pty.c revision 3308 
1/*
2 * Copyright (c) 1982, 1986, 1989, 1993
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 * 3. All advertising materials mentioning features or use of this software
14 *    must display the following acknowledgement:
15 *	This product includes software developed by the University of
16 *	California, Berkeley and its contributors.
17 * 4. Neither the name of the University nor the names of its contributors
18 *    may be used to endorse or promote products derived from this software
19 *    without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 *
33 *	@(#)tty_pty.c	8.2 (Berkeley) 9/23/93
34 * $Id: tty_pty.c,v 1.4 1994/09/15 19:47:16 bde Exp $
35 */
36
37/*
38 * Pseudo-teletype Driver
39 * (Actually two drivers, requiring two entries in 'cdevsw')
40 */
41#include "pty.h"		/* XXX */
42
43#include <sys/param.h>
44#include <sys/systm.h>
45#include <sys/ioctl.h>
46#include <sys/proc.h>
47#include <sys/tty.h>
48#include <sys/conf.h>
49#include <sys/file.h>
50#include <sys/uio.h>
51#include <sys/kernel.h>
52#include <sys/vnode.h>
53#include <sys/signalvar.h>
54
55#if NPTY == 1
56#undef NPTY
57#define	NPTY	32		/* crude XXX */
58#endif
59
60#define BUFSIZ 100		/* Chunk size iomoved to/from user */
61
62/*
63 * pts == /dev/tty[pqrs]?
64 * ptc == /dev/pty[pqrs]?
65 */
66struct	tty pt_tty[NPTY];	/* XXX */
67struct	pt_ioctl {
68	int	pt_flags;
69	struct	selinfo pt_selr, pt_selw;
70	u_char	pt_send;
71	u_char	pt_ucntl;
72} pt_ioctl[NPTY];		/* XXX */
73int	npty = NPTY;		/* for pstat -t */
74
75#define	PF_PKT		0x08		/* packet mode */
76#define	PF_STOPPED	0x10		/* user told stopped */
77#define	PF_REMOTE	0x20		/* remote and flow controlled input */
78#define	PF_NOSTOP	0x40
79#define PF_UCNTL	0x80		/* user control mode */
80
81void	ptsstop		__P((struct tty *, int));
82void	ptcwakeup	__P((struct tty *, int));
83
84/*
85 * Establish n (or default if n is 1) ptys in the system.
86 *
87 * XXX cdevsw & pstat require the array `pty[]' to be an array
88 */
89void
90ptyattach(n)
91	int n;
92{
93#ifdef notyet
94	char *mem;
95	register u_long ntb;
96#define	DEFAULT_NPTY	32
97
98	/* maybe should allow 0 => none? */
99	if (n <= 1)
100		n = DEFAULT_NPTY;
101	ntb = n * sizeof(struct tty);
102	mem = malloc(ntb + ALIGNBYTES + n * sizeof(struct pt_ioctl),
103	    M_DEVBUF, M_WAITOK);
104	pt_tty = (struct tty *)mem;
105	mem = (char *)ALIGN(mem + ntb);
106	pt_ioctl = (struct pt_ioctl *)mem;
107	npty = n;
108#endif
109}
110
111/*ARGSUSED*/
112int
113ptsopen(dev, flag, devtype, p)
114	dev_t dev;
115	int flag, devtype;
116	struct proc *p;
117{
118	register struct tty *tp;
119	int error;
120
121	if (minor(dev) >= npty)
122		return (ENXIO);
123	tp = &pt_tty[minor(dev)];
124	if ((tp->t_state & TS_ISOPEN) == 0) {
125		tp->t_state |= TS_WOPEN;
126		ttychars(tp);		/* Set up default chars */
127		tp->t_iflag = TTYDEF_IFLAG;
128		tp->t_oflag = TTYDEF_OFLAG;
129		tp->t_lflag = TTYDEF_LFLAG;
130		tp->t_cflag = TTYDEF_CFLAG;
131		tp->t_ispeed = tp->t_ospeed = TTYDEF_SPEED;
132		ttsetwater(tp);		/* would be done in xxparam() */
133	} else if (tp->t_state&TS_XCLUDE && p->p_ucred->cr_uid != 0)
134		return (EBUSY);
135	if (tp->t_oproc)			/* Ctrlr still around. */
136		tp->t_state |= TS_CARR_ON;
137	while ((tp->t_state & TS_CARR_ON) == 0) {
138		tp->t_state |= TS_WOPEN;
139		if (flag&FNONBLOCK)
140			break;
141		error = ttysleep(tp, (caddr_t)&tp->t_rawq, TTIPRI | PCATCH,
142		    ttopen, 0);
143		if (error)
144			return (error);
145	}
146	error = (*linesw[tp->t_line].l_open)(dev, tp);
147	ptcwakeup(tp, FREAD|FWRITE);
148	return (error);
149}
150
151int
152ptsclose(dev, flag, mode, p)
153	dev_t dev;
154	int flag, mode;
155	struct proc *p;
156{
157	register struct tty *tp;
158	int err;
159
160	tp = &pt_tty[minor(dev)];
161	err = (*linesw[tp->t_line].l_close)(tp, flag);
162	err |= ttyclose(tp);
163	ptcwakeup(tp, FREAD|FWRITE);
164	return (err);
165}
166
167int
168ptsread(dev, uio, flag)
169	dev_t dev;
170	struct uio *uio;
171	int flag;
172{
173	struct proc *p = curproc;
174	register struct tty *tp = &pt_tty[minor(dev)];
175	register struct pt_ioctl *pti = &pt_ioctl[minor(dev)];
176	int error = 0;
177
178again:
179	if (pti->pt_flags & PF_REMOTE) {
180		while (isbackground(p, tp)) {
181			if ((p->p_sigignore & sigmask(SIGTTIN)) ||
182			    (p->p_sigmask & sigmask(SIGTTIN)) ||
183			    p->p_pgrp->pg_jobc == 0 ||
184			    p->p_flag & P_PPWAIT)
185				return (EIO);
186			pgsignal(p->p_pgrp, SIGTTIN, 1);
187			error = ttysleep(tp, (caddr_t)&lbolt,
188			    TTIPRI | PCATCH, ttybg, 0);
189			if (error)
190				return (error);
191		}
192		if (tp->t_canq.c_cc == 0) {
193			if (flag & IO_NDELAY)
194				return (EWOULDBLOCK);
195			error = ttysleep(tp, (caddr_t)&tp->t_canq,
196			    TTIPRI | PCATCH, ttyin, 0);
197			if (error)
198				return (error);
199			goto again;
200		}
201		while (tp->t_canq.c_cc > 1 && uio->uio_resid > 0)
202			if (ureadc(getc(&tp->t_canq), uio) < 0) {
203				error = EFAULT;
204				break;
205			}
206		if (tp->t_canq.c_cc == 1)
207			(void) getc(&tp->t_canq);
208		if (tp->t_canq.c_cc)
209			return (error);
210	} else
211		if (tp->t_oproc)
212			error = (*linesw[tp->t_line].l_read)(tp, uio, flag);
213	ptcwakeup(tp, FWRITE);
214	return (error);
215}
216
217/*
218 * Write to pseudo-tty.
219 * Wakeups of controlling tty will happen
220 * indirectly, when tty driver calls ptsstart.
221 */
222int
223ptswrite(dev, uio, flag)
224	dev_t dev;
225	struct uio *uio;
226	int flag;
227{
228	register struct tty *tp;
229
230	tp = &pt_tty[minor(dev)];
231	if (tp->t_oproc == 0)
232		return (EIO);
233	return ((*linesw[tp->t_line].l_write)(tp, uio, flag));
234}
235
236/*
237 * Start output on pseudo-tty.
238 * Wake up process selecting or sleeping for input from controlling tty.
239 */
240void
241ptsstart(tp)
242	struct tty *tp;
243{
244	register struct pt_ioctl *pti = &pt_ioctl[minor(tp->t_dev)];
245
246	if (tp->t_state & TS_TTSTOP)
247		return;
248	if (pti->pt_flags & PF_STOPPED) {
249		pti->pt_flags &= ~PF_STOPPED;
250		pti->pt_send = TIOCPKT_START;
251	}
252	ptcwakeup(tp, FREAD);
253}
254
255void
256ptcwakeup(tp, flag)
257	struct tty *tp;
258	int flag;
259{
260	struct pt_ioctl *pti = &pt_ioctl[minor(tp->t_dev)];
261
262	if (flag & FREAD) {
263		selwakeup(&pti->pt_selr);
264		wakeup((caddr_t)&tp->t_outq.c_cf);
265	}
266	if (flag & FWRITE) {
267		selwakeup(&pti->pt_selw);
268		wakeup((caddr_t)&tp->t_rawq.c_cf);
269	}
270}
271
272/*ARGSUSED*/
273#ifdef __STDC__
274int
275ptcopen(dev_t dev, int flag, int devtype, struct proc *p)
276#else
277int
278ptcopen(dev, flag, devtype, p)
279	dev_t dev;
280	int flag, devtype;
281	struct proc *p;
282#endif
283{
284	register struct tty *tp;
285	struct pt_ioctl *pti;
286
287	if (minor(dev) >= npty)
288		return (ENXIO);
289	tp = &pt_tty[minor(dev)];
290	if (tp->t_oproc)
291		return (EIO);
292	tp->t_oproc = ptsstart;
293#ifdef sun4c
294	tp->t_stop = ptsstop;
295#endif
296	(void)(*linesw[tp->t_line].l_modem)(tp, 1);
297	tp->t_lflag &= ~EXTPROC;
298	pti = &pt_ioctl[minor(dev)];
299	pti->pt_flags = 0;
300	pti->pt_send = 0;
301	pti->pt_ucntl = 0;
302	return (0);
303}
304
305int
306ptcclose(dev)
307	dev_t dev;
308{
309	register struct tty *tp;
310
311	tp = &pt_tty[minor(dev)];
312	(void)(*linesw[tp->t_line].l_modem)(tp, 0);
313	tp->t_state &= ~TS_CARR_ON;
314	tp->t_oproc = 0;		/* mark closed */
315	tp->t_session = 0;
316	return (0);
317}
318
319int
320ptcread(dev, uio, flag)
321	dev_t dev;
322	struct uio *uio;
323	int flag;
324{
325	register struct tty *tp = &pt_tty[minor(dev)];
326	struct pt_ioctl *pti = &pt_ioctl[minor(dev)];
327	char buf[BUFSIZ];
328	int error = 0, cc;
329
330	/*
331	 * We want to block until the slave
332	 * is open, and there's something to read;
333	 * but if we lost the slave or we're NBIO,
334	 * then return the appropriate error instead.
335	 */
336	for (;;) {
337		if (tp->t_state&TS_ISOPEN) {
338			if (pti->pt_flags&PF_PKT && pti->pt_send) {
339				error = ureadc((int)pti->pt_send, uio);
340				if (error)
341					return (error);
342				if (pti->pt_send & TIOCPKT_IOCTL) {
343					cc = min(uio->uio_resid,
344						sizeof(tp->t_termios));
345					uiomove((caddr_t)&tp->t_termios, cc,
346						uio);
347				}
348				pti->pt_send = 0;
349				return (0);
350			}
351			if (pti->pt_flags&PF_UCNTL && pti->pt_ucntl) {
352				error = ureadc((int)pti->pt_ucntl, uio);
353				if (error)
354					return (error);
355				pti->pt_ucntl = 0;
356				return (0);
357			}
358			if (tp->t_outq.c_cc && (tp->t_state&TS_TTSTOP) == 0)
359				break;
360		}
361		if ((tp->t_state&TS_CARR_ON) == 0)
362			return (0);	/* EOF */
363		if (flag & IO_NDELAY)
364			return (EWOULDBLOCK);
365		error = tsleep((caddr_t)&tp->t_outq.c_cf, TTIPRI | PCATCH,
366		    ttyin, 0);
367		if (error)
368			return (error);
369	}
370	if (pti->pt_flags & (PF_PKT|PF_UCNTL))
371		error = ureadc(0, uio);
372	while (uio->uio_resid > 0 && error == 0) {
373		cc = q_to_b(&tp->t_outq, buf, min(uio->uio_resid, BUFSIZ));
374		if (cc <= 0)
375			break;
376		error = uiomove(buf, cc, uio);
377	}
378	if (tp->t_outq.c_cc <= tp->t_lowat) {
379		if (tp->t_state&TS_ASLEEP) {
380			tp->t_state &= ~TS_ASLEEP;
381			wakeup((caddr_t)&tp->t_outq);
382		}
383		selwakeup(&tp->t_wsel);
384	}
385	return (error);
386}
387
388void
389ptsstop(tp, flush)
390	register struct tty *tp;
391	int flush;
392{
393	struct pt_ioctl *pti = &pt_ioctl[minor(tp->t_dev)];
394	int flag;
395
396	/* note: FLUSHREAD and FLUSHWRITE already ok */
397	if (flush == 0) {
398		flush = TIOCPKT_STOP;
399		pti->pt_flags |= PF_STOPPED;
400	} else
401		pti->pt_flags &= ~PF_STOPPED;
402	pti->pt_send |= flush;
403	/* change of perspective */
404	flag = 0;
405	if (flush & FREAD)
406		flag |= FWRITE;
407	if (flush & FWRITE)
408		flag |= FREAD;
409	ptcwakeup(tp, flag);
410}
411
412int
413ptcselect(dev, rw, p)
414	dev_t dev;
415	int rw;
416	struct proc *p;
417{
418	register struct tty *tp = &pt_tty[minor(dev)];
419	struct pt_ioctl *pti = &pt_ioctl[minor(dev)];
420	int s;
421
422	if ((tp->t_state&TS_CARR_ON) == 0)
423		return (1);
424	switch (rw) {
425
426	case FREAD:
427		/*
428		 * Need to block timeouts (ttrstart).
429		 */
430		s = spltty();
431		if ((tp->t_state&TS_ISOPEN) &&
432		     tp->t_outq.c_cc && (tp->t_state&TS_TTSTOP) == 0) {
433			splx(s);
434			return (1);
435		}
436		splx(s);
437		/* FALLTHROUGH */
438
439	case 0:					/* exceptional */
440		if ((tp->t_state&TS_ISOPEN) &&
441		    ((pti->pt_flags&PF_PKT && pti->pt_send) ||
442		     (pti->pt_flags&PF_UCNTL && pti->pt_ucntl)))
443			return (1);
444		selrecord(p, &pti->pt_selr);
445		break;
446
447
448	case FWRITE:
449		if (tp->t_state&TS_ISOPEN) {
450			if (pti->pt_flags & PF_REMOTE) {
451			    if (tp->t_canq.c_cc == 0)
452				return (1);
453			} else {
454			    if (tp->t_rawq.c_cc + tp->t_canq.c_cc < TTYHOG-2)
455				    return (1);
456			    if (tp->t_canq.c_cc == 0 && (tp->t_iflag&ICANON))
457				    return (1);
458			}
459		}
460		selrecord(p, &pti->pt_selw);
461		break;
462
463	}
464	return (0);
465}
466
467int
468ptcwrite(dev, uio, flag)
469	dev_t dev;
470	register struct uio *uio;
471	int flag;
472{
473	register struct tty *tp = &pt_tty[minor(dev)];
474	register u_char *cp = 0;
475	register int cc = 0;
476	u_char locbuf[BUFSIZ];
477	int cnt = 0;
478	struct pt_ioctl *pti = &pt_ioctl[minor(dev)];
479	int error = 0;
480
481again:
482	if ((tp->t_state&TS_ISOPEN) == 0)
483		goto block;
484	if (pti->pt_flags & PF_REMOTE) {
485		if (tp->t_canq.c_cc)
486			goto block;
487		while (uio->uio_resid > 0 && tp->t_canq.c_cc < TTYHOG - 1) {
488			if (cc == 0) {
489				cc = min(uio->uio_resid, BUFSIZ);
490				cc = min(cc, TTYHOG - 1 - tp->t_canq.c_cc);
491				cp = locbuf;
492				error = uiomove((caddr_t)cp, cc, uio);
493				if (error)
494					return (error);
495				/* check again for safety */
496				if ((tp->t_state&TS_ISOPEN) == 0)
497					return (EIO);
498			}
499			if (cc)
500				(void) b_to_q((char *)cp, cc, &tp->t_canq);
501			cc = 0;
502		}
503		(void) putc(0, &tp->t_canq);
504		ttwakeup(tp);
505		wakeup((caddr_t)&tp->t_canq);
506		return (0);
507	}
508	while (uio->uio_resid > 0) {
509		if (cc == 0) {
510			cc = min(uio->uio_resid, BUFSIZ);
511			cp = locbuf;
512			error = uiomove((caddr_t)cp, cc, uio);
513			if (error)
514				return (error);
515			/* check again for safety */
516			if ((tp->t_state&TS_ISOPEN) == 0)
517				return (EIO);
518		}
519		while (cc > 0) {
520			if ((tp->t_rawq.c_cc + tp->t_canq.c_cc) >= TTYHOG - 2 &&
521			   (tp->t_canq.c_cc > 0 || !(tp->t_iflag&ICANON))) {
522				wakeup((caddr_t)&tp->t_rawq);
523				goto block;
524			}
525			(*linesw[tp->t_line].l_rint)(*cp++, tp);
526			cnt++;
527			cc--;
528		}
529		cc = 0;
530	}
531	return (0);
532block:
533	/*
534	 * Come here to wait for slave to open, for space
535	 * in outq, or space in rawq.
536	 */
537	if ((tp->t_state&TS_CARR_ON) == 0)
538		return (EIO);
539	if (flag & IO_NDELAY) {
540		/* adjust for data copied in but not written */
541		uio->uio_resid += cc;
542		if (cnt == 0)
543			return (EWOULDBLOCK);
544		return (0);
545	}
546	error = tsleep((caddr_t)&tp->t_rawq.c_cf, TTOPRI | PCATCH, ttyout, 0);
547	if (error) {
548		/* adjust for data copied in but not written */
549		uio->uio_resid += cc;
550		return (error);
551	}
552	goto again;
553}
554
555/*ARGSUSED*/
556int
557ptyioctl(dev, cmd, data, flag, p)
558	dev_t dev;
559	int cmd;
560	caddr_t data;
561	int flag;
562	struct proc *p;
563{
564	register struct tty *tp = &pt_tty[minor(dev)];
565	register struct pt_ioctl *pti = &pt_ioctl[minor(dev)];
566	register u_char *cc = tp->t_cc;
567	int stop, error;
568
569	/*
570	 * IF CONTROLLER STTY THEN MUST FLUSH TO PREVENT A HANG.
571	 * ttywflush(tp) will hang if there are characters in the outq.
572	 */
573	if (cmd == TIOCEXT) {
574		/*
575		 * When the EXTPROC bit is being toggled, we need
576		 * to send an TIOCPKT_IOCTL if the packet driver
577		 * is turned on.
578		 */
579		if (*(int *)data) {
580			if (pti->pt_flags & PF_PKT) {
581				pti->pt_send |= TIOCPKT_IOCTL;
582				ptcwakeup(tp, FREAD);
583			}
584			tp->t_lflag |= EXTPROC;
585		} else {
586			if ((tp->t_state & EXTPROC) &&
587			    (pti->pt_flags & PF_PKT)) {
588				pti->pt_send |= TIOCPKT_IOCTL;
589				ptcwakeup(tp, FREAD);
590			}
591			tp->t_lflag &= ~EXTPROC;
592		}
593		return(0);
594	} else
595	if (cdevsw[major(dev)].d_open == ptcopen)
596		switch (cmd) {
597
598		case TIOCGPGRP:
599			/*
600			 * We aviod calling ttioctl on the controller since,
601			 * in that case, tp must be the controlling terminal.
602			 */
603			*(int *)data = tp->t_pgrp ? tp->t_pgrp->pg_id : 0;
604			return (0);
605
606		case TIOCPKT:
607			if (*(int *)data) {
608				if (pti->pt_flags & PF_UCNTL)
609					return (EINVAL);
610				pti->pt_flags |= PF_PKT;
611			} else
612				pti->pt_flags &= ~PF_PKT;
613			return (0);
614
615		case TIOCUCNTL:
616			if (*(int *)data) {
617				if (pti->pt_flags & PF_PKT)
618					return (EINVAL);
619				pti->pt_flags |= PF_UCNTL;
620			} else
621				pti->pt_flags &= ~PF_UCNTL;
622			return (0);
623
624		case TIOCREMOTE:
625			if (*(int *)data)
626				pti->pt_flags |= PF_REMOTE;
627			else
628				pti->pt_flags &= ~PF_REMOTE;
629			ttyflush(tp, FREAD|FWRITE);
630			return (0);
631
632#ifdef COMPAT_43
633		case TIOCSETP:
634		case TIOCSETN:
635#endif
636		case TIOCSETD:
637		case TIOCSETA:
638		case TIOCSETAW:
639		case TIOCSETAF:
640			ndflush(&tp->t_outq, tp->t_outq.c_cc);
641			break;
642
643		case TIOCSIG:
644			if (*(unsigned int *)data >= NSIG)
645				return(EINVAL);
646			if ((tp->t_lflag&NOFLSH) == 0)
647				ttyflush(tp, FREAD|FWRITE);
648			pgsignal(tp->t_pgrp, *(unsigned int *)data, 1);
649			if ((*(unsigned int *)data == SIGINFO) &&
650			    ((tp->t_lflag&NOKERNINFO) == 0))
651				ttyinfo(tp);
652			return(0);
653		}
654	error = (*linesw[tp->t_line].l_ioctl)(tp, cmd, data, flag, p);
655	if (error < 0)
656		 error = ttioctl(tp, cmd, data, flag);
657	if (error < 0) {
658		if (pti->pt_flags & PF_UCNTL &&
659		    (cmd & ~0xff) == UIOCCMD(0)) {
660			if (cmd & 0xff) {
661				pti->pt_ucntl = (u_char)cmd;
662				ptcwakeup(tp, FREAD);
663			}
664			return (0);
665		}
666		error = ENOTTY;
667	}
668	/*
669	 * If external processing and packet mode send ioctl packet.
670	 */
671	if ((tp->t_lflag&EXTPROC) && (pti->pt_flags & PF_PKT)) {
672		switch(cmd) {
673		case TIOCSETA:
674		case TIOCSETAW:
675		case TIOCSETAF:
676#ifdef COMPAT_43
677		case TIOCSETP:
678		case TIOCSETN:
679#endif
680#if defined(COMPAT_43) || defined(COMPAT_SUNOS)
681		case TIOCSETC:
682		case TIOCSLTC:
683		case TIOCLBIS:
684		case TIOCLBIC:
685		case TIOCLSET:
686#endif
687			pti->pt_send |= TIOCPKT_IOCTL;
688			ptcwakeup(tp, FREAD);
689		default:
690			break;
691		}
692	}
693	stop = (tp->t_iflag & IXON) && CCEQ(cc[VSTOP], CTRL('s'))
694		&& CCEQ(cc[VSTART], CTRL('q'));
695	if (pti->pt_flags & PF_NOSTOP) {
696		if (stop) {
697			pti->pt_send &= ~TIOCPKT_NOSTOP;
698			pti->pt_send |= TIOCPKT_DOSTOP;
699			pti->pt_flags &= ~PF_NOSTOP;
700			ptcwakeup(tp, FREAD);
701		}
702	} else {
703		if (!stop) {
704			pti->pt_send &= ~TIOCPKT_DOSTOP;
705			pti->pt_send |= TIOCPKT_NOSTOP;
706			pti->pt_flags |= PF_NOSTOP;
707			ptcwakeup(tp, FREAD);
708		}
709	}
710	return (error);
711}
712