FreeBSD/Linux Kernel Cross Reference
sys/kern/tty_pts.c
1 /*-
2 * Copyright (c) 2008 Ed Schouten <ed@FreeBSD.org>
3 * All rights reserved.
4 *
5 * Portions of this software were developed under sponsorship from Snow
6 * B.V., the Netherlands.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 */
29
30 #include <sys/cdefs.h>
31 __FBSDID("$FreeBSD: releng/9.2/sys/kern/tty_pts.c 250973 2013-05-24 18:59:44Z jilles $");
32
33 /* Add compatibility bits for FreeBSD. */
34 #define PTS_COMPAT
35 /* Add pty(4) compat bits. */
36 #define PTS_EXTERNAL
37 /* Add bits to make Linux binaries work. */
38 #define PTS_LINUX
39
40 #include <sys/param.h>
41 #include <sys/lock.h>
42 #include <sys/condvar.h>
43 #include <sys/conf.h>
44 #include <sys/fcntl.h>
45 #include <sys/file.h>
46 #include <sys/filedesc.h>
47 #include <sys/filio.h>
48 #include <sys/kernel.h>
49 #include <sys/limits.h>
50 #include <sys/malloc.h>
51 #include <sys/poll.h>
52 #include <sys/proc.h>
53 #include <sys/racct.h>
54 #include <sys/resourcevar.h>
55 #include <sys/serial.h>
56 #include <sys/stat.h>
57 #include <sys/syscall.h>
58 #include <sys/syscallsubr.h>
59 #include <sys/sysctl.h>
60 #include <sys/sysent.h>
61 #include <sys/sysproto.h>
62 #include <sys/systm.h>
63 #include <sys/tty.h>
64 #include <sys/ttycom.h>
65
66 #include <machine/stdarg.h>
67
68 /*
69 * Our utmp(5) format is limited to 8-byte TTY line names. This means
70 * we can at most allocate 1000 pseudo-terminals ("pts/999"). Allow
71 * users to increase this number, assuming they have manually increased
72 * UT_LINESIZE.
73 */
74 static struct unrhdr *pts_pool;
75
76 static MALLOC_DEFINE(M_PTS, "pts", "pseudo tty device");
77
78 /*
79 * Per-PTS structure.
80 *
81 * List of locks
82 * (t) locked by tty_lock()
83 * (c) const until freeing
84 */
85 struct pts_softc {
86 int pts_unit; /* (c) Device unit number. */
87 unsigned int pts_flags; /* (t) Device flags. */
88 #define PTS_PKT 0x1 /* Packet mode. */
89 #define PTS_FINISHED 0x2 /* Return errors on read()/write(). */
90 char pts_pkt; /* (t) Unread packet mode data. */
91
92 struct cv pts_inwait; /* (t) Blocking write() on master. */
93 struct selinfo pts_inpoll; /* (t) Select queue for write(). */
94 struct cv pts_outwait; /* (t) Blocking read() on master. */
95 struct selinfo pts_outpoll; /* (t) Select queue for read(). */
96
97 #ifdef PTS_EXTERNAL
98 struct cdev *pts_cdev; /* (c) Master device node. */
99 #endif /* PTS_EXTERNAL */
100
101 struct ucred *pts_cred; /* (c) Resource limit. */
102 };
103
104 /*
105 * Controller-side file operations.
106 */
107
108 static int
109 ptsdev_read(struct file *fp, struct uio *uio, struct ucred *active_cred,
110 int flags, struct thread *td)
111 {
112 struct tty *tp = fp->f_data;
113 struct pts_softc *psc = tty_softc(tp);
114 int error = 0;
115 char pkt;
116
117 if (uio->uio_resid == 0)
118 return (0);
119
120 tty_lock(tp);
121
122 for (;;) {
123 /*
124 * Implement packet mode. When packet mode is turned on,
125 * the first byte contains a bitmask of events that
126 * occured (start, stop, flush, window size, etc).
127 */
128 if (psc->pts_flags & PTS_PKT && psc->pts_pkt) {
129 pkt = psc->pts_pkt;
130 psc->pts_pkt = 0;
131 tty_unlock(tp);
132
133 error = ureadc(pkt, uio);
134 return (error);
135 }
136
137 /*
138 * Transmit regular data.
139 *
140 * XXX: We shouldn't use ttydisc_getc_poll()! Even
141 * though in this implementation, there is likely going
142 * to be data, we should just call ttydisc_getc_uio()
143 * and use its return value to sleep.
144 */
145 if (ttydisc_getc_poll(tp)) {
146 if (psc->pts_flags & PTS_PKT) {
147 /*
148 * XXX: Small race. Fortunately PTY
149 * consumers aren't multithreaded.
150 */
151
152 tty_unlock(tp);
153 error = ureadc(TIOCPKT_DATA, uio);
154 if (error)
155 return (error);
156 tty_lock(tp);
157 }
158
159 error = ttydisc_getc_uio(tp, uio);
160 break;
161 }
162
163 /* Maybe the device isn't used anyway. */
164 if (psc->pts_flags & PTS_FINISHED)
165 break;
166
167 /* Wait for more data. */
168 if (fp->f_flag & O_NONBLOCK) {
169 error = EWOULDBLOCK;
170 break;
171 }
172 error = cv_wait_sig(&psc->pts_outwait, tp->t_mtx);
173 if (error != 0)
174 break;
175 }
176
177 tty_unlock(tp);
178
179 return (error);
180 }
181
182 static int
183 ptsdev_write(struct file *fp, struct uio *uio, struct ucred *active_cred,
184 int flags, struct thread *td)
185 {
186 struct tty *tp = fp->f_data;
187 struct pts_softc *psc = tty_softc(tp);
188 char ib[256], *ibstart;
189 size_t iblen, rintlen;
190 int error = 0;
191
192 if (uio->uio_resid == 0)
193 return (0);
194
195 for (;;) {
196 ibstart = ib;
197 iblen = MIN(uio->uio_resid, sizeof ib);
198 error = uiomove(ib, iblen, uio);
199
200 tty_lock(tp);
201 if (error != 0) {
202 iblen = 0;
203 goto done;
204 }
205
206 /*
207 * When possible, avoid the slow path. rint_bypass()
208 * copies all input to the input queue at once.
209 */
210 MPASS(iblen > 0);
211 do {
212 rintlen = ttydisc_rint_simple(tp, ibstart, iblen);
213 ibstart += rintlen;
214 iblen -= rintlen;
215 if (iblen == 0) {
216 /* All data written. */
217 break;
218 }
219
220 /* Maybe the device isn't used anyway. */
221 if (psc->pts_flags & PTS_FINISHED) {
222 error = EIO;
223 goto done;
224 }
225
226 /* Wait for more data. */
227 if (fp->f_flag & O_NONBLOCK) {
228 error = EWOULDBLOCK;
229 goto done;
230 }
231
232 /* Wake up users on the slave side. */
233 ttydisc_rint_done(tp);
234 error = cv_wait_sig(&psc->pts_inwait, tp->t_mtx);
235 if (error != 0)
236 goto done;
237 } while (iblen > 0);
238
239 if (uio->uio_resid == 0)
240 break;
241 tty_unlock(tp);
242 }
243
244 done: ttydisc_rint_done(tp);
245 tty_unlock(tp);
246
247 /*
248 * Don't account for the part of the buffer that we couldn't
249 * pass to the TTY.
250 */
251 uio->uio_resid += iblen;
252 return (error);
253 }
254
255 static int
256 ptsdev_truncate(struct file *fp, off_t length, struct ucred *active_cred,
257 struct thread *td)
258 {
259
260 return (EINVAL);
261 }
262
263 static int
264 ptsdev_ioctl(struct file *fp, u_long cmd, void *data,
265 struct ucred *active_cred, struct thread *td)
266 {
267 struct tty *tp = fp->f_data;
268 struct pts_softc *psc = tty_softc(tp);
269 int error = 0, sig;
270
271 switch (cmd) {
272 case FIONBIO:
273 /* This device supports non-blocking operation. */
274 return (0);
275 case FIONREAD:
276 tty_lock(tp);
277 if (psc->pts_flags & PTS_FINISHED) {
278 /* Force read() to be called. */
279 *(int *)data = 1;
280 } else {
281 *(int *)data = ttydisc_getc_poll(tp);
282 }
283 tty_unlock(tp);
284 return (0);
285 case FIODGNAME: {
286 struct fiodgname_arg *fgn;
287 const char *p;
288 int i;
289
290 /* Reverse device name lookups, for ptsname() and ttyname(). */
291 fgn = data;
292 p = tty_devname(tp);
293 i = strlen(p) + 1;
294 if (i > fgn->len)
295 return (EINVAL);
296 return copyout(p, fgn->buf, i);
297 }
298
299 /*
300 * We need to implement TIOCGPGRP and TIOCGSID here again. When
301 * called on the pseudo-terminal master, it should not check if
302 * the terminal is the foreground terminal of the calling
303 * process.
304 *
305 * TIOCGETA is also implemented here. Various Linux PTY routines
306 * often call isatty(), which is implemented by tcgetattr().
307 */
308 #ifdef PTS_LINUX
309 case TIOCGETA:
310 /* Obtain terminal flags through tcgetattr(). */
311 tty_lock(tp);
312 *(struct termios*)data = tp->t_termios;
313 tty_unlock(tp);
314 return (0);
315 #endif /* PTS_LINUX */
316 case TIOCSETAF:
317 case TIOCSETAW:
318 /*
319 * We must make sure we turn tcsetattr() calls of TCSAFLUSH and
320 * TCSADRAIN into something different. If an application would
321 * call TCSAFLUSH or TCSADRAIN on the master descriptor, it may
322 * deadlock waiting for all data to be read.
323 */
324 cmd = TIOCSETA;
325 break;
326 #if defined(PTS_COMPAT) || defined(PTS_LINUX)
327 case TIOCGPTN:
328 /*
329 * Get the device unit number.
330 */
331 if (psc->pts_unit < 0)
332 return (ENOTTY);
333 *(unsigned int *)data = psc->pts_unit;
334 return (0);
335 #endif /* PTS_COMPAT || PTS_LINUX */
336 case TIOCGPGRP:
337 /* Get the foreground process group ID. */
338 tty_lock(tp);
339 if (tp->t_pgrp != NULL)
340 *(int *)data = tp->t_pgrp->pg_id;
341 else
342 *(int *)data = NO_PID;
343 tty_unlock(tp);
344 return (0);
345 case TIOCGSID:
346 /* Get the session leader process ID. */
347 tty_lock(tp);
348 if (tp->t_session == NULL)
349 error = ENOTTY;
350 else
351 *(int *)data = tp->t_session->s_sid;
352 tty_unlock(tp);
353 return (error);
354 case TIOCPTMASTER:
355 /* Yes, we are a pseudo-terminal master. */
356 return (0);
357 case TIOCSIG:
358 /* Signal the foreground process group. */
359 sig = *(int *)data;
360 if (sig < 1 || sig >= NSIG)
361 return (EINVAL);
362
363 tty_lock(tp);
364 tty_signal_pgrp(tp, sig);
365 tty_unlock(tp);
366 return (0);
367 case TIOCPKT:
368 /* Enable/disable packet mode. */
369 tty_lock(tp);
370 if (*(int *)data)
371 psc->pts_flags |= PTS_PKT;
372 else
373 psc->pts_flags &= ~PTS_PKT;
374 tty_unlock(tp);
375 return (0);
376 }
377
378 /* Just redirect this ioctl to the slave device. */
379 tty_lock(tp);
380 error = tty_ioctl(tp, cmd, data, fp->f_flag, td);
381 tty_unlock(tp);
382 if (error == ENOIOCTL)
383 error = ENOTTY;
384
385 return (error);
386 }
387
388 static int
389 ptsdev_poll(struct file *fp, int events, struct ucred *active_cred,
390 struct thread *td)
391 {
392 struct tty *tp = fp->f_data;
393 struct pts_softc *psc = tty_softc(tp);
394 int revents = 0;
395
396 tty_lock(tp);
397
398 if (psc->pts_flags & PTS_FINISHED) {
399 /* Slave device is not opened. */
400 tty_unlock(tp);
401 return ((events & (POLLIN|POLLRDNORM)) | POLLHUP);
402 }
403
404 if (events & (POLLIN|POLLRDNORM)) {
405 /* See if we can getc something. */
406 if (ttydisc_getc_poll(tp) ||
407 (psc->pts_flags & PTS_PKT && psc->pts_pkt))
408 revents |= events & (POLLIN|POLLRDNORM);
409 }
410 if (events & (POLLOUT|POLLWRNORM)) {
411 /* See if we can rint something. */
412 if (ttydisc_rint_poll(tp))
413 revents |= events & (POLLOUT|POLLWRNORM);
414 }
415
416 /*
417 * No need to check for POLLHUP here. This device cannot be used
418 * as a callout device, which means we always have a carrier,
419 * because the master is.
420 */
421
422 if (revents == 0) {
423 /*
424 * This code might look misleading, but the naming of
425 * poll events on this side is the opposite of the slave
426 * device.
427 */
428 if (events & (POLLIN|POLLRDNORM))
429 selrecord(td, &psc->pts_outpoll);
430 if (events & (POLLOUT|POLLWRNORM))
431 selrecord(td, &psc->pts_inpoll);
432 }
433
434 tty_unlock(tp);
435
436 return (revents);
437 }
438
439 /*
440 * kqueue support.
441 */
442
443 static void
444 pts_kqops_read_detach(struct knote *kn)
445 {
446 struct file *fp = kn->kn_fp;
447 struct tty *tp = fp->f_data;
448 struct pts_softc *psc = tty_softc(tp);
449
450 knlist_remove(&psc->pts_outpoll.si_note, kn, 0);
451 }
452
453 static int
454 pts_kqops_read_event(struct knote *kn, long hint)
455 {
456 struct file *fp = kn->kn_fp;
457 struct tty *tp = fp->f_data;
458 struct pts_softc *psc = tty_softc(tp);
459
460 if (psc->pts_flags & PTS_FINISHED) {
461 kn->kn_flags |= EV_EOF;
462 return (1);
463 } else {
464 kn->kn_data = ttydisc_getc_poll(tp);
465 return (kn->kn_data > 0);
466 }
467 }
468
469 static void
470 pts_kqops_write_detach(struct knote *kn)
471 {
472 struct file *fp = kn->kn_fp;
473 struct tty *tp = fp->f_data;
474 struct pts_softc *psc = tty_softc(tp);
475
476 knlist_remove(&psc->pts_inpoll.si_note, kn, 0);
477 }
478
479 static int
480 pts_kqops_write_event(struct knote *kn, long hint)
481 {
482 struct file *fp = kn->kn_fp;
483 struct tty *tp = fp->f_data;
484 struct pts_softc *psc = tty_softc(tp);
485
486 if (psc->pts_flags & PTS_FINISHED) {
487 kn->kn_flags |= EV_EOF;
488 return (1);
489 } else {
490 kn->kn_data = ttydisc_rint_poll(tp);
491 return (kn->kn_data > 0);
492 }
493 }
494
495 static struct filterops pts_kqops_read = {
496 .f_isfd = 1,
497 .f_detach = pts_kqops_read_detach,
498 .f_event = pts_kqops_read_event,
499 };
500 static struct filterops pts_kqops_write = {
501 .f_isfd = 1,
502 .f_detach = pts_kqops_write_detach,
503 .f_event = pts_kqops_write_event,
504 };
505
506 static int
507 ptsdev_kqfilter(struct file *fp, struct knote *kn)
508 {
509 struct tty *tp = fp->f_data;
510 struct pts_softc *psc = tty_softc(tp);
511 int error = 0;
512
513 tty_lock(tp);
514
515 switch (kn->kn_filter) {
516 case EVFILT_READ:
517 kn->kn_fop = &pts_kqops_read;
518 knlist_add(&psc->pts_outpoll.si_note, kn, 1);
519 break;
520 case EVFILT_WRITE:
521 kn->kn_fop = &pts_kqops_write;
522 knlist_add(&psc->pts_inpoll.si_note, kn, 1);
523 break;
524 default:
525 error = EINVAL;
526 break;
527 }
528
529 tty_unlock(tp);
530 return (error);
531 }
532
533 static int
534 ptsdev_stat(struct file *fp, struct stat *sb, struct ucred *active_cred,
535 struct thread *td)
536 {
537 struct tty *tp = fp->f_data;
538 #ifdef PTS_EXTERNAL
539 struct pts_softc *psc = tty_softc(tp);
540 #endif /* PTS_EXTERNAL */
541 struct cdev *dev = tp->t_dev;
542
543 /*
544 * According to POSIX, we must implement an fstat(). This also
545 * makes this implementation compatible with Linux binaries,
546 * because Linux calls fstat() on the pseudo-terminal master to
547 * obtain st_rdev.
548 *
549 * XXX: POSIX also mentions we must fill in st_dev, but how?
550 */
551
552 bzero(sb, sizeof *sb);
553 #ifdef PTS_EXTERNAL
554 if (psc->pts_cdev != NULL)
555 sb->st_ino = sb->st_rdev = dev2udev(psc->pts_cdev);
556 else
557 #endif /* PTS_EXTERNAL */
558 sb->st_ino = sb->st_rdev = tty_udev(tp);
559
560 sb->st_atim = dev->si_atime;
561 sb->st_ctim = dev->si_ctime;
562 sb->st_mtim = dev->si_mtime;
563 sb->st_uid = dev->si_uid;
564 sb->st_gid = dev->si_gid;
565 sb->st_mode = dev->si_mode | S_IFCHR;
566
567 return (0);
568 }
569
570 static int
571 ptsdev_close(struct file *fp, struct thread *td)
572 {
573 struct tty *tp = fp->f_data;
574
575 /* Deallocate TTY device. */
576 tty_lock(tp);
577 tty_rel_gone(tp);
578
579 /*
580 * Open of /dev/ptmx or /dev/ptyXX changes the type of file
581 * from DTYPE_VNODE to DTYPE_PTS. vn_open() increases vnode
582 * use count, we need to decrement it, and possibly do other
583 * required cleanup.
584 */
585 if (fp->f_vnode != NULL)
586 return (vnops.fo_close(fp, td));
587
588 return (0);
589 }
590
591 static struct fileops ptsdev_ops = {
592 .fo_read = ptsdev_read,
593 .fo_write = ptsdev_write,
594 .fo_truncate = ptsdev_truncate,
595 .fo_ioctl = ptsdev_ioctl,
596 .fo_poll = ptsdev_poll,
597 .fo_kqfilter = ptsdev_kqfilter,
598 .fo_stat = ptsdev_stat,
599 .fo_close = ptsdev_close,
600 .fo_chmod = invfo_chmod,
601 .fo_chown = invfo_chown,
602 .fo_flags = DFLAG_PASSABLE,
603 };
604
605 /*
606 * Driver-side hooks.
607 */
608
609 static void
610 ptsdrv_outwakeup(struct tty *tp)
611 {
612 struct pts_softc *psc = tty_softc(tp);
613
614 cv_broadcast(&psc->pts_outwait);
615 selwakeup(&psc->pts_outpoll);
616 KNOTE_LOCKED(&psc->pts_outpoll.si_note, 0);
617 }
618
619 static void
620 ptsdrv_inwakeup(struct tty *tp)
621 {
622 struct pts_softc *psc = tty_softc(tp);
623
624 cv_broadcast(&psc->pts_inwait);
625 selwakeup(&psc->pts_inpoll);
626 KNOTE_LOCKED(&psc->pts_inpoll.si_note, 0);
627 }
628
629 static int
630 ptsdrv_open(struct tty *tp)
631 {
632 struct pts_softc *psc = tty_softc(tp);
633
634 psc->pts_flags &= ~PTS_FINISHED;
635
636 return (0);
637 }
638
639 static void
640 ptsdrv_close(struct tty *tp)
641 {
642 struct pts_softc *psc = tty_softc(tp);
643
644 /* Wake up any blocked readers/writers. */
645 psc->pts_flags |= PTS_FINISHED;
646 ptsdrv_outwakeup(tp);
647 ptsdrv_inwakeup(tp);
648 }
649
650 static void
651 ptsdrv_pktnotify(struct tty *tp, char event)
652 {
653 struct pts_softc *psc = tty_softc(tp);
654
655 /*
656 * Clear conflicting flags.
657 */
658
659 switch (event) {
660 case TIOCPKT_STOP:
661 psc->pts_pkt &= ~TIOCPKT_START;
662 break;
663 case TIOCPKT_START:
664 psc->pts_pkt &= ~TIOCPKT_STOP;
665 break;
666 case TIOCPKT_NOSTOP:
667 psc->pts_pkt &= ~TIOCPKT_DOSTOP;
668 break;
669 case TIOCPKT_DOSTOP:
670 psc->pts_pkt &= ~TIOCPKT_NOSTOP;
671 break;
672 }
673
674 psc->pts_pkt |= event;
675 ptsdrv_outwakeup(tp);
676 }
677
678 static void
679 ptsdrv_free(void *softc)
680 {
681 struct pts_softc *psc = softc;
682
683 /* Make device number available again. */
684 if (psc->pts_unit >= 0)
685 free_unr(pts_pool, psc->pts_unit);
686
687 chgptscnt(psc->pts_cred->cr_ruidinfo, -1, 0);
688 racct_sub_cred(psc->pts_cred, RACCT_NPTS, 1);
689 crfree(psc->pts_cred);
690
691 seldrain(&psc->pts_inpoll);
692 seldrain(&psc->pts_outpoll);
693 knlist_destroy(&psc->pts_inpoll.si_note);
694 knlist_destroy(&psc->pts_outpoll.si_note);
695
696 #ifdef PTS_EXTERNAL
697 /* Destroy master device as well. */
698 if (psc->pts_cdev != NULL)
699 destroy_dev_sched(psc->pts_cdev);
700 #endif /* PTS_EXTERNAL */
701
702 free(psc, M_PTS);
703 }
704
705 static struct ttydevsw pts_class = {
706 .tsw_flags = TF_NOPREFIX,
707 .tsw_outwakeup = ptsdrv_outwakeup,
708 .tsw_inwakeup = ptsdrv_inwakeup,
709 .tsw_open = ptsdrv_open,
710 .tsw_close = ptsdrv_close,
711 .tsw_pktnotify = ptsdrv_pktnotify,
712 .tsw_free = ptsdrv_free,
713 };
714
715 #ifndef PTS_EXTERNAL
716 static
717 #endif /* !PTS_EXTERNAL */
718 int
719 pts_alloc(int fflags, struct thread *td, struct file *fp)
720 {
721 int unit, ok, error;
722 struct tty *tp;
723 struct pts_softc *psc;
724 struct proc *p = td->td_proc;
725 struct ucred *cred = td->td_ucred;
726
727 /* Resource limiting. */
728 PROC_LOCK(p);
729 error = racct_add(p, RACCT_NPTS, 1);
730 if (error != 0) {
731 PROC_UNLOCK(p);
732 return (EAGAIN);
733 }
734 ok = chgptscnt(cred->cr_ruidinfo, 1, lim_cur(p, RLIMIT_NPTS));
735 if (!ok) {
736 racct_sub(p, RACCT_NPTS, 1);
737 PROC_UNLOCK(p);
738 return (EAGAIN);
739 }
740 PROC_UNLOCK(p);
741
742 /* Try to allocate a new pts unit number. */
743 unit = alloc_unr(pts_pool);
744 if (unit < 0) {
745 racct_sub(p, RACCT_NPTS, 1);
746 chgptscnt(cred->cr_ruidinfo, -1, 0);
747 return (EAGAIN);
748 }
749
750 /* Allocate TTY and softc. */
751 psc = malloc(sizeof(struct pts_softc), M_PTS, M_WAITOK|M_ZERO);
752 cv_init(&psc->pts_inwait, "ptsin");
753 cv_init(&psc->pts_outwait, "ptsout");
754
755 psc->pts_unit = unit;
756 psc->pts_cred = crhold(cred);
757
758 tp = tty_alloc(&pts_class, psc);
759 knlist_init_mtx(&psc->pts_inpoll.si_note, tp->t_mtx);
760 knlist_init_mtx(&psc->pts_outpoll.si_note, tp->t_mtx);
761
762 /* Expose the slave device as well. */
763 tty_makedev(tp, td->td_ucred, "pts/%u", psc->pts_unit);
764
765 finit(fp, fflags, DTYPE_PTS, tp, &ptsdev_ops);
766
767 return (0);
768 }
769
770 #ifdef PTS_EXTERNAL
771 int
772 pts_alloc_external(int fflags, struct thread *td, struct file *fp,
773 struct cdev *dev, const char *name)
774 {
775 int ok, error;
776 struct tty *tp;
777 struct pts_softc *psc;
778 struct proc *p = td->td_proc;
779 struct ucred *cred = td->td_ucred;
780
781 /* Resource limiting. */
782 PROC_LOCK(p);
783 error = racct_add(p, RACCT_NPTS, 1);
784 if (error != 0) {
785 PROC_UNLOCK(p);
786 return (EAGAIN);
787 }
788 ok = chgptscnt(cred->cr_ruidinfo, 1, lim_cur(p, RLIMIT_NPTS));
789 if (!ok) {
790 racct_sub(p, RACCT_NPTS, 1);
791 PROC_UNLOCK(p);
792 return (EAGAIN);
793 }
794 PROC_UNLOCK(p);
795
796 /* Allocate TTY and softc. */
797 psc = malloc(sizeof(struct pts_softc), M_PTS, M_WAITOK|M_ZERO);
798 cv_init(&psc->pts_inwait, "ptsin");
799 cv_init(&psc->pts_outwait, "ptsout");
800
801 psc->pts_unit = -1;
802 psc->pts_cdev = dev;
803 psc->pts_cred = crhold(cred);
804
805 tp = tty_alloc(&pts_class, psc);
806 knlist_init_mtx(&psc->pts_inpoll.si_note, tp->t_mtx);
807 knlist_init_mtx(&psc->pts_outpoll.si_note, tp->t_mtx);
808
809 /* Expose the slave device as well. */
810 tty_makedev(tp, td->td_ucred, "%s", name);
811
812 finit(fp, fflags, DTYPE_PTS, tp, &ptsdev_ops);
813
814 return (0);
815 }
816 #endif /* PTS_EXTERNAL */
817
818 int
819 sys_posix_openpt(struct thread *td, struct posix_openpt_args *uap)
820 {
821 int error, fd;
822 struct file *fp;
823
824 /*
825 * POSIX states it's unspecified when other flags are passed. We
826 * don't allow this.
827 */
828 if (uap->flags & ~(O_RDWR|O_NOCTTY|O_CLOEXEC))
829 return (EINVAL);
830
831 error = falloc(td, &fp, &fd, uap->flags);
832 if (error)
833 return (error);
834
835 /* Allocate the actual pseudo-TTY. */
836 error = pts_alloc(FFLAGS(uap->flags & O_ACCMODE), td, fp);
837 if (error != 0) {
838 fdclose(td->td_proc->p_fd, fp, fd, td);
839 fdrop(fp, td);
840 return (error);
841 }
842
843 /* Pass it back to userspace. */
844 td->td_retval[0] = fd;
845 fdrop(fp, td);
846
847 return (0);
848 }
849
850 static void
851 pts_init(void *unused)
852 {
853
854 pts_pool = new_unrhdr(0, INT_MAX, NULL);
855 }
856
857 SYSINIT(pts, SI_SUB_DRIVERS, SI_ORDER_MIDDLE, pts_init, NULL);
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