysleep(tp, &tp->t_rawq, TTIPRI | PCATCH,
				 ttopen, 0);
		if (error)
			return (error);
	}
	error = (*linesw[tp->t_line].l_open)(dev, tp);
	ptcwakeup(tp, FREAD|FWRITE);
	return (error);
}

int
ptsclose(dev, flag, mode, p)
	dev_t dev;
	int flag, mode;
	struct proc *p;
{
	register struct pt_softc *pti = &pt_softc[minor(dev)];
	register struct tty *tp = pti->pt_tty;
	int error;

	error = (*linesw[tp->t_line].l_close)(tp, flag);
	error |= ttyclose(tp);
	ptcwakeup(tp, FREAD|FWRITE);
	return (error);
}

int
ptsread(dev, uio, flag)
	dev_t dev;
	struct uio *uio;
	int flag;
{
	struct proc *p = curproc;
	register struct pt_softc *pti = &pt_softc[minor(dev)];
	register struct tty *tp = pti->pt_tty;
	int error = 0;

again:
	if (pti->pt_flags & PF_REMOTE) {
		while (isbackground(p, tp)) {
			if ((p->p_sigignore & sigmask(SIGTTIN)) ||
			    (p->p_sigmask & sigmask(SIGTTIN)) ||
			    p->p_pgrp->pg_jobc == 0 ||
			    p->p_flag & P_PPWAIT)
				return (EIO);
			pgsignal(p->p_pgrp, SIGTTIN, 1);
			error = ttysleep(tp, &lbolt, 
					 TTIPRI | PCATCH, ttybg, 0);
			if (error)
				return (error);
		}
		if (tp->t_canq.c_cc == 0) {
			if (flag & IO_NDELAY)
				return (EWOULDBLOCK);
			error = ttysleep(tp, &tp->t_canq,
					 TTIPRI | PCATCH, ttyin, 0);
			if (error)
				return (error);
			goto again;
		}
		while (tp->t_canq.c_cc > 1 && uio->uio_resid > 0)
			if (ureadc(getc(&tp->t_canq), uio) < 0) {
				error = EFAULT;
				break;
			}
		if (tp->t_canq.c_cc == 1)
			(void) getc(&tp->t_canq);
		if (tp->t_canq.c_cc)
			return (error);
	} else
		if (tp->t_oproc)
			error = (*linesw[tp->t_line].l_read)(tp, uio, flag);
	ptcwakeup(tp, FWRITE);
	return (error);
}

/*
 * Write to pseudo-tty.
 * Wakeups of controlling tty will happen
 * indirectly, when tty driver calls ptsstart.
 */
int
ptswrite(dev, uio, flag)
	dev_t dev;
	struct uio *uio;
	int flag;
{
	register struct pt_softc *pti = &pt_softc[minor(dev)];
	register struct tty *tp = pti->pt_tty;

	if (tp->t_oproc == 0)
		return (EIO);
	return ((*linesw[tp->t_line].l_write)(tp, uio, flag));
}

/*
 * Start output on pseudo-tty.
 * Wake up process polling or sleeping for input from controlling tty.
 */
void
ptsstart(tp)
	struct tty *tp;
{
	register struct pt_softc *pti = &pt_softc[minor(tp->t_dev)];

	if (tp->t_state & TS_TTSTOP)
		return;
	if (pti->pt_flags & PF_STOPPED) {
		pti->pt_flags &= ~PF_STOPPED;
		pti->pt_send = TIOCPKT_START;
	}
	ptcwakeup(tp, FREAD);
}

int
ptsstop(tp, flush)
	register struct tty *tp;
	int flush;
{
	struct pt_softc *pti = &pt_softc[minor(tp->t_dev)];
	int flag;

	/* note: FLUSHREAD and FLUSHWRITE already ok */
	if (flush == 0) {
		flush = TIOCPKT_STOP;
		pti->pt_flags |= PF_STOPPED;
	} else
		pti->pt_flags &= ~PF_STOPPED;
	pti->pt_send |= flush;
	/* change of perspective */
	flag = 0;
	if (flush & FREAD)
		flag |= FWRITE;
	if (flush & FWRITE)
		flag |= FREAD;
	ptcwakeup(tp, flag);
	return 0;
}

void
ptcwakeup(tp, flag)
	struct tty *tp;
	int flag;
{
	struct pt_softc *pti = &pt_softc[minor(tp->t_dev)];

	if (flag & FREAD) {
		selwakeup(&pti->pt_selr);
		wakeup(&tp->t_outq.c_cf);
		KNOTE(&pti->pt_selr.si_note, 0);
	}
	if (flag & FWRITE) {
		selwakeup(&pti->pt_selw);
		wakeup(&tp->t_rawq.c_cf);
		KNOTE(&pti->pt_selw.si_note, 0);
	}
}

int ptcopen(dev_t, int, int, struct proc *);

/*ARGSUSED*/
int
ptcopen(dev, flag, devtype, p)
	dev_t dev;
	int flag, devtype;
	struct proc *p;
{
	struct pt_softc *pti;
	register struct tty *tp;

	if (minor(dev) >= npty)
		return (ENXIO);
	pti = &pt_softc[minor(dev)];
	if (!pti->pt_tty) {
		tp = pti->pt_tty = ttymalloc();
	} else
		tp = pti->pt_tty;
	if (tp->t_oproc)
		return (EIO);
	tp->t_oproc = ptsstart;
	(void)(*linesw[tp->t_line].l_modem)(tp, 1);
	tp->t_lflag &= ~EXTPROC;
	pti->pt_flags = 0;
	pti->pt_send = 0;
	pti->pt_ucntl = 0;
	return (0);
}

/*ARGSUSED*/
int
ptcclose(dev, flag, devtype, p)
	dev_t dev;
	int flag, devtype;
	struct proc *p;
{
	register struct pt_softc *pti = &pt_softc[minor(dev)];
	register struct tty *tp = pti->pt_tty;

	(void)(*linesw[tp->t_line].l_modem)(tp, 0);
	tp->t_state &= ~TS_CARR_ON;
	tp->t_oproc = 0;		/* mark closed */
	return (0);
}

int
ptcread(dev, uio, flag)
	dev_t dev;
	struct uio *uio;
	int flag;
{
	register struct pt_softc *pti = &pt_softc[minor(dev)];
	register struct tty *tp = pti->pt_tty;
	char buf[BUFSIZ];
	int error = 0, cc;

	/*
	 * We want to block until the slave
	 * is open, and there's something to read;
	 * but if we lost the slave or we're NBIO,
	 * then return the appropriate error instead.
	 */
	for (;;) {
		if (tp->t_state&TS_ISOPEN) {
			if (pti->pt_flags&PF_PKT && pti->pt_send) {
				error = ureadc((int)pti->pt_send, uio);
				if (error)
					return (error);
				if (pti->pt_send & TIOCPKT_IOCTL) {
					cc = min(uio->uio_resid,
						sizeof(tp->t_termios));
					uiomove(&tp->t_termios, cc, uio);
				}
				pti->pt_send = 0;
				return (0);
			}
			if (pti->pt_flags&PF_UCNTL && pti->pt_ucntl) {
				error = ureadc((int)pti->pt_ucntl, uio);
				if (error)
					return (error);
				pti->pt_ucntl = 0;
				return (0);
			}
			if (tp->t_outq.c_cc && (tp->t_state&TS_TTSTOP) == 0)
				break;
		}
		if ((tp->t_state&TS_CARR_ON) == 0)
			return (0);	/* EOF */
		if (flag & IO_NDELAY)
			return (EWOULDBLOCK);
		error = tsleep(&tp->t_outq.c_cf, TTIPRI | PCATCH,
			       ttyin, 0);
		if (error)
			return (error);
	}
	if (pti->pt_flags & (PF_PKT|PF_UCNTL))
		error = ureadc(0, uio);
	while (uio->uio_resid > 0 && error == 0) {
		cc = q_to_b(&tp->t_outq, buf, min(uio->uio_resid, BUFSIZ));
		if (cc <= 0)
			break;
		error = uiomove(buf, cc, uio);
	}
	if (tp->t_outq.c_cc <= tp->t_lowat) {
		if (tp->t_state&TS_ASLEEP) {
			tp->t_state &= ~TS_ASLEEP;
			wakeup(&tp->t_outq);
		}
		selwakeup(&tp->t_wsel);
	}
	return (error);
}


int
ptcwrite(dev, uio, flag)
	dev_t dev;
	register struct uio *uio;
	int flag;
{
	register struct pt_softc *pti = &pt_softc[minor(dev)];
	register struct tty *tp = pti->pt_tty;
	register u_char *cp = NULL;
	register int cc = 0;
	u_char locbuf[BUFSIZ];
	int cnt = 0;
	int error = 0;

again:
	if ((tp->t_state&TS_ISOPEN) == 0)
		goto block;
	if (pti->pt_flags & PF_REMOTE) {
		if (tp->t_canq.c_cc)
			goto block;
		while (uio->uio_resid > 0 && tp->t_canq.c_cc < TTYHOG - 1) {
			if (cc == 0) {
				cc = min(uio->uio_resid, BUFSIZ);
				cc = min(cc, TTYHOG - 1 - tp->t_canq.c_cc);
				cp = locbuf;
				error = uiomove(cp, cc, uio);
				if (error)
					return (error);
				/* check again for safety */
				if ((tp->t_state&TS_ISOPEN) == 0)
					return (EIO);
			}
			if (cc)
				(void) b_to_q((char *)cp, cc, &tp->t_canq);
			cc = 0;
		}
		(void) putc(0, &tp->t_canq);
		ttwakeup(tp);
		wakeup(&tp->t_canq);
		return (0);
	}
	while (uio->uio_resid > 0) {
		if (cc == 0) {
			cc = min(uio->uio_resid, BUFSIZ);
			cp = locbuf;
			error = uiomove(cp, cc, uio);
			if (error)
				return (error);
			/* check again for safety */
			if ((tp->t_state&TS_ISOPEN) == 0)
				return (EIO);
		}
		while (cc > 0) {
			if ((tp->t_rawq.c_cc + tp->t_canq.c_cc) >= TTYHOG - 2 &&
			   (tp->t_canq.c_cc > 0 || !ISSET(tp->t_lflag, ICANON))) {
				wakeup(&tp->t_rawq);
				goto block;
			}
			(*linesw[tp->t_line].l_rint)(*cp++, tp);
			cnt++;
			cc--;
		}
		cc = 0;
	}
	return (0);
block:
	/*
	 * Come here to wait for slave to open, for space
	 * in outq, or space in rawq.
	 */
	if ((tp->t_state&TS_CARR_ON) == 0)
		return (EIO);
	if (flag & IO_NDELAY) {
		/* adjust for data copied in but not written */
		uio->uio_resid += cc;
		if (cnt == 0)
			return (EWOULDBLOCK);
		return (0);
	}
	error = tsleep(&tp->t_rawq.c_cf, TTOPRI | PCATCH,
		       ttyout, 0);
	if (error) {
		/* adjust for data copied in but not written */
		uio->uio_resid += cc;
		return (error);
	}
	goto again;
}

int
ptcpoll(dev_t dev, int events, struct proc *p)
{
	struct pt_softc *pti = &pt_softc[minor(dev)];
	struct tty *tp = pti->pt_tty;
	int revents = 0, s;

	if (!ISSET(tp->t_state, TS_CARR_ON))
		return (POLLHUP);

	if (!ISSET(tp->t_state, TS_ISOPEN))
		goto notopen;

	if (events & (POLLIN | POLLRDNORM)) {
		/*
		 * Need to protect access to t_outq
		 */
		s = spltty();
		if ((tp->t_outq.c_cc && !ISSET(tp->t_state, TS_TTSTOP)) ||
		     ((pti->pt_flags & PF_PKT) && pti->pt_send) ||
		     ((pti->pt_flags & PF_UCNTL) && pti->pt_ucntl))
			revents |= events & (POLLIN | POLLRDNORM);
		splx(s);
	}
	if (events & (POLLOUT | POLLWRNORM)) {
		if ((pti->pt_flags & PF_REMOTE) ?
		     (tp->t_canq.c_cc == 0) :
		     ((tp->t_rawq.c_cc + tp->t_canq.c_cc < TTYHOG - 2) ||
		      (tp->t_canq.c_cc == 0 && ISSET(tp->t_lflag, ICANON))))
			revents |= events & (POLLOUT | POLLWRNORM);
	}
	if (events & (POLLPRI | POLLRDBAND)) {
		/* If in packet or user control mode, check for data. */
		if (((pti->pt_flags & PF_PKT) && pti->pt_send) ||
		     ((pti->pt_flags & PF_UCNTL) && pti->pt_ucntl))
			revents |= events & (POLLPRI | POLLRDBAND);
	}

	if (revents == 0) {
notopen:
		if (events & (POLLIN | POLLPRI | POLLRDNORM | POLLRDBAND))
			selrecord(p, &pti->pt_selr);
		if (events & (POLLOUT | POLLWRNORM))
			selrecord(p, &pti->pt_selw);
	}

	return (revents);
}

void
filt_ptcrdetach(struct knote *kn)
{
	struct pt_softc *pti = (struct pt_softc *)kn->kn_hook;
	int s;

	s = spltty();
	SLIST_REMOVE(&pti->pt_selr.si_note, kn, knote, kn_selnext);
	splx(s);
}

int
filt_ptcread(struct knote *kn, long hint)
{
	struct pt_softc *pti = (struct pt_softc *)kn->kn_hook;
	struct tty *tp;

	tp = pti->pt_tty;
	kn->kn_data = 0;

	if (ISSET(tp->t_state, TS_ISOPEN)) {
		if (!ISSET(tp->t_state, TS_TTSTOP))
			kn->kn_data = tp->t_outq.c_cc;
		if (((pti->pt_flags & PF_PKT) && pti->pt_send) ||
		    ((pti->pt_flags & PF_UCNTL) && pti->pt_ucntl))
			kn->kn_data++;
	}
	return (kn->kn_data > 0);
}

void
filt_ptcwdetach(struct knote *kn)
{
	struct pt_softc *pti = (struct pt_softc *)kn->kn_hook;
	int s;

	s = spltty();
	SLIST_REMOVE(&pti->pt_selw.si_note, kn, knote, kn_selnext);
	splx(s);
}

int
filt_ptcwrite(struct knote *kn, long hint)
{
	struct pt_softc *pti = (struct pt_softc *)kn->kn_hook;
	struct tty *tp;

	tp = pti->pt_tty;
	kn->kn_data = 0;

	if (ISSET(tp->t_state, TS_ISOPEN)) {
		if (ISSET(pti->pt_flags, PF_REMOTE)) {
			if (tp->t_canq.c_cc == 0)
				kn->kn_data = tp->t_canq.c_cn;
		} else if (tp->t_rawq.c_cc + tp->t_canq.c_cc < TTYHOG-2)
			kn->kn_data = tp->t_canq.c_cn -
			    (tp->t_rawq.c_cc + tp->t_canq.c_cc);
	}

	return (kn->kn_data > 0);
}

struct filterops ptcread_filtops =
	{ 1, NULL, filt_ptcrdetach, filt_ptcread };
struct filterops ptcwrite_filtops =
	{ 1, NULL, filt_ptcwdetach, filt_ptcwrite };

int
ptckqfilter(dev_t dev, struct knote *kn)
{
	struct pt_softc *pti = &pt_softc[minor(dev)];
	struct klist *klist;
	int s;

	switch (kn->kn_filter) {
	case EVFILT_READ:
		klist = &pti->pt_selr.si_note;
		kn->kn_fop = &ptcread_filtops;
		break;
	case EVFILT_WRITE:
		klist = &pti->pt_selw.si_note;
		kn->kn_fop = &ptcwrite_filtops;
		break;
	default:
		return (1);
	}

	kn->kn_hook = (caddr_t)pti;

	s = spltty();
	SLIST_INSERT_HEAD(klist, kn, kn_selnext);
	splx(s);

	return (0);
}

struct tty *
ptytty(dev)
	dev_t dev;
{
	register struct pt_softc *pti = &pt_softc[minor(dev)];
	register struct tty *tp = pti->pt_tty;

	return (tp);
}

/*ARGSUSED*/
int
ptyioctl(dev, cmd, data, flag, p)
	dev_t dev;
	u_long cmd;
	caddr_t data;
	int flag;
	struct proc *p;
{
	register struct pt_softc *pti = &pt_softc[minor(dev)];
	register struct tty *tp = pti->pt_tty;
	register u_char *cc = tp->t_cc;
	int stop, error;

	/*
	 * IF CONTROLLER STTY THEN MUST FLUSH TO PREVENT A HANG.
	 * ttywflush(tp) will hang if there are characters in the outq.
	 */
	if (cmd == TIOCEXT) {
		/*
		 * When the EXTPROC bit is being toggled, we need
		 * to send an TIOCPKT_IOCTL if the packet driver
		 * is turned on.
		 */
		if (*(int *)data) {
			if (pti->pt_flags & PF_PKT) {
				pti->pt_send |= TIOCPKT_IOCTL;
				ptcwakeup(tp, FREAD);
			}
			tp->t_lflag |= EXTPROC;
		} else {
			if ((tp->t_lflag & EXTPROC) &&
			    (pti->pt_flags & PF_PKT)) {
				pti->pt_send |= TIOCPKT_IOCTL;
				ptcwakeup(tp, FREAD);
			}
			tp->t_lflag &= ~EXTPROC;
		}
		return(0);
	} else
	if (cdevsw[major(dev)].d_open == ptcopen)
		switch (cmd) {

		case TIOCGPGRP:
#ifdef COMPAT_SUNOS
			{
			/*
			 * I'm not sure about SunOS TIOCGPGRP semantics
			 * on PTYs, but it's something like this:
			 */
			extern struct emul emul_sunos;
			if (p->p_emul == &emul_sunos && tp->t_pgrp == 0)
				return (EIO);
			*(int *)data = tp->t_pgrp->pg_id;
			return (0);
			}
#endif
			/*
			 * We aviod calling ttioctl on the controller since,
			 * in that case, tp must be the controlling terminal.
			 */
			*(int *)data = tp->t_pgrp ? tp->t_pgrp->pg_id : 0;
			return (0);

		case TIOCPKT:
			if (*(int *)data) {
				if (pti->pt_flags & PF_UCNTL)
					return (EINVAL);
				pti->pt_flags |= PF_PKT;
			} else
				pti->pt_flags &= ~PF_PKT;
			return (0);

		case TIOCUCNTL:
			if (*(int *)data) {
				if (pti->pt_flags & PF_PKT)
					return (EINVAL);
				pti->pt_flags |= PF_UCNTL;
			} else
				pti->pt_flags &= ~PF_UCNTL;
			return (0);

		case TIOCREMOTE:
			if (*(int *)data)
				pti->pt_flags |= PF_REMOTE;
			else
				pti->pt_flags &= ~PF_REMOTE;
			ttyflush(tp, FREAD|FWRITE);
			return (0);

#ifdef COMPAT_OLDTTY
		case TIOCSETP:		
		case TIOCSETN:
#endif
		case TIOCSETD:
		case TIOCSETA:
		case TIOCSETAW:
		case TIOCSETAF:
			ndflush(&tp->t_outq, tp->t_outq.c_cc);
			break;

		case TIOCSIG:
			if (*(unsigned int *)data >= NSIG)
				return(EINVAL);
			if ((tp->t_lflag&NOFLSH) == 0)
				ttyflush(tp, FREAD|FWRITE);
			pgsignal(tp->t_pgrp, *(unsigned int *)data, 1);
			if ((*(unsigned int *)data == SIGINFO) &&
			    ((tp->t_lflag&NOKERNINFO) == 0))
				ttyinfo(tp);
			return(0);
		}
	error = (*linesw[tp->t_line].l_ioctl)(tp, cmd, data, flag, p);
	if (error < 0)
		 error = ttioctl(tp, cmd, data, flag, p);
	if (error < 0) {
		if (pti->pt_flags & PF_UCNTL &&
		    (cmd & ~0xff) == UIOCCMD(0)) {
			if (cmd & 0xff) {
				pti->pt_ucntl = (u_char)cmd;
				ptcwakeup(tp, FREAD);
			}
			return (0);
		}
		error = ENOTTY;
	}
	/*
	 * If external processing and packet mode send ioctl packet.
	 */
	if ((tp->t_lflag&EXTPROC) && (pti->pt_flags & PF_PKT)) {
		switch(cmd) {
		case TIOCSETA:
		case TIOCSETAW:
		case TIOCSETAF:
#ifdef COMPAT_OLDTTY
		case TIOCSETP:
		case TIOCSETN:
		case TIOCSETC:
		case TIOCSLTC:
		case TIOCLBIS:
		case TIOCLBIC:
		case TIOCLSET:
#endif
			pti->pt_send |= TIOCPKT_IOCTL;
			ptcwakeup(tp, FREAD);
		default:
			break;
		}
	}
	stop = (tp->t_iflag & IXON) && CCEQ(cc[VSTOP], CTRL('s')) 
		&& CCEQ(cc[VSTART], CTRL('q'));
	if (pti->pt_flags & PF_NOSTOP) {
		if (stop) {
			pti->pt_send &= ~TIOCPKT_NOSTOP;
			pti->pt_send |= TIOCPKT_DOSTOP;
			pti->pt_flags &= ~PF_NOSTOP;
			ptcwakeup(tp, FREAD);
		}
	} else {
		if (!stop) {
			pti->pt_send &= ~TIOCPKT_DOSTOP;
			pti->pt_send |= TIOCPKT_NOSTOP;
			pti->pt_flags |= PF_NOSTOP;
			ptcwakeup(tp, FREAD);
		}
	}
	return (error);
}