xref: /freebsd/sys/kern/tty.c (revision 2e3f49888ec8851bafb22011533217487764fdb0)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause
3  *
4  * Copyright (c) 2008 Ed Schouten <ed@FreeBSD.org>
5  * All rights reserved.
6  *
7  * Portions of this software were developed under sponsorship from Snow
8  * B.V., the Netherlands.
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29  * SUCH DAMAGE.
30  */
31 
32 #include <sys/cdefs.h>
33 #include "opt_capsicum.h"
34 #include "opt_printf.h"
35 
36 #include <sys/param.h>
37 #include <sys/capsicum.h>
38 #include <sys/conf.h>
39 #include <sys/cons.h>
40 #include <sys/fcntl.h>
41 #include <sys/file.h>
42 #include <sys/filedesc.h>
43 #include <sys/filio.h>
44 #ifdef COMPAT_43TTY
45 #include <sys/ioctl_compat.h>
46 #endif /* COMPAT_43TTY */
47 #include <sys/jail.h>
48 #include <sys/kernel.h>
49 #include <sys/limits.h>
50 #include <sys/malloc.h>
51 #include <sys/mount.h>
52 #include <sys/poll.h>
53 #include <sys/priv.h>
54 #include <sys/proc.h>
55 #include <sys/serial.h>
56 #include <sys/signal.h>
57 #include <sys/stat.h>
58 #include <sys/sx.h>
59 #include <sys/sysctl.h>
60 #include <sys/systm.h>
61 #include <sys/tty.h>
62 #include <sys/ttycom.h>
63 #define TTYDEFCHARS
64 #include <sys/ttydefaults.h>
65 #undef TTYDEFCHARS
66 #include <sys/ucred.h>
67 #include <sys/vnode.h>
68 
69 #include <fs/devfs/devfs.h>
70 
71 #include <machine/stdarg.h>
72 
73 static MALLOC_DEFINE(M_TTY, "tty", "tty device");
74 
75 static void tty_rel_free(struct tty *tp);
76 
77 static TAILQ_HEAD(, tty) tty_list = TAILQ_HEAD_INITIALIZER(tty_list);
78 static struct sx tty_list_sx;
79 SX_SYSINIT(tty_list, &tty_list_sx, "tty list");
80 static unsigned int tty_list_count = 0;
81 
82 /* Character device of /dev/console. */
83 static struct cdev	*dev_console;
84 static const char	*dev_console_filename;
85 
86 /*
87  * Flags that are supported and stored by this implementation.
88  */
89 #define TTYSUP_IFLAG	(IGNBRK|BRKINT|IGNPAR|PARMRK|INPCK|ISTRIP|INLCR|\
90 			IGNCR|ICRNL|IXON|IXOFF|IXANY|IMAXBEL|IUTF8)
91 #define TTYSUP_OFLAG	(OPOST|ONLCR|TAB3|ONOEOT|OCRNL|ONOCR|ONLRET)
92 #define TTYSUP_LFLAG	(ECHOKE|ECHOE|ECHOK|ECHO|ECHONL|ECHOPRT|\
93 			ECHOCTL|ISIG|ICANON|ALTWERASE|IEXTEN|TOSTOP|\
94 			FLUSHO|NOKERNINFO|NOFLSH)
95 #define TTYSUP_CFLAG	(CIGNORE|CSIZE|CSTOPB|CREAD|PARENB|PARODD|\
96 			HUPCL|CLOCAL|CCTS_OFLOW|CRTS_IFLOW|CDTR_IFLOW|\
97 			CDSR_OFLOW|CCAR_OFLOW|CNO_RTSDTR)
98 
99 #define	TTY_CALLOUT(tp,d) (dev2unit(d) & TTYUNIT_CALLOUT)
100 
101 static int  tty_drainwait = 5 * 60;
102 SYSCTL_INT(_kern, OID_AUTO, tty_drainwait, CTLFLAG_RWTUN,
103     &tty_drainwait, 0, "Default output drain timeout in seconds");
104 
105 /*
106  * Set TTY buffer sizes.
107  */
108 
109 #define	TTYBUF_MAX	65536
110 
111 #ifdef PRINTF_BUFR_SIZE
112 #define	TTY_PRBUF_SIZE	PRINTF_BUFR_SIZE
113 #else
114 #define	TTY_PRBUF_SIZE	256
115 #endif
116 
117 /*
118  * Allocate buffer space if necessary, and set low watermarks, based on speed.
119  * Note that the ttyxxxq_setsize() functions may drop and then reacquire the tty
120  * lock during memory allocation.  They will return ENXIO if the tty disappears
121  * while unlocked.
122  */
123 static int
124 tty_watermarks(struct tty *tp)
125 {
126 	size_t bs = 0;
127 	int error;
128 
129 	/* Provide an input buffer for 2 seconds of data. */
130 	if (tp->t_termios.c_cflag & CREAD)
131 		bs = MIN(tp->t_termios.c_ispeed / 5, TTYBUF_MAX);
132 	error = ttyinq_setsize(&tp->t_inq, tp, bs);
133 	if (error != 0)
134 		return (error);
135 
136 	/* Set low watermark at 10% (when 90% is available). */
137 	tp->t_inlow = (ttyinq_getallocatedsize(&tp->t_inq) * 9) / 10;
138 
139 	/* Provide an output buffer for 2 seconds of data. */
140 	bs = MIN(tp->t_termios.c_ospeed / 5, TTYBUF_MAX);
141 	error = ttyoutq_setsize(&tp->t_outq, tp, bs);
142 	if (error != 0)
143 		return (error);
144 
145 	/* Set low watermark at 10% (when 90% is available). */
146 	tp->t_outlow = (ttyoutq_getallocatedsize(&tp->t_outq) * 9) / 10;
147 
148 	return (0);
149 }
150 
151 static int
152 tty_drain(struct tty *tp, int leaving)
153 {
154 	sbintime_t timeout_at;
155 	size_t bytes;
156 	int error;
157 
158 	if (ttyhook_hashook(tp, getc_inject))
159 		/* buffer is inaccessible */
160 		return (0);
161 
162 	/*
163 	 * For close(), use the recent historic timeout of "1 second without
164 	 * making progress".  For tcdrain(), use t_drainwait as the timeout,
165 	 * with zero meaning "no timeout" which gives POSIX behavior.
166 	 */
167 	if (leaving)
168 		timeout_at = getsbinuptime() + SBT_1S;
169 	else if (tp->t_drainwait != 0)
170 		timeout_at = getsbinuptime() + SBT_1S * tp->t_drainwait;
171 	else
172 		timeout_at = 0;
173 
174 	/*
175 	 * Poll the output buffer and the hardware for completion, at 10 Hz.
176 	 * Polling is required for devices which are not able to signal an
177 	 * interrupt when the transmitter becomes idle (most USB serial devs).
178 	 * The unusual structure of this loop ensures we check for busy one more
179 	 * time after tty_timedwait() returns EWOULDBLOCK, so that success has
180 	 * higher priority than timeout if the IO completed in the last 100mS.
181 	 */
182 	error = 0;
183 	bytes = ttyoutq_bytesused(&tp->t_outq);
184 	for (;;) {
185 		if (ttyoutq_bytesused(&tp->t_outq) == 0 && !ttydevsw_busy(tp))
186 			return (0);
187 		if (error != 0)
188 			return (error);
189 		ttydevsw_outwakeup(tp);
190 		error = tty_timedwait(tp, &tp->t_outwait, hz / 10);
191 		if (error != 0 && error != EWOULDBLOCK)
192 			return (error);
193 		else if (timeout_at == 0 || getsbinuptime() < timeout_at)
194 			error = 0;
195 		else if (leaving && ttyoutq_bytesused(&tp->t_outq) < bytes) {
196 			/* In close, making progress, grant an extra second. */
197 			error = 0;
198 			timeout_at += SBT_1S;
199 			bytes = ttyoutq_bytesused(&tp->t_outq);
200 		}
201 	}
202 }
203 
204 /*
205  * Though ttydev_enter() and ttydev_leave() seem to be related, they
206  * don't have to be used together. ttydev_enter() is used by the cdev
207  * operations to prevent an actual operation from being processed when
208  * the TTY has been abandoned. ttydev_leave() is used by ttydev_open()
209  * and ttydev_close() to determine whether per-TTY data should be
210  * deallocated.
211  */
212 
213 static __inline int
214 ttydev_enter(struct tty *tp)
215 {
216 
217 	tty_lock(tp);
218 
219 	if (tty_gone(tp) || !tty_opened(tp)) {
220 		/* Device is already gone. */
221 		tty_unlock(tp);
222 		return (ENXIO);
223 	}
224 
225 	return (0);
226 }
227 
228 static void
229 ttydev_leave(struct tty *tp)
230 {
231 
232 	tty_assert_locked(tp);
233 
234 	if (tty_opened(tp) || tp->t_flags & TF_OPENCLOSE) {
235 		/* Device is still opened somewhere. */
236 		tty_unlock(tp);
237 		return;
238 	}
239 
240 	tp->t_flags |= TF_OPENCLOSE;
241 
242 	/* Remove console TTY. */
243 	constty_clear(tp);
244 
245 	/* Drain any output. */
246 	if (!tty_gone(tp))
247 		tty_drain(tp, 1);
248 
249 	ttydisc_close(tp);
250 
251 	/* Free i/o queues now since they might be large. */
252 	ttyinq_free(&tp->t_inq);
253 	tp->t_inlow = 0;
254 	ttyoutq_free(&tp->t_outq);
255 	tp->t_outlow = 0;
256 
257 	if (!tty_gone(tp))
258 		ttydevsw_close(tp);
259 
260 	tp->t_flags &= ~TF_OPENCLOSE;
261 	cv_broadcast(&tp->t_dcdwait);
262 	tty_rel_free(tp);
263 }
264 
265 /*
266  * Operations that are exposed through the character device in /dev.
267  */
268 static int
269 ttydev_open(struct cdev *dev, int oflags, int devtype __unused,
270     struct thread *td)
271 {
272 	struct tty *tp;
273 	int error;
274 
275 	tp = dev->si_drv1;
276 	error = 0;
277 	tty_lock(tp);
278 	if (tty_gone(tp)) {
279 		/* Device is already gone. */
280 		tty_unlock(tp);
281 		return (ENXIO);
282 	}
283 
284 	/*
285 	 * Block when other processes are currently opening or closing
286 	 * the TTY.
287 	 */
288 	while (tp->t_flags & TF_OPENCLOSE) {
289 		error = tty_wait(tp, &tp->t_dcdwait);
290 		if (error != 0) {
291 			tty_unlock(tp);
292 			return (error);
293 		}
294 	}
295 	tp->t_flags |= TF_OPENCLOSE;
296 
297 	/*
298 	 * Make sure the "tty" and "cua" device cannot be opened at the
299 	 * same time.  The console is a "tty" device.
300 	 */
301 	if (TTY_CALLOUT(tp, dev)) {
302 		if (tp->t_flags & (TF_OPENED_CONS | TF_OPENED_IN)) {
303 			error = EBUSY;
304 			goto done;
305 		}
306 	} else {
307 		if (tp->t_flags & TF_OPENED_OUT) {
308 			error = EBUSY;
309 			goto done;
310 		}
311 	}
312 
313 	if (tp->t_flags & TF_EXCLUDE && priv_check(td, PRIV_TTY_EXCLUSIVE)) {
314 		error = EBUSY;
315 		goto done;
316 	}
317 
318 	if (!tty_opened(tp)) {
319 		/* Set proper termios flags. */
320 		if (TTY_CALLOUT(tp, dev))
321 			tp->t_termios = tp->t_termios_init_out;
322 		else
323 			tp->t_termios = tp->t_termios_init_in;
324 		ttydevsw_param(tp, &tp->t_termios);
325 		/* Prevent modem control on callout devices and /dev/console. */
326 		if (TTY_CALLOUT(tp, dev) || dev == dev_console)
327 			tp->t_termios.c_cflag |= CLOCAL;
328 
329 		if ((tp->t_termios.c_cflag & CNO_RTSDTR) == 0)
330 			ttydevsw_modem(tp, SER_DTR|SER_RTS, 0);
331 
332 		error = ttydevsw_open(tp);
333 		if (error != 0)
334 			goto done;
335 
336 		ttydisc_open(tp);
337 		error = tty_watermarks(tp);
338 		if (error != 0)
339 			goto done;
340 	}
341 
342 	/* Wait for Carrier Detect. */
343 	if ((oflags & O_NONBLOCK) == 0 &&
344 	    (tp->t_termios.c_cflag & CLOCAL) == 0) {
345 		while ((ttydevsw_modem(tp, 0, 0) & SER_DCD) == 0) {
346 			error = tty_wait(tp, &tp->t_dcdwait);
347 			if (error != 0)
348 				goto done;
349 		}
350 	}
351 
352 	if (dev == dev_console)
353 		tp->t_flags |= TF_OPENED_CONS;
354 	else if (TTY_CALLOUT(tp, dev))
355 		tp->t_flags |= TF_OPENED_OUT;
356 	else
357 		tp->t_flags |= TF_OPENED_IN;
358 	MPASS((tp->t_flags & (TF_OPENED_CONS | TF_OPENED_IN)) == 0 ||
359 	    (tp->t_flags & TF_OPENED_OUT) == 0);
360 
361 done:	tp->t_flags &= ~TF_OPENCLOSE;
362 	cv_broadcast(&tp->t_dcdwait);
363 	ttydev_leave(tp);
364 
365 	return (error);
366 }
367 
368 static int
369 ttydev_close(struct cdev *dev, int fflag, int devtype __unused,
370     struct thread *td)
371 {
372 	struct tty *tp = dev->si_drv1;
373 
374 	tty_lock(tp);
375 
376 	/*
377 	 * Don't actually close the device if it is being used as the
378 	 * console.
379 	 */
380 	MPASS((tp->t_flags & (TF_OPENED_CONS | TF_OPENED_IN)) == 0 ||
381 	    (tp->t_flags & TF_OPENED_OUT) == 0);
382 	if (dev == dev_console)
383 		tp->t_flags &= ~TF_OPENED_CONS;
384 	else
385 		tp->t_flags &= ~(TF_OPENED_IN|TF_OPENED_OUT);
386 
387 	if (tp->t_flags & TF_OPENED) {
388 		tty_unlock(tp);
389 		return (0);
390 	}
391 
392 	/* If revoking, flush output now to avoid draining it later. */
393 	if ((fflag & FREVOKE) != 0) {
394 		tty_flush(tp, FWRITE);
395 		knlist_delete(&tp->t_inpoll.si_note, td, 1);
396 		knlist_delete(&tp->t_outpoll.si_note, td, 1);
397 	}
398 
399 	tp->t_flags &= ~TF_EXCLUDE;
400 
401 	/* Properly wake up threads that are stuck - revoke(). */
402 	tp->t_revokecnt++;
403 	tty_wakeup(tp, FREAD|FWRITE);
404 	cv_broadcast(&tp->t_bgwait);
405 	cv_broadcast(&tp->t_dcdwait);
406 
407 	ttydev_leave(tp);
408 
409 	return (0);
410 }
411 
412 static __inline int
413 tty_is_ctty(struct tty *tp, struct proc *p)
414 {
415 
416 	tty_assert_locked(tp);
417 
418 	return (p->p_session == tp->t_session && p->p_flag & P_CONTROLT);
419 }
420 
421 int
422 tty_wait_background(struct tty *tp, struct thread *td, int sig)
423 {
424 	struct proc *p;
425 	struct pgrp *pg;
426 	ksiginfo_t ksi;
427 	int error;
428 
429 	MPASS(sig == SIGTTIN || sig == SIGTTOU);
430 	tty_assert_locked(tp);
431 
432 	p = td->td_proc;
433 	for (;;) {
434 		pg = p->p_pgrp;
435 		PGRP_LOCK(pg);
436 		PROC_LOCK(p);
437 
438 		/*
439 		 * pg may no longer be our process group.
440 		 * Re-check after locking.
441 		 */
442 		if (p->p_pgrp != pg) {
443 			PROC_UNLOCK(p);
444 			PGRP_UNLOCK(pg);
445 			continue;
446 		}
447 
448 		/*
449 		 * The process should only sleep, when:
450 		 * - This terminal is the controlling terminal
451 		 * - Its process group is not the foreground process
452 		 *   group
453 		 * - The parent process isn't waiting for the child to
454 		 *   exit
455 		 * - the signal to send to the process isn't masked
456 		 */
457 		if (!tty_is_ctty(tp, p) || p->p_pgrp == tp->t_pgrp) {
458 			/* Allow the action to happen. */
459 			PROC_UNLOCK(p);
460 			PGRP_UNLOCK(pg);
461 			return (0);
462 		}
463 
464 		if (SIGISMEMBER(p->p_sigacts->ps_sigignore, sig) ||
465 		    SIGISMEMBER(td->td_sigmask, sig)) {
466 			/* Only allow them in write()/ioctl(). */
467 			PROC_UNLOCK(p);
468 			PGRP_UNLOCK(pg);
469 			return (sig == SIGTTOU ? 0 : EIO);
470 		}
471 
472 		if ((p->p_flag & P_PPWAIT) != 0 ||
473 		    (pg->pg_flags & PGRP_ORPHANED) != 0) {
474 			/* Don't allow the action to happen. */
475 			PROC_UNLOCK(p);
476 			PGRP_UNLOCK(pg);
477 			return (EIO);
478 		}
479 		PROC_UNLOCK(p);
480 
481 		/*
482 		 * Send the signal and sleep until we're the new
483 		 * foreground process group.
484 		 */
485 		if (sig != 0) {
486 			ksiginfo_init(&ksi);
487 			ksi.ksi_code = SI_KERNEL;
488 			ksi.ksi_signo = sig;
489 			sig = 0;
490 		}
491 
492 		pgsignal(pg, ksi.ksi_signo, 1, &ksi);
493 		PGRP_UNLOCK(pg);
494 
495 		error = tty_wait(tp, &tp->t_bgwait);
496 		if (error)
497 			return (error);
498 	}
499 }
500 
501 static int
502 ttydev_read(struct cdev *dev, struct uio *uio, int ioflag)
503 {
504 	struct tty *tp = dev->si_drv1;
505 	int error;
506 
507 	error = ttydev_enter(tp);
508 	if (error)
509 		goto done;
510 	error = ttydisc_read(tp, uio, ioflag);
511 	tty_unlock(tp);
512 
513 	/*
514 	 * The read() call should not throw an error when the device is
515 	 * being destroyed. Silently convert it to an EOF.
516 	 */
517 done:	if (error == ENXIO)
518 		error = 0;
519 	return (error);
520 }
521 
522 static int
523 ttydev_write(struct cdev *dev, struct uio *uio, int ioflag)
524 {
525 	struct tty *tp = dev->si_drv1;
526 	int defer, error;
527 
528 	error = ttydev_enter(tp);
529 	if (error)
530 		return (error);
531 
532 	if (tp->t_termios.c_lflag & TOSTOP) {
533 		error = tty_wait_background(tp, curthread, SIGTTOU);
534 		if (error)
535 			goto done;
536 	}
537 
538 	if (ioflag & IO_NDELAY && tp->t_flags & TF_BUSY_OUT) {
539 		/* Allow non-blocking writes to bypass serialization. */
540 		error = ttydisc_write(tp, uio, ioflag);
541 	} else {
542 		/* Serialize write() calls. */
543 		while (tp->t_flags & TF_BUSY_OUT) {
544 			error = tty_wait(tp, &tp->t_outserwait);
545 			if (error)
546 				goto done;
547 		}
548 
549 		tp->t_flags |= TF_BUSY_OUT;
550 		defer = sigdeferstop(SIGDEFERSTOP_ERESTART);
551 		error = ttydisc_write(tp, uio, ioflag);
552 		sigallowstop(defer);
553 		tp->t_flags &= ~TF_BUSY_OUT;
554 		cv_signal(&tp->t_outserwait);
555 	}
556 
557 done:	tty_unlock(tp);
558 	return (error);
559 }
560 
561 static int
562 ttydev_ioctl(struct cdev *dev, u_long cmd, caddr_t data, int fflag,
563     struct thread *td)
564 {
565 	struct tty *tp = dev->si_drv1;
566 	int error;
567 
568 	error = ttydev_enter(tp);
569 	if (error)
570 		return (error);
571 
572 	switch (cmd) {
573 	case TIOCCBRK:
574 	case TIOCCONS:
575 	case TIOCDRAIN:
576 	case TIOCEXCL:
577 	case TIOCFLUSH:
578 	case TIOCNXCL:
579 	case TIOCSBRK:
580 	case TIOCSCTTY:
581 	case TIOCSETA:
582 	case TIOCSETAF:
583 	case TIOCSETAW:
584 	case TIOCSPGRP:
585 	case TIOCSTART:
586 	case TIOCSTAT:
587 	case TIOCSTI:
588 	case TIOCSTOP:
589 	case TIOCSWINSZ:
590 #if 0
591 	case TIOCSDRAINWAIT:
592 	case TIOCSETD:
593 #endif
594 #ifdef COMPAT_43TTY
595 	case  TIOCLBIC:
596 	case  TIOCLBIS:
597 	case  TIOCLSET:
598 	case  TIOCSETC:
599 	case OTIOCSETD:
600 	case  TIOCSETN:
601 	case  TIOCSETP:
602 	case  TIOCSLTC:
603 #endif /* COMPAT_43TTY */
604 		/*
605 		 * If the ioctl() causes the TTY to be modified, let it
606 		 * wait in the background.
607 		 */
608 		error = tty_wait_background(tp, curthread, SIGTTOU);
609 		if (error)
610 			goto done;
611 	}
612 
613 	if (cmd == TIOCSETA || cmd == TIOCSETAW || cmd == TIOCSETAF) {
614 		struct termios *old = &tp->t_termios;
615 		struct termios *new = (struct termios *)data;
616 		struct termios *lock = TTY_CALLOUT(tp, dev) ?
617 		    &tp->t_termios_lock_out : &tp->t_termios_lock_in;
618 		int cc;
619 
620 		/*
621 		 * Lock state devices.  Just overwrite the values of the
622 		 * commands that are currently in use.
623 		 */
624 		new->c_iflag = (old->c_iflag & lock->c_iflag) |
625 		    (new->c_iflag & ~lock->c_iflag);
626 		new->c_oflag = (old->c_oflag & lock->c_oflag) |
627 		    (new->c_oflag & ~lock->c_oflag);
628 		new->c_cflag = (old->c_cflag & lock->c_cflag) |
629 		    (new->c_cflag & ~lock->c_cflag);
630 		new->c_lflag = (old->c_lflag & lock->c_lflag) |
631 		    (new->c_lflag & ~lock->c_lflag);
632 		for (cc = 0; cc < NCCS; ++cc)
633 			if (lock->c_cc[cc])
634 				new->c_cc[cc] = old->c_cc[cc];
635 		if (lock->c_ispeed)
636 			new->c_ispeed = old->c_ispeed;
637 		if (lock->c_ospeed)
638 			new->c_ospeed = old->c_ospeed;
639 	}
640 
641 	error = tty_ioctl(tp, cmd, data, fflag, td);
642 done:	tty_unlock(tp);
643 
644 	return (error);
645 }
646 
647 static int
648 ttydev_poll(struct cdev *dev, int events, struct thread *td)
649 {
650 	struct tty *tp = dev->si_drv1;
651 	int error, revents = 0;
652 
653 	error = ttydev_enter(tp);
654 	if (error)
655 		return ((events & (POLLIN|POLLRDNORM)) | POLLHUP);
656 
657 	if (events & (POLLIN|POLLRDNORM)) {
658 		/* See if we can read something. */
659 		if (ttydisc_read_poll(tp) > 0)
660 			revents |= events & (POLLIN|POLLRDNORM);
661 	}
662 
663 	if (tp->t_flags & TF_ZOMBIE) {
664 		/* Hangup flag on zombie state. */
665 		revents |= POLLHUP;
666 	} else if (events & (POLLOUT|POLLWRNORM)) {
667 		/* See if we can write something. */
668 		if (ttydisc_write_poll(tp) > 0)
669 			revents |= events & (POLLOUT|POLLWRNORM);
670 	}
671 
672 	if (revents == 0) {
673 		if (events & (POLLIN|POLLRDNORM))
674 			selrecord(td, &tp->t_inpoll);
675 		if (events & (POLLOUT|POLLWRNORM))
676 			selrecord(td, &tp->t_outpoll);
677 	}
678 
679 	tty_unlock(tp);
680 
681 	return (revents);
682 }
683 
684 static int
685 ttydev_mmap(struct cdev *dev, vm_ooffset_t offset, vm_paddr_t *paddr,
686     int nprot, vm_memattr_t *memattr)
687 {
688 	struct tty *tp = dev->si_drv1;
689 	int error;
690 
691 	/* Handle mmap() through the driver. */
692 
693 	error = ttydev_enter(tp);
694 	if (error)
695 		return (-1);
696 	error = ttydevsw_mmap(tp, offset, paddr, nprot, memattr);
697 	tty_unlock(tp);
698 
699 	return (error);
700 }
701 
702 /*
703  * kqueue support.
704  */
705 
706 static void
707 tty_kqops_read_detach(struct knote *kn)
708 {
709 	struct tty *tp = kn->kn_hook;
710 
711 	knlist_remove(&tp->t_inpoll.si_note, kn, 0);
712 }
713 
714 static int
715 tty_kqops_read_event(struct knote *kn, long hint __unused)
716 {
717 	struct tty *tp = kn->kn_hook;
718 
719 	tty_assert_locked(tp);
720 
721 	if (tty_gone(tp) || tp->t_flags & TF_ZOMBIE) {
722 		kn->kn_flags |= EV_EOF;
723 		return (1);
724 	} else {
725 		kn->kn_data = ttydisc_read_poll(tp);
726 		return (kn->kn_data > 0);
727 	}
728 }
729 
730 static void
731 tty_kqops_write_detach(struct knote *kn)
732 {
733 	struct tty *tp = kn->kn_hook;
734 
735 	knlist_remove(&tp->t_outpoll.si_note, kn, 0);
736 }
737 
738 static int
739 tty_kqops_write_event(struct knote *kn, long hint __unused)
740 {
741 	struct tty *tp = kn->kn_hook;
742 
743 	tty_assert_locked(tp);
744 
745 	if (tty_gone(tp)) {
746 		kn->kn_flags |= EV_EOF;
747 		return (1);
748 	} else {
749 		kn->kn_data = ttydisc_write_poll(tp);
750 		return (kn->kn_data > 0);
751 	}
752 }
753 
754 static struct filterops tty_kqops_read = {
755 	.f_isfd = 1,
756 	.f_detach = tty_kqops_read_detach,
757 	.f_event = tty_kqops_read_event,
758 };
759 
760 static struct filterops tty_kqops_write = {
761 	.f_isfd = 1,
762 	.f_detach = tty_kqops_write_detach,
763 	.f_event = tty_kqops_write_event,
764 };
765 
766 static int
767 ttydev_kqfilter(struct cdev *dev, struct knote *kn)
768 {
769 	struct tty *tp = dev->si_drv1;
770 	int error;
771 
772 	error = ttydev_enter(tp);
773 	if (error)
774 		return (error);
775 
776 	switch (kn->kn_filter) {
777 	case EVFILT_READ:
778 		kn->kn_hook = tp;
779 		kn->kn_fop = &tty_kqops_read;
780 		knlist_add(&tp->t_inpoll.si_note, kn, 1);
781 		break;
782 	case EVFILT_WRITE:
783 		kn->kn_hook = tp;
784 		kn->kn_fop = &tty_kqops_write;
785 		knlist_add(&tp->t_outpoll.si_note, kn, 1);
786 		break;
787 	default:
788 		error = EINVAL;
789 		break;
790 	}
791 
792 	tty_unlock(tp);
793 	return (error);
794 }
795 
796 static struct cdevsw ttydev_cdevsw = {
797 	.d_version	= D_VERSION,
798 	.d_open		= ttydev_open,
799 	.d_close	= ttydev_close,
800 	.d_read		= ttydev_read,
801 	.d_write	= ttydev_write,
802 	.d_ioctl	= ttydev_ioctl,
803 	.d_kqfilter	= ttydev_kqfilter,
804 	.d_poll		= ttydev_poll,
805 	.d_mmap		= ttydev_mmap,
806 	.d_name		= "ttydev",
807 	.d_flags	= D_TTY,
808 };
809 
810 /*
811  * Init/lock-state devices
812  */
813 
814 static int
815 ttyil_open(struct cdev *dev, int oflags __unused, int devtype __unused,
816     struct thread *td)
817 {
818 	struct tty *tp;
819 	int error;
820 
821 	tp = dev->si_drv1;
822 	error = 0;
823 	tty_lock(tp);
824 	if (tty_gone(tp))
825 		error = ENODEV;
826 	tty_unlock(tp);
827 
828 	return (error);
829 }
830 
831 static int
832 ttyil_close(struct cdev *dev __unused, int flag __unused, int mode __unused,
833     struct thread *td __unused)
834 {
835 
836 	return (0);
837 }
838 
839 static int
840 ttyil_rdwr(struct cdev *dev __unused, struct uio *uio __unused,
841     int ioflag __unused)
842 {
843 
844 	return (ENODEV);
845 }
846 
847 static int
848 ttyil_ioctl(struct cdev *dev, u_long cmd, caddr_t data, int fflag,
849     struct thread *td)
850 {
851 	struct tty *tp = dev->si_drv1;
852 	int error;
853 
854 	tty_lock(tp);
855 	if (tty_gone(tp)) {
856 		error = ENODEV;
857 		goto done;
858 	}
859 
860 	error = ttydevsw_cioctl(tp, dev2unit(dev), cmd, data, td);
861 	if (error != ENOIOCTL)
862 		goto done;
863 	error = 0;
864 
865 	switch (cmd) {
866 	case TIOCGETA:
867 		/* Obtain terminal flags through tcgetattr(). */
868 		*(struct termios*)data = *(struct termios*)dev->si_drv2;
869 		break;
870 	case TIOCSETA:
871 		/* Set terminal flags through tcsetattr(). */
872 		error = priv_check(td, PRIV_TTY_SETA);
873 		if (error)
874 			break;
875 		*(struct termios*)dev->si_drv2 = *(struct termios*)data;
876 		break;
877 	case TIOCGETD:
878 		*(int *)data = TTYDISC;
879 		break;
880 	case TIOCGWINSZ:
881 		bzero(data, sizeof(struct winsize));
882 		break;
883 	default:
884 		error = ENOTTY;
885 	}
886 
887 done:	tty_unlock(tp);
888 	return (error);
889 }
890 
891 static struct cdevsw ttyil_cdevsw = {
892 	.d_version	= D_VERSION,
893 	.d_open		= ttyil_open,
894 	.d_close	= ttyil_close,
895 	.d_read		= ttyil_rdwr,
896 	.d_write	= ttyil_rdwr,
897 	.d_ioctl	= ttyil_ioctl,
898 	.d_name		= "ttyil",
899 	.d_flags	= D_TTY,
900 };
901 
902 static void
903 tty_init_termios(struct tty *tp)
904 {
905 	struct termios *t = &tp->t_termios_init_in;
906 
907 	t->c_cflag = TTYDEF_CFLAG;
908 	t->c_iflag = TTYDEF_IFLAG;
909 	t->c_lflag = TTYDEF_LFLAG;
910 	t->c_oflag = TTYDEF_OFLAG;
911 	t->c_ispeed = TTYDEF_SPEED;
912 	t->c_ospeed = TTYDEF_SPEED;
913 	memcpy(&t->c_cc, ttydefchars, sizeof ttydefchars);
914 
915 	tp->t_termios_init_out = *t;
916 }
917 
918 void
919 tty_init_console(struct tty *tp, speed_t s)
920 {
921 	struct termios *ti = &tp->t_termios_init_in;
922 	struct termios *to = &tp->t_termios_init_out;
923 
924 	if (s != 0) {
925 		ti->c_ispeed = ti->c_ospeed = s;
926 		to->c_ispeed = to->c_ospeed = s;
927 	}
928 
929 	ti->c_cflag |= CLOCAL;
930 	to->c_cflag |= CLOCAL;
931 }
932 
933 /*
934  * Standard device routine implementations, mostly meant for
935  * pseudo-terminal device drivers. When a driver creates a new terminal
936  * device class, missing routines are patched.
937  */
938 
939 static int
940 ttydevsw_defopen(struct tty *tp __unused)
941 {
942 
943 	return (0);
944 }
945 
946 static void
947 ttydevsw_defclose(struct tty *tp __unused)
948 {
949 
950 }
951 
952 static void
953 ttydevsw_defoutwakeup(struct tty *tp __unused)
954 {
955 
956 	panic("Terminal device has output, while not implemented");
957 }
958 
959 static void
960 ttydevsw_definwakeup(struct tty *tp __unused)
961 {
962 
963 }
964 
965 static int
966 ttydevsw_defioctl(struct tty *tp __unused, u_long cmd __unused,
967     caddr_t data __unused, struct thread *td __unused)
968 {
969 
970 	return (ENOIOCTL);
971 }
972 
973 static int
974 ttydevsw_defcioctl(struct tty *tp __unused, int unit __unused,
975     u_long cmd __unused, caddr_t data __unused, struct thread *td __unused)
976 {
977 
978 	return (ENOIOCTL);
979 }
980 
981 static int
982 ttydevsw_defparam(struct tty *tp __unused, struct termios *t)
983 {
984 
985 	/*
986 	 * Allow the baud rate to be adjusted for pseudo-devices, but at
987 	 * least restrict it to 115200 to prevent excessive buffer
988 	 * usage.  Also disallow 0, to prevent foot shooting.
989 	 */
990 	if (t->c_ispeed < B50)
991 		t->c_ispeed = B50;
992 	else if (t->c_ispeed > B115200)
993 		t->c_ispeed = B115200;
994 	if (t->c_ospeed < B50)
995 		t->c_ospeed = B50;
996 	else if (t->c_ospeed > B115200)
997 		t->c_ospeed = B115200;
998 	t->c_cflag |= CREAD;
999 
1000 	return (0);
1001 }
1002 
1003 static int
1004 ttydevsw_defmodem(struct tty *tp __unused, int sigon __unused,
1005     int sigoff __unused)
1006 {
1007 
1008 	/* Simulate a carrier to make the TTY layer happy. */
1009 	return (SER_DCD);
1010 }
1011 
1012 static int
1013 ttydevsw_defmmap(struct tty *tp __unused, vm_ooffset_t offset __unused,
1014     vm_paddr_t *paddr __unused, int nprot __unused,
1015     vm_memattr_t *memattr __unused)
1016 {
1017 
1018 	return (-1);
1019 }
1020 
1021 static void
1022 ttydevsw_defpktnotify(struct tty *tp __unused, char event __unused)
1023 {
1024 
1025 }
1026 
1027 static void
1028 ttydevsw_deffree(void *softc __unused)
1029 {
1030 
1031 	panic("Terminal device freed without a free-handler");
1032 }
1033 
1034 static bool
1035 ttydevsw_defbusy(struct tty *tp __unused)
1036 {
1037 
1038 	return (FALSE);
1039 }
1040 
1041 /*
1042  * TTY allocation and deallocation. TTY devices can be deallocated when
1043  * the driver doesn't use it anymore, when the TTY isn't a session's
1044  * controlling TTY and when the device node isn't opened through devfs.
1045  */
1046 
1047 struct tty *
1048 tty_alloc(struct ttydevsw *tsw, void *sc)
1049 {
1050 
1051 	return (tty_alloc_mutex(tsw, sc, NULL));
1052 }
1053 
1054 struct tty *
1055 tty_alloc_mutex(struct ttydevsw *tsw, void *sc, struct mtx *mutex)
1056 {
1057 	struct tty *tp;
1058 
1059 	/* Make sure the driver defines all routines. */
1060 #define PATCH_FUNC(x) do {				\
1061 	if (tsw->tsw_ ## x == NULL)			\
1062 		tsw->tsw_ ## x = ttydevsw_def ## x;	\
1063 } while (0)
1064 	PATCH_FUNC(open);
1065 	PATCH_FUNC(close);
1066 	PATCH_FUNC(outwakeup);
1067 	PATCH_FUNC(inwakeup);
1068 	PATCH_FUNC(ioctl);
1069 	PATCH_FUNC(cioctl);
1070 	PATCH_FUNC(param);
1071 	PATCH_FUNC(modem);
1072 	PATCH_FUNC(mmap);
1073 	PATCH_FUNC(pktnotify);
1074 	PATCH_FUNC(free);
1075 	PATCH_FUNC(busy);
1076 #undef PATCH_FUNC
1077 
1078 	tp = malloc(sizeof(struct tty) + TTY_PRBUF_SIZE, M_TTY,
1079 	    M_WAITOK | M_ZERO);
1080 	tp->t_prbufsz = TTY_PRBUF_SIZE;
1081 	tp->t_devsw = tsw;
1082 	tp->t_devswsoftc = sc;
1083 	tp->t_flags = tsw->tsw_flags;
1084 	tp->t_drainwait = tty_drainwait;
1085 
1086 	tty_init_termios(tp);
1087 
1088 	cv_init(&tp->t_inwait, "ttyin");
1089 	cv_init(&tp->t_outwait, "ttyout");
1090 	cv_init(&tp->t_outserwait, "ttyosr");
1091 	cv_init(&tp->t_bgwait, "ttybg");
1092 	cv_init(&tp->t_dcdwait, "ttydcd");
1093 
1094 	/* Allow drivers to use a custom mutex to lock the TTY. */
1095 	if (mutex != NULL) {
1096 		tp->t_mtx = mutex;
1097 	} else {
1098 		tp->t_mtx = &tp->t_mtxobj;
1099 		mtx_init(&tp->t_mtxobj, "ttymtx", NULL, MTX_DEF);
1100 	}
1101 
1102 	knlist_init_mtx(&tp->t_inpoll.si_note, tp->t_mtx);
1103 	knlist_init_mtx(&tp->t_outpoll.si_note, tp->t_mtx);
1104 
1105 	return (tp);
1106 }
1107 
1108 static void
1109 tty_dealloc(void *arg)
1110 {
1111 	struct tty *tp = arg;
1112 
1113 	/*
1114 	 * ttyydev_leave() usually frees the i/o queues earlier, but it is
1115 	 * not always called between queue allocation and here.  The queues
1116 	 * may be allocated by ioctls on a pty control device without the
1117 	 * corresponding pty slave device ever being open, or after it is
1118 	 * closed.
1119 	 */
1120 	ttyinq_free(&tp->t_inq);
1121 	ttyoutq_free(&tp->t_outq);
1122 	seldrain(&tp->t_inpoll);
1123 	seldrain(&tp->t_outpoll);
1124 	knlist_clear(&tp->t_inpoll.si_note, 0);
1125 	knlist_clear(&tp->t_outpoll.si_note, 0);
1126 	knlist_destroy(&tp->t_inpoll.si_note);
1127 	knlist_destroy(&tp->t_outpoll.si_note);
1128 
1129 	cv_destroy(&tp->t_inwait);
1130 	cv_destroy(&tp->t_outwait);
1131 	cv_destroy(&tp->t_bgwait);
1132 	cv_destroy(&tp->t_dcdwait);
1133 	cv_destroy(&tp->t_outserwait);
1134 
1135 	if (tp->t_mtx == &tp->t_mtxobj)
1136 		mtx_destroy(&tp->t_mtxobj);
1137 	ttydevsw_free(tp);
1138 	free(tp, M_TTY);
1139 }
1140 
1141 static void
1142 tty_rel_free(struct tty *tp)
1143 {
1144 	struct cdev *dev;
1145 
1146 	tty_assert_locked(tp);
1147 
1148 #define	TF_ACTIVITY	(TF_GONE|TF_OPENED|TF_HOOK|TF_OPENCLOSE)
1149 	if (tp->t_sessioncnt != 0 || (tp->t_flags & TF_ACTIVITY) != TF_GONE) {
1150 		/* TTY is still in use. */
1151 		tty_unlock(tp);
1152 		return;
1153 	}
1154 
1155 	/* Stop asynchronous I/O. */
1156 	funsetown(&tp->t_sigio);
1157 
1158 	/* TTY can be deallocated. */
1159 	dev = tp->t_dev;
1160 	tp->t_dev = NULL;
1161 	tty_unlock(tp);
1162 
1163 	if (dev != NULL) {
1164 		sx_xlock(&tty_list_sx);
1165 		TAILQ_REMOVE(&tty_list, tp, t_list);
1166 		tty_list_count--;
1167 		sx_xunlock(&tty_list_sx);
1168 		destroy_dev_sched_cb(dev, tty_dealloc, tp);
1169 	}
1170 }
1171 
1172 void
1173 tty_rel_pgrp(struct tty *tp, struct pgrp *pg)
1174 {
1175 
1176 	MPASS(tp->t_sessioncnt > 0);
1177 	tty_assert_locked(tp);
1178 
1179 	if (tp->t_pgrp == pg)
1180 		tp->t_pgrp = NULL;
1181 
1182 	tty_unlock(tp);
1183 }
1184 
1185 void
1186 tty_rel_sess(struct tty *tp, struct session *sess)
1187 {
1188 
1189 	MPASS(tp->t_sessioncnt > 0);
1190 
1191 	/* Current session has left. */
1192 	if (tp->t_session == sess) {
1193 		tp->t_session = NULL;
1194 		MPASS(tp->t_pgrp == NULL);
1195 	}
1196 	tp->t_sessioncnt--;
1197 	tty_rel_free(tp);
1198 }
1199 
1200 void
1201 tty_rel_gone(struct tty *tp)
1202 {
1203 
1204 	tty_assert_locked(tp);
1205 	MPASS(!tty_gone(tp));
1206 
1207 	/* Simulate carrier removal. */
1208 	ttydisc_modem(tp, 0);
1209 
1210 	/* Wake up all blocked threads. */
1211 	tty_wakeup(tp, FREAD|FWRITE);
1212 	cv_broadcast(&tp->t_bgwait);
1213 	cv_broadcast(&tp->t_dcdwait);
1214 
1215 	tp->t_flags |= TF_GONE;
1216 	tty_rel_free(tp);
1217 }
1218 
1219 static int
1220 tty_drop_ctty(struct tty *tp, struct proc *p)
1221 {
1222 	struct session *session;
1223 	struct vnode *vp;
1224 
1225 	/*
1226 	 * This looks terrible, but it's generally safe as long as the tty
1227 	 * hasn't gone away while we had the lock dropped.  All of our sanity
1228 	 * checking that this operation is OK happens after we've picked it back
1229 	 * up, so other state changes are generally not fatal and the potential
1230 	 * for this particular operation to happen out-of-order in a
1231 	 * multithreaded scenario is likely a non-issue.
1232 	 */
1233 	tty_unlock(tp);
1234 	sx_xlock(&proctree_lock);
1235 	tty_lock(tp);
1236 	if (tty_gone(tp)) {
1237 		sx_xunlock(&proctree_lock);
1238 		return (ENODEV);
1239 	}
1240 
1241 	/*
1242 	 * If the session doesn't have a controlling TTY, or if we weren't
1243 	 * invoked on the controlling TTY, we'll return ENOIOCTL as we've
1244 	 * historically done.
1245 	 */
1246 	session = p->p_session;
1247 	if (session->s_ttyp == NULL || session->s_ttyp != tp) {
1248 		sx_xunlock(&proctree_lock);
1249 		return (ENOTTY);
1250 	}
1251 
1252 	if (!SESS_LEADER(p)) {
1253 		sx_xunlock(&proctree_lock);
1254 		return (EPERM);
1255 	}
1256 
1257 	PROC_LOCK(p);
1258 	SESS_LOCK(session);
1259 	vp = session->s_ttyvp;
1260 	session->s_ttyp = NULL;
1261 	session->s_ttyvp = NULL;
1262 	session->s_ttydp = NULL;
1263 	SESS_UNLOCK(session);
1264 
1265 	tp->t_sessioncnt--;
1266 	p->p_flag &= ~P_CONTROLT;
1267 	PROC_UNLOCK(p);
1268 	sx_xunlock(&proctree_lock);
1269 
1270 	/*
1271 	 * If we did have a vnode, release our reference.  Ordinarily we manage
1272 	 * these at the devfs layer, but we can't necessarily know that we were
1273 	 * invoked on the vnode referenced in the session (i.e. the vnode we
1274 	 * hold a reference to).  We explicitly don't check VBAD/VIRF_DOOMED here
1275 	 * to avoid a vnode leak -- in circumstances elsewhere where we'd hit a
1276 	 * VIRF_DOOMED vnode, release has been deferred until the controlling TTY
1277 	 * is either changed or released.
1278 	 */
1279 	if (vp != NULL)
1280 		devfs_ctty_unref(vp);
1281 	return (0);
1282 }
1283 
1284 /*
1285  * Exposing information about current TTY's through sysctl
1286  */
1287 
1288 static void
1289 tty_to_xtty(struct tty *tp, struct xtty *xt)
1290 {
1291 
1292 	tty_assert_locked(tp);
1293 
1294 	memset(xt, 0, sizeof(*xt));
1295 	xt->xt_size = sizeof(struct xtty);
1296 	xt->xt_insize = ttyinq_getsize(&tp->t_inq);
1297 	xt->xt_incc = ttyinq_bytescanonicalized(&tp->t_inq);
1298 	xt->xt_inlc = ttyinq_bytesline(&tp->t_inq);
1299 	xt->xt_inlow = tp->t_inlow;
1300 	xt->xt_outsize = ttyoutq_getsize(&tp->t_outq);
1301 	xt->xt_outcc = ttyoutq_bytesused(&tp->t_outq);
1302 	xt->xt_outlow = tp->t_outlow;
1303 	xt->xt_column = tp->t_column;
1304 	xt->xt_pgid = tp->t_pgrp ? tp->t_pgrp->pg_id : 0;
1305 	xt->xt_sid = tp->t_session ? tp->t_session->s_sid : 0;
1306 	xt->xt_flags = tp->t_flags;
1307 	xt->xt_dev = tp->t_dev ? dev2udev(tp->t_dev) : (uint32_t)NODEV;
1308 }
1309 
1310 static int
1311 sysctl_kern_ttys(SYSCTL_HANDLER_ARGS)
1312 {
1313 	unsigned long lsize;
1314 	struct thread *td = curthread;
1315 	struct xtty *xtlist, *xt;
1316 	struct tty *tp;
1317 	struct proc *p;
1318 	int cansee, error;
1319 
1320 	sx_slock(&tty_list_sx);
1321 	lsize = tty_list_count * sizeof(struct xtty);
1322 	if (lsize == 0) {
1323 		sx_sunlock(&tty_list_sx);
1324 		return (0);
1325 	}
1326 
1327 	xtlist = xt = malloc(lsize, M_TTY, M_WAITOK);
1328 
1329 	TAILQ_FOREACH(tp, &tty_list, t_list) {
1330 		tty_lock(tp);
1331 		if (tp->t_session != NULL) {
1332 			p = tp->t_session->s_leader;
1333 			PROC_LOCK(p);
1334 			cansee = (p_cansee(td, p) == 0);
1335 			PROC_UNLOCK(p);
1336 		} else {
1337 			cansee = !jailed(td->td_ucred);
1338 		}
1339 		if (cansee) {
1340 			tty_to_xtty(tp, xt);
1341 			xt++;
1342 		}
1343 		tty_unlock(tp);
1344 	}
1345 	sx_sunlock(&tty_list_sx);
1346 
1347 	lsize = (xt - xtlist) * sizeof(struct xtty);
1348 	if (lsize > 0) {
1349 		error = SYSCTL_OUT(req, xtlist, lsize);
1350 	} else {
1351 		error = 0;
1352 	}
1353 	free(xtlist, M_TTY);
1354 	return (error);
1355 }
1356 
1357 SYSCTL_PROC(_kern, OID_AUTO, ttys, CTLTYPE_OPAQUE|CTLFLAG_RD|CTLFLAG_MPSAFE,
1358 	0, 0, sysctl_kern_ttys, "S,xtty", "List of TTYs");
1359 
1360 /*
1361  * Device node creation. Device has been set up, now we can expose it to
1362  * the user.
1363  */
1364 
1365 int
1366 tty_makedevf(struct tty *tp, struct ucred *cred, int flags,
1367     const char *fmt, ...)
1368 {
1369 	va_list ap;
1370 	struct make_dev_args args;
1371 	struct cdev *dev, *init, *lock, *cua, *cinit, *clock;
1372 	const char *prefix = "tty";
1373 	char name[SPECNAMELEN - 3]; /* for "tty" and "cua". */
1374 	uid_t uid;
1375 	gid_t gid;
1376 	mode_t mode;
1377 	int error;
1378 
1379 	/* Remove "tty" prefix from devices like PTY's. */
1380 	if (tp->t_flags & TF_NOPREFIX)
1381 		prefix = "";
1382 
1383 	va_start(ap, fmt);
1384 	vsnrprintf(name, sizeof name, 32, fmt, ap);
1385 	va_end(ap);
1386 
1387 	if (cred == NULL) {
1388 		/* System device. */
1389 		uid = UID_ROOT;
1390 		gid = GID_WHEEL;
1391 		mode = S_IRUSR|S_IWUSR;
1392 	} else {
1393 		/* User device. */
1394 		uid = cred->cr_ruid;
1395 		gid = GID_TTY;
1396 		mode = S_IRUSR|S_IWUSR|S_IWGRP;
1397 	}
1398 
1399 	flags = flags & TTYMK_CLONING ? MAKEDEV_REF : 0;
1400 	flags |= MAKEDEV_CHECKNAME;
1401 
1402 	/* Master call-in device. */
1403 	make_dev_args_init(&args);
1404 	args.mda_flags = flags;
1405 	args.mda_devsw = &ttydev_cdevsw;
1406 	args.mda_cr = cred;
1407 	args.mda_uid = uid;
1408 	args.mda_gid = gid;
1409 	args.mda_mode = mode;
1410 	args.mda_si_drv1 = tp;
1411 	error = make_dev_s(&args, &dev, "%s%s", prefix, name);
1412 	if (error != 0)
1413 		return (error);
1414 	tp->t_dev = dev;
1415 
1416 	init = lock = cua = cinit = clock = NULL;
1417 
1418 	/* Slave call-in devices. */
1419 	if (tp->t_flags & TF_INITLOCK) {
1420 		args.mda_devsw = &ttyil_cdevsw;
1421 		args.mda_unit = TTYUNIT_INIT;
1422 		args.mda_si_drv1 = tp;
1423 		args.mda_si_drv2 = &tp->t_termios_init_in;
1424 		error = make_dev_s(&args, &init, "%s%s.init", prefix, name);
1425 		if (error != 0)
1426 			goto fail;
1427 		dev_depends(dev, init);
1428 
1429 		args.mda_unit = TTYUNIT_LOCK;
1430 		args.mda_si_drv2 = &tp->t_termios_lock_in;
1431 		error = make_dev_s(&args, &lock, "%s%s.lock", prefix, name);
1432 		if (error != 0)
1433 			goto fail;
1434 		dev_depends(dev, lock);
1435 	}
1436 
1437 	/* Call-out devices. */
1438 	if (tp->t_flags & TF_CALLOUT) {
1439 		make_dev_args_init(&args);
1440 		args.mda_flags = flags;
1441 		args.mda_devsw = &ttydev_cdevsw;
1442 		args.mda_cr = cred;
1443 		args.mda_uid = UID_UUCP;
1444 		args.mda_gid = GID_DIALER;
1445 		args.mda_mode = 0660;
1446 		args.mda_unit = TTYUNIT_CALLOUT;
1447 		args.mda_si_drv1 = tp;
1448 		error = make_dev_s(&args, &cua, "cua%s", name);
1449 		if (error != 0)
1450 			goto fail;
1451 		dev_depends(dev, cua);
1452 
1453 		/* Slave call-out devices. */
1454 		if (tp->t_flags & TF_INITLOCK) {
1455 			args.mda_devsw = &ttyil_cdevsw;
1456 			args.mda_unit = TTYUNIT_CALLOUT | TTYUNIT_INIT;
1457 			args.mda_si_drv2 = &tp->t_termios_init_out;
1458 			error = make_dev_s(&args, &cinit, "cua%s.init", name);
1459 			if (error != 0)
1460 				goto fail;
1461 			dev_depends(dev, cinit);
1462 
1463 			args.mda_unit = TTYUNIT_CALLOUT | TTYUNIT_LOCK;
1464 			args.mda_si_drv2 = &tp->t_termios_lock_out;
1465 			error = make_dev_s(&args, &clock, "cua%s.lock", name);
1466 			if (error != 0)
1467 				goto fail;
1468 			dev_depends(dev, clock);
1469 		}
1470 	}
1471 
1472 	sx_xlock(&tty_list_sx);
1473 	TAILQ_INSERT_TAIL(&tty_list, tp, t_list);
1474 	tty_list_count++;
1475 	sx_xunlock(&tty_list_sx);
1476 
1477 	return (0);
1478 
1479 fail:
1480 	destroy_dev(dev);
1481 	if (init)
1482 		destroy_dev(init);
1483 	if (lock)
1484 		destroy_dev(lock);
1485 	if (cinit)
1486 		destroy_dev(cinit);
1487 	if (clock)
1488 		destroy_dev(clock);
1489 
1490 	return (error);
1491 }
1492 
1493 /*
1494  * Signalling processes.
1495  */
1496 
1497 void
1498 tty_signal_sessleader(struct tty *tp, int sig)
1499 {
1500 	struct proc *p;
1501 	struct session *s;
1502 
1503 	tty_assert_locked(tp);
1504 	MPASS(sig >= 1 && sig < NSIG);
1505 
1506 	/* Make signals start output again. */
1507 	tp->t_flags &= ~TF_STOPPED;
1508 	tp->t_termios.c_lflag &= ~FLUSHO;
1509 
1510 	/*
1511 	 * Load s_leader exactly once to avoid race where s_leader is
1512 	 * set to NULL by a concurrent invocation of killjobc() by the
1513 	 * session leader.  Note that we are not holding t_session's
1514 	 * lock for the read.
1515 	 */
1516 	if ((s = tp->t_session) != NULL &&
1517 	    (p = atomic_load_ptr(&s->s_leader)) != NULL) {
1518 		PROC_LOCK(p);
1519 		kern_psignal(p, sig);
1520 		PROC_UNLOCK(p);
1521 	}
1522 }
1523 
1524 void
1525 tty_signal_pgrp(struct tty *tp, int sig)
1526 {
1527 	ksiginfo_t ksi;
1528 
1529 	tty_assert_locked(tp);
1530 	MPASS(sig >= 1 && sig < NSIG);
1531 
1532 	/* Make signals start output again. */
1533 	tp->t_flags &= ~TF_STOPPED;
1534 	tp->t_termios.c_lflag &= ~FLUSHO;
1535 
1536 	if (sig == SIGINFO && !(tp->t_termios.c_lflag & NOKERNINFO))
1537 		tty_info(tp);
1538 	if (tp->t_pgrp != NULL) {
1539 		ksiginfo_init(&ksi);
1540 		ksi.ksi_signo = sig;
1541 		ksi.ksi_code = SI_KERNEL;
1542 		PGRP_LOCK(tp->t_pgrp);
1543 		pgsignal(tp->t_pgrp, sig, 1, &ksi);
1544 		PGRP_UNLOCK(tp->t_pgrp);
1545 	}
1546 }
1547 
1548 void
1549 tty_wakeup(struct tty *tp, int flags)
1550 {
1551 
1552 	if (tp->t_flags & TF_ASYNC && tp->t_sigio != NULL)
1553 		pgsigio(&tp->t_sigio, SIGIO, (tp->t_session != NULL));
1554 
1555 	if (flags & FWRITE) {
1556 		cv_broadcast(&tp->t_outwait);
1557 		selwakeup(&tp->t_outpoll);
1558 		KNOTE_LOCKED(&tp->t_outpoll.si_note, 0);
1559 	}
1560 	if (flags & FREAD) {
1561 		cv_broadcast(&tp->t_inwait);
1562 		selwakeup(&tp->t_inpoll);
1563 		KNOTE_LOCKED(&tp->t_inpoll.si_note, 0);
1564 	}
1565 }
1566 
1567 int
1568 tty_wait(struct tty *tp, struct cv *cv)
1569 {
1570 	int error;
1571 	int revokecnt = tp->t_revokecnt;
1572 
1573 	tty_lock_assert(tp, MA_OWNED|MA_NOTRECURSED);
1574 	MPASS(!tty_gone(tp));
1575 
1576 	error = cv_wait_sig(cv, tp->t_mtx);
1577 
1578 	/* Bail out when the device slipped away. */
1579 	if (tty_gone(tp))
1580 		return (ENXIO);
1581 
1582 	/* Restart the system call when we may have been revoked. */
1583 	if (tp->t_revokecnt != revokecnt)
1584 		return (ERESTART);
1585 
1586 	return (error);
1587 }
1588 
1589 int
1590 tty_timedwait(struct tty *tp, struct cv *cv, int hz)
1591 {
1592 	int error;
1593 	int revokecnt = tp->t_revokecnt;
1594 
1595 	tty_lock_assert(tp, MA_OWNED|MA_NOTRECURSED);
1596 	MPASS(!tty_gone(tp));
1597 
1598 	error = cv_timedwait_sig(cv, tp->t_mtx, hz);
1599 
1600 	/* Bail out when the device slipped away. */
1601 	if (tty_gone(tp))
1602 		return (ENXIO);
1603 
1604 	/* Restart the system call when we may have been revoked. */
1605 	if (tp->t_revokecnt != revokecnt)
1606 		return (ERESTART);
1607 
1608 	return (error);
1609 }
1610 
1611 void
1612 tty_flush(struct tty *tp, int flags)
1613 {
1614 
1615 	if (flags & FWRITE) {
1616 		tp->t_flags &= ~TF_HIWAT_OUT;
1617 		ttyoutq_flush(&tp->t_outq);
1618 		tty_wakeup(tp, FWRITE);
1619 		if (!tty_gone(tp)) {
1620 			ttydevsw_outwakeup(tp);
1621 			ttydevsw_pktnotify(tp, TIOCPKT_FLUSHWRITE);
1622 		}
1623 	}
1624 	if (flags & FREAD) {
1625 		tty_hiwat_in_unblock(tp);
1626 		ttyinq_flush(&tp->t_inq);
1627 		tty_wakeup(tp, FREAD);
1628 		if (!tty_gone(tp)) {
1629 			ttydevsw_inwakeup(tp);
1630 			ttydevsw_pktnotify(tp, TIOCPKT_FLUSHREAD);
1631 		}
1632 	}
1633 }
1634 
1635 void
1636 tty_set_winsize(struct tty *tp, const struct winsize *wsz)
1637 {
1638 
1639 	if (memcmp(&tp->t_winsize, wsz, sizeof(*wsz)) == 0)
1640 		return;
1641 	tp->t_winsize = *wsz;
1642 	tty_signal_pgrp(tp, SIGWINCH);
1643 }
1644 
1645 static int
1646 tty_generic_ioctl(struct tty *tp, u_long cmd, void *data, int fflag,
1647     struct thread *td)
1648 {
1649 	int error;
1650 
1651 	switch (cmd) {
1652 	/*
1653 	 * Modem commands.
1654 	 * The SER_* and TIOCM_* flags are the same, but one bit
1655 	 * shifted. I don't know why.
1656 	 */
1657 	case TIOCSDTR:
1658 		ttydevsw_modem(tp, SER_DTR, 0);
1659 		return (0);
1660 	case TIOCCDTR:
1661 		ttydevsw_modem(tp, 0, SER_DTR);
1662 		return (0);
1663 	case TIOCMSET: {
1664 		int bits = *(int *)data;
1665 		ttydevsw_modem(tp,
1666 		    (bits & (TIOCM_DTR | TIOCM_RTS)) >> 1,
1667 		    ((~bits) & (TIOCM_DTR | TIOCM_RTS)) >> 1);
1668 		return (0);
1669 	}
1670 	case TIOCMBIS: {
1671 		int bits = *(int *)data;
1672 		ttydevsw_modem(tp, (bits & (TIOCM_DTR | TIOCM_RTS)) >> 1, 0);
1673 		return (0);
1674 	}
1675 	case TIOCMBIC: {
1676 		int bits = *(int *)data;
1677 		ttydevsw_modem(tp, 0, (bits & (TIOCM_DTR | TIOCM_RTS)) >> 1);
1678 		return (0);
1679 	}
1680 	case TIOCMGET:
1681 		*(int *)data = TIOCM_LE + (ttydevsw_modem(tp, 0, 0) << 1);
1682 		return (0);
1683 
1684 	case FIOASYNC:
1685 		if (*(int *)data)
1686 			tp->t_flags |= TF_ASYNC;
1687 		else
1688 			tp->t_flags &= ~TF_ASYNC;
1689 		return (0);
1690 	case FIONBIO:
1691 		/* This device supports non-blocking operation. */
1692 		return (0);
1693 	case FIONREAD:
1694 		*(int *)data = ttydisc_bytesavail(tp);
1695 		return (0);
1696 	case FIONWRITE:
1697 	case TIOCOUTQ:
1698 		*(int *)data = ttyoutq_bytesused(&tp->t_outq);
1699 		return (0);
1700 	case FIOSETOWN:
1701 		if (tp->t_session != NULL && !tty_is_ctty(tp, td->td_proc))
1702 			/* Not allowed to set ownership. */
1703 			return (ENOTTY);
1704 
1705 		/* Temporarily unlock the TTY to set ownership. */
1706 		tty_unlock(tp);
1707 		error = fsetown(*(int *)data, &tp->t_sigio);
1708 		tty_lock(tp);
1709 		return (error);
1710 	case FIOGETOWN:
1711 		if (tp->t_session != NULL && !tty_is_ctty(tp, td->td_proc))
1712 			/* Not allowed to set ownership. */
1713 			return (ENOTTY);
1714 
1715 		/* Get ownership. */
1716 		*(int *)data = fgetown(&tp->t_sigio);
1717 		return (0);
1718 	case TIOCGETA:
1719 		/* Obtain terminal flags through tcgetattr(). */
1720 		*(struct termios*)data = tp->t_termios;
1721 		return (0);
1722 	case TIOCSETA:
1723 	case TIOCSETAW:
1724 	case TIOCSETAF: {
1725 		struct termios *t = data;
1726 		bool canonicalize = false;
1727 
1728 		/*
1729 		 * Who makes up these funny rules? According to POSIX,
1730 		 * input baud rate is set equal to the output baud rate
1731 		 * when zero.
1732 		 */
1733 		if (t->c_ispeed == 0)
1734 			t->c_ispeed = t->c_ospeed;
1735 
1736 		/* Discard any unsupported bits. */
1737 		t->c_iflag &= TTYSUP_IFLAG;
1738 		t->c_oflag &= TTYSUP_OFLAG;
1739 		t->c_lflag &= TTYSUP_LFLAG;
1740 		t->c_cflag &= TTYSUP_CFLAG;
1741 
1742 		/* Set terminal flags through tcsetattr(). */
1743 		if (cmd == TIOCSETAW || cmd == TIOCSETAF) {
1744 			error = tty_drain(tp, 0);
1745 			if (error)
1746 				return (error);
1747 			if (cmd == TIOCSETAF)
1748 				tty_flush(tp, FREAD);
1749 		}
1750 
1751 		/*
1752 		 * Only call param() when the flags really change.
1753 		 */
1754 		if ((t->c_cflag & CIGNORE) == 0 &&
1755 		    (tp->t_termios.c_cflag != t->c_cflag ||
1756 		    ((tp->t_termios.c_iflag ^ t->c_iflag) &
1757 		    (IXON|IXOFF|IXANY)) ||
1758 		    tp->t_termios.c_ispeed != t->c_ispeed ||
1759 		    tp->t_termios.c_ospeed != t->c_ospeed)) {
1760 			error = ttydevsw_param(tp, t);
1761 			if (error)
1762 				return (error);
1763 
1764 			/* XXX: CLOCAL? */
1765 
1766 			tp->t_termios.c_cflag = t->c_cflag & ~CIGNORE;
1767 			tp->t_termios.c_ispeed = t->c_ispeed;
1768 			tp->t_termios.c_ospeed = t->c_ospeed;
1769 
1770 			/* Baud rate has changed - update watermarks. */
1771 			error = tty_watermarks(tp);
1772 			if (error)
1773 				return (error);
1774 		}
1775 
1776 		/*
1777 		 * We'll canonicalize any partial input if we're transitioning
1778 		 * ICANON one way or the other.  If we're going from -ICANON ->
1779 		 * ICANON, then in the worst case scenario we're in the middle
1780 		 * of a line but both ttydisc_read() and FIONREAD will search
1781 		 * for one of our line terminals.
1782 		 */
1783 		if ((t->c_lflag & ICANON) != (tp->t_termios.c_lflag & ICANON))
1784 			canonicalize = true;
1785 		else if (tp->t_termios.c_cc[VEOF] != t->c_cc[VEOF] ||
1786 		    tp->t_termios.c_cc[VEOL] != t->c_cc[VEOL])
1787 			canonicalize = true;
1788 
1789 		/* Copy new non-device driver parameters. */
1790 		tp->t_termios.c_iflag = t->c_iflag;
1791 		tp->t_termios.c_oflag = t->c_oflag;
1792 		tp->t_termios.c_lflag = t->c_lflag;
1793 		memcpy(&tp->t_termios.c_cc, t->c_cc, sizeof t->c_cc);
1794 
1795 		ttydisc_optimize(tp);
1796 
1797 		if (canonicalize)
1798 			ttydisc_canonicalize(tp);
1799 		if ((t->c_lflag & ICANON) == 0) {
1800 			/*
1801 			 * When in non-canonical mode, wake up all
1802 			 * readers. Any partial input has already been
1803 			 * canonicalized above if we were in canonical mode.
1804 			 * VMIN and VTIME could also be adjusted.
1805 			 */
1806 			tty_wakeup(tp, FREAD);
1807 		}
1808 
1809 		/*
1810 		 * For packet mode: notify the PTY consumer that VSTOP
1811 		 * and VSTART may have been changed.
1812 		 */
1813 		if (tp->t_termios.c_iflag & IXON &&
1814 		    tp->t_termios.c_cc[VSTOP] == CTRL('S') &&
1815 		    tp->t_termios.c_cc[VSTART] == CTRL('Q'))
1816 			ttydevsw_pktnotify(tp, TIOCPKT_DOSTOP);
1817 		else
1818 			ttydevsw_pktnotify(tp, TIOCPKT_NOSTOP);
1819 		return (0);
1820 	}
1821 	case TIOCGETD:
1822 		/* For compatibility - we only support TTYDISC. */
1823 		*(int *)data = TTYDISC;
1824 		return (0);
1825 	case TIOCGPGRP:
1826 		if (!tty_is_ctty(tp, td->td_proc))
1827 			return (ENOTTY);
1828 
1829 		if (tp->t_pgrp != NULL)
1830 			*(int *)data = tp->t_pgrp->pg_id;
1831 		else
1832 			*(int *)data = NO_PID;
1833 		return (0);
1834 	case TIOCGSID:
1835 		if (!tty_is_ctty(tp, td->td_proc))
1836 			return (ENOTTY);
1837 
1838 		MPASS(tp->t_session);
1839 		*(int *)data = tp->t_session->s_sid;
1840 		return (0);
1841 	case TIOCNOTTY:
1842 		return (tty_drop_ctty(tp, td->td_proc));
1843 	case TIOCSCTTY: {
1844 		struct proc *p = td->td_proc;
1845 
1846 		/* XXX: This looks awful. */
1847 		tty_unlock(tp);
1848 		sx_xlock(&proctree_lock);
1849 		tty_lock(tp);
1850 
1851 		if (!SESS_LEADER(p)) {
1852 			/* Only the session leader may do this. */
1853 			sx_xunlock(&proctree_lock);
1854 			return (EPERM);
1855 		}
1856 
1857 		if (tp->t_session != NULL && tp->t_session == p->p_session) {
1858 			/* This is already our controlling TTY. */
1859 			sx_xunlock(&proctree_lock);
1860 			return (0);
1861 		}
1862 
1863 		if (p->p_session->s_ttyp != NULL ||
1864 		    (tp->t_session != NULL && tp->t_session->s_ttyvp != NULL &&
1865 		    tp->t_session->s_ttyvp->v_type != VBAD)) {
1866 			/*
1867 			 * There is already a relation between a TTY and
1868 			 * a session, or the caller is not the session
1869 			 * leader.
1870 			 *
1871 			 * Allow the TTY to be stolen when the vnode is
1872 			 * invalid, but the reference to the TTY is
1873 			 * still active.  This allows immediate reuse of
1874 			 * TTYs of which the session leader has been
1875 			 * killed or the TTY revoked.
1876 			 */
1877 			sx_xunlock(&proctree_lock);
1878 			return (EPERM);
1879 		}
1880 
1881 		/* Connect the session to the TTY. */
1882 		tp->t_session = p->p_session;
1883 		tp->t_session->s_ttyp = tp;
1884 		tp->t_sessioncnt++;
1885 
1886 		/* Assign foreground process group. */
1887 		tp->t_pgrp = p->p_pgrp;
1888 		PROC_LOCK(p);
1889 		p->p_flag |= P_CONTROLT;
1890 		PROC_UNLOCK(p);
1891 
1892 		sx_xunlock(&proctree_lock);
1893 		return (0);
1894 	}
1895 	case TIOCSPGRP: {
1896 		struct pgrp *pg;
1897 
1898 		/*
1899 		 * XXX: Temporarily unlock the TTY to locate the process
1900 		 * group. This code would be lot nicer if we would ever
1901 		 * decompose proctree_lock.
1902 		 */
1903 		tty_unlock(tp);
1904 		sx_slock(&proctree_lock);
1905 		pg = pgfind(*(int *)data);
1906 		if (pg != NULL)
1907 			PGRP_UNLOCK(pg);
1908 		if (pg == NULL || pg->pg_session != td->td_proc->p_session) {
1909 			sx_sunlock(&proctree_lock);
1910 			tty_lock(tp);
1911 			return (EPERM);
1912 		}
1913 		tty_lock(tp);
1914 
1915 		/*
1916 		 * Determine if this TTY is the controlling TTY after
1917 		 * relocking the TTY.
1918 		 */
1919 		if (!tty_is_ctty(tp, td->td_proc)) {
1920 			sx_sunlock(&proctree_lock);
1921 			return (ENOTTY);
1922 		}
1923 		tp->t_pgrp = pg;
1924 		sx_sunlock(&proctree_lock);
1925 
1926 		/* Wake up the background process groups. */
1927 		cv_broadcast(&tp->t_bgwait);
1928 		return (0);
1929 	}
1930 	case TIOCFLUSH: {
1931 		int flags = *(int *)data;
1932 
1933 		if (flags == 0)
1934 			flags = (FREAD|FWRITE);
1935 		else
1936 			flags &= (FREAD|FWRITE);
1937 		tty_flush(tp, flags);
1938 		return (0);
1939 	}
1940 	case TIOCDRAIN:
1941 		/* Drain TTY output. */
1942 		return tty_drain(tp, 0);
1943 	case TIOCGDRAINWAIT:
1944 		*(int *)data = tp->t_drainwait;
1945 		return (0);
1946 	case TIOCSDRAINWAIT:
1947 		error = priv_check(td, PRIV_TTY_DRAINWAIT);
1948 		if (error == 0)
1949 			tp->t_drainwait = *(int *)data;
1950 		return (error);
1951 	case TIOCCONS:
1952 		/* Set terminal as console TTY. */
1953 		if (*(int *)data) {
1954 			error = priv_check(td, PRIV_TTY_CONSOLE);
1955 			if (error)
1956 				return (error);
1957 			error = constty_set(tp);
1958 		} else {
1959 			error = constty_clear(tp);
1960 		}
1961 		return (error);
1962 	case TIOCGWINSZ:
1963 		/* Obtain window size. */
1964 		*(struct winsize*)data = tp->t_winsize;
1965 		return (0);
1966 	case TIOCSWINSZ:
1967 		/* Set window size. */
1968 		tty_set_winsize(tp, data);
1969 		return (0);
1970 	case TIOCEXCL:
1971 		tp->t_flags |= TF_EXCLUDE;
1972 		return (0);
1973 	case TIOCNXCL:
1974 		tp->t_flags &= ~TF_EXCLUDE;
1975 		return (0);
1976 	case TIOCSTOP:
1977 		tp->t_flags |= TF_STOPPED;
1978 		ttydevsw_pktnotify(tp, TIOCPKT_STOP);
1979 		return (0);
1980 	case TIOCSTART:
1981 		tp->t_flags &= ~TF_STOPPED;
1982 		tp->t_termios.c_lflag &= ~FLUSHO;
1983 		ttydevsw_outwakeup(tp);
1984 		ttydevsw_pktnotify(tp, TIOCPKT_START);
1985 		return (0);
1986 	case TIOCSTAT:
1987 		tty_info(tp);
1988 		return (0);
1989 	case TIOCSTI:
1990 		if ((fflag & FREAD) == 0 && priv_check(td, PRIV_TTY_STI))
1991 			return (EPERM);
1992 		if (!tty_is_ctty(tp, td->td_proc) &&
1993 		    priv_check(td, PRIV_TTY_STI))
1994 			return (EACCES);
1995 		ttydisc_rint(tp, *(char *)data, 0);
1996 		ttydisc_rint_done(tp);
1997 		return (0);
1998 	}
1999 
2000 #ifdef COMPAT_43TTY
2001 	return tty_ioctl_compat(tp, cmd, data, fflag, td);
2002 #else /* !COMPAT_43TTY */
2003 	return (ENOIOCTL);
2004 #endif /* COMPAT_43TTY */
2005 }
2006 
2007 int
2008 tty_ioctl(struct tty *tp, u_long cmd, void *data, int fflag, struct thread *td)
2009 {
2010 	int error;
2011 
2012 	tty_assert_locked(tp);
2013 
2014 	if (tty_gone(tp))
2015 		return (ENXIO);
2016 
2017 	error = ttydevsw_ioctl(tp, cmd, data, td);
2018 	if (error == ENOIOCTL)
2019 		error = tty_generic_ioctl(tp, cmd, data, fflag, td);
2020 
2021 	return (error);
2022 }
2023 
2024 dev_t
2025 tty_udev(struct tty *tp)
2026 {
2027 
2028 	if (tp->t_dev)
2029 		return (dev2udev(tp->t_dev));
2030 	else
2031 		return (NODEV);
2032 }
2033 
2034 int
2035 tty_checkoutq(struct tty *tp)
2036 {
2037 
2038 	/* 256 bytes should be enough to print a log message. */
2039 	return (ttyoutq_bytesleft(&tp->t_outq) >= 256);
2040 }
2041 
2042 void
2043 tty_hiwat_in_block(struct tty *tp)
2044 {
2045 
2046 	if ((tp->t_flags & TF_HIWAT_IN) == 0 &&
2047 	    tp->t_termios.c_iflag & IXOFF &&
2048 	    tp->t_termios.c_cc[VSTOP] != _POSIX_VDISABLE) {
2049 		/*
2050 		 * Input flow control. Only enter the high watermark when we
2051 		 * can successfully store the VSTOP character.
2052 		 */
2053 		if (ttyoutq_write_nofrag(&tp->t_outq,
2054 		    &tp->t_termios.c_cc[VSTOP], 1) == 0)
2055 			tp->t_flags |= TF_HIWAT_IN;
2056 	} else {
2057 		/* No input flow control. */
2058 		tp->t_flags |= TF_HIWAT_IN;
2059 	}
2060 }
2061 
2062 void
2063 tty_hiwat_in_unblock(struct tty *tp)
2064 {
2065 
2066 	if (tp->t_flags & TF_HIWAT_IN &&
2067 	    tp->t_termios.c_iflag & IXOFF &&
2068 	    tp->t_termios.c_cc[VSTART] != _POSIX_VDISABLE) {
2069 		/*
2070 		 * Input flow control. Only leave the high watermark when we
2071 		 * can successfully store the VSTART character.
2072 		 */
2073 		if (ttyoutq_write_nofrag(&tp->t_outq,
2074 		    &tp->t_termios.c_cc[VSTART], 1) == 0)
2075 			tp->t_flags &= ~TF_HIWAT_IN;
2076 	} else {
2077 		/* No input flow control. */
2078 		tp->t_flags &= ~TF_HIWAT_IN;
2079 	}
2080 
2081 	if (!tty_gone(tp))
2082 		ttydevsw_inwakeup(tp);
2083 }
2084 
2085 /*
2086  * TTY hooks interface.
2087  */
2088 
2089 static int
2090 ttyhook_defrint(struct tty *tp, char c, int flags)
2091 {
2092 
2093 	if (ttyhook_rint_bypass(tp, &c, 1) != 1)
2094 		return (-1);
2095 
2096 	return (0);
2097 }
2098 
2099 int
2100 ttyhook_register(struct tty **rtp, struct proc *p, int fd, struct ttyhook *th,
2101     void *softc)
2102 {
2103 	struct tty *tp;
2104 	struct file *fp;
2105 	struct cdev *dev;
2106 	struct cdevsw *cdp;
2107 	struct filedesc *fdp;
2108 	cap_rights_t rights;
2109 	int error, ref;
2110 
2111 	/* Validate the file descriptor. */
2112 	/*
2113 	 * XXX this code inspects a file descriptor from a different process,
2114 	 * but there is no dedicated routine to do it in fd code, making the
2115 	 * ordeal highly questionable.
2116 	 */
2117 	fdp = p->p_fd;
2118 	FILEDESC_SLOCK(fdp);
2119 	error = fget_cap_noref(fdp, fd, cap_rights_init_one(&rights, CAP_TTYHOOK),
2120 	    &fp, NULL);
2121 	if (error == 0 && !fhold(fp))
2122 		error = EBADF;
2123 	FILEDESC_SUNLOCK(fdp);
2124 	if (error != 0)
2125 		return (error);
2126 	if (fp->f_ops == &badfileops) {
2127 		error = EBADF;
2128 		goto done1;
2129 	}
2130 
2131 	/*
2132 	 * Make sure the vnode is bound to a character device.
2133 	 * Unlocked check for the vnode type is ok there, because we
2134 	 * only shall prevent calling devvn_refthread on the file that
2135 	 * never has been opened over a character device.
2136 	 */
2137 	if (fp->f_type != DTYPE_VNODE || fp->f_vnode->v_type != VCHR) {
2138 		error = EINVAL;
2139 		goto done1;
2140 	}
2141 
2142 	/* Make sure it is a TTY. */
2143 	cdp = devvn_refthread(fp->f_vnode, &dev, &ref);
2144 	if (cdp == NULL) {
2145 		error = ENXIO;
2146 		goto done1;
2147 	}
2148 	if (dev != fp->f_data) {
2149 		error = ENXIO;
2150 		goto done2;
2151 	}
2152 	if (cdp != &ttydev_cdevsw) {
2153 		error = ENOTTY;
2154 		goto done2;
2155 	}
2156 	tp = dev->si_drv1;
2157 
2158 	/* Try to attach the hook to the TTY. */
2159 	error = EBUSY;
2160 	tty_lock(tp);
2161 	MPASS((tp->t_hook == NULL) == ((tp->t_flags & TF_HOOK) == 0));
2162 	if (tp->t_flags & TF_HOOK)
2163 		goto done3;
2164 
2165 	tp->t_flags |= TF_HOOK;
2166 	tp->t_hook = th;
2167 	tp->t_hooksoftc = softc;
2168 	*rtp = tp;
2169 	error = 0;
2170 
2171 	/* Maybe we can switch into bypass mode now. */
2172 	ttydisc_optimize(tp);
2173 
2174 	/* Silently convert rint() calls to rint_bypass() when possible. */
2175 	if (!ttyhook_hashook(tp, rint) && ttyhook_hashook(tp, rint_bypass))
2176 		th->th_rint = ttyhook_defrint;
2177 
2178 done3:	tty_unlock(tp);
2179 done2:	dev_relthread(dev, ref);
2180 done1:	fdrop(fp, curthread);
2181 	return (error);
2182 }
2183 
2184 void
2185 ttyhook_unregister(struct tty *tp)
2186 {
2187 
2188 	tty_assert_locked(tp);
2189 	MPASS(tp->t_flags & TF_HOOK);
2190 
2191 	/* Disconnect the hook. */
2192 	tp->t_flags &= ~TF_HOOK;
2193 	tp->t_hook = NULL;
2194 
2195 	/* Maybe we need to leave bypass mode. */
2196 	ttydisc_optimize(tp);
2197 
2198 	/* Maybe deallocate the TTY as well. */
2199 	tty_rel_free(tp);
2200 }
2201 
2202 /*
2203  * /dev/console handling.
2204  */
2205 
2206 static int
2207 ttyconsdev_open(struct cdev *dev, int oflags, int devtype, struct thread *td)
2208 {
2209 	struct tty *tp;
2210 
2211 	/* System has no console device. */
2212 	if (dev_console_filename == NULL)
2213 		return (ENXIO);
2214 
2215 	/* Look up corresponding TTY by device name. */
2216 	sx_slock(&tty_list_sx);
2217 	TAILQ_FOREACH(tp, &tty_list, t_list) {
2218 		if (strcmp(dev_console_filename, tty_devname(tp)) == 0) {
2219 			dev_console->si_drv1 = tp;
2220 			break;
2221 		}
2222 	}
2223 	sx_sunlock(&tty_list_sx);
2224 
2225 	/* System console has no TTY associated. */
2226 	if (dev_console->si_drv1 == NULL)
2227 		return (ENXIO);
2228 
2229 	return (ttydev_open(dev, oflags, devtype, td));
2230 }
2231 
2232 static int
2233 ttyconsdev_write(struct cdev *dev, struct uio *uio, int ioflag)
2234 {
2235 
2236 	log_console(uio);
2237 
2238 	return (ttydev_write(dev, uio, ioflag));
2239 }
2240 
2241 /*
2242  * /dev/console is a little different than normal TTY's.  When opened,
2243  * it determines which TTY to use.  When data gets written to it, it
2244  * will be logged in the kernel message buffer.
2245  */
2246 static struct cdevsw ttyconsdev_cdevsw = {
2247 	.d_version	= D_VERSION,
2248 	.d_open		= ttyconsdev_open,
2249 	.d_close	= ttydev_close,
2250 	.d_read		= ttydev_read,
2251 	.d_write	= ttyconsdev_write,
2252 	.d_ioctl	= ttydev_ioctl,
2253 	.d_kqfilter	= ttydev_kqfilter,
2254 	.d_poll		= ttydev_poll,
2255 	.d_mmap		= ttydev_mmap,
2256 	.d_name		= "ttyconsdev",
2257 	.d_flags	= D_TTY,
2258 };
2259 
2260 static void
2261 ttyconsdev_init(void *unused __unused)
2262 {
2263 
2264 	dev_console = make_dev_credf(MAKEDEV_ETERNAL, &ttyconsdev_cdevsw, 0,
2265 	    NULL, UID_ROOT, GID_WHEEL, 0600, "console");
2266 }
2267 
2268 SYSINIT(tty, SI_SUB_DRIVERS, SI_ORDER_FIRST, ttyconsdev_init, NULL);
2269 
2270 void
2271 ttyconsdev_select(const char *name)
2272 {
2273 
2274 	dev_console_filename = name;
2275 }
2276 
2277 /*
2278  * Debugging routines.
2279  */
2280 
2281 #include "opt_ddb.h"
2282 #ifdef DDB
2283 #include <ddb/ddb.h>
2284 #include <ddb/db_sym.h>
2285 
2286 static const struct {
2287 	int flag;
2288 	char val;
2289 } ttystates[] = {
2290 #if 0
2291 	{ TF_NOPREFIX,		'N' },
2292 #endif
2293 	{ TF_INITLOCK,		'I' },
2294 	{ TF_CALLOUT,		'C' },
2295 
2296 	/* Keep these together -> 'Oi' and 'Oo'. */
2297 	{ TF_OPENED,		'O' },
2298 	{ TF_OPENED_IN,		'i' },
2299 	{ TF_OPENED_OUT,	'o' },
2300 	{ TF_OPENED_CONS,	'c' },
2301 
2302 	{ TF_GONE,		'G' },
2303 	{ TF_OPENCLOSE,		'B' },
2304 	{ TF_ASYNC,		'Y' },
2305 	{ TF_LITERAL,		'L' },
2306 
2307 	/* Keep these together -> 'Hi' and 'Ho'. */
2308 	{ TF_HIWAT,		'H' },
2309 	{ TF_HIWAT_IN,		'i' },
2310 	{ TF_HIWAT_OUT,		'o' },
2311 
2312 	{ TF_STOPPED,		'S' },
2313 	{ TF_EXCLUDE,		'X' },
2314 	{ TF_BYPASS,		'l' },
2315 	{ TF_ZOMBIE,		'Z' },
2316 	{ TF_HOOK,		's' },
2317 
2318 	/* Keep these together -> 'bi' and 'bo'. */
2319 	{ TF_BUSY,		'b' },
2320 	{ TF_BUSY_IN,		'i' },
2321 	{ TF_BUSY_OUT,		'o' },
2322 
2323 	{ 0,			'\0'},
2324 };
2325 
2326 #define	TTY_FLAG_BITS \
2327 	"\20\1NOPREFIX\2INITLOCK\3CALLOUT\4OPENED_IN" \
2328 	"\5OPENED_OUT\6OPENED_CONS\7GONE\10OPENCLOSE" \
2329 	"\11ASYNC\12LITERAL\13HIWAT_IN\14HIWAT_OUT" \
2330 	"\15STOPPED\16EXCLUDE\17BYPASS\20ZOMBIE" \
2331 	"\21HOOK\22BUSY_IN\23BUSY_OUT"
2332 
2333 #define DB_PRINTSYM(name, addr) \
2334 	db_printf("%s  " #name ": ", sep); \
2335 	db_printsym((db_addr_t) addr, DB_STGY_ANY); \
2336 	db_printf("\n");
2337 
2338 static void
2339 _db_show_devsw(const char *sep, const struct ttydevsw *tsw)
2340 {
2341 
2342 	db_printf("%sdevsw: ", sep);
2343 	db_printsym((db_addr_t)tsw, DB_STGY_ANY);
2344 	db_printf(" (%p)\n", tsw);
2345 	DB_PRINTSYM(open, tsw->tsw_open);
2346 	DB_PRINTSYM(close, tsw->tsw_close);
2347 	DB_PRINTSYM(outwakeup, tsw->tsw_outwakeup);
2348 	DB_PRINTSYM(inwakeup, tsw->tsw_inwakeup);
2349 	DB_PRINTSYM(ioctl, tsw->tsw_ioctl);
2350 	DB_PRINTSYM(param, tsw->tsw_param);
2351 	DB_PRINTSYM(modem, tsw->tsw_modem);
2352 	DB_PRINTSYM(mmap, tsw->tsw_mmap);
2353 	DB_PRINTSYM(pktnotify, tsw->tsw_pktnotify);
2354 	DB_PRINTSYM(free, tsw->tsw_free);
2355 }
2356 
2357 static void
2358 _db_show_hooks(const char *sep, const struct ttyhook *th)
2359 {
2360 
2361 	db_printf("%shook: ", sep);
2362 	db_printsym((db_addr_t)th, DB_STGY_ANY);
2363 	db_printf(" (%p)\n", th);
2364 	if (th == NULL)
2365 		return;
2366 	DB_PRINTSYM(rint, th->th_rint);
2367 	DB_PRINTSYM(rint_bypass, th->th_rint_bypass);
2368 	DB_PRINTSYM(rint_done, th->th_rint_done);
2369 	DB_PRINTSYM(rint_poll, th->th_rint_poll);
2370 	DB_PRINTSYM(getc_inject, th->th_getc_inject);
2371 	DB_PRINTSYM(getc_capture, th->th_getc_capture);
2372 	DB_PRINTSYM(getc_poll, th->th_getc_poll);
2373 	DB_PRINTSYM(close, th->th_close);
2374 }
2375 
2376 static void
2377 _db_show_termios(const char *name, const struct termios *t)
2378 {
2379 
2380 	db_printf("%s: iflag 0x%x oflag 0x%x cflag 0x%x "
2381 	    "lflag 0x%x ispeed %u ospeed %u\n", name,
2382 	    t->c_iflag, t->c_oflag, t->c_cflag, t->c_lflag,
2383 	    t->c_ispeed, t->c_ospeed);
2384 }
2385 
2386 /* DDB command to show TTY statistics. */
2387 DB_SHOW_COMMAND(tty, db_show_tty)
2388 {
2389 	struct tty *tp;
2390 
2391 	if (!have_addr) {
2392 		db_printf("usage: show tty <addr>\n");
2393 		return;
2394 	}
2395 	tp = (struct tty *)addr;
2396 
2397 	db_printf("%p: %s\n", tp, tty_devname(tp));
2398 	db_printf("\tmtx: %p\n", tp->t_mtx);
2399 	db_printf("\tflags: 0x%b\n", tp->t_flags, TTY_FLAG_BITS);
2400 	db_printf("\trevokecnt: %u\n", tp->t_revokecnt);
2401 
2402 	/* Buffering mechanisms. */
2403 	db_printf("\tinq: %p begin %u linestart %u reprint %u end %u "
2404 	    "nblocks %u quota %u\n", &tp->t_inq, tp->t_inq.ti_begin,
2405 	    tp->t_inq.ti_linestart, tp->t_inq.ti_reprint, tp->t_inq.ti_end,
2406 	    tp->t_inq.ti_nblocks, tp->t_inq.ti_quota);
2407 	db_printf("\toutq: %p begin %u end %u nblocks %u quota %u\n",
2408 	    &tp->t_outq, tp->t_outq.to_begin, tp->t_outq.to_end,
2409 	    tp->t_outq.to_nblocks, tp->t_outq.to_quota);
2410 	db_printf("\tinlow: %zu\n", tp->t_inlow);
2411 	db_printf("\toutlow: %zu\n", tp->t_outlow);
2412 	_db_show_termios("\ttermios", &tp->t_termios);
2413 	db_printf("\twinsize: row %u col %u xpixel %u ypixel %u\n",
2414 	    tp->t_winsize.ws_row, tp->t_winsize.ws_col,
2415 	    tp->t_winsize.ws_xpixel, tp->t_winsize.ws_ypixel);
2416 	db_printf("\tcolumn: %u\n", tp->t_column);
2417 	db_printf("\twritepos: %u\n", tp->t_writepos);
2418 	db_printf("\tcompatflags: 0x%x\n", tp->t_compatflags);
2419 
2420 	/* Init/lock-state devices. */
2421 	_db_show_termios("\ttermios_init_in", &tp->t_termios_init_in);
2422 	_db_show_termios("\ttermios_init_out", &tp->t_termios_init_out);
2423 	_db_show_termios("\ttermios_lock_in", &tp->t_termios_lock_in);
2424 	_db_show_termios("\ttermios_lock_out", &tp->t_termios_lock_out);
2425 
2426 	/* Hooks */
2427 	_db_show_devsw("\t", tp->t_devsw);
2428 	_db_show_hooks("\t", tp->t_hook);
2429 
2430 	/* Process info. */
2431 	db_printf("\tpgrp: %p gid %d\n", tp->t_pgrp,
2432 	    tp->t_pgrp ? tp->t_pgrp->pg_id : 0);
2433 	db_printf("\tsession: %p", tp->t_session);
2434 	if (tp->t_session != NULL)
2435 	    db_printf(" count %u leader %p tty %p sid %d login %s",
2436 		tp->t_session->s_count, tp->t_session->s_leader,
2437 		tp->t_session->s_ttyp, tp->t_session->s_sid,
2438 		tp->t_session->s_login);
2439 	db_printf("\n");
2440 	db_printf("\tsessioncnt: %u\n", tp->t_sessioncnt);
2441 	db_printf("\tdevswsoftc: %p\n", tp->t_devswsoftc);
2442 	db_printf("\thooksoftc: %p\n", tp->t_hooksoftc);
2443 	db_printf("\tdev: %p\n", tp->t_dev);
2444 }
2445 
2446 /* DDB command to list TTYs. */
2447 DB_SHOW_ALL_COMMAND(ttys, db_show_all_ttys)
2448 {
2449 	struct tty *tp;
2450 	size_t isiz, osiz;
2451 	int i, j;
2452 
2453 	/* Make the output look like `pstat -t'. */
2454 	db_printf("PTR        ");
2455 #if defined(__LP64__)
2456 	db_printf("        ");
2457 #endif
2458 	db_printf("      LINE   INQ  CAN  LIN  LOW  OUTQ  USE  LOW   "
2459 	    "COL  SESS  PGID STATE\n");
2460 
2461 	TAILQ_FOREACH(tp, &tty_list, t_list) {
2462 		isiz = tp->t_inq.ti_nblocks * TTYINQ_DATASIZE;
2463 		osiz = tp->t_outq.to_nblocks * TTYOUTQ_DATASIZE;
2464 
2465 		db_printf("%p %10s %5zu %4u %4u %4zu %5zu %4u %4zu %5u %5d "
2466 		    "%5d ", tp, tty_devname(tp), isiz,
2467 		    tp->t_inq.ti_linestart - tp->t_inq.ti_begin,
2468 		    tp->t_inq.ti_end - tp->t_inq.ti_linestart,
2469 		    isiz - tp->t_inlow, osiz,
2470 		    tp->t_outq.to_end - tp->t_outq.to_begin,
2471 		    osiz - tp->t_outlow, MIN(tp->t_column, 99999),
2472 		    tp->t_session ? tp->t_session->s_sid : 0,
2473 		    tp->t_pgrp ? tp->t_pgrp->pg_id : 0);
2474 
2475 		/* Flag bits. */
2476 		for (i = j = 0; ttystates[i].flag; i++)
2477 			if (tp->t_flags & ttystates[i].flag) {
2478 				db_printf("%c", ttystates[i].val);
2479 				j++;
2480 			}
2481 		if (j == 0)
2482 			db_printf("-");
2483 		db_printf("\n");
2484 	}
2485 }
2486 #endif /* DDB */
2487