pty.c revision 7724 
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 1.8 1995/02/28 00:21:05 pst 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	if (error == 0)
148		ptcwakeup(tp, FREAD|FWRITE);
149	return (error);
150}
151
152int
153ptsclose(dev, flag, mode, p)
154	dev_t dev;
155	int flag, mode;
156	struct proc *p;
157{
158	register struct tty *tp;
159	int err;
160
161	tp = &pt_tty[minor(dev)];
162	ptcwakeup(tp, FREAD|FWRITE);
163	err = (*linesw[tp->t_line].l_close)(tp, flag);
164	(void) ttyclose(tp);
165	return (err);
166}
167
168int
169ptsread(dev, uio, flag)
170	dev_t dev;
171	struct uio *uio;
172	int flag;
173{
174	struct proc *p = curproc;
175	register struct tty *tp = &pt_tty[minor(dev)];
176	register struct pt_ioctl *pti = &pt_ioctl[minor(dev)];
177	int error = 0;
178
179again:
180	if (pti->pt_flags & PF_REMOTE) {
181		while (isbackground(p, tp)) {
182			if ((p->p_sigignore & sigmask(SIGTTIN)) ||
183			    (p->p_sigmask & sigmask(SIGTTIN)) ||
184			    p->p_pgrp->pg_jobc == 0 ||
185			    p->p_flag & P_PPWAIT)
186				return (EIO);
187			pgsignal(p->p_pgrp, SIGTTIN, 1);
188			error = ttysleep(tp, (caddr_t)&lbolt,
189			    TTIPRI | PCATCH, ttybg, 0);
190			if (error)
191				return (error);
192		}
193		if (tp->t_canq.c_cc == 0) {
194			if (flag & IO_NDELAY)
195				return (EWOULDBLOCK);
196			error = ttysleep(tp, (caddr_t)&tp->t_canq,
197			    TTIPRI | PCATCH, ttyin, 0);
198			if (error)
199				return (error);
200			goto again;
201		}
202		while (tp->t_canq.c_cc > 1 && uio->uio_resid > 0)
203			if (ureadc(getc(&tp->t_canq), uio) < 0) {
204				error = EFAULT;
205				break;
206			}
207		if (tp->t_canq.c_cc == 1)
208			(void) getc(&tp->t_canq);
209		if (tp->t_canq.c_cc)
210			return (error);
211	} else
212		if (tp->t_oproc)
213			error = (*linesw[tp->t_line].l_read)(tp, uio, flag);
214	ptcwakeup(tp, FWRITE);
215	return (error);
216}
217
218/*
219 * Write to pseudo-tty.
220 * Wakeups of controlling tty will happen
221 * indirectly, when tty driver calls ptsstart.
222 */
223int
224ptswrite(dev, uio, flag)
225	dev_t dev;
226	struct uio *uio;
227	int flag;
228{
229	register struct tty *tp;
230
231	tp = &pt_tty[minor(dev)];
232	if (tp->t_oproc == 0)
233		return (EIO);
234	return ((*linesw[tp->t_line].l_write)(tp, uio, flag));
235}
236
237/*
238 * Start output on pseudo-tty.
239 * Wake up process selecting or sleeping for input from controlling tty.
240 */
241void
242ptsstart(tp)
243	struct tty *tp;
244{
245	register struct pt_ioctl *pti = &pt_ioctl[minor(tp->t_dev)];
246
247	if (tp->t_state & TS_TTSTOP)
248		return;
249	if (pti->pt_flags & PF_STOPPED) {
250		pti->pt_flags &= ~PF_STOPPED;
251		pti->pt_send = TIOCPKT_START;
252	}
253	ptcwakeup(tp, FREAD);
254}
255
256void
257ptcwakeup(tp, flag)
258	struct tty *tp;
259	int flag;
260{
261	struct pt_ioctl *pti = &pt_ioctl[minor(tp->t_dev)];
262
263	if (flag & FREAD) {
264		selwakeup(&pti->pt_selr);
265		wakeup((caddr_t)&tp->t_outq.c_cf);
266	}
267	if (flag & FWRITE) {
268		selwakeup(&pti->pt_selw);
269		wakeup((caddr_t)&tp->t_rawq.c_cl);
270	}
271}
272
273/*ARGSUSED*/
274#ifdef __STDC__
275int
276ptcopen(dev_t dev, int flag, int devtype, struct proc *p)
277#else
278int
279ptcopen(dev, flag, devtype, p)
280	dev_t dev;
281	int flag, devtype;
282	struct proc *p;
283#endif
284{
285	register struct tty *tp;
286	struct pt_ioctl *pti;
287
288	if (minor(dev) >= npty)
289		return (ENXIO);
290	tp = &pt_tty[minor(dev)];
291	if (tp->t_oproc)
292		return (EIO);
293	tp->t_oproc = ptsstart;
294#ifdef sun4c
295	tp->t_stop = ptsstop;
296#endif
297	(void)(*linesw[tp->t_line].l_modem)(tp, 1);
298	tp->t_lflag &= ~EXTPROC;
299	pti = &pt_ioctl[minor(dev)];
300	pti->pt_flags = 0;
301	pti->pt_send = 0;
302	pti->pt_ucntl = 0;
303	return (0);
304}
305
306int
307ptcclose(dev)
308	dev_t dev;
309{
310	register struct tty *tp;
311
312	tp = &pt_tty[minor(dev)];
313	(void)(*linesw[tp->t_line].l_modem)(tp, 0);
314	tp->t_state &= ~TS_CARR_ON;
315	tp->t_oproc = 0;		/* mark closed */
316	tp->t_session = 0;
317	return (0);
318}
319
320int
321ptcread(dev, uio, flag)
322	dev_t dev;
323	struct uio *uio;
324	int flag;
325{
326	register struct tty *tp = &pt_tty[minor(dev)];
327	struct pt_ioctl *pti = &pt_ioctl[minor(dev)];
328	char buf[BUFSIZ];
329	int error = 0, cc;
330
331	/*
332	 * We want to block until the slave
333	 * is open, and there's something to read;
334	 * but if we lost the slave or we're NBIO,
335	 * then return the appropriate error instead.
336	 */
337	for (;;) {
338		if (tp->t_state&TS_ISOPEN) {
339			if (pti->pt_flags&PF_PKT && pti->pt_send) {
340				error = ureadc((int)pti->pt_send, uio);
341				if (error)
342					return (error);
343				if (pti->pt_send & TIOCPKT_IOCTL) {
344					cc = min(uio->uio_resid,
345						sizeof(tp->t_termios));
346					uiomove((caddr_t)&tp->t_termios, cc,
347						uio);
348				}
349				pti->pt_send = 0;
350				return (0);
351			}
352			if (pti->pt_flags&PF_UCNTL && pti->pt_ucntl) {
353				error = ureadc((int)pti->pt_ucntl, uio);
354				if (error)
355					return (error);
356				pti->pt_ucntl = 0;
357				return (0);
358			}
359			if (tp->t_outq.c_cc && (tp->t_state&TS_TTSTOP) == 0)
360				break;
361		}
362		if ((tp->t_state&TS_CARR_ON) == 0)
363			return (0);	/* EOF */
364		if (flag & IO_NDELAY)
365			return (EWOULDBLOCK);
366		error = tsleep((caddr_t)&tp->t_outq.c_cf, TTIPRI | PCATCH,
367		    ttyin, 0);
368		if (error)
369			return (error);
370	}
371	if (pti->pt_flags & (PF_PKT|PF_UCNTL))
372		error = ureadc(0, uio);
373	while (uio->uio_resid > 0 && error == 0) {
374		cc = q_to_b(&tp->t_outq, buf, min(uio->uio_resid, BUFSIZ));
375		if (cc <= 0)
376			break;
377		error = uiomove(buf, cc, uio);
378	}
379	if (tp->t_outq.c_cc <= tp->t_lowat) {
380		if (tp->t_state&TS_ASLEEP) {
381			tp->t_state &= ~TS_ASLEEP;
382			wakeup((caddr_t)&tp->t_outq);
383		}
384		selwakeup(&tp->t_wsel);
385	}
386	return (error);
387}
388
389void
390ptsstop(tp, flush)
391	register struct tty *tp;
392	int flush;
393{
394	struct pt_ioctl *pti = &pt_ioctl[minor(tp->t_dev)];
395	int flag;
396
397	/* note: FLUSHREAD and FLUSHWRITE already ok */
398	if (flush == 0) {
399		flush = TIOCPKT_STOP;
400		pti->pt_flags |= PF_STOPPED;
401	} else
402		pti->pt_flags &= ~PF_STOPPED;
403	pti->pt_send |= flush;
404	/* change of perspective */
405	flag = 0;
406	if (flush & FREAD)
407		flag |= FWRITE;
408	if (flush & FWRITE)
409		flag |= FREAD;
410	ptcwakeup(tp, flag);
411}
412
413int
414ptcselect(dev, rw, p)
415	dev_t dev;
416	int rw;
417	struct proc *p;
418{
419	register struct tty *tp = &pt_tty[minor(dev)];
420	struct pt_ioctl *pti = &pt_ioctl[minor(dev)];
421	int s;
422
423	if ((tp->t_state&TS_CARR_ON) == 0)
424		return (1);
425	switch (rw) {
426
427	case FREAD:
428		/*
429		 * Need to block timeouts (ttrstart).
430		 */
431		s = spltty();
432		if ((tp->t_state&TS_ISOPEN) &&
433		     tp->t_outq.c_cc && (tp->t_state&TS_TTSTOP) == 0) {
434			splx(s);
435			return (1);
436		}
437		splx(s);
438		/* FALLTHROUGH */
439
440	case 0:					/* exceptional */
441		if ((tp->t_state&TS_ISOPEN) &&
442		    ((pti->pt_flags&PF_PKT && pti->pt_send) ||
443		     (pti->pt_flags&PF_UCNTL && pti->pt_ucntl)))
444			return (1);
445		selrecord(p, &pti->pt_selr);
446		break;
447
448
449	case FWRITE:
450		if (tp->t_state&TS_ISOPEN) {
451			if (pti->pt_flags & PF_REMOTE) {
452			    if (tp->t_canq.c_cc == 0)
453				return (1);
454			} else {
455			    if (tp->t_rawq.c_cc + tp->t_canq.c_cc < TTYHOG-2)
456				    return (1);
457			    if (tp->t_canq.c_cc == 0 && (tp->t_iflag&ICANON))
458				    return (1);
459			}
460		}
461		selrecord(p, &pti->pt_selw);
462		break;
463
464	}
465	return (0);
466}
467
468int
469ptcwrite(dev, uio, flag)
470	dev_t dev;
471	register struct uio *uio;
472	int flag;
473{
474	register struct tty *tp = &pt_tty[minor(dev)];
475	register u_char *cp = 0;
476	register int cc = 0;
477	u_char locbuf[BUFSIZ];
478	int cnt = 0;
479	struct pt_ioctl *pti = &pt_ioctl[minor(dev)];
480	int error = 0;
481
482again:
483	if ((tp->t_state&TS_ISOPEN) == 0)
484		goto block;
485	if (pti->pt_flags & PF_REMOTE) {
486		if (tp->t_canq.c_cc)
487			goto block;
488		while (uio->uio_resid > 0 && tp->t_canq.c_cc < TTYHOG - 1) {
489			if (cc == 0) {
490				cc = min(uio->uio_resid, BUFSIZ);
491				cc = min(cc, TTYHOG - 1 - tp->t_canq.c_cc);
492				cp = locbuf;
493				error = uiomove((caddr_t)cp, cc, uio);
494				if (error)
495					return (error);
496				/* check again for safety */
497				if ((tp->t_state&TS_ISOPEN) == 0)
498					return (EIO);
499			}
500			if (cc)
501				(void) b_to_q((char *)cp, cc, &tp->t_canq);
502			cc = 0;
503		}
504		(void) putc(0, &tp->t_canq);
505		ttwakeup(tp);
506		wakeup((caddr_t)&tp->t_canq);
507		return (0);
508	}
509	while (uio->uio_resid > 0) {
510		if (cc == 0) {
511			cc = min(uio->uio_resid, BUFSIZ);
512			cp = locbuf;
513			error = uiomove((caddr_t)cp, cc, uio);
514			if (error)
515				return (error);
516			/* check again for safety */
517			if ((tp->t_state&TS_ISOPEN) == 0)
518				return (EIO);
519		}
520		while (cc > 0) {
521			if ((tp->t_rawq.c_cc + tp->t_canq.c_cc) >= TTYHOG - 2 &&
522			   (tp->t_canq.c_cc > 0 || !(tp->t_iflag&ICANON))) {
523				wakeup((caddr_t)&tp->t_rawq);
524				goto block;
525			}
526			(*linesw[tp->t_line].l_rint)(*cp++, tp);
527			cnt++;
528			cc--;
529		}
530		cc = 0;
531	}
532	return (0);
533block:
534	/*
535	 * Come here to wait for slave to open, for space
536	 * in outq, or space in rawq.
537	 */
538	if ((tp->t_state&TS_CARR_ON) == 0)
539		return (EIO);
540	if (flag & IO_NDELAY) {
541		/* adjust for data copied in but not written */
542		uio->uio_resid += cc;
543		if (cnt == 0)
544			return (EWOULDBLOCK);
545		return (0);
546	}
547	error = tsleep((caddr_t)&tp->t_rawq.c_cl, TTOPRI | PCATCH, ttyout, 0);
548	if (error) {
549		/* adjust for data copied in but not written */
550		uio->uio_resid += cc;
551		return (error);
552	}
553	goto again;
554}
555
556struct tty *
557ptydevtotty(dev)
558	dev_t		dev;
559{
560	if (minor(dev) >= npty)
561		return (NULL);
562
563	return &pt_tty[minor(dev)];
564}
565
566/*ARGSUSED*/
567int
568ptyioctl(dev, cmd, data, flag, p)
569	dev_t dev;
570	int cmd;
571	caddr_t data;
572	int flag;
573	struct proc *p;
574{
575	register struct tty *tp = &pt_tty[minor(dev)];
576	register struct pt_ioctl *pti = &pt_ioctl[minor(dev)];
577	register u_char *cc = tp->t_cc;
578	int stop, error;
579
580	/*
581	 * IF CONTROLLER STTY THEN MUST FLUSH TO PREVENT A HANG.
582	 * ttywflush(tp) will hang if there are characters in the outq.
583	 */
584	if (cmd == TIOCEXT) {
585		/*
586		 * When the EXTPROC bit is being toggled, we need
587		 * to send an TIOCPKT_IOCTL if the packet driver
588		 * is turned on.
589		 */
590		if (*(int *)data) {
591			if (pti->pt_flags & PF_PKT) {
592				pti->pt_send |= TIOCPKT_IOCTL;
593				ptcwakeup(tp, FREAD);
594			}
595			tp->t_lflag |= EXTPROC;
596		} else {
597			if ((tp->t_state & EXTPROC) &&
598			    (pti->pt_flags & PF_PKT)) {
599				pti->pt_send |= TIOCPKT_IOCTL;
600				ptcwakeup(tp, FREAD);
601			}
602			tp->t_lflag &= ~EXTPROC;
603		}
604		return(0);
605	} else
606	if (cdevsw[major(dev)].d_open == ptcopen)
607		switch (cmd) {
608
609		case TIOCGPGRP:
610			/*
611			 * We aviod calling ttioctl on the controller since,
612			 * in that case, tp must be the controlling terminal.
613			 */
614			*(int *)data = tp->t_pgrp ? tp->t_pgrp->pg_id : 0;
615			return (0);
616
617		case TIOCPKT:
618			if (*(int *)data) {
619				if (pti->pt_flags & PF_UCNTL)
620					return (EINVAL);
621				pti->pt_flags |= PF_PKT;
622			} else
623				pti->pt_flags &= ~PF_PKT;
624			return (0);
625
626		case TIOCUCNTL:
627			if (*(int *)data) {
628				if (pti->pt_flags & PF_PKT)
629					return (EINVAL);
630				pti->pt_flags |= PF_UCNTL;
631			} else
632				pti->pt_flags &= ~PF_UCNTL;
633			return (0);
634
635		case TIOCREMOTE:
636			if (*(int *)data)
637				pti->pt_flags |= PF_REMOTE;
638			else
639				pti->pt_flags &= ~PF_REMOTE;
640			ttyflush(tp, FREAD|FWRITE);
641			return (0);
642
643#ifdef COMPAT_43
644		case TIOCSETP:
645		case TIOCSETN:
646#endif
647		case TIOCSETD:
648		case TIOCSETA:
649		case TIOCSETAW:
650		case TIOCSETAF:
651			ndflush(&tp->t_outq, tp->t_outq.c_cc);
652			break;
653
654		case TIOCSIG:
655			if (*(unsigned int *)data >= NSIG)
656				return(EINVAL);
657			if ((tp->t_lflag&NOFLSH) == 0)
658				ttyflush(tp, FREAD|FWRITE);
659			pgsignal(tp->t_pgrp, *(unsigned int *)data, 1);
660			if ((*(unsigned int *)data == SIGINFO) &&
661			    ((tp->t_lflag&NOKERNINFO) == 0))
662				ttyinfo(tp);
663			return(0);
664		}
665	error = (*linesw[tp->t_line].l_ioctl)(tp, cmd, data, flag, p);
666	if (error < 0)
667		 error = ttioctl(tp, cmd, data, flag);
668	if (error < 0) {
669		if (pti->pt_flags & PF_UCNTL &&
670		    (cmd & ~0xff) == UIOCCMD(0)) {
671			if (cmd & 0xff) {
672				pti->pt_ucntl = (u_char)cmd;
673				ptcwakeup(tp, FREAD);
674			}
675			return (0);
676		}
677		error = ENOTTY;
678	}
679	/*
680	 * If external processing and packet mode send ioctl packet.
681	 */
682	if ((tp->t_lflag&EXTPROC) && (pti->pt_flags & PF_PKT)) {
683		switch(cmd) {
684		case TIOCSETA:
685		case TIOCSETAW:
686		case TIOCSETAF:
687#ifdef COMPAT_43
688		case TIOCSETP:
689		case TIOCSETN:
690#endif
691#if defined(COMPAT_43) || defined(COMPAT_SUNOS)
692		case TIOCSETC:
693		case TIOCSLTC:
694		case TIOCLBIS:
695		case TIOCLBIC:
696		case TIOCLSET:
697#endif
698			pti->pt_send |= TIOCPKT_IOCTL;
699			ptcwakeup(tp, FREAD);
700		default:
701			break;
702		}
703	}
704	stop = (tp->t_iflag & IXON) && CCEQ(cc[VSTOP], CTRL('s'))
705		&& CCEQ(cc[VSTART], CTRL('q'));
706	if (pti->pt_flags & PF_NOSTOP) {
707		if (stop) {
708			pti->pt_send &= ~TIOCPKT_NOSTOP;
709			pti->pt_send |= TIOCPKT_DOSTOP;
710			pti->pt_flags &= ~PF_NOSTOP;
711			ptcwakeup(tp, FREAD);
712		}
713	} else {
714		if (!stop) {
715			pti->pt_send &= ~TIOCPKT_DOSTOP;
716			pti->pt_send |= TIOCPKT_NOSTOP;
717			pti->pt_flags |= PF_NOSTOP;
718			ptcwakeup(tp, FREAD);
719		}
720	}
721	return (error);
722}
723