xref: /freebsd/sys/kern/tty.c (revision dd41de95a84d979615a2ef11df6850622bf6184e)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
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 __FBSDID("$FreeBSD$");
34 
35 #include "opt_capsicum.h"
36 #include "opt_printf.h"
37 
38 #include <sys/param.h>
39 #include <sys/capsicum.h>
40 #include <sys/conf.h>
41 #include <sys/cons.h>
42 #include <sys/fcntl.h>
43 #include <sys/file.h>
44 #include <sys/filedesc.h>
45 #include <sys/filio.h>
46 #ifdef COMPAT_43TTY
47 #include <sys/ioctl_compat.h>
48 #endif /* COMPAT_43TTY */
49 #include <sys/kernel.h>
50 #include <sys/limits.h>
51 #include <sys/malloc.h>
52 #include <sys/mount.h>
53 #include <sys/poll.h>
54 #include <sys/priv.h>
55 #include <sys/proc.h>
56 #include <sys/serial.h>
57 #include <sys/signal.h>
58 #include <sys/stat.h>
59 #include <sys/sx.h>
60 #include <sys/sysctl.h>
61 #include <sys/systm.h>
62 #include <sys/tty.h>
63 #include <sys/ttycom.h>
64 #define TTYDEFCHARS
65 #include <sys/ttydefaults.h>
66 #undef TTYDEFCHARS
67 #include <sys/ucred.h>
68 #include <sys/vnode.h>
69 
70 #include <fs/devfs/devfs.h>
71 
72 #include <machine/stdarg.h>
73 
74 static MALLOC_DEFINE(M_TTY, "tty", "tty device");
75 
76 static void tty_rel_free(struct tty *tp);
77 
78 static TAILQ_HEAD(, tty) tty_list = TAILQ_HEAD_INITIALIZER(tty_list);
79 static struct sx tty_list_sx;
80 SX_SYSINIT(tty_list, &tty_list_sx, "tty list");
81 static unsigned int tty_list_count = 0;
82 
83 /* Character device of /dev/console. */
84 static struct cdev	*dev_console;
85 static const char	*dev_console_filename;
86 
87 /*
88  * Flags that are supported and stored by this implementation.
89  */
90 #define TTYSUP_IFLAG	(IGNBRK|BRKINT|IGNPAR|PARMRK|INPCK|ISTRIP|\
91 			INLCR|IGNCR|ICRNL|IXON|IXOFF|IXANY|IMAXBEL)
92 #define TTYSUP_OFLAG	(OPOST|ONLCR|TAB3|ONOEOT|OCRNL|ONOCR|ONLRET)
93 #define TTYSUP_LFLAG	(ECHOKE|ECHOE|ECHOK|ECHO|ECHONL|ECHOPRT|\
94 			ECHOCTL|ISIG|ICANON|ALTWERASE|IEXTEN|TOSTOP|\
95 			FLUSHO|NOKERNINFO|NOFLSH)
96 #define TTYSUP_CFLAG	(CIGNORE|CSIZE|CSTOPB|CREAD|PARENB|PARODD|\
97 			HUPCL|CLOCAL|CCTS_OFLOW|CRTS_IFLOW|CDTR_IFLOW|\
98 			CDSR_OFLOW|CCAR_OFLOW|CNO_RTSDTR)
99 
100 #define	TTY_CALLOUT(tp,d) (dev2unit(d) & TTYUNIT_CALLOUT)
101 
102 static int  tty_drainwait = 5 * 60;
103 SYSCTL_INT(_kern, OID_AUTO, tty_drainwait, CTLFLAG_RWTUN,
104     &tty_drainwait, 0, "Default output drain timeout in seconds");
105 
106 /*
107  * Set TTY buffer sizes.
108  */
109 
110 #define	TTYBUF_MAX	65536
111 
112 #ifdef PRINTF_BUFR_SIZE
113 #define	TTY_PRBUF_SIZE	PRINTF_BUFR_SIZE
114 #else
115 #define	TTY_PRBUF_SIZE	256
116 #endif
117 
118 /*
119  * Allocate buffer space if necessary, and set low watermarks, based on speed.
120  * Note that the ttyxxxq_setsize() functions may drop and then reacquire the tty
121  * lock during memory allocation.  They will return ENXIO if the tty disappears
122  * while unlocked.
123  */
124 static int
125 tty_watermarks(struct tty *tp)
126 {
127 	size_t bs = 0;
128 	int error;
129 
130 	/* Provide an input buffer for 2 seconds of data. */
131 	if (tp->t_termios.c_cflag & CREAD)
132 		bs = MIN(tp->t_termios.c_ispeed / 5, TTYBUF_MAX);
133 	error = ttyinq_setsize(&tp->t_inq, tp, bs);
134 	if (error != 0)
135 		return (error);
136 
137 	/* Set low watermark at 10% (when 90% is available). */
138 	tp->t_inlow = (ttyinq_getallocatedsize(&tp->t_inq) * 9) / 10;
139 
140 	/* Provide an output buffer for 2 seconds of data. */
141 	bs = MIN(tp->t_termios.c_ospeed / 5, TTYBUF_MAX);
142 	error = ttyoutq_setsize(&tp->t_outq, tp, bs);
143 	if (error != 0)
144 		return (error);
145 
146 	/* Set low watermark at 10% (when 90% is available). */
147 	tp->t_outlow = (ttyoutq_getallocatedsize(&tp->t_outq) * 9) / 10;
148 
149 	return (0);
150 }
151 
152 static int
153 tty_drain(struct tty *tp, int leaving)
154 {
155 	sbintime_t timeout_at;
156 	size_t bytes;
157 	int error;
158 
159 	if (ttyhook_hashook(tp, getc_inject))
160 		/* buffer is inaccessible */
161 		return (0);
162 
163 	/*
164 	 * For close(), use the recent historic timeout of "1 second without
165 	 * making progress".  For tcdrain(), use t_drainwait as the timeout,
166 	 * with zero meaning "no timeout" which gives POSIX behavior.
167 	 */
168 	if (leaving)
169 		timeout_at = getsbinuptime() + SBT_1S;
170 	else if (tp->t_drainwait != 0)
171 		timeout_at = getsbinuptime() + SBT_1S * tp->t_drainwait;
172 	else
173 		timeout_at = 0;
174 
175 	/*
176 	 * Poll the output buffer and the hardware for completion, at 10 Hz.
177 	 * Polling is required for devices which are not able to signal an
178 	 * interrupt when the transmitter becomes idle (most USB serial devs).
179 	 * The unusual structure of this loop ensures we check for busy one more
180 	 * time after tty_timedwait() returns EWOULDBLOCK, so that success has
181 	 * higher priority than timeout if the IO completed in the last 100mS.
182 	 */
183 	error = 0;
184 	bytes = ttyoutq_bytesused(&tp->t_outq);
185 	for (;;) {
186 		if (ttyoutq_bytesused(&tp->t_outq) == 0 && !ttydevsw_busy(tp))
187 			return (0);
188 		if (error != 0)
189 			return (error);
190 		ttydevsw_outwakeup(tp);
191 		error = tty_timedwait(tp, &tp->t_outwait, hz / 10);
192 		if (error != 0 && error != EWOULDBLOCK)
193 			return (error);
194 		else if (timeout_at == 0 || getsbinuptime() < timeout_at)
195 			error = 0;
196 		else if (leaving && ttyoutq_bytesused(&tp->t_outq) < bytes) {
197 			/* In close, making progress, grant an extra second. */
198 			error = 0;
199 			timeout_at += SBT_1S;
200 			bytes = ttyoutq_bytesused(&tp->t_outq);
201 		}
202 	}
203 }
204 
205 /*
206  * Though ttydev_enter() and ttydev_leave() seem to be related, they
207  * don't have to be used together. ttydev_enter() is used by the cdev
208  * operations to prevent an actual operation from being processed when
209  * the TTY has been abandoned. ttydev_leave() is used by ttydev_open()
210  * and ttydev_close() to determine whether per-TTY data should be
211  * deallocated.
212  */
213 
214 static __inline int
215 ttydev_enter(struct tty *tp)
216 {
217 
218 	tty_lock(tp);
219 
220 	if (tty_gone(tp) || !tty_opened(tp)) {
221 		/* Device is already gone. */
222 		tty_unlock(tp);
223 		return (ENXIO);
224 	}
225 
226 	return (0);
227 }
228 
229 static void
230 ttydev_leave(struct tty *tp)
231 {
232 
233 	tty_assert_locked(tp);
234 
235 	if (tty_opened(tp) || tp->t_flags & TF_OPENCLOSE) {
236 		/* Device is still opened somewhere. */
237 		tty_unlock(tp);
238 		return;
239 	}
240 
241 	tp->t_flags |= TF_OPENCLOSE;
242 
243 	/* Remove console TTY. */
244 	if (constty == tp)
245 		constty_clear();
246 
247 	/* Drain any output. */
248 	if (!tty_gone(tp))
249 		tty_drain(tp, 1);
250 
251 	ttydisc_close(tp);
252 
253 	/* Free i/o queues now since they might be large. */
254 	ttyinq_free(&tp->t_inq);
255 	tp->t_inlow = 0;
256 	ttyoutq_free(&tp->t_outq);
257 	tp->t_outlow = 0;
258 
259 	knlist_clear(&tp->t_inpoll.si_note, 1);
260 	knlist_clear(&tp->t_outpoll.si_note, 1);
261 
262 	if (!tty_gone(tp))
263 		ttydevsw_close(tp);
264 
265 	tp->t_flags &= ~TF_OPENCLOSE;
266 	cv_broadcast(&tp->t_dcdwait);
267 	tty_rel_free(tp);
268 }
269 
270 /*
271  * Operations that are exposed through the character device in /dev.
272  */
273 static int
274 ttydev_open(struct cdev *dev, int oflags, int devtype __unused,
275     struct thread *td)
276 {
277 	struct tty *tp;
278 	int error;
279 
280 	tp = dev->si_drv1;
281 	error = 0;
282 	tty_lock(tp);
283 	if (tty_gone(tp)) {
284 		/* Device is already gone. */
285 		tty_unlock(tp);
286 		return (ENXIO);
287 	}
288 
289 	/*
290 	 * Block when other processes are currently opening or closing
291 	 * the TTY.
292 	 */
293 	while (tp->t_flags & TF_OPENCLOSE) {
294 		error = tty_wait(tp, &tp->t_dcdwait);
295 		if (error != 0) {
296 			tty_unlock(tp);
297 			return (error);
298 		}
299 	}
300 	tp->t_flags |= TF_OPENCLOSE;
301 
302 	/*
303 	 * Make sure the "tty" and "cua" device cannot be opened at the
304 	 * same time.  The console is a "tty" device.
305 	 */
306 	if (TTY_CALLOUT(tp, dev)) {
307 		if (tp->t_flags & (TF_OPENED_CONS | TF_OPENED_IN)) {
308 			error = EBUSY;
309 			goto done;
310 		}
311 	} else {
312 		if (tp->t_flags & TF_OPENED_OUT) {
313 			error = EBUSY;
314 			goto done;
315 		}
316 	}
317 
318 	if (tp->t_flags & TF_EXCLUDE && priv_check(td, PRIV_TTY_EXCLUSIVE)) {
319 		error = EBUSY;
320 		goto done;
321 	}
322 
323 	if (!tty_opened(tp)) {
324 		/* Set proper termios flags. */
325 		if (TTY_CALLOUT(tp, dev))
326 			tp->t_termios = tp->t_termios_init_out;
327 		else
328 			tp->t_termios = tp->t_termios_init_in;
329 		ttydevsw_param(tp, &tp->t_termios);
330 		/* Prevent modem control on callout devices and /dev/console. */
331 		if (TTY_CALLOUT(tp, dev) || dev == dev_console)
332 			tp->t_termios.c_cflag |= CLOCAL;
333 
334 		if ((tp->t_termios.c_cflag & CNO_RTSDTR) == 0)
335 			ttydevsw_modem(tp, SER_DTR|SER_RTS, 0);
336 
337 		error = ttydevsw_open(tp);
338 		if (error != 0)
339 			goto done;
340 
341 		ttydisc_open(tp);
342 		error = tty_watermarks(tp);
343 		if (error != 0)
344 			goto done;
345 	}
346 
347 	/* Wait for Carrier Detect. */
348 	if ((oflags & O_NONBLOCK) == 0 &&
349 	    (tp->t_termios.c_cflag & CLOCAL) == 0) {
350 		while ((ttydevsw_modem(tp, 0, 0) & SER_DCD) == 0) {
351 			error = tty_wait(tp, &tp->t_dcdwait);
352 			if (error != 0)
353 				goto done;
354 		}
355 	}
356 
357 	if (dev == dev_console)
358 		tp->t_flags |= TF_OPENED_CONS;
359 	else if (TTY_CALLOUT(tp, dev))
360 		tp->t_flags |= TF_OPENED_OUT;
361 	else
362 		tp->t_flags |= TF_OPENED_IN;
363 	MPASS((tp->t_flags & (TF_OPENED_CONS | TF_OPENED_IN)) == 0 ||
364 	    (tp->t_flags & TF_OPENED_OUT) == 0);
365 
366 done:	tp->t_flags &= ~TF_OPENCLOSE;
367 	cv_broadcast(&tp->t_dcdwait);
368 	ttydev_leave(tp);
369 
370 	return (error);
371 }
372 
373 static int
374 ttydev_close(struct cdev *dev, int fflag, int devtype __unused,
375     struct thread *td __unused)
376 {
377 	struct tty *tp = dev->si_drv1;
378 
379 	tty_lock(tp);
380 
381 	/*
382 	 * Don't actually close the device if it is being used as the
383 	 * console.
384 	 */
385 	MPASS((tp->t_flags & (TF_OPENED_CONS | TF_OPENED_IN)) == 0 ||
386 	    (tp->t_flags & TF_OPENED_OUT) == 0);
387 	if (dev == dev_console)
388 		tp->t_flags &= ~TF_OPENED_CONS;
389 	else
390 		tp->t_flags &= ~(TF_OPENED_IN|TF_OPENED_OUT);
391 
392 	if (tp->t_flags & TF_OPENED) {
393 		tty_unlock(tp);
394 		return (0);
395 	}
396 
397 	/* If revoking, flush output now to avoid draining it later. */
398 	if (fflag & FREVOKE)
399 		tty_flush(tp, FWRITE);
400 
401 	tp->t_flags &= ~TF_EXCLUDE;
402 
403 	/* Properly wake up threads that are stuck - revoke(). */
404 	tp->t_revokecnt++;
405 	tty_wakeup(tp, FREAD|FWRITE);
406 	cv_broadcast(&tp->t_bgwait);
407 	cv_broadcast(&tp->t_dcdwait);
408 
409 	ttydev_leave(tp);
410 
411 	return (0);
412 }
413 
414 static __inline int
415 tty_is_ctty(struct tty *tp, struct proc *p)
416 {
417 
418 	tty_assert_locked(tp);
419 
420 	return (p->p_session == tp->t_session && p->p_flag & P_CONTROLT);
421 }
422 
423 int
424 tty_wait_background(struct tty *tp, struct thread *td, int sig)
425 {
426 	struct proc *p;
427 	struct pgrp *pg;
428 	ksiginfo_t ksi;
429 	int error;
430 
431 	MPASS(sig == SIGTTIN || sig == SIGTTOU);
432 	tty_assert_locked(tp);
433 
434 	p = td->td_proc;
435 	for (;;) {
436 		pg = p->p_pgrp;
437 		PGRP_LOCK(pg);
438 		PROC_LOCK(p);
439 
440 		/*
441 		 * pg may no longer be our process group.
442 		 * Re-check after locking.
443 		 */
444 		if (p->p_pgrp != pg) {
445 			PROC_UNLOCK(p);
446 			PGRP_UNLOCK(pg);
447 			continue;
448 		}
449 
450 		/*
451 		 * The process should only sleep, when:
452 		 * - This terminal is the controlling terminal
453 		 * - Its process group is not the foreground process
454 		 *   group
455 		 * - The parent process isn't waiting for the child to
456 		 *   exit
457 		 * - the signal to send to the process isn't masked
458 		 */
459 		if (!tty_is_ctty(tp, p) || p->p_pgrp == tp->t_pgrp) {
460 			/* Allow the action to happen. */
461 			PROC_UNLOCK(p);
462 			PGRP_UNLOCK(pg);
463 			return (0);
464 		}
465 
466 		if (SIGISMEMBER(p->p_sigacts->ps_sigignore, sig) ||
467 		    SIGISMEMBER(td->td_sigmask, sig)) {
468 			/* Only allow them in write()/ioctl(). */
469 			PROC_UNLOCK(p);
470 			PGRP_UNLOCK(pg);
471 			return (sig == SIGTTOU ? 0 : EIO);
472 		}
473 
474 		if ((p->p_flag & P_PPWAIT) != 0 ||
475 		    (pg->pg_flags & PGRP_ORPHANED) != 0) {
476 			/* Don't allow the action to happen. */
477 			PROC_UNLOCK(p);
478 			PGRP_UNLOCK(pg);
479 			return (EIO);
480 		}
481 		PROC_UNLOCK(p);
482 
483 		/*
484 		 * Send the signal and sleep until we're the new
485 		 * foreground process group.
486 		 */
487 		if (sig != 0) {
488 			ksiginfo_init(&ksi);
489 			ksi.ksi_code = SI_KERNEL;
490 			ksi.ksi_signo = sig;
491 			sig = 0;
492 		}
493 
494 		pgsignal(pg, ksi.ksi_signo, 1, &ksi);
495 		PGRP_UNLOCK(pg);
496 
497 		error = tty_wait(tp, &tp->t_bgwait);
498 		if (error)
499 			return (error);
500 	}
501 }
502 
503 static int
504 ttydev_read(struct cdev *dev, struct uio *uio, int ioflag)
505 {
506 	struct tty *tp = dev->si_drv1;
507 	int error;
508 
509 	error = ttydev_enter(tp);
510 	if (error)
511 		goto done;
512 	error = ttydisc_read(tp, uio, ioflag);
513 	tty_unlock(tp);
514 
515 	/*
516 	 * The read() call should not throw an error when the device is
517 	 * being destroyed. Silently convert it to an EOF.
518 	 */
519 done:	if (error == ENXIO)
520 		error = 0;
521 	return (error);
522 }
523 
524 static int
525 ttydev_write(struct cdev *dev, struct uio *uio, int ioflag)
526 {
527 	struct tty *tp = dev->si_drv1;
528 	int defer, error;
529 
530 	error = ttydev_enter(tp);
531 	if (error)
532 		return (error);
533 
534 	if (tp->t_termios.c_lflag & TOSTOP) {
535 		error = tty_wait_background(tp, curthread, SIGTTOU);
536 		if (error)
537 			goto done;
538 	}
539 
540 	if (ioflag & IO_NDELAY && tp->t_flags & TF_BUSY_OUT) {
541 		/* Allow non-blocking writes to bypass serialization. */
542 		error = ttydisc_write(tp, uio, ioflag);
543 	} else {
544 		/* Serialize write() calls. */
545 		while (tp->t_flags & TF_BUSY_OUT) {
546 			error = tty_wait(tp, &tp->t_outserwait);
547 			if (error)
548 				goto done;
549 		}
550 
551 		tp->t_flags |= TF_BUSY_OUT;
552 		defer = sigdeferstop(SIGDEFERSTOP_ERESTART);
553 		error = ttydisc_write(tp, uio, ioflag);
554 		sigallowstop(defer);
555 		tp->t_flags &= ~TF_BUSY_OUT;
556 		cv_signal(&tp->t_outserwait);
557 	}
558 
559 done:	tty_unlock(tp);
560 	return (error);
561 }
562 
563 static int
564 ttydev_ioctl(struct cdev *dev, u_long cmd, caddr_t data, int fflag,
565     struct thread *td)
566 {
567 	struct tty *tp = dev->si_drv1;
568 	int error;
569 
570 	error = ttydev_enter(tp);
571 	if (error)
572 		return (error);
573 
574 	switch (cmd) {
575 	case TIOCCBRK:
576 	case TIOCCONS:
577 	case TIOCDRAIN:
578 	case TIOCEXCL:
579 	case TIOCFLUSH:
580 	case TIOCNXCL:
581 	case TIOCSBRK:
582 	case TIOCSCTTY:
583 	case TIOCSETA:
584 	case TIOCSETAF:
585 	case TIOCSETAW:
586 	case TIOCSPGRP:
587 	case TIOCSTART:
588 	case TIOCSTAT:
589 	case TIOCSTI:
590 	case TIOCSTOP:
591 	case TIOCSWINSZ:
592 #if 0
593 	case TIOCSDRAINWAIT:
594 	case TIOCSETD:
595 #endif
596 #ifdef COMPAT_43TTY
597 	case  TIOCLBIC:
598 	case  TIOCLBIS:
599 	case  TIOCLSET:
600 	case  TIOCSETC:
601 	case OTIOCSETD:
602 	case  TIOCSETN:
603 	case  TIOCSETP:
604 	case  TIOCSLTC:
605 #endif /* COMPAT_43TTY */
606 		/*
607 		 * If the ioctl() causes the TTY to be modified, let it
608 		 * wait in the background.
609 		 */
610 		error = tty_wait_background(tp, curthread, SIGTTOU);
611 		if (error)
612 			goto done;
613 	}
614 
615 	if (cmd == TIOCSETA || cmd == TIOCSETAW || cmd == TIOCSETAF) {
616 		struct termios *old = &tp->t_termios;
617 		struct termios *new = (struct termios *)data;
618 		struct termios *lock = TTY_CALLOUT(tp, dev) ?
619 		    &tp->t_termios_lock_out : &tp->t_termios_lock_in;
620 		int cc;
621 
622 		/*
623 		 * Lock state devices.  Just overwrite the values of the
624 		 * commands that are currently in use.
625 		 */
626 		new->c_iflag = (old->c_iflag & lock->c_iflag) |
627 		    (new->c_iflag & ~lock->c_iflag);
628 		new->c_oflag = (old->c_oflag & lock->c_oflag) |
629 		    (new->c_oflag & ~lock->c_oflag);
630 		new->c_cflag = (old->c_cflag & lock->c_cflag) |
631 		    (new->c_cflag & ~lock->c_cflag);
632 		new->c_lflag = (old->c_lflag & lock->c_lflag) |
633 		    (new->c_lflag & ~lock->c_lflag);
634 		for (cc = 0; cc < NCCS; ++cc)
635 			if (lock->c_cc[cc])
636 				new->c_cc[cc] = old->c_cc[cc];
637 		if (lock->c_ispeed)
638 			new->c_ispeed = old->c_ispeed;
639 		if (lock->c_ospeed)
640 			new->c_ospeed = old->c_ospeed;
641 	}
642 
643 	error = tty_ioctl(tp, cmd, data, fflag, td);
644 done:	tty_unlock(tp);
645 
646 	return (error);
647 }
648 
649 static int
650 ttydev_poll(struct cdev *dev, int events, struct thread *td)
651 {
652 	struct tty *tp = dev->si_drv1;
653 	int error, revents = 0;
654 
655 	error = ttydev_enter(tp);
656 	if (error)
657 		return ((events & (POLLIN|POLLRDNORM)) | POLLHUP);
658 
659 	if (events & (POLLIN|POLLRDNORM)) {
660 		/* See if we can read something. */
661 		if (ttydisc_read_poll(tp) > 0)
662 			revents |= events & (POLLIN|POLLRDNORM);
663 	}
664 
665 	if (tp->t_flags & TF_ZOMBIE) {
666 		/* Hangup flag on zombie state. */
667 		revents |= POLLHUP;
668 	} else if (events & (POLLOUT|POLLWRNORM)) {
669 		/* See if we can write something. */
670 		if (ttydisc_write_poll(tp) > 0)
671 			revents |= events & (POLLOUT|POLLWRNORM);
672 	}
673 
674 	if (revents == 0) {
675 		if (events & (POLLIN|POLLRDNORM))
676 			selrecord(td, &tp->t_inpoll);
677 		if (events & (POLLOUT|POLLWRNORM))
678 			selrecord(td, &tp->t_outpoll);
679 	}
680 
681 	tty_unlock(tp);
682 
683 	return (revents);
684 }
685 
686 static int
687 ttydev_mmap(struct cdev *dev, vm_ooffset_t offset, vm_paddr_t *paddr,
688     int nprot, vm_memattr_t *memattr)
689 {
690 	struct tty *tp = dev->si_drv1;
691 	int error;
692 
693 	/* Handle mmap() through the driver. */
694 
695 	error = ttydev_enter(tp);
696 	if (error)
697 		return (-1);
698 	error = ttydevsw_mmap(tp, offset, paddr, nprot, memattr);
699 	tty_unlock(tp);
700 
701 	return (error);
702 }
703 
704 /*
705  * kqueue support.
706  */
707 
708 static void
709 tty_kqops_read_detach(struct knote *kn)
710 {
711 	struct tty *tp = kn->kn_hook;
712 
713 	knlist_remove(&tp->t_inpoll.si_note, kn, 0);
714 }
715 
716 static int
717 tty_kqops_read_event(struct knote *kn, long hint __unused)
718 {
719 	struct tty *tp = kn->kn_hook;
720 
721 	tty_assert_locked(tp);
722 
723 	if (tty_gone(tp) || tp->t_flags & TF_ZOMBIE) {
724 		kn->kn_flags |= EV_EOF;
725 		return (1);
726 	} else {
727 		kn->kn_data = ttydisc_read_poll(tp);
728 		return (kn->kn_data > 0);
729 	}
730 }
731 
732 static void
733 tty_kqops_write_detach(struct knote *kn)
734 {
735 	struct tty *tp = kn->kn_hook;
736 
737 	knlist_remove(&tp->t_outpoll.si_note, kn, 0);
738 }
739 
740 static int
741 tty_kqops_write_event(struct knote *kn, long hint __unused)
742 {
743 	struct tty *tp = kn->kn_hook;
744 
745 	tty_assert_locked(tp);
746 
747 	if (tty_gone(tp)) {
748 		kn->kn_flags |= EV_EOF;
749 		return (1);
750 	} else {
751 		kn->kn_data = ttydisc_write_poll(tp);
752 		return (kn->kn_data > 0);
753 	}
754 }
755 
756 static struct filterops tty_kqops_read = {
757 	.f_isfd = 1,
758 	.f_detach = tty_kqops_read_detach,
759 	.f_event = tty_kqops_read_event,
760 };
761 
762 static struct filterops tty_kqops_write = {
763 	.f_isfd = 1,
764 	.f_detach = tty_kqops_write_detach,
765 	.f_event = tty_kqops_write_event,
766 };
767 
768 static int
769 ttydev_kqfilter(struct cdev *dev, struct knote *kn)
770 {
771 	struct tty *tp = dev->si_drv1;
772 	int error;
773 
774 	error = ttydev_enter(tp);
775 	if (error)
776 		return (error);
777 
778 	switch (kn->kn_filter) {
779 	case EVFILT_READ:
780 		kn->kn_hook = tp;
781 		kn->kn_fop = &tty_kqops_read;
782 		knlist_add(&tp->t_inpoll.si_note, kn, 1);
783 		break;
784 	case EVFILT_WRITE:
785 		kn->kn_hook = tp;
786 		kn->kn_fop = &tty_kqops_write;
787 		knlist_add(&tp->t_outpoll.si_note, kn, 1);
788 		break;
789 	default:
790 		error = EINVAL;
791 		break;
792 	}
793 
794 	tty_unlock(tp);
795 	return (error);
796 }
797 
798 static struct cdevsw ttydev_cdevsw = {
799 	.d_version	= D_VERSION,
800 	.d_open		= ttydev_open,
801 	.d_close	= ttydev_close,
802 	.d_read		= ttydev_read,
803 	.d_write	= ttydev_write,
804 	.d_ioctl	= ttydev_ioctl,
805 	.d_kqfilter	= ttydev_kqfilter,
806 	.d_poll		= ttydev_poll,
807 	.d_mmap		= ttydev_mmap,
808 	.d_name		= "ttydev",
809 	.d_flags	= D_TTY,
810 };
811 
812 /*
813  * Init/lock-state devices
814  */
815 
816 static int
817 ttyil_open(struct cdev *dev, int oflags __unused, int devtype __unused,
818     struct thread *td)
819 {
820 	struct tty *tp;
821 	int error;
822 
823 	tp = dev->si_drv1;
824 	error = 0;
825 	tty_lock(tp);
826 	if (tty_gone(tp))
827 		error = ENODEV;
828 	tty_unlock(tp);
829 
830 	return (error);
831 }
832 
833 static int
834 ttyil_close(struct cdev *dev __unused, int flag __unused, int mode __unused,
835     struct thread *td __unused)
836 {
837 
838 	return (0);
839 }
840 
841 static int
842 ttyil_rdwr(struct cdev *dev __unused, struct uio *uio __unused,
843     int ioflag __unused)
844 {
845 
846 	return (ENODEV);
847 }
848 
849 static int
850 ttyil_ioctl(struct cdev *dev, u_long cmd, caddr_t data, int fflag,
851     struct thread *td)
852 {
853 	struct tty *tp = dev->si_drv1;
854 	int error;
855 
856 	tty_lock(tp);
857 	if (tty_gone(tp)) {
858 		error = ENODEV;
859 		goto done;
860 	}
861 
862 	error = ttydevsw_cioctl(tp, dev2unit(dev), cmd, data, td);
863 	if (error != ENOIOCTL)
864 		goto done;
865 	error = 0;
866 
867 	switch (cmd) {
868 	case TIOCGETA:
869 		/* Obtain terminal flags through tcgetattr(). */
870 		*(struct termios*)data = *(struct termios*)dev->si_drv2;
871 		break;
872 	case TIOCSETA:
873 		/* Set terminal flags through tcsetattr(). */
874 		error = priv_check(td, PRIV_TTY_SETA);
875 		if (error)
876 			break;
877 		*(struct termios*)dev->si_drv2 = *(struct termios*)data;
878 		break;
879 	case TIOCGETD:
880 		*(int *)data = TTYDISC;
881 		break;
882 	case TIOCGWINSZ:
883 		bzero(data, sizeof(struct winsize));
884 		break;
885 	default:
886 		error = ENOTTY;
887 	}
888 
889 done:	tty_unlock(tp);
890 	return (error);
891 }
892 
893 static struct cdevsw ttyil_cdevsw = {
894 	.d_version	= D_VERSION,
895 	.d_open		= ttyil_open,
896 	.d_close	= ttyil_close,
897 	.d_read		= ttyil_rdwr,
898 	.d_write	= ttyil_rdwr,
899 	.d_ioctl	= ttyil_ioctl,
900 	.d_name		= "ttyil",
901 	.d_flags	= D_TTY,
902 };
903 
904 static void
905 tty_init_termios(struct tty *tp)
906 {
907 	struct termios *t = &tp->t_termios_init_in;
908 
909 	t->c_cflag = TTYDEF_CFLAG;
910 	t->c_iflag = TTYDEF_IFLAG;
911 	t->c_lflag = TTYDEF_LFLAG;
912 	t->c_oflag = TTYDEF_OFLAG;
913 	t->c_ispeed = TTYDEF_SPEED;
914 	t->c_ospeed = TTYDEF_SPEED;
915 	memcpy(&t->c_cc, ttydefchars, sizeof ttydefchars);
916 
917 	tp->t_termios_init_out = *t;
918 }
919 
920 void
921 tty_init_console(struct tty *tp, speed_t s)
922 {
923 	struct termios *ti = &tp->t_termios_init_in;
924 	struct termios *to = &tp->t_termios_init_out;
925 
926 	if (s != 0) {
927 		ti->c_ispeed = ti->c_ospeed = s;
928 		to->c_ispeed = to->c_ospeed = s;
929 	}
930 
931 	ti->c_cflag |= CLOCAL;
932 	to->c_cflag |= CLOCAL;
933 }
934 
935 /*
936  * Standard device routine implementations, mostly meant for
937  * pseudo-terminal device drivers. When a driver creates a new terminal
938  * device class, missing routines are patched.
939  */
940 
941 static int
942 ttydevsw_defopen(struct tty *tp __unused)
943 {
944 
945 	return (0);
946 }
947 
948 static void
949 ttydevsw_defclose(struct tty *tp __unused)
950 {
951 
952 }
953 
954 static void
955 ttydevsw_defoutwakeup(struct tty *tp __unused)
956 {
957 
958 	panic("Terminal device has output, while not implemented");
959 }
960 
961 static void
962 ttydevsw_definwakeup(struct tty *tp __unused)
963 {
964 
965 }
966 
967 static int
968 ttydevsw_defioctl(struct tty *tp __unused, u_long cmd __unused,
969     caddr_t data __unused, struct thread *td __unused)
970 {
971 
972 	return (ENOIOCTL);
973 }
974 
975 static int
976 ttydevsw_defcioctl(struct tty *tp __unused, int unit __unused,
977     u_long cmd __unused, caddr_t data __unused, struct thread *td __unused)
978 {
979 
980 	return (ENOIOCTL);
981 }
982 
983 static int
984 ttydevsw_defparam(struct tty *tp __unused, struct termios *t)
985 {
986 
987 	/*
988 	 * Allow the baud rate to be adjusted for pseudo-devices, but at
989 	 * least restrict it to 115200 to prevent excessive buffer
990 	 * usage.  Also disallow 0, to prevent foot shooting.
991 	 */
992 	if (t->c_ispeed < B50)
993 		t->c_ispeed = B50;
994 	else if (t->c_ispeed > B115200)
995 		t->c_ispeed = B115200;
996 	if (t->c_ospeed < B50)
997 		t->c_ospeed = B50;
998 	else if (t->c_ospeed > B115200)
999 		t->c_ospeed = B115200;
1000 	t->c_cflag |= CREAD;
1001 
1002 	return (0);
1003 }
1004 
1005 static int
1006 ttydevsw_defmodem(struct tty *tp __unused, int sigon __unused,
1007     int sigoff __unused)
1008 {
1009 
1010 	/* Simulate a carrier to make the TTY layer happy. */
1011 	return (SER_DCD);
1012 }
1013 
1014 static int
1015 ttydevsw_defmmap(struct tty *tp __unused, vm_ooffset_t offset __unused,
1016     vm_paddr_t *paddr __unused, int nprot __unused,
1017     vm_memattr_t *memattr __unused)
1018 {
1019 
1020 	return (-1);
1021 }
1022 
1023 static void
1024 ttydevsw_defpktnotify(struct tty *tp __unused, char event __unused)
1025 {
1026 
1027 }
1028 
1029 static void
1030 ttydevsw_deffree(void *softc __unused)
1031 {
1032 
1033 	panic("Terminal device freed without a free-handler");
1034 }
1035 
1036 static bool
1037 ttydevsw_defbusy(struct tty *tp __unused)
1038 {
1039 
1040 	return (FALSE);
1041 }
1042 
1043 /*
1044  * TTY allocation and deallocation. TTY devices can be deallocated when
1045  * the driver doesn't use it anymore, when the TTY isn't a session's
1046  * controlling TTY and when the device node isn't opened through devfs.
1047  */
1048 
1049 struct tty *
1050 tty_alloc(struct ttydevsw *tsw, void *sc)
1051 {
1052 
1053 	return (tty_alloc_mutex(tsw, sc, NULL));
1054 }
1055 
1056 struct tty *
1057 tty_alloc_mutex(struct ttydevsw *tsw, void *sc, struct mtx *mutex)
1058 {
1059 	struct tty *tp;
1060 
1061 	/* Make sure the driver defines all routines. */
1062 #define PATCH_FUNC(x) do {				\
1063 	if (tsw->tsw_ ## x == NULL)			\
1064 		tsw->tsw_ ## x = ttydevsw_def ## x;	\
1065 } while (0)
1066 	PATCH_FUNC(open);
1067 	PATCH_FUNC(close);
1068 	PATCH_FUNC(outwakeup);
1069 	PATCH_FUNC(inwakeup);
1070 	PATCH_FUNC(ioctl);
1071 	PATCH_FUNC(cioctl);
1072 	PATCH_FUNC(param);
1073 	PATCH_FUNC(modem);
1074 	PATCH_FUNC(mmap);
1075 	PATCH_FUNC(pktnotify);
1076 	PATCH_FUNC(free);
1077 	PATCH_FUNC(busy);
1078 #undef PATCH_FUNC
1079 
1080 	tp = malloc(sizeof(struct tty) + TTY_PRBUF_SIZE, M_TTY,
1081 	    M_WAITOK | M_ZERO);
1082 	tp->t_prbufsz = TTY_PRBUF_SIZE;
1083 	tp->t_devsw = tsw;
1084 	tp->t_devswsoftc = sc;
1085 	tp->t_flags = tsw->tsw_flags;
1086 	tp->t_drainwait = tty_drainwait;
1087 
1088 	tty_init_termios(tp);
1089 
1090 	cv_init(&tp->t_inwait, "ttyin");
1091 	cv_init(&tp->t_outwait, "ttyout");
1092 	cv_init(&tp->t_outserwait, "ttyosr");
1093 	cv_init(&tp->t_bgwait, "ttybg");
1094 	cv_init(&tp->t_dcdwait, "ttydcd");
1095 
1096 	/* Allow drivers to use a custom mutex to lock the TTY. */
1097 	if (mutex != NULL) {
1098 		tp->t_mtx = mutex;
1099 	} else {
1100 		tp->t_mtx = &tp->t_mtxobj;
1101 		mtx_init(&tp->t_mtxobj, "ttymtx", NULL, MTX_DEF);
1102 	}
1103 
1104 	knlist_init_mtx(&tp->t_inpoll.si_note, tp->t_mtx);
1105 	knlist_init_mtx(&tp->t_outpoll.si_note, tp->t_mtx);
1106 
1107 	return (tp);
1108 }
1109 
1110 static void
1111 tty_dealloc(void *arg)
1112 {
1113 	struct tty *tp = arg;
1114 
1115 	/*
1116 	 * ttyydev_leave() usually frees the i/o queues earlier, but it is
1117 	 * not always called between queue allocation and here.  The queues
1118 	 * may be allocated by ioctls on a pty control device without the
1119 	 * corresponding pty slave device ever being open, or after it is
1120 	 * closed.
1121 	 */
1122 	ttyinq_free(&tp->t_inq);
1123 	ttyoutq_free(&tp->t_outq);
1124 	seldrain(&tp->t_inpoll);
1125 	seldrain(&tp->t_outpoll);
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 	xt->xt_size = sizeof(struct xtty);
1295 	xt->xt_insize = ttyinq_getsize(&tp->t_inq);
1296 	xt->xt_incc = ttyinq_bytescanonicalized(&tp->t_inq);
1297 	xt->xt_inlc = ttyinq_bytesline(&tp->t_inq);
1298 	xt->xt_inlow = tp->t_inlow;
1299 	xt->xt_outsize = ttyoutq_getsize(&tp->t_outq);
1300 	xt->xt_outcc = ttyoutq_bytesused(&tp->t_outq);
1301 	xt->xt_outlow = tp->t_outlow;
1302 	xt->xt_column = tp->t_column;
1303 	xt->xt_pgid = tp->t_pgrp ? tp->t_pgrp->pg_id : 0;
1304 	xt->xt_sid = tp->t_session ? tp->t_session->s_sid : 0;
1305 	xt->xt_flags = tp->t_flags;
1306 	xt->xt_dev = tp->t_dev ? dev2udev(tp->t_dev) : (uint32_t)NODEV;
1307 }
1308 
1309 static int
1310 sysctl_kern_ttys(SYSCTL_HANDLER_ARGS)
1311 {
1312 	unsigned long lsize;
1313 	struct xtty *xtlist, *xt;
1314 	struct tty *tp;
1315 	int error;
1316 
1317 	sx_slock(&tty_list_sx);
1318 	lsize = tty_list_count * sizeof(struct xtty);
1319 	if (lsize == 0) {
1320 		sx_sunlock(&tty_list_sx);
1321 		return (0);
1322 	}
1323 
1324 	xtlist = xt = malloc(lsize, M_TTY, M_WAITOK);
1325 
1326 	TAILQ_FOREACH(tp, &tty_list, t_list) {
1327 		tty_lock(tp);
1328 		tty_to_xtty(tp, xt);
1329 		tty_unlock(tp);
1330 		xt++;
1331 	}
1332 	sx_sunlock(&tty_list_sx);
1333 
1334 	error = SYSCTL_OUT(req, xtlist, lsize);
1335 	free(xtlist, M_TTY);
1336 	return (error);
1337 }
1338 
1339 SYSCTL_PROC(_kern, OID_AUTO, ttys, CTLTYPE_OPAQUE|CTLFLAG_RD|CTLFLAG_MPSAFE,
1340 	0, 0, sysctl_kern_ttys, "S,xtty", "List of TTYs");
1341 
1342 /*
1343  * Device node creation. Device has been set up, now we can expose it to
1344  * the user.
1345  */
1346 
1347 int
1348 tty_makedevf(struct tty *tp, struct ucred *cred, int flags,
1349     const char *fmt, ...)
1350 {
1351 	va_list ap;
1352 	struct make_dev_args args;
1353 	struct cdev *dev, *init, *lock, *cua, *cinit, *clock;
1354 	const char *prefix = "tty";
1355 	char name[SPECNAMELEN - 3]; /* for "tty" and "cua". */
1356 	uid_t uid;
1357 	gid_t gid;
1358 	mode_t mode;
1359 	int error;
1360 
1361 	/* Remove "tty" prefix from devices like PTY's. */
1362 	if (tp->t_flags & TF_NOPREFIX)
1363 		prefix = "";
1364 
1365 	va_start(ap, fmt);
1366 	vsnrprintf(name, sizeof name, 32, fmt, ap);
1367 	va_end(ap);
1368 
1369 	if (cred == NULL) {
1370 		/* System device. */
1371 		uid = UID_ROOT;
1372 		gid = GID_WHEEL;
1373 		mode = S_IRUSR|S_IWUSR;
1374 	} else {
1375 		/* User device. */
1376 		uid = cred->cr_ruid;
1377 		gid = GID_TTY;
1378 		mode = S_IRUSR|S_IWUSR|S_IWGRP;
1379 	}
1380 
1381 	flags = flags & TTYMK_CLONING ? MAKEDEV_REF : 0;
1382 	flags |= MAKEDEV_CHECKNAME;
1383 
1384 	/* Master call-in device. */
1385 	make_dev_args_init(&args);
1386 	args.mda_flags = flags;
1387 	args.mda_devsw = &ttydev_cdevsw;
1388 	args.mda_cr = cred;
1389 	args.mda_uid = uid;
1390 	args.mda_gid = gid;
1391 	args.mda_mode = mode;
1392 	args.mda_si_drv1 = tp;
1393 	error = make_dev_s(&args, &dev, "%s%s", prefix, name);
1394 	if (error != 0)
1395 		return (error);
1396 	tp->t_dev = dev;
1397 
1398 	init = lock = cua = cinit = clock = NULL;
1399 
1400 	/* Slave call-in devices. */
1401 	if (tp->t_flags & TF_INITLOCK) {
1402 		args.mda_devsw = &ttyil_cdevsw;
1403 		args.mda_unit = TTYUNIT_INIT;
1404 		args.mda_si_drv1 = tp;
1405 		args.mda_si_drv2 = &tp->t_termios_init_in;
1406 		error = make_dev_s(&args, &init, "%s%s.init", prefix, name);
1407 		if (error != 0)
1408 			goto fail;
1409 		dev_depends(dev, init);
1410 
1411 		args.mda_unit = TTYUNIT_LOCK;
1412 		args.mda_si_drv2 = &tp->t_termios_lock_in;
1413 		error = make_dev_s(&args, &lock, "%s%s.lock", prefix, name);
1414 		if (error != 0)
1415 			goto fail;
1416 		dev_depends(dev, lock);
1417 	}
1418 
1419 	/* Call-out devices. */
1420 	if (tp->t_flags & TF_CALLOUT) {
1421 		make_dev_args_init(&args);
1422 		args.mda_flags = flags;
1423 		args.mda_devsw = &ttydev_cdevsw;
1424 		args.mda_cr = cred;
1425 		args.mda_uid = UID_UUCP;
1426 		args.mda_gid = GID_DIALER;
1427 		args.mda_mode = 0660;
1428 		args.mda_unit = TTYUNIT_CALLOUT;
1429 		args.mda_si_drv1 = tp;
1430 		error = make_dev_s(&args, &cua, "cua%s", name);
1431 		if (error != 0)
1432 			goto fail;
1433 		dev_depends(dev, cua);
1434 
1435 		/* Slave call-out devices. */
1436 		if (tp->t_flags & TF_INITLOCK) {
1437 			args.mda_devsw = &ttyil_cdevsw;
1438 			args.mda_unit = TTYUNIT_CALLOUT | TTYUNIT_INIT;
1439 			args.mda_si_drv2 = &tp->t_termios_init_out;
1440 			error = make_dev_s(&args, &cinit, "cua%s.init", name);
1441 			if (error != 0)
1442 				goto fail;
1443 			dev_depends(dev, cinit);
1444 
1445 			args.mda_unit = TTYUNIT_CALLOUT | TTYUNIT_LOCK;
1446 			args.mda_si_drv2 = &tp->t_termios_lock_out;
1447 			error = make_dev_s(&args, &clock, "cua%s.lock", name);
1448 			if (error != 0)
1449 				goto fail;
1450 			dev_depends(dev, clock);
1451 		}
1452 	}
1453 
1454 	sx_xlock(&tty_list_sx);
1455 	TAILQ_INSERT_TAIL(&tty_list, tp, t_list);
1456 	tty_list_count++;
1457 	sx_xunlock(&tty_list_sx);
1458 
1459 	return (0);
1460 
1461 fail:
1462 	destroy_dev(dev);
1463 	if (init)
1464 		destroy_dev(init);
1465 	if (lock)
1466 		destroy_dev(lock);
1467 	if (cinit)
1468 		destroy_dev(cinit);
1469 	if (clock)
1470 		destroy_dev(clock);
1471 
1472 	return (error);
1473 }
1474 
1475 /*
1476  * Signalling processes.
1477  */
1478 
1479 void
1480 tty_signal_sessleader(struct tty *tp, int sig)
1481 {
1482 	struct proc *p;
1483 	struct session *s;
1484 
1485 	tty_assert_locked(tp);
1486 	MPASS(sig >= 1 && sig < NSIG);
1487 
1488 	/* Make signals start output again. */
1489 	tp->t_flags &= ~TF_STOPPED;
1490 	tp->t_termios.c_lflag &= ~FLUSHO;
1491 
1492 	/*
1493 	 * Load s_leader exactly once to avoid race where s_leader is
1494 	 * set to NULL by a concurrent invocation of killjobc() by the
1495 	 * session leader.  Note that we are not holding t_session's
1496 	 * lock for the read.
1497 	 */
1498 	if ((s = tp->t_session) != NULL &&
1499 	    (p = atomic_load_ptr(&s->s_leader)) != NULL) {
1500 		PROC_LOCK(p);
1501 		kern_psignal(p, sig);
1502 		PROC_UNLOCK(p);
1503 	}
1504 }
1505 
1506 void
1507 tty_signal_pgrp(struct tty *tp, int sig)
1508 {
1509 	ksiginfo_t ksi;
1510 
1511 	tty_assert_locked(tp);
1512 	MPASS(sig >= 1 && sig < NSIG);
1513 
1514 	/* Make signals start output again. */
1515 	tp->t_flags &= ~TF_STOPPED;
1516 	tp->t_termios.c_lflag &= ~FLUSHO;
1517 
1518 	if (sig == SIGINFO && !(tp->t_termios.c_lflag & NOKERNINFO))
1519 		tty_info(tp);
1520 	if (tp->t_pgrp != NULL) {
1521 		ksiginfo_init(&ksi);
1522 		ksi.ksi_signo = sig;
1523 		ksi.ksi_code = SI_KERNEL;
1524 		PGRP_LOCK(tp->t_pgrp);
1525 		pgsignal(tp->t_pgrp, sig, 1, &ksi);
1526 		PGRP_UNLOCK(tp->t_pgrp);
1527 	}
1528 }
1529 
1530 void
1531 tty_wakeup(struct tty *tp, int flags)
1532 {
1533 
1534 	if (tp->t_flags & TF_ASYNC && tp->t_sigio != NULL)
1535 		pgsigio(&tp->t_sigio, SIGIO, (tp->t_session != NULL));
1536 
1537 	if (flags & FWRITE) {
1538 		cv_broadcast(&tp->t_outwait);
1539 		selwakeup(&tp->t_outpoll);
1540 		KNOTE_LOCKED(&tp->t_outpoll.si_note, 0);
1541 	}
1542 	if (flags & FREAD) {
1543 		cv_broadcast(&tp->t_inwait);
1544 		selwakeup(&tp->t_inpoll);
1545 		KNOTE_LOCKED(&tp->t_inpoll.si_note, 0);
1546 	}
1547 }
1548 
1549 int
1550 tty_wait(struct tty *tp, struct cv *cv)
1551 {
1552 	int error;
1553 	int revokecnt = tp->t_revokecnt;
1554 
1555 	tty_lock_assert(tp, MA_OWNED|MA_NOTRECURSED);
1556 	MPASS(!tty_gone(tp));
1557 
1558 	error = cv_wait_sig(cv, tp->t_mtx);
1559 
1560 	/* Bail out when the device slipped away. */
1561 	if (tty_gone(tp))
1562 		return (ENXIO);
1563 
1564 	/* Restart the system call when we may have been revoked. */
1565 	if (tp->t_revokecnt != revokecnt)
1566 		return (ERESTART);
1567 
1568 	return (error);
1569 }
1570 
1571 int
1572 tty_timedwait(struct tty *tp, struct cv *cv, int hz)
1573 {
1574 	int error;
1575 	int revokecnt = tp->t_revokecnt;
1576 
1577 	tty_lock_assert(tp, MA_OWNED|MA_NOTRECURSED);
1578 	MPASS(!tty_gone(tp));
1579 
1580 	error = cv_timedwait_sig(cv, tp->t_mtx, hz);
1581 
1582 	/* Bail out when the device slipped away. */
1583 	if (tty_gone(tp))
1584 		return (ENXIO);
1585 
1586 	/* Restart the system call when we may have been revoked. */
1587 	if (tp->t_revokecnt != revokecnt)
1588 		return (ERESTART);
1589 
1590 	return (error);
1591 }
1592 
1593 void
1594 tty_flush(struct tty *tp, int flags)
1595 {
1596 
1597 	if (flags & FWRITE) {
1598 		tp->t_flags &= ~TF_HIWAT_OUT;
1599 		ttyoutq_flush(&tp->t_outq);
1600 		tty_wakeup(tp, FWRITE);
1601 		if (!tty_gone(tp)) {
1602 			ttydevsw_outwakeup(tp);
1603 			ttydevsw_pktnotify(tp, TIOCPKT_FLUSHWRITE);
1604 		}
1605 	}
1606 	if (flags & FREAD) {
1607 		tty_hiwat_in_unblock(tp);
1608 		ttyinq_flush(&tp->t_inq);
1609 		tty_wakeup(tp, FREAD);
1610 		if (!tty_gone(tp)) {
1611 			ttydevsw_inwakeup(tp);
1612 			ttydevsw_pktnotify(tp, TIOCPKT_FLUSHREAD);
1613 		}
1614 	}
1615 }
1616 
1617 void
1618 tty_set_winsize(struct tty *tp, const struct winsize *wsz)
1619 {
1620 
1621 	if (memcmp(&tp->t_winsize, wsz, sizeof(*wsz)) == 0)
1622 		return;
1623 	tp->t_winsize = *wsz;
1624 	tty_signal_pgrp(tp, SIGWINCH);
1625 }
1626 
1627 static int
1628 tty_generic_ioctl(struct tty *tp, u_long cmd, void *data, int fflag,
1629     struct thread *td)
1630 {
1631 	int error;
1632 
1633 	switch (cmd) {
1634 	/*
1635 	 * Modem commands.
1636 	 * The SER_* and TIOCM_* flags are the same, but one bit
1637 	 * shifted. I don't know why.
1638 	 */
1639 	case TIOCSDTR:
1640 		ttydevsw_modem(tp, SER_DTR, 0);
1641 		return (0);
1642 	case TIOCCDTR:
1643 		ttydevsw_modem(tp, 0, SER_DTR);
1644 		return (0);
1645 	case TIOCMSET: {
1646 		int bits = *(int *)data;
1647 		ttydevsw_modem(tp,
1648 		    (bits & (TIOCM_DTR | TIOCM_RTS)) >> 1,
1649 		    ((~bits) & (TIOCM_DTR | TIOCM_RTS)) >> 1);
1650 		return (0);
1651 	}
1652 	case TIOCMBIS: {
1653 		int bits = *(int *)data;
1654 		ttydevsw_modem(tp, (bits & (TIOCM_DTR | TIOCM_RTS)) >> 1, 0);
1655 		return (0);
1656 	}
1657 	case TIOCMBIC: {
1658 		int bits = *(int *)data;
1659 		ttydevsw_modem(tp, 0, (bits & (TIOCM_DTR | TIOCM_RTS)) >> 1);
1660 		return (0);
1661 	}
1662 	case TIOCMGET:
1663 		*(int *)data = TIOCM_LE + (ttydevsw_modem(tp, 0, 0) << 1);
1664 		return (0);
1665 
1666 	case FIOASYNC:
1667 		if (*(int *)data)
1668 			tp->t_flags |= TF_ASYNC;
1669 		else
1670 			tp->t_flags &= ~TF_ASYNC;
1671 		return (0);
1672 	case FIONBIO:
1673 		/* This device supports non-blocking operation. */
1674 		return (0);
1675 	case FIONREAD:
1676 		*(int *)data = ttyinq_bytescanonicalized(&tp->t_inq);
1677 		return (0);
1678 	case FIONWRITE:
1679 	case TIOCOUTQ:
1680 		*(int *)data = ttyoutq_bytesused(&tp->t_outq);
1681 		return (0);
1682 	case FIOSETOWN:
1683 		if (tp->t_session != NULL && !tty_is_ctty(tp, td->td_proc))
1684 			/* Not allowed to set ownership. */
1685 			return (ENOTTY);
1686 
1687 		/* Temporarily unlock the TTY to set ownership. */
1688 		tty_unlock(tp);
1689 		error = fsetown(*(int *)data, &tp->t_sigio);
1690 		tty_lock(tp);
1691 		return (error);
1692 	case FIOGETOWN:
1693 		if (tp->t_session != NULL && !tty_is_ctty(tp, td->td_proc))
1694 			/* Not allowed to set ownership. */
1695 			return (ENOTTY);
1696 
1697 		/* Get ownership. */
1698 		*(int *)data = fgetown(&tp->t_sigio);
1699 		return (0);
1700 	case TIOCGETA:
1701 		/* Obtain terminal flags through tcgetattr(). */
1702 		*(struct termios*)data = tp->t_termios;
1703 		return (0);
1704 	case TIOCSETA:
1705 	case TIOCSETAW:
1706 	case TIOCSETAF: {
1707 		struct termios *t = data;
1708 
1709 		/*
1710 		 * Who makes up these funny rules? According to POSIX,
1711 		 * input baud rate is set equal to the output baud rate
1712 		 * when zero.
1713 		 */
1714 		if (t->c_ispeed == 0)
1715 			t->c_ispeed = t->c_ospeed;
1716 
1717 		/* Discard any unsupported bits. */
1718 		t->c_iflag &= TTYSUP_IFLAG;
1719 		t->c_oflag &= TTYSUP_OFLAG;
1720 		t->c_lflag &= TTYSUP_LFLAG;
1721 		t->c_cflag &= TTYSUP_CFLAG;
1722 
1723 		/* Set terminal flags through tcsetattr(). */
1724 		if (cmd == TIOCSETAW || cmd == TIOCSETAF) {
1725 			error = tty_drain(tp, 0);
1726 			if (error)
1727 				return (error);
1728 			if (cmd == TIOCSETAF)
1729 				tty_flush(tp, FREAD);
1730 		}
1731 
1732 		/*
1733 		 * Only call param() when the flags really change.
1734 		 */
1735 		if ((t->c_cflag & CIGNORE) == 0 &&
1736 		    (tp->t_termios.c_cflag != t->c_cflag ||
1737 		    ((tp->t_termios.c_iflag ^ t->c_iflag) &
1738 		    (IXON|IXOFF|IXANY)) ||
1739 		    tp->t_termios.c_ispeed != t->c_ispeed ||
1740 		    tp->t_termios.c_ospeed != t->c_ospeed)) {
1741 			error = ttydevsw_param(tp, t);
1742 			if (error)
1743 				return (error);
1744 
1745 			/* XXX: CLOCAL? */
1746 
1747 			tp->t_termios.c_cflag = t->c_cflag & ~CIGNORE;
1748 			tp->t_termios.c_ispeed = t->c_ispeed;
1749 			tp->t_termios.c_ospeed = t->c_ospeed;
1750 
1751 			/* Baud rate has changed - update watermarks. */
1752 			error = tty_watermarks(tp);
1753 			if (error)
1754 				return (error);
1755 		}
1756 
1757 		/* Copy new non-device driver parameters. */
1758 		tp->t_termios.c_iflag = t->c_iflag;
1759 		tp->t_termios.c_oflag = t->c_oflag;
1760 		tp->t_termios.c_lflag = t->c_lflag;
1761 		memcpy(&tp->t_termios.c_cc, t->c_cc, sizeof t->c_cc);
1762 
1763 		ttydisc_optimize(tp);
1764 
1765 		if ((t->c_lflag & ICANON) == 0) {
1766 			/*
1767 			 * When in non-canonical mode, wake up all
1768 			 * readers. Canonicalize any partial input. VMIN
1769 			 * and VTIME could also be adjusted.
1770 			 */
1771 			ttyinq_canonicalize(&tp->t_inq);
1772 			tty_wakeup(tp, FREAD);
1773 		}
1774 
1775 		/*
1776 		 * For packet mode: notify the PTY consumer that VSTOP
1777 		 * and VSTART may have been changed.
1778 		 */
1779 		if (tp->t_termios.c_iflag & IXON &&
1780 		    tp->t_termios.c_cc[VSTOP] == CTRL('S') &&
1781 		    tp->t_termios.c_cc[VSTART] == CTRL('Q'))
1782 			ttydevsw_pktnotify(tp, TIOCPKT_DOSTOP);
1783 		else
1784 			ttydevsw_pktnotify(tp, TIOCPKT_NOSTOP);
1785 		return (0);
1786 	}
1787 	case TIOCGETD:
1788 		/* For compatibility - we only support TTYDISC. */
1789 		*(int *)data = TTYDISC;
1790 		return (0);
1791 	case TIOCGPGRP:
1792 		if (!tty_is_ctty(tp, td->td_proc))
1793 			return (ENOTTY);
1794 
1795 		if (tp->t_pgrp != NULL)
1796 			*(int *)data = tp->t_pgrp->pg_id;
1797 		else
1798 			*(int *)data = NO_PID;
1799 		return (0);
1800 	case TIOCGSID:
1801 		if (!tty_is_ctty(tp, td->td_proc))
1802 			return (ENOTTY);
1803 
1804 		MPASS(tp->t_session);
1805 		*(int *)data = tp->t_session->s_sid;
1806 		return (0);
1807 	case TIOCNOTTY:
1808 		return (tty_drop_ctty(tp, td->td_proc));
1809 	case TIOCSCTTY: {
1810 		struct proc *p = td->td_proc;
1811 
1812 		/* XXX: This looks awful. */
1813 		tty_unlock(tp);
1814 		sx_xlock(&proctree_lock);
1815 		tty_lock(tp);
1816 
1817 		if (!SESS_LEADER(p)) {
1818 			/* Only the session leader may do this. */
1819 			sx_xunlock(&proctree_lock);
1820 			return (EPERM);
1821 		}
1822 
1823 		if (tp->t_session != NULL && tp->t_session == p->p_session) {
1824 			/* This is already our controlling TTY. */
1825 			sx_xunlock(&proctree_lock);
1826 			return (0);
1827 		}
1828 
1829 		if (p->p_session->s_ttyp != NULL ||
1830 		    (tp->t_session != NULL && tp->t_session->s_ttyvp != NULL &&
1831 		    tp->t_session->s_ttyvp->v_type != VBAD)) {
1832 			/*
1833 			 * There is already a relation between a TTY and
1834 			 * a session, or the caller is not the session
1835 			 * leader.
1836 			 *
1837 			 * Allow the TTY to be stolen when the vnode is
1838 			 * invalid, but the reference to the TTY is
1839 			 * still active.  This allows immediate reuse of
1840 			 * TTYs of which the session leader has been
1841 			 * killed or the TTY revoked.
1842 			 */
1843 			sx_xunlock(&proctree_lock);
1844 			return (EPERM);
1845 		}
1846 
1847 		/* Connect the session to the TTY. */
1848 		tp->t_session = p->p_session;
1849 		tp->t_session->s_ttyp = tp;
1850 		tp->t_sessioncnt++;
1851 
1852 		/* Assign foreground process group. */
1853 		tp->t_pgrp = p->p_pgrp;
1854 		PROC_LOCK(p);
1855 		p->p_flag |= P_CONTROLT;
1856 		PROC_UNLOCK(p);
1857 
1858 		sx_xunlock(&proctree_lock);
1859 		return (0);
1860 	}
1861 	case TIOCSPGRP: {
1862 		struct pgrp *pg;
1863 
1864 		/*
1865 		 * XXX: Temporarily unlock the TTY to locate the process
1866 		 * group. This code would be lot nicer if we would ever
1867 		 * decompose proctree_lock.
1868 		 */
1869 		tty_unlock(tp);
1870 		sx_slock(&proctree_lock);
1871 		pg = pgfind(*(int *)data);
1872 		if (pg != NULL)
1873 			PGRP_UNLOCK(pg);
1874 		if (pg == NULL || pg->pg_session != td->td_proc->p_session) {
1875 			sx_sunlock(&proctree_lock);
1876 			tty_lock(tp);
1877 			return (EPERM);
1878 		}
1879 		tty_lock(tp);
1880 
1881 		/*
1882 		 * Determine if this TTY is the controlling TTY after
1883 		 * relocking the TTY.
1884 		 */
1885 		if (!tty_is_ctty(tp, td->td_proc)) {
1886 			sx_sunlock(&proctree_lock);
1887 			return (ENOTTY);
1888 		}
1889 		tp->t_pgrp = pg;
1890 		sx_sunlock(&proctree_lock);
1891 
1892 		/* Wake up the background process groups. */
1893 		cv_broadcast(&tp->t_bgwait);
1894 		return (0);
1895 	}
1896 	case TIOCFLUSH: {
1897 		int flags = *(int *)data;
1898 
1899 		if (flags == 0)
1900 			flags = (FREAD|FWRITE);
1901 		else
1902 			flags &= (FREAD|FWRITE);
1903 		tty_flush(tp, flags);
1904 		return (0);
1905 	}
1906 	case TIOCDRAIN:
1907 		/* Drain TTY output. */
1908 		return tty_drain(tp, 0);
1909 	case TIOCGDRAINWAIT:
1910 		*(int *)data = tp->t_drainwait;
1911 		return (0);
1912 	case TIOCSDRAINWAIT:
1913 		error = priv_check(td, PRIV_TTY_DRAINWAIT);
1914 		if (error == 0)
1915 			tp->t_drainwait = *(int *)data;
1916 		return (error);
1917 	case TIOCCONS:
1918 		/* Set terminal as console TTY. */
1919 		if (*(int *)data) {
1920 			error = priv_check(td, PRIV_TTY_CONSOLE);
1921 			if (error)
1922 				return (error);
1923 
1924 			/*
1925 			 * XXX: constty should really need to be locked!
1926 			 * XXX: allow disconnected constty's to be stolen!
1927 			 */
1928 
1929 			if (constty == tp)
1930 				return (0);
1931 			if (constty != NULL)
1932 				return (EBUSY);
1933 
1934 			tty_unlock(tp);
1935 			constty_set(tp);
1936 			tty_lock(tp);
1937 		} else if (constty == tp) {
1938 			constty_clear();
1939 		}
1940 		return (0);
1941 	case TIOCGWINSZ:
1942 		/* Obtain window size. */
1943 		*(struct winsize*)data = tp->t_winsize;
1944 		return (0);
1945 	case TIOCSWINSZ:
1946 		/* Set window size. */
1947 		tty_set_winsize(tp, data);
1948 		return (0);
1949 	case TIOCEXCL:
1950 		tp->t_flags |= TF_EXCLUDE;
1951 		return (0);
1952 	case TIOCNXCL:
1953 		tp->t_flags &= ~TF_EXCLUDE;
1954 		return (0);
1955 	case TIOCSTOP:
1956 		tp->t_flags |= TF_STOPPED;
1957 		ttydevsw_pktnotify(tp, TIOCPKT_STOP);
1958 		return (0);
1959 	case TIOCSTART:
1960 		tp->t_flags &= ~TF_STOPPED;
1961 		tp->t_termios.c_lflag &= ~FLUSHO;
1962 		ttydevsw_outwakeup(tp);
1963 		ttydevsw_pktnotify(tp, TIOCPKT_START);
1964 		return (0);
1965 	case TIOCSTAT:
1966 		tty_info(tp);
1967 		return (0);
1968 	case TIOCSTI:
1969 		if ((fflag & FREAD) == 0 && priv_check(td, PRIV_TTY_STI))
1970 			return (EPERM);
1971 		if (!tty_is_ctty(tp, td->td_proc) &&
1972 		    priv_check(td, PRIV_TTY_STI))
1973 			return (EACCES);
1974 		ttydisc_rint(tp, *(char *)data, 0);
1975 		ttydisc_rint_done(tp);
1976 		return (0);
1977 	}
1978 
1979 #ifdef COMPAT_43TTY
1980 	return tty_ioctl_compat(tp, cmd, data, fflag, td);
1981 #else /* !COMPAT_43TTY */
1982 	return (ENOIOCTL);
1983 #endif /* COMPAT_43TTY */
1984 }
1985 
1986 int
1987 tty_ioctl(struct tty *tp, u_long cmd, void *data, int fflag, struct thread *td)
1988 {
1989 	int error;
1990 
1991 	tty_assert_locked(tp);
1992 
1993 	if (tty_gone(tp))
1994 		return (ENXIO);
1995 
1996 	error = ttydevsw_ioctl(tp, cmd, data, td);
1997 	if (error == ENOIOCTL)
1998 		error = tty_generic_ioctl(tp, cmd, data, fflag, td);
1999 
2000 	return (error);
2001 }
2002 
2003 dev_t
2004 tty_udev(struct tty *tp)
2005 {
2006 
2007 	if (tp->t_dev)
2008 		return (dev2udev(tp->t_dev));
2009 	else
2010 		return (NODEV);
2011 }
2012 
2013 int
2014 tty_checkoutq(struct tty *tp)
2015 {
2016 
2017 	/* 256 bytes should be enough to print a log message. */
2018 	return (ttyoutq_bytesleft(&tp->t_outq) >= 256);
2019 }
2020 
2021 void
2022 tty_hiwat_in_block(struct tty *tp)
2023 {
2024 
2025 	if ((tp->t_flags & TF_HIWAT_IN) == 0 &&
2026 	    tp->t_termios.c_iflag & IXOFF &&
2027 	    tp->t_termios.c_cc[VSTOP] != _POSIX_VDISABLE) {
2028 		/*
2029 		 * Input flow control. Only enter the high watermark when we
2030 		 * can successfully store the VSTOP character.
2031 		 */
2032 		if (ttyoutq_write_nofrag(&tp->t_outq,
2033 		    &tp->t_termios.c_cc[VSTOP], 1) == 0)
2034 			tp->t_flags |= TF_HIWAT_IN;
2035 	} else {
2036 		/* No input flow control. */
2037 		tp->t_flags |= TF_HIWAT_IN;
2038 	}
2039 }
2040 
2041 void
2042 tty_hiwat_in_unblock(struct tty *tp)
2043 {
2044 
2045 	if (tp->t_flags & TF_HIWAT_IN &&
2046 	    tp->t_termios.c_iflag & IXOFF &&
2047 	    tp->t_termios.c_cc[VSTART] != _POSIX_VDISABLE) {
2048 		/*
2049 		 * Input flow control. Only leave the high watermark when we
2050 		 * can successfully store the VSTART character.
2051 		 */
2052 		if (ttyoutq_write_nofrag(&tp->t_outq,
2053 		    &tp->t_termios.c_cc[VSTART], 1) == 0)
2054 			tp->t_flags &= ~TF_HIWAT_IN;
2055 	} else {
2056 		/* No input flow control. */
2057 		tp->t_flags &= ~TF_HIWAT_IN;
2058 	}
2059 
2060 	if (!tty_gone(tp))
2061 		ttydevsw_inwakeup(tp);
2062 }
2063 
2064 /*
2065  * TTY hooks interface.
2066  */
2067 
2068 static int
2069 ttyhook_defrint(struct tty *tp, char c, int flags)
2070 {
2071 
2072 	if (ttyhook_rint_bypass(tp, &c, 1) != 1)
2073 		return (-1);
2074 
2075 	return (0);
2076 }
2077 
2078 int
2079 ttyhook_register(struct tty **rtp, struct proc *p, int fd, struct ttyhook *th,
2080     void *softc)
2081 {
2082 	struct tty *tp;
2083 	struct file *fp;
2084 	struct cdev *dev;
2085 	struct cdevsw *cdp;
2086 	struct filedesc *fdp;
2087 	cap_rights_t rights;
2088 	int error, ref;
2089 
2090 	/* Validate the file descriptor. */
2091 	fdp = p->p_fd;
2092 	error = fget_unlocked(fdp, fd, cap_rights_init_one(&rights, CAP_TTYHOOK),
2093 	    &fp);
2094 	if (error != 0)
2095 		return (error);
2096 	if (fp->f_ops == &badfileops) {
2097 		error = EBADF;
2098 		goto done1;
2099 	}
2100 
2101 	/*
2102 	 * Make sure the vnode is bound to a character device.
2103 	 * Unlocked check for the vnode type is ok there, because we
2104 	 * only shall prevent calling devvn_refthread on the file that
2105 	 * never has been opened over a character device.
2106 	 */
2107 	if (fp->f_type != DTYPE_VNODE || fp->f_vnode->v_type != VCHR) {
2108 		error = EINVAL;
2109 		goto done1;
2110 	}
2111 
2112 	/* Make sure it is a TTY. */
2113 	cdp = devvn_refthread(fp->f_vnode, &dev, &ref);
2114 	if (cdp == NULL) {
2115 		error = ENXIO;
2116 		goto done1;
2117 	}
2118 	if (dev != fp->f_data) {
2119 		error = ENXIO;
2120 		goto done2;
2121 	}
2122 	if (cdp != &ttydev_cdevsw) {
2123 		error = ENOTTY;
2124 		goto done2;
2125 	}
2126 	tp = dev->si_drv1;
2127 
2128 	/* Try to attach the hook to the TTY. */
2129 	error = EBUSY;
2130 	tty_lock(tp);
2131 	MPASS((tp->t_hook == NULL) == ((tp->t_flags & TF_HOOK) == 0));
2132 	if (tp->t_flags & TF_HOOK)
2133 		goto done3;
2134 
2135 	tp->t_flags |= TF_HOOK;
2136 	tp->t_hook = th;
2137 	tp->t_hooksoftc = softc;
2138 	*rtp = tp;
2139 	error = 0;
2140 
2141 	/* Maybe we can switch into bypass mode now. */
2142 	ttydisc_optimize(tp);
2143 
2144 	/* Silently convert rint() calls to rint_bypass() when possible. */
2145 	if (!ttyhook_hashook(tp, rint) && ttyhook_hashook(tp, rint_bypass))
2146 		th->th_rint = ttyhook_defrint;
2147 
2148 done3:	tty_unlock(tp);
2149 done2:	dev_relthread(dev, ref);
2150 done1:	fdrop(fp, curthread);
2151 	return (error);
2152 }
2153 
2154 void
2155 ttyhook_unregister(struct tty *tp)
2156 {
2157 
2158 	tty_assert_locked(tp);
2159 	MPASS(tp->t_flags & TF_HOOK);
2160 
2161 	/* Disconnect the hook. */
2162 	tp->t_flags &= ~TF_HOOK;
2163 	tp->t_hook = NULL;
2164 
2165 	/* Maybe we need to leave bypass mode. */
2166 	ttydisc_optimize(tp);
2167 
2168 	/* Maybe deallocate the TTY as well. */
2169 	tty_rel_free(tp);
2170 }
2171 
2172 /*
2173  * /dev/console handling.
2174  */
2175 
2176 static int
2177 ttyconsdev_open(struct cdev *dev, int oflags, int devtype, struct thread *td)
2178 {
2179 	struct tty *tp;
2180 
2181 	/* System has no console device. */
2182 	if (dev_console_filename == NULL)
2183 		return (ENXIO);
2184 
2185 	/* Look up corresponding TTY by device name. */
2186 	sx_slock(&tty_list_sx);
2187 	TAILQ_FOREACH(tp, &tty_list, t_list) {
2188 		if (strcmp(dev_console_filename, tty_devname(tp)) == 0) {
2189 			dev_console->si_drv1 = tp;
2190 			break;
2191 		}
2192 	}
2193 	sx_sunlock(&tty_list_sx);
2194 
2195 	/* System console has no TTY associated. */
2196 	if (dev_console->si_drv1 == NULL)
2197 		return (ENXIO);
2198 
2199 	return (ttydev_open(dev, oflags, devtype, td));
2200 }
2201 
2202 static int
2203 ttyconsdev_write(struct cdev *dev, struct uio *uio, int ioflag)
2204 {
2205 
2206 	log_console(uio);
2207 
2208 	return (ttydev_write(dev, uio, ioflag));
2209 }
2210 
2211 /*
2212  * /dev/console is a little different than normal TTY's.  When opened,
2213  * it determines which TTY to use.  When data gets written to it, it
2214  * will be logged in the kernel message buffer.
2215  */
2216 static struct cdevsw ttyconsdev_cdevsw = {
2217 	.d_version	= D_VERSION,
2218 	.d_open		= ttyconsdev_open,
2219 	.d_close	= ttydev_close,
2220 	.d_read		= ttydev_read,
2221 	.d_write	= ttyconsdev_write,
2222 	.d_ioctl	= ttydev_ioctl,
2223 	.d_kqfilter	= ttydev_kqfilter,
2224 	.d_poll		= ttydev_poll,
2225 	.d_mmap		= ttydev_mmap,
2226 	.d_name		= "ttyconsdev",
2227 	.d_flags	= D_TTY,
2228 };
2229 
2230 static void
2231 ttyconsdev_init(void *unused __unused)
2232 {
2233 
2234 	dev_console = make_dev_credf(MAKEDEV_ETERNAL, &ttyconsdev_cdevsw, 0,
2235 	    NULL, UID_ROOT, GID_WHEEL, 0600, "console");
2236 }
2237 
2238 SYSINIT(tty, SI_SUB_DRIVERS, SI_ORDER_FIRST, ttyconsdev_init, NULL);
2239 
2240 void
2241 ttyconsdev_select(const char *name)
2242 {
2243 
2244 	dev_console_filename = name;
2245 }
2246 
2247 /*
2248  * Debugging routines.
2249  */
2250 
2251 #include "opt_ddb.h"
2252 #ifdef DDB
2253 #include <ddb/ddb.h>
2254 #include <ddb/db_sym.h>
2255 
2256 static const struct {
2257 	int flag;
2258 	char val;
2259 } ttystates[] = {
2260 #if 0
2261 	{ TF_NOPREFIX,		'N' },
2262 #endif
2263 	{ TF_INITLOCK,		'I' },
2264 	{ TF_CALLOUT,		'C' },
2265 
2266 	/* Keep these together -> 'Oi' and 'Oo'. */
2267 	{ TF_OPENED,		'O' },
2268 	{ TF_OPENED_IN,		'i' },
2269 	{ TF_OPENED_OUT,	'o' },
2270 	{ TF_OPENED_CONS,	'c' },
2271 
2272 	{ TF_GONE,		'G' },
2273 	{ TF_OPENCLOSE,		'B' },
2274 	{ TF_ASYNC,		'Y' },
2275 	{ TF_LITERAL,		'L' },
2276 
2277 	/* Keep these together -> 'Hi' and 'Ho'. */
2278 	{ TF_HIWAT,		'H' },
2279 	{ TF_HIWAT_IN,		'i' },
2280 	{ TF_HIWAT_OUT,		'o' },
2281 
2282 	{ TF_STOPPED,		'S' },
2283 	{ TF_EXCLUDE,		'X' },
2284 	{ TF_BYPASS,		'l' },
2285 	{ TF_ZOMBIE,		'Z' },
2286 	{ TF_HOOK,		's' },
2287 
2288 	/* Keep these together -> 'bi' and 'bo'. */
2289 	{ TF_BUSY,		'b' },
2290 	{ TF_BUSY_IN,		'i' },
2291 	{ TF_BUSY_OUT,		'o' },
2292 
2293 	{ 0,			'\0'},
2294 };
2295 
2296 #define	TTY_FLAG_BITS \
2297 	"\20\1NOPREFIX\2INITLOCK\3CALLOUT\4OPENED_IN" \
2298 	"\5OPENED_OUT\6OPENED_CONS\7GONE\10OPENCLOSE" \
2299 	"\11ASYNC\12LITERAL\13HIWAT_IN\14HIWAT_OUT" \
2300 	"\15STOPPED\16EXCLUDE\17BYPASS\20ZOMBIE" \
2301 	"\21HOOK\22BUSY_IN\23BUSY_OUT"
2302 
2303 #define DB_PRINTSYM(name, addr) \
2304 	db_printf("%s  " #name ": ", sep); \
2305 	db_printsym((db_addr_t) addr, DB_STGY_ANY); \
2306 	db_printf("\n");
2307 
2308 static void
2309 _db_show_devsw(const char *sep, const struct ttydevsw *tsw)
2310 {
2311 
2312 	db_printf("%sdevsw: ", sep);
2313 	db_printsym((db_addr_t)tsw, DB_STGY_ANY);
2314 	db_printf(" (%p)\n", tsw);
2315 	DB_PRINTSYM(open, tsw->tsw_open);
2316 	DB_PRINTSYM(close, tsw->tsw_close);
2317 	DB_PRINTSYM(outwakeup, tsw->tsw_outwakeup);
2318 	DB_PRINTSYM(inwakeup, tsw->tsw_inwakeup);
2319 	DB_PRINTSYM(ioctl, tsw->tsw_ioctl);
2320 	DB_PRINTSYM(param, tsw->tsw_param);
2321 	DB_PRINTSYM(modem, tsw->tsw_modem);
2322 	DB_PRINTSYM(mmap, tsw->tsw_mmap);
2323 	DB_PRINTSYM(pktnotify, tsw->tsw_pktnotify);
2324 	DB_PRINTSYM(free, tsw->tsw_free);
2325 }
2326 
2327 static void
2328 _db_show_hooks(const char *sep, const struct ttyhook *th)
2329 {
2330 
2331 	db_printf("%shook: ", sep);
2332 	db_printsym((db_addr_t)th, DB_STGY_ANY);
2333 	db_printf(" (%p)\n", th);
2334 	if (th == NULL)
2335 		return;
2336 	DB_PRINTSYM(rint, th->th_rint);
2337 	DB_PRINTSYM(rint_bypass, th->th_rint_bypass);
2338 	DB_PRINTSYM(rint_done, th->th_rint_done);
2339 	DB_PRINTSYM(rint_poll, th->th_rint_poll);
2340 	DB_PRINTSYM(getc_inject, th->th_getc_inject);
2341 	DB_PRINTSYM(getc_capture, th->th_getc_capture);
2342 	DB_PRINTSYM(getc_poll, th->th_getc_poll);
2343 	DB_PRINTSYM(close, th->th_close);
2344 }
2345 
2346 static void
2347 _db_show_termios(const char *name, const struct termios *t)
2348 {
2349 
2350 	db_printf("%s: iflag 0x%x oflag 0x%x cflag 0x%x "
2351 	    "lflag 0x%x ispeed %u ospeed %u\n", name,
2352 	    t->c_iflag, t->c_oflag, t->c_cflag, t->c_lflag,
2353 	    t->c_ispeed, t->c_ospeed);
2354 }
2355 
2356 /* DDB command to show TTY statistics. */
2357 DB_SHOW_COMMAND(tty, db_show_tty)
2358 {
2359 	struct tty *tp;
2360 
2361 	if (!have_addr) {
2362 		db_printf("usage: show tty <addr>\n");
2363 		return;
2364 	}
2365 	tp = (struct tty *)addr;
2366 
2367 	db_printf("%p: %s\n", tp, tty_devname(tp));
2368 	db_printf("\tmtx: %p\n", tp->t_mtx);
2369 	db_printf("\tflags: 0x%b\n", tp->t_flags, TTY_FLAG_BITS);
2370 	db_printf("\trevokecnt: %u\n", tp->t_revokecnt);
2371 
2372 	/* Buffering mechanisms. */
2373 	db_printf("\tinq: %p begin %u linestart %u reprint %u end %u "
2374 	    "nblocks %u quota %u\n", &tp->t_inq, tp->t_inq.ti_begin,
2375 	    tp->t_inq.ti_linestart, tp->t_inq.ti_reprint, tp->t_inq.ti_end,
2376 	    tp->t_inq.ti_nblocks, tp->t_inq.ti_quota);
2377 	db_printf("\toutq: %p begin %u end %u nblocks %u quota %u\n",
2378 	    &tp->t_outq, tp->t_outq.to_begin, tp->t_outq.to_end,
2379 	    tp->t_outq.to_nblocks, tp->t_outq.to_quota);
2380 	db_printf("\tinlow: %zu\n", tp->t_inlow);
2381 	db_printf("\toutlow: %zu\n", tp->t_outlow);
2382 	_db_show_termios("\ttermios", &tp->t_termios);
2383 	db_printf("\twinsize: row %u col %u xpixel %u ypixel %u\n",
2384 	    tp->t_winsize.ws_row, tp->t_winsize.ws_col,
2385 	    tp->t_winsize.ws_xpixel, tp->t_winsize.ws_ypixel);
2386 	db_printf("\tcolumn: %u\n", tp->t_column);
2387 	db_printf("\twritepos: %u\n", tp->t_writepos);
2388 	db_printf("\tcompatflags: 0x%x\n", tp->t_compatflags);
2389 
2390 	/* Init/lock-state devices. */
2391 	_db_show_termios("\ttermios_init_in", &tp->t_termios_init_in);
2392 	_db_show_termios("\ttermios_init_out", &tp->t_termios_init_out);
2393 	_db_show_termios("\ttermios_lock_in", &tp->t_termios_lock_in);
2394 	_db_show_termios("\ttermios_lock_out", &tp->t_termios_lock_out);
2395 
2396 	/* Hooks */
2397 	_db_show_devsw("\t", tp->t_devsw);
2398 	_db_show_hooks("\t", tp->t_hook);
2399 
2400 	/* Process info. */
2401 	db_printf("\tpgrp: %p gid %d\n", tp->t_pgrp,
2402 	    tp->t_pgrp ? tp->t_pgrp->pg_id : 0);
2403 	db_printf("\tsession: %p", tp->t_session);
2404 	if (tp->t_session != NULL)
2405 	    db_printf(" count %u leader %p tty %p sid %d login %s",
2406 		tp->t_session->s_count, tp->t_session->s_leader,
2407 		tp->t_session->s_ttyp, tp->t_session->s_sid,
2408 		tp->t_session->s_login);
2409 	db_printf("\n");
2410 	db_printf("\tsessioncnt: %u\n", tp->t_sessioncnt);
2411 	db_printf("\tdevswsoftc: %p\n", tp->t_devswsoftc);
2412 	db_printf("\thooksoftc: %p\n", tp->t_hooksoftc);
2413 	db_printf("\tdev: %p\n", tp->t_dev);
2414 }
2415 
2416 /* DDB command to list TTYs. */
2417 DB_SHOW_ALL_COMMAND(ttys, db_show_all_ttys)
2418 {
2419 	struct tty *tp;
2420 	size_t isiz, osiz;
2421 	int i, j;
2422 
2423 	/* Make the output look like `pstat -t'. */
2424 	db_printf("PTR        ");
2425 #if defined(__LP64__)
2426 	db_printf("        ");
2427 #endif
2428 	db_printf("      LINE   INQ  CAN  LIN  LOW  OUTQ  USE  LOW   "
2429 	    "COL  SESS  PGID STATE\n");
2430 
2431 	TAILQ_FOREACH(tp, &tty_list, t_list) {
2432 		isiz = tp->t_inq.ti_nblocks * TTYINQ_DATASIZE;
2433 		osiz = tp->t_outq.to_nblocks * TTYOUTQ_DATASIZE;
2434 
2435 		db_printf("%p %10s %5zu %4u %4u %4zu %5zu %4u %4zu %5u %5d "
2436 		    "%5d ", tp, tty_devname(tp), isiz,
2437 		    tp->t_inq.ti_linestart - tp->t_inq.ti_begin,
2438 		    tp->t_inq.ti_end - tp->t_inq.ti_linestart,
2439 		    isiz - tp->t_inlow, osiz,
2440 		    tp->t_outq.to_end - tp->t_outq.to_begin,
2441 		    osiz - tp->t_outlow, MIN(tp->t_column, 99999),
2442 		    tp->t_session ? tp->t_session->s_sid : 0,
2443 		    tp->t_pgrp ? tp->t_pgrp->pg_id : 0);
2444 
2445 		/* Flag bits. */
2446 		for (i = j = 0; ttystates[i].flag; i++)
2447 			if (tp->t_flags & ttystates[i].flag) {
2448 				db_printf("%c", ttystates[i].val);
2449 				j++;
2450 			}
2451 		if (j == 0)
2452 			db_printf("-");
2453 		db_printf("\n");
2454 	}
2455 }
2456 #endif /* DDB */
2457