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/11.1/sys/kern/tty_pts.c 298819 2016-04-29 22:15:33Z pfg $");
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 #include <sys/user.h>
66
67 #include <machine/stdarg.h>
68
69 /*
70 * Our utmp(5) format is limited to 8-byte TTY line names. This means
71 * we can at most allocate 1000 pseudo-terminals ("pts/999"). Allow
72 * users to increase this number, assuming they have manually increased
73 * UT_LINESIZE.
74 */
75 static struct unrhdr *pts_pool;
76
77 static MALLOC_DEFINE(M_PTS, "pts", "pseudo tty device");
78
79 /*
80 * Per-PTS structure.
81 *
82 * List of locks
83 * (t) locked by tty_lock()
84 * (c) const until freeing
85 */
86 struct pts_softc {
87 int pts_unit; /* (c) Device unit number. */
88 unsigned int pts_flags; /* (t) Device flags. */
89 #define PTS_PKT 0x1 /* Packet mode. */
90 #define PTS_FINISHED 0x2 /* Return errors on read()/write(). */
91 char pts_pkt; /* (t) Unread packet mode data. */
92
93 struct cv pts_inwait; /* (t) Blocking write() on master. */
94 struct selinfo pts_inpoll; /* (t) Select queue for write(). */
95 struct cv pts_outwait; /* (t) Blocking read() on master. */
96 struct selinfo pts_outpoll; /* (t) Select queue for read(). */
97
98 #ifdef PTS_EXTERNAL
99 struct cdev *pts_cdev; /* (c) Master device node. */
100 #endif /* PTS_EXTERNAL */
101
102 struct ucred *pts_cred; /* (c) Resource limit. */
103 };
104
105 /*
106 * Controller-side file operations.
107 */
108
109 static int
110 ptsdev_read(struct file *fp, struct uio *uio, struct ucred *active_cred,
111 int flags, struct thread *td)
112 {
113 struct tty *tp = fp->f_data;
114 struct pts_softc *psc = tty_softc(tp);
115 int error = 0;
116 char pkt;
117
118 if (uio->uio_resid == 0)
119 return (0);
120
121 tty_lock(tp);
122
123 for (;;) {
124 /*
125 * Implement packet mode. When packet mode is turned on,
126 * the first byte contains a bitmask of events that
127 * occurred (start, stop, flush, window size, etc).
128 */
129 if (psc->pts_flags & PTS_PKT && psc->pts_pkt) {
130 pkt = psc->pts_pkt;
131 psc->pts_pkt = 0;
132 tty_unlock(tp);
133
134 error = ureadc(pkt, uio);
135 return (error);
136 }
137
138 /*
139 * Transmit regular data.
140 *
141 * XXX: We shouldn't use ttydisc_getc_poll()! Even
142 * though in this implementation, there is likely going
143 * to be data, we should just call ttydisc_getc_uio()
144 * and use its return value to sleep.
145 */
146 if (ttydisc_getc_poll(tp)) {
147 if (psc->pts_flags & PTS_PKT) {
148 /*
149 * XXX: Small race. Fortunately PTY
150 * consumers aren't multithreaded.
151 */
152
153 tty_unlock(tp);
154 error = ureadc(TIOCPKT_DATA, uio);
155 if (error)
156 return (error);
157 tty_lock(tp);
158 }
159
160 error = ttydisc_getc_uio(tp, uio);
161 break;
162 }
163
164 /* Maybe the device isn't used anyway. */
165 if (psc->pts_flags & PTS_FINISHED)
166 break;
167
168 /* Wait for more data. */
169 if (fp->f_flag & O_NONBLOCK) {
170 error = EWOULDBLOCK;
171 break;
172 }
173 error = cv_wait_sig(&psc->pts_outwait, tp->t_mtx);
174 if (error != 0)
175 break;
176 }
177
178 tty_unlock(tp);
179
180 return (error);
181 }
182
183 static int
184 ptsdev_write(struct file *fp, struct uio *uio, struct ucred *active_cred,
185 int flags, struct thread *td)
186 {
187 struct tty *tp = fp->f_data;
188 struct pts_softc *psc = tty_softc(tp);
189 char ib[256], *ibstart;
190 size_t iblen, rintlen;
191 int error = 0;
192
193 if (uio->uio_resid == 0)
194 return (0);
195
196 for (;;) {
197 ibstart = ib;
198 iblen = MIN(uio->uio_resid, sizeof ib);
199 error = uiomove(ib, iblen, uio);
200
201 tty_lock(tp);
202 if (error != 0) {
203 iblen = 0;
204 goto done;
205 }
206
207 /*
208 * When possible, avoid the slow path. rint_bypass()
209 * copies all input to the input queue at once.
210 */
211 MPASS(iblen > 0);
212 do {
213 rintlen = ttydisc_rint_simple(tp, ibstart, iblen);
214 ibstart += rintlen;
215 iblen -= rintlen;
216 if (iblen == 0) {
217 /* All data written. */
218 break;
219 }
220
221 /* Maybe the device isn't used anyway. */
222 if (psc->pts_flags & PTS_FINISHED) {
223 error = EIO;
224 goto done;
225 }
226
227 /* Wait for more data. */
228 if (fp->f_flag & O_NONBLOCK) {
229 error = EWOULDBLOCK;
230 goto done;
231 }
232
233 /* Wake up users on the slave side. */
234 ttydisc_rint_done(tp);
235 error = cv_wait_sig(&psc->pts_inwait, tp->t_mtx);
236 if (error != 0)
237 goto done;
238 } while (iblen > 0);
239
240 if (uio->uio_resid == 0)
241 break;
242 tty_unlock(tp);
243 }
244
245 done: ttydisc_rint_done(tp);
246 tty_unlock(tp);
247
248 /*
249 * Don't account for the part of the buffer that we couldn't
250 * pass to the TTY.
251 */
252 uio->uio_resid += iblen;
253 return (error);
254 }
255
256 static int
257 ptsdev_ioctl(struct file *fp, u_long cmd, void *data,
258 struct ucred *active_cred, struct thread *td)
259 {
260 struct tty *tp = fp->f_data;
261 struct pts_softc *psc = tty_softc(tp);
262 int error = 0, sig;
263
264 switch (cmd) {
265 case FIODTYPE:
266 *(int *)data = D_TTY;
267 return (0);
268 case FIONBIO:
269 /* This device supports non-blocking operation. */
270 return (0);
271 case FIONREAD:
272 tty_lock(tp);
273 if (psc->pts_flags & PTS_FINISHED) {
274 /* Force read() to be called. */
275 *(int *)data = 1;
276 } else {
277 *(int *)data = ttydisc_getc_poll(tp);
278 }
279 tty_unlock(tp);
280 return (0);
281 case FIODGNAME: {
282 struct fiodgname_arg *fgn;
283 const char *p;
284 int i;
285
286 /* Reverse device name lookups, for ptsname() and ttyname(). */
287 fgn = data;
288 p = tty_devname(tp);
289 i = strlen(p) + 1;
290 if (i > fgn->len)
291 return (EINVAL);
292 return copyout(p, fgn->buf, i);
293 }
294
295 /*
296 * We need to implement TIOCGPGRP and TIOCGSID here again. When
297 * called on the pseudo-terminal master, it should not check if
298 * the terminal is the foreground terminal of the calling
299 * process.
300 *
301 * TIOCGETA is also implemented here. Various Linux PTY routines
302 * often call isatty(), which is implemented by tcgetattr().
303 */
304 #ifdef PTS_LINUX
305 case TIOCGETA:
306 /* Obtain terminal flags through tcgetattr(). */
307 tty_lock(tp);
308 *(struct termios*)data = tp->t_termios;
309 tty_unlock(tp);
310 return (0);
311 #endif /* PTS_LINUX */
312 case TIOCSETAF:
313 case TIOCSETAW:
314 /*
315 * We must make sure we turn tcsetattr() calls of TCSAFLUSH and
316 * TCSADRAIN into something different. If an application would
317 * call TCSAFLUSH or TCSADRAIN on the master descriptor, it may
318 * deadlock waiting for all data to be read.
319 */
320 cmd = TIOCSETA;
321 break;
322 #if defined(PTS_COMPAT) || defined(PTS_LINUX)
323 case TIOCGPTN:
324 /*
325 * Get the device unit number.
326 */
327 if (psc->pts_unit < 0)
328 return (ENOTTY);
329 *(unsigned int *)data = psc->pts_unit;
330 return (0);
331 #endif /* PTS_COMPAT || PTS_LINUX */
332 case TIOCGPGRP:
333 /* Get the foreground process group ID. */
334 tty_lock(tp);
335 if (tp->t_pgrp != NULL)
336 *(int *)data = tp->t_pgrp->pg_id;
337 else
338 *(int *)data = NO_PID;
339 tty_unlock(tp);
340 return (0);
341 case TIOCGSID:
342 /* Get the session leader process ID. */
343 tty_lock(tp);
344 if (tp->t_session == NULL)
345 error = ENOTTY;
346 else
347 *(int *)data = tp->t_session->s_sid;
348 tty_unlock(tp);
349 return (error);
350 case TIOCPTMASTER:
351 /* Yes, we are a pseudo-terminal master. */
352 return (0);
353 case TIOCSIG:
354 /* Signal the foreground process group. */
355 sig = *(int *)data;
356 if (sig < 1 || sig >= NSIG)
357 return (EINVAL);
358
359 tty_lock(tp);
360 tty_signal_pgrp(tp, sig);
361 tty_unlock(tp);
362 return (0);
363 case TIOCPKT:
364 /* Enable/disable packet mode. */
365 tty_lock(tp);
366 if (*(int *)data)
367 psc->pts_flags |= PTS_PKT;
368 else
369 psc->pts_flags &= ~PTS_PKT;
370 tty_unlock(tp);
371 return (0);
372 }
373
374 /* Just redirect this ioctl to the slave device. */
375 tty_lock(tp);
376 error = tty_ioctl(tp, cmd, data, fp->f_flag, td);
377 tty_unlock(tp);
378 if (error == ENOIOCTL)
379 error = ENOTTY;
380
381 return (error);
382 }
383
384 static int
385 ptsdev_poll(struct file *fp, int events, struct ucred *active_cred,
386 struct thread *td)
387 {
388 struct tty *tp = fp->f_data;
389 struct pts_softc *psc = tty_softc(tp);
390 int revents = 0;
391
392 tty_lock(tp);
393
394 if (psc->pts_flags & PTS_FINISHED) {
395 /* Slave device is not opened. */
396 tty_unlock(tp);
397 return ((events & (POLLIN|POLLRDNORM)) | POLLHUP);
398 }
399
400 if (events & (POLLIN|POLLRDNORM)) {
401 /* See if we can getc something. */
402 if (ttydisc_getc_poll(tp) ||
403 (psc->pts_flags & PTS_PKT && psc->pts_pkt))
404 revents |= events & (POLLIN|POLLRDNORM);
405 }
406 if (events & (POLLOUT|POLLWRNORM)) {
407 /* See if we can rint something. */
408 if (ttydisc_rint_poll(tp))
409 revents |= events & (POLLOUT|POLLWRNORM);
410 }
411
412 /*
413 * No need to check for POLLHUP here. This device cannot be used
414 * as a callout device, which means we always have a carrier,
415 * because the master is.
416 */
417
418 if (revents == 0) {
419 /*
420 * This code might look misleading, but the naming of
421 * poll events on this side is the opposite of the slave
422 * device.
423 */
424 if (events & (POLLIN|POLLRDNORM))
425 selrecord(td, &psc->pts_outpoll);
426 if (events & (POLLOUT|POLLWRNORM))
427 selrecord(td, &psc->pts_inpoll);
428 }
429
430 tty_unlock(tp);
431
432 return (revents);
433 }
434
435 /*
436 * kqueue support.
437 */
438
439 static void
440 pts_kqops_read_detach(struct knote *kn)
441 {
442 struct file *fp = kn->kn_fp;
443 struct tty *tp = fp->f_data;
444 struct pts_softc *psc = tty_softc(tp);
445
446 knlist_remove(&psc->pts_outpoll.si_note, kn, 0);
447 }
448
449 static int
450 pts_kqops_read_event(struct knote *kn, long hint)
451 {
452 struct file *fp = kn->kn_fp;
453 struct tty *tp = fp->f_data;
454 struct pts_softc *psc = tty_softc(tp);
455
456 if (psc->pts_flags & PTS_FINISHED) {
457 kn->kn_flags |= EV_EOF;
458 return (1);
459 } else {
460 kn->kn_data = ttydisc_getc_poll(tp);
461 return (kn->kn_data > 0);
462 }
463 }
464
465 static void
466 pts_kqops_write_detach(struct knote *kn)
467 {
468 struct file *fp = kn->kn_fp;
469 struct tty *tp = fp->f_data;
470 struct pts_softc *psc = tty_softc(tp);
471
472 knlist_remove(&psc->pts_inpoll.si_note, kn, 0);
473 }
474
475 static int
476 pts_kqops_write_event(struct knote *kn, long hint)
477 {
478 struct file *fp = kn->kn_fp;
479 struct tty *tp = fp->f_data;
480 struct pts_softc *psc = tty_softc(tp);
481
482 if (psc->pts_flags & PTS_FINISHED) {
483 kn->kn_flags |= EV_EOF;
484 return (1);
485 } else {
486 kn->kn_data = ttydisc_rint_poll(tp);
487 return (kn->kn_data > 0);
488 }
489 }
490
491 static struct filterops pts_kqops_read = {
492 .f_isfd = 1,
493 .f_detach = pts_kqops_read_detach,
494 .f_event = pts_kqops_read_event,
495 };
496 static struct filterops pts_kqops_write = {
497 .f_isfd = 1,
498 .f_detach = pts_kqops_write_detach,
499 .f_event = pts_kqops_write_event,
500 };
501
502 static int
503 ptsdev_kqfilter(struct file *fp, struct knote *kn)
504 {
505 struct tty *tp = fp->f_data;
506 struct pts_softc *psc = tty_softc(tp);
507 int error = 0;
508
509 tty_lock(tp);
510
511 switch (kn->kn_filter) {
512 case EVFILT_READ:
513 kn->kn_fop = &pts_kqops_read;
514 knlist_add(&psc->pts_outpoll.si_note, kn, 1);
515 break;
516 case EVFILT_WRITE:
517 kn->kn_fop = &pts_kqops_write;
518 knlist_add(&psc->pts_inpoll.si_note, kn, 1);
519 break;
520 default:
521 error = EINVAL;
522 break;
523 }
524
525 tty_unlock(tp);
526 return (error);
527 }
528
529 static int
530 ptsdev_stat(struct file *fp, struct stat *sb, struct ucred *active_cred,
531 struct thread *td)
532 {
533 struct tty *tp = fp->f_data;
534 #ifdef PTS_EXTERNAL
535 struct pts_softc *psc = tty_softc(tp);
536 #endif /* PTS_EXTERNAL */
537 struct cdev *dev = tp->t_dev;
538
539 /*
540 * According to POSIX, we must implement an fstat(). This also
541 * makes this implementation compatible with Linux binaries,
542 * because Linux calls fstat() on the pseudo-terminal master to
543 * obtain st_rdev.
544 *
545 * XXX: POSIX also mentions we must fill in st_dev, but how?
546 */
547
548 bzero(sb, sizeof *sb);
549 #ifdef PTS_EXTERNAL
550 if (psc->pts_cdev != NULL)
551 sb->st_ino = sb->st_rdev = dev2udev(psc->pts_cdev);
552 else
553 #endif /* PTS_EXTERNAL */
554 sb->st_ino = sb->st_rdev = tty_udev(tp);
555
556 sb->st_atim = dev->si_atime;
557 sb->st_ctim = dev->si_ctime;
558 sb->st_mtim = dev->si_mtime;
559 sb->st_uid = dev->si_uid;
560 sb->st_gid = dev->si_gid;
561 sb->st_mode = dev->si_mode | S_IFCHR;
562
563 return (0);
564 }
565
566 static int
567 ptsdev_close(struct file *fp, struct thread *td)
568 {
569 struct tty *tp = fp->f_data;
570
571 /* Deallocate TTY device. */
572 tty_lock(tp);
573 tty_rel_gone(tp);
574
575 /*
576 * Open of /dev/ptmx or /dev/ptyXX changes the type of file
577 * from DTYPE_VNODE to DTYPE_PTS. vn_open() increases vnode
578 * use count, we need to decrement it, and possibly do other
579 * required cleanup.
580 */
581 if (fp->f_vnode != NULL)
582 return (vnops.fo_close(fp, td));
583
584 return (0);
585 }
586
587 static int
588 ptsdev_fill_kinfo(struct file *fp, struct kinfo_file *kif, struct filedesc *fdp)
589 {
590 struct tty *tp;
591
592 kif->kf_type = KF_TYPE_PTS;
593 tp = fp->f_data;
594 kif->kf_un.kf_pts.kf_pts_dev = tty_udev(tp);
595 strlcpy(kif->kf_path, tty_devname(tp), sizeof(kif->kf_path));
596 return (0);
597 }
598
599 static struct fileops ptsdev_ops = {
600 .fo_read = ptsdev_read,
601 .fo_write = ptsdev_write,
602 .fo_truncate = invfo_truncate,
603 .fo_ioctl = ptsdev_ioctl,
604 .fo_poll = ptsdev_poll,
605 .fo_kqfilter = ptsdev_kqfilter,
606 .fo_stat = ptsdev_stat,
607 .fo_close = ptsdev_close,
608 .fo_chmod = invfo_chmod,
609 .fo_chown = invfo_chown,
610 .fo_sendfile = invfo_sendfile,
611 .fo_fill_kinfo = ptsdev_fill_kinfo,
612 .fo_flags = DFLAG_PASSABLE,
613 };
614
615 /*
616 * Driver-side hooks.
617 */
618
619 static void
620 ptsdrv_outwakeup(struct tty *tp)
621 {
622 struct pts_softc *psc = tty_softc(tp);
623
624 cv_broadcast(&psc->pts_outwait);
625 selwakeup(&psc->pts_outpoll);
626 KNOTE_LOCKED(&psc->pts_outpoll.si_note, 0);
627 }
628
629 static void
630 ptsdrv_inwakeup(struct tty *tp)
631 {
632 struct pts_softc *psc = tty_softc(tp);
633
634 cv_broadcast(&psc->pts_inwait);
635 selwakeup(&psc->pts_inpoll);
636 KNOTE_LOCKED(&psc->pts_inpoll.si_note, 0);
637 }
638
639 static int
640 ptsdrv_open(struct tty *tp)
641 {
642 struct pts_softc *psc = tty_softc(tp);
643
644 psc->pts_flags &= ~PTS_FINISHED;
645
646 return (0);
647 }
648
649 static void
650 ptsdrv_close(struct tty *tp)
651 {
652 struct pts_softc *psc = tty_softc(tp);
653
654 /* Wake up any blocked readers/writers. */
655 psc->pts_flags |= PTS_FINISHED;
656 ptsdrv_outwakeup(tp);
657 ptsdrv_inwakeup(tp);
658 }
659
660 static void
661 ptsdrv_pktnotify(struct tty *tp, char event)
662 {
663 struct pts_softc *psc = tty_softc(tp);
664
665 /*
666 * Clear conflicting flags.
667 */
668
669 switch (event) {
670 case TIOCPKT_STOP:
671 psc->pts_pkt &= ~TIOCPKT_START;
672 break;
673 case TIOCPKT_START:
674 psc->pts_pkt &= ~TIOCPKT_STOP;
675 break;
676 case TIOCPKT_NOSTOP:
677 psc->pts_pkt &= ~TIOCPKT_DOSTOP;
678 break;
679 case TIOCPKT_DOSTOP:
680 psc->pts_pkt &= ~TIOCPKT_NOSTOP;
681 break;
682 }
683
684 psc->pts_pkt |= event;
685 ptsdrv_outwakeup(tp);
686 }
687
688 static void
689 ptsdrv_free(void *softc)
690 {
691 struct pts_softc *psc = softc;
692
693 /* Make device number available again. */
694 if (psc->pts_unit >= 0)
695 free_unr(pts_pool, psc->pts_unit);
696
697 chgptscnt(psc->pts_cred->cr_ruidinfo, -1, 0);
698 racct_sub_cred(psc->pts_cred, RACCT_NPTS, 1);
699 crfree(psc->pts_cred);
700
701 seldrain(&psc->pts_inpoll);
702 seldrain(&psc->pts_outpoll);
703 knlist_destroy(&psc->pts_inpoll.si_note);
704 knlist_destroy(&psc->pts_outpoll.si_note);
705
706 #ifdef PTS_EXTERNAL
707 /* Destroy master device as well. */
708 if (psc->pts_cdev != NULL)
709 destroy_dev_sched(psc->pts_cdev);
710 #endif /* PTS_EXTERNAL */
711
712 free(psc, M_PTS);
713 }
714
715 static struct ttydevsw pts_class = {
716 .tsw_flags = TF_NOPREFIX,
717 .tsw_outwakeup = ptsdrv_outwakeup,
718 .tsw_inwakeup = ptsdrv_inwakeup,
719 .tsw_open = ptsdrv_open,
720 .tsw_close = ptsdrv_close,
721 .tsw_pktnotify = ptsdrv_pktnotify,
722 .tsw_free = ptsdrv_free,
723 };
724
725 #ifndef PTS_EXTERNAL
726 static
727 #endif /* !PTS_EXTERNAL */
728 int
729 pts_alloc(int fflags, struct thread *td, struct file *fp)
730 {
731 int unit, ok, error;
732 struct tty *tp;
733 struct pts_softc *psc;
734 struct proc *p = td->td_proc;
735 struct ucred *cred = td->td_ucred;
736
737 /* Resource limiting. */
738 PROC_LOCK(p);
739 error = racct_add(p, RACCT_NPTS, 1);
740 if (error != 0) {
741 PROC_UNLOCK(p);
742 return (EAGAIN);
743 }
744 ok = chgptscnt(cred->cr_ruidinfo, 1, lim_cur(td, RLIMIT_NPTS));
745 if (!ok) {
746 racct_sub(p, RACCT_NPTS, 1);
747 PROC_UNLOCK(p);
748 return (EAGAIN);
749 }
750 PROC_UNLOCK(p);
751
752 /* Try to allocate a new pts unit number. */
753 unit = alloc_unr(pts_pool);
754 if (unit < 0) {
755 racct_sub(p, RACCT_NPTS, 1);
756 chgptscnt(cred->cr_ruidinfo, -1, 0);
757 return (EAGAIN);
758 }
759
760 /* Allocate TTY and softc. */
761 psc = malloc(sizeof(struct pts_softc), M_PTS, M_WAITOK|M_ZERO);
762 cv_init(&psc->pts_inwait, "ptsin");
763 cv_init(&psc->pts_outwait, "ptsout");
764
765 psc->pts_unit = unit;
766 psc->pts_cred = crhold(cred);
767
768 tp = tty_alloc(&pts_class, psc);
769 knlist_init_mtx(&psc->pts_inpoll.si_note, tp->t_mtx);
770 knlist_init_mtx(&psc->pts_outpoll.si_note, tp->t_mtx);
771
772 /* Expose the slave device as well. */
773 tty_makedev(tp, td->td_ucred, "pts/%u", psc->pts_unit);
774
775 finit(fp, fflags, DTYPE_PTS, tp, &ptsdev_ops);
776
777 return (0);
778 }
779
780 #ifdef PTS_EXTERNAL
781 int
782 pts_alloc_external(int fflags, struct thread *td, struct file *fp,
783 struct cdev *dev, const char *name)
784 {
785 int ok, error;
786 struct tty *tp;
787 struct pts_softc *psc;
788 struct proc *p = td->td_proc;
789 struct ucred *cred = td->td_ucred;
790
791 /* Resource limiting. */
792 PROC_LOCK(p);
793 error = racct_add(p, RACCT_NPTS, 1);
794 if (error != 0) {
795 PROC_UNLOCK(p);
796 return (EAGAIN);
797 }
798 ok = chgptscnt(cred->cr_ruidinfo, 1, lim_cur(td, RLIMIT_NPTS));
799 if (!ok) {
800 racct_sub(p, RACCT_NPTS, 1);
801 PROC_UNLOCK(p);
802 return (EAGAIN);
803 }
804 PROC_UNLOCK(p);
805
806 /* Allocate TTY and softc. */
807 psc = malloc(sizeof(struct pts_softc), M_PTS, M_WAITOK|M_ZERO);
808 cv_init(&psc->pts_inwait, "ptsin");
809 cv_init(&psc->pts_outwait, "ptsout");
810
811 psc->pts_unit = -1;
812 psc->pts_cdev = dev;
813 psc->pts_cred = crhold(cred);
814
815 tp = tty_alloc(&pts_class, psc);
816 knlist_init_mtx(&psc->pts_inpoll.si_note, tp->t_mtx);
817 knlist_init_mtx(&psc->pts_outpoll.si_note, tp->t_mtx);
818
819 /* Expose the slave device as well. */
820 tty_makedev(tp, td->td_ucred, "%s", name);
821
822 finit(fp, fflags, DTYPE_PTS, tp, &ptsdev_ops);
823
824 return (0);
825 }
826 #endif /* PTS_EXTERNAL */
827
828 int
829 sys_posix_openpt(struct thread *td, struct posix_openpt_args *uap)
830 {
831 int error, fd;
832 struct file *fp;
833
834 /*
835 * POSIX states it's unspecified when other flags are passed. We
836 * don't allow this.
837 */
838 if (uap->flags & ~(O_RDWR|O_NOCTTY|O_CLOEXEC))
839 return (EINVAL);
840
841 error = falloc(td, &fp, &fd, uap->flags);
842 if (error)
843 return (error);
844
845 /* Allocate the actual pseudo-TTY. */
846 error = pts_alloc(FFLAGS(uap->flags & O_ACCMODE), td, fp);
847 if (error != 0) {
848 fdclose(td, fp, fd);
849 fdrop(fp, td);
850 return (error);
851 }
852
853 /* Pass it back to userspace. */
854 td->td_retval[0] = fd;
855 fdrop(fp, td);
856
857 return (0);
858 }
859
860 static void
861 pts_init(void *unused)
862 {
863
864 pts_pool = new_unrhdr(0, INT_MAX, NULL);
865 }
866
867 SYSINIT(pts, SI_SUB_DRIVERS, SI_ORDER_MIDDLE, pts_init, NULL);
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