FreeBSD/Linux Kernel Cross Reference
sys/kern/tty_pts.c
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 /* Add compatibility bits for FreeBSD. */
36 #define PTS_COMPAT
37 /* Add pty(4) compat bits. */
38 #define PTS_EXTERNAL
39 /* Add bits to make Linux binaries work. */
40 #define PTS_LINUX
41
42 #include <sys/param.h>
43 #include <sys/lock.h>
44 #include <sys/condvar.h>
45 #include <sys/conf.h>
46 #include <sys/fcntl.h>
47 #include <sys/file.h>
48 #include <sys/filedesc.h>
49 #include <sys/filio.h>
50 #include <sys/kernel.h>
51 #include <sys/limits.h>
52 #include <sys/malloc.h>
53 #include <sys/mutex.h>
54 #include <sys/poll.h>
55 #include <sys/proc.h>
56 #include <sys/racct.h>
57 #include <sys/resourcevar.h>
58 #include <sys/serial.h>
59 #include <sys/stat.h>
60 #include <sys/syscall.h>
61 #include <sys/syscallsubr.h>
62 #include <sys/sysctl.h>
63 #include <sys/sysproto.h>
64 #include <sys/systm.h>
65 #include <sys/tty.h>
66 #include <sys/ttycom.h>
67 #include <sys/uio.h>
68 #include <sys/user.h>
69
70 #include <machine/stdarg.h>
71
72 /*
73 * Our utmp(5) format is limited to 8-byte TTY line names. This means
74 * we can at most allocate 1000 pseudo-terminals ("pts/999"). Allow
75 * users to increase this number, assuming they have manually increased
76 * UT_LINESIZE.
77 */
78 static struct unrhdr *pts_pool;
79
80 static MALLOC_DEFINE(M_PTS, "pts", "pseudo tty device");
81
82 /*
83 * Per-PTS structure.
84 *
85 * List of locks
86 * (t) locked by tty_lock()
87 * (c) const until freeing
88 */
89 struct pts_softc {
90 int pts_unit; /* (c) Device unit number. */
91 unsigned int pts_flags; /* (t) Device flags. */
92 #define PTS_PKT 0x1 /* Packet mode. */
93 #define PTS_FINISHED 0x2 /* Return errors on read()/write(). */
94 char pts_pkt; /* (t) Unread packet mode data. */
95
96 struct cv pts_inwait; /* (t) Blocking write() on master. */
97 struct selinfo pts_inpoll; /* (t) Select queue for write(). */
98 struct cv pts_outwait; /* (t) Blocking read() on master. */
99 struct selinfo pts_outpoll; /* (t) Select queue for read(). */
100
101 #ifdef PTS_EXTERNAL
102 struct cdev *pts_cdev; /* (c) Master device node. */
103 #endif /* PTS_EXTERNAL */
104
105 struct ucred *pts_cred; /* (c) Resource limit. */
106 };
107
108 /*
109 * Controller-side file operations.
110 */
111
112 static int
113 ptsdev_read(struct file *fp, struct uio *uio, struct ucred *active_cred,
114 int flags, struct thread *td)
115 {
116 struct tty *tp = fp->f_data;
117 struct pts_softc *psc = tty_softc(tp);
118 int error = 0;
119 char pkt;
120
121 if (uio->uio_resid == 0)
122 return (0);
123
124 tty_lock(tp);
125
126 for (;;) {
127 /*
128 * Implement packet mode. When packet mode is turned on,
129 * the first byte contains a bitmask of events that
130 * occurred (start, stop, flush, window size, etc).
131 */
132 if (psc->pts_flags & PTS_PKT && psc->pts_pkt) {
133 pkt = psc->pts_pkt;
134 psc->pts_pkt = 0;
135 tty_unlock(tp);
136
137 error = ureadc(pkt, uio);
138 return (error);
139 }
140
141 /*
142 * Transmit regular data.
143 *
144 * XXX: We shouldn't use ttydisc_getc_poll()! Even
145 * though in this implementation, there is likely going
146 * to be data, we should just call ttydisc_getc_uio()
147 * and use its return value to sleep.
148 */
149 if (ttydisc_getc_poll(tp)) {
150 if (psc->pts_flags & PTS_PKT) {
151 /*
152 * XXX: Small race. Fortunately PTY
153 * consumers aren't multithreaded.
154 */
155
156 tty_unlock(tp);
157 error = ureadc(TIOCPKT_DATA, uio);
158 if (error)
159 return (error);
160 tty_lock(tp);
161 }
162
163 error = ttydisc_getc_uio(tp, uio);
164 break;
165 }
166
167 /* Maybe the device isn't used anyway. */
168 if (psc->pts_flags & PTS_FINISHED)
169 break;
170
171 /* Wait for more data. */
172 if (fp->f_flag & O_NONBLOCK) {
173 error = EWOULDBLOCK;
174 break;
175 }
176 error = cv_wait_sig(&psc->pts_outwait, tp->t_mtx);
177 if (error != 0)
178 break;
179 }
180
181 tty_unlock(tp);
182
183 return (error);
184 }
185
186 static int
187 ptsdev_write(struct file *fp, struct uio *uio, struct ucred *active_cred,
188 int flags, struct thread *td)
189 {
190 struct tty *tp = fp->f_data;
191 struct pts_softc *psc = tty_softc(tp);
192 char ib[256], *ibstart;
193 size_t iblen, rintlen;
194 int error = 0;
195
196 if (uio->uio_resid == 0)
197 return (0);
198
199 for (;;) {
200 ibstart = ib;
201 iblen = MIN(uio->uio_resid, sizeof ib);
202 error = uiomove(ib, iblen, uio);
203
204 tty_lock(tp);
205 if (error != 0) {
206 iblen = 0;
207 goto done;
208 }
209
210 /*
211 * When possible, avoid the slow path. rint_bypass()
212 * copies all input to the input queue at once.
213 */
214 MPASS(iblen > 0);
215 do {
216 rintlen = ttydisc_rint_simple(tp, ibstart, iblen);
217 ibstart += rintlen;
218 iblen -= rintlen;
219 if (iblen == 0) {
220 /* All data written. */
221 break;
222 }
223
224 /* Maybe the device isn't used anyway. */
225 if (psc->pts_flags & PTS_FINISHED) {
226 error = EIO;
227 goto done;
228 }
229
230 /* Wait for more data. */
231 if (fp->f_flag & O_NONBLOCK) {
232 error = EWOULDBLOCK;
233 goto done;
234 }
235
236 /* Wake up users on the slave side. */
237 ttydisc_rint_done(tp);
238 error = cv_wait_sig(&psc->pts_inwait, tp->t_mtx);
239 if (error != 0)
240 goto done;
241 } while (iblen > 0);
242
243 if (uio->uio_resid == 0)
244 break;
245 tty_unlock(tp);
246 }
247
248 done: ttydisc_rint_done(tp);
249 tty_unlock(tp);
250
251 /*
252 * Don't account for the part of the buffer that we couldn't
253 * pass to the TTY.
254 */
255 uio->uio_resid += iblen;
256 return (error);
257 }
258
259 static int
260 ptsdev_ioctl(struct file *fp, u_long cmd, void *data,
261 struct ucred *active_cred, struct thread *td)
262 {
263 struct tty *tp = fp->f_data;
264 struct pts_softc *psc = tty_softc(tp);
265 int error = 0, sig;
266
267 switch (cmd) {
268 case FIODTYPE:
269 *(int *)data = D_TTY;
270 return (0);
271 case FIONBIO:
272 /* This device supports non-blocking operation. */
273 return (0);
274 case FIONREAD:
275 tty_lock(tp);
276 if (psc->pts_flags & PTS_FINISHED) {
277 /* Force read() to be called. */
278 *(int *)data = 1;
279 } else {
280 *(int *)data = ttydisc_getc_poll(tp);
281 }
282 tty_unlock(tp);
283 return (0);
284 case FIODGNAME:
285 #ifdef COMPAT_FREEBSD32
286 case FIODGNAME_32:
287 #endif
288 {
289 struct fiodgname_arg *fgn;
290 const char *p;
291 int i;
292
293 /* Reverse device name lookups, for ptsname() and ttyname(). */
294 fgn = data;
295 p = tty_devname(tp);
296 i = strlen(p) + 1;
297 if (i > fgn->len)
298 return (EINVAL);
299 return (copyout(p, fiodgname_buf_get_ptr(fgn, cmd), i));
300 }
301
302 /*
303 * We need to implement TIOCGPGRP and TIOCGSID here again. When
304 * called on the pseudo-terminal master, it should not check if
305 * the terminal is the foreground terminal of the calling
306 * process.
307 *
308 * TIOCGETA is also implemented here. Various Linux PTY routines
309 * often call isatty(), which is implemented by tcgetattr().
310 */
311 #ifdef PTS_LINUX
312 case TIOCGETA:
313 /* Obtain terminal flags through tcgetattr(). */
314 tty_lock(tp);
315 *(struct termios*)data = tp->t_termios;
316 tty_unlock(tp);
317 return (0);
318 #endif /* PTS_LINUX */
319 case TIOCSETAF:
320 case TIOCSETAW:
321 /*
322 * We must make sure we turn tcsetattr() calls of TCSAFLUSH and
323 * TCSADRAIN into something different. If an application would
324 * call TCSAFLUSH or TCSADRAIN on the master descriptor, it may
325 * deadlock waiting for all data to be read.
326 */
327 cmd = TIOCSETA;
328 break;
329 #if defined(PTS_COMPAT) || defined(PTS_LINUX)
330 case TIOCGPTN:
331 /*
332 * Get the device unit number.
333 */
334 if (psc->pts_unit < 0)
335 return (ENOTTY);
336 *(unsigned int *)data = psc->pts_unit;
337 return (0);
338 #endif /* PTS_COMPAT || PTS_LINUX */
339 case TIOCGPGRP:
340 /* Get the foreground process group ID. */
341 tty_lock(tp);
342 if (tp->t_pgrp != NULL)
343 *(int *)data = tp->t_pgrp->pg_id;
344 else
345 *(int *)data = NO_PID;
346 tty_unlock(tp);
347 return (0);
348 case TIOCGSID:
349 /* Get the session leader process ID. */
350 tty_lock(tp);
351 if (tp->t_session == NULL)
352 error = ENOTTY;
353 else
354 *(int *)data = tp->t_session->s_sid;
355 tty_unlock(tp);
356 return (error);
357 case TIOCPTMASTER:
358 /* Yes, we are a pseudo-terminal master. */
359 return (0);
360 case TIOCSIG:
361 /* Signal the foreground process group. */
362 sig = *(int *)data;
363 if (sig < 1 || sig >= NSIG)
364 return (EINVAL);
365
366 tty_lock(tp);
367 tty_signal_pgrp(tp, sig);
368 tty_unlock(tp);
369 return (0);
370 case TIOCPKT:
371 /* Enable/disable packet mode. */
372 tty_lock(tp);
373 if (*(int *)data)
374 psc->pts_flags |= PTS_PKT;
375 else
376 psc->pts_flags &= ~PTS_PKT;
377 tty_unlock(tp);
378 return (0);
379 }
380
381 /* Just redirect this ioctl to the slave device. */
382 tty_lock(tp);
383 error = tty_ioctl(tp, cmd, data, fp->f_flag, td);
384 tty_unlock(tp);
385 if (error == ENOIOCTL)
386 error = ENOTTY;
387
388 return (error);
389 }
390
391 static int
392 ptsdev_poll(struct file *fp, int events, struct ucred *active_cred,
393 struct thread *td)
394 {
395 struct tty *tp = fp->f_data;
396 struct pts_softc *psc = tty_softc(tp);
397 int revents = 0;
398
399 tty_lock(tp);
400
401 if (psc->pts_flags & PTS_FINISHED) {
402 /* Slave device is not opened. */
403 tty_unlock(tp);
404 return ((events & (POLLIN|POLLRDNORM)) | POLLHUP);
405 }
406
407 if (events & (POLLIN|POLLRDNORM)) {
408 /* See if we can getc something. */
409 if (ttydisc_getc_poll(tp) ||
410 (psc->pts_flags & PTS_PKT && psc->pts_pkt))
411 revents |= events & (POLLIN|POLLRDNORM);
412 }
413 if (events & (POLLOUT|POLLWRNORM)) {
414 /* See if we can rint something. */
415 if (ttydisc_rint_poll(tp))
416 revents |= events & (POLLOUT|POLLWRNORM);
417 }
418
419 /*
420 * No need to check for POLLHUP here. This device cannot be used
421 * as a callout device, which means we always have a carrier,
422 * because the master is.
423 */
424
425 if (revents == 0) {
426 /*
427 * This code might look misleading, but the naming of
428 * poll events on this side is the opposite of the slave
429 * device.
430 */
431 if (events & (POLLIN|POLLRDNORM))
432 selrecord(td, &psc->pts_outpoll);
433 if (events & (POLLOUT|POLLWRNORM))
434 selrecord(td, &psc->pts_inpoll);
435 }
436
437 tty_unlock(tp);
438
439 return (revents);
440 }
441
442 /*
443 * kqueue support.
444 */
445
446 static void
447 pts_kqops_read_detach(struct knote *kn)
448 {
449 struct file *fp = kn->kn_fp;
450 struct tty *tp = fp->f_data;
451 struct pts_softc *psc = tty_softc(tp);
452
453 knlist_remove(&psc->pts_outpoll.si_note, kn, 0);
454 }
455
456 static int
457 pts_kqops_read_event(struct knote *kn, long hint)
458 {
459 struct file *fp = kn->kn_fp;
460 struct tty *tp = fp->f_data;
461 struct pts_softc *psc = tty_softc(tp);
462
463 if (psc->pts_flags & PTS_FINISHED) {
464 kn->kn_flags |= EV_EOF;
465 return (1);
466 } else {
467 kn->kn_data = ttydisc_getc_poll(tp);
468 return (kn->kn_data > 0);
469 }
470 }
471
472 static void
473 pts_kqops_write_detach(struct knote *kn)
474 {
475 struct file *fp = kn->kn_fp;
476 struct tty *tp = fp->f_data;
477 struct pts_softc *psc = tty_softc(tp);
478
479 knlist_remove(&psc->pts_inpoll.si_note, kn, 0);
480 }
481
482 static int
483 pts_kqops_write_event(struct knote *kn, long hint)
484 {
485 struct file *fp = kn->kn_fp;
486 struct tty *tp = fp->f_data;
487 struct pts_softc *psc = tty_softc(tp);
488
489 if (psc->pts_flags & PTS_FINISHED) {
490 kn->kn_flags |= EV_EOF;
491 return (1);
492 } else {
493 kn->kn_data = ttydisc_rint_poll(tp);
494 return (kn->kn_data > 0);
495 }
496 }
497
498 static struct filterops pts_kqops_read = {
499 .f_isfd = 1,
500 .f_detach = pts_kqops_read_detach,
501 .f_event = pts_kqops_read_event,
502 };
503 static struct filterops pts_kqops_write = {
504 .f_isfd = 1,
505 .f_detach = pts_kqops_write_detach,
506 .f_event = pts_kqops_write_event,
507 };
508
509 static int
510 ptsdev_kqfilter(struct file *fp, struct knote *kn)
511 {
512 struct tty *tp = fp->f_data;
513 struct pts_softc *psc = tty_softc(tp);
514 int error = 0;
515
516 tty_lock(tp);
517
518 switch (kn->kn_filter) {
519 case EVFILT_READ:
520 kn->kn_fop = &pts_kqops_read;
521 knlist_add(&psc->pts_outpoll.si_note, kn, 1);
522 break;
523 case EVFILT_WRITE:
524 kn->kn_fop = &pts_kqops_write;
525 knlist_add(&psc->pts_inpoll.si_note, kn, 1);
526 break;
527 default:
528 error = EINVAL;
529 break;
530 }
531
532 tty_unlock(tp);
533 return (error);
534 }
535
536 static int
537 ptsdev_stat(struct file *fp, struct stat *sb, struct ucred *active_cred)
538 {
539 struct tty *tp = fp->f_data;
540 #ifdef PTS_EXTERNAL
541 struct pts_softc *psc = tty_softc(tp);
542 #endif /* PTS_EXTERNAL */
543 struct cdev *dev = tp->t_dev;
544
545 /*
546 * According to POSIX, we must implement an fstat(). This also
547 * makes this implementation compatible with Linux binaries,
548 * because Linux calls fstat() on the pseudo-terminal master to
549 * obtain st_rdev.
550 *
551 * XXX: POSIX also mentions we must fill in st_dev, but how?
552 */
553
554 bzero(sb, sizeof *sb);
555 #ifdef PTS_EXTERNAL
556 if (psc->pts_cdev != NULL)
557 sb->st_ino = sb->st_rdev = dev2udev(psc->pts_cdev);
558 else
559 #endif /* PTS_EXTERNAL */
560 sb->st_ino = sb->st_rdev = tty_udev(tp);
561
562 sb->st_atim = dev->si_atime;
563 sb->st_ctim = dev->si_ctime;
564 sb->st_mtim = dev->si_mtime;
565 sb->st_uid = dev->si_uid;
566 sb->st_gid = dev->si_gid;
567 sb->st_mode = dev->si_mode | S_IFCHR;
568
569 return (0);
570 }
571
572 static int
573 ptsdev_close(struct file *fp, struct thread *td)
574 {
575 struct tty *tp = fp->f_data;
576
577 /* Deallocate TTY device. */
578 tty_lock(tp);
579 tty_rel_gone(tp);
580
581 /*
582 * Open of /dev/ptmx or /dev/ptyXX changes the type of file
583 * from DTYPE_VNODE to DTYPE_PTS. vn_open() increases vnode
584 * use count, we need to decrement it, and possibly do other
585 * required cleanup.
586 */
587 if (fp->f_vnode != NULL)
588 return (vnops.fo_close(fp, td));
589
590 return (0);
591 }
592
593 static int
594 ptsdev_fill_kinfo(struct file *fp, struct kinfo_file *kif, struct filedesc *fdp)
595 {
596 struct tty *tp;
597
598 kif->kf_type = KF_TYPE_PTS;
599 tp = fp->f_data;
600 kif->kf_un.kf_pts.kf_pts_dev = tty_udev(tp);
601 kif->kf_un.kf_pts.kf_pts_dev_freebsd11 =
602 kif->kf_un.kf_pts.kf_pts_dev; /* truncate */
603 strlcpy(kif->kf_path, tty_devname(tp), sizeof(kif->kf_path));
604 return (0);
605 }
606
607 static struct fileops ptsdev_ops = {
608 .fo_read = ptsdev_read,
609 .fo_write = ptsdev_write,
610 .fo_truncate = invfo_truncate,
611 .fo_ioctl = ptsdev_ioctl,
612 .fo_poll = ptsdev_poll,
613 .fo_kqfilter = ptsdev_kqfilter,
614 .fo_stat = ptsdev_stat,
615 .fo_close = ptsdev_close,
616 .fo_chmod = invfo_chmod,
617 .fo_chown = invfo_chown,
618 .fo_sendfile = invfo_sendfile,
619 .fo_fill_kinfo = ptsdev_fill_kinfo,
620 .fo_flags = DFLAG_PASSABLE,
621 };
622
623 /*
624 * Driver-side hooks.
625 */
626
627 static void
628 ptsdrv_outwakeup(struct tty *tp)
629 {
630 struct pts_softc *psc = tty_softc(tp);
631
632 cv_broadcast(&psc->pts_outwait);
633 selwakeup(&psc->pts_outpoll);
634 KNOTE_LOCKED(&psc->pts_outpoll.si_note, 0);
635 }
636
637 static void
638 ptsdrv_inwakeup(struct tty *tp)
639 {
640 struct pts_softc *psc = tty_softc(tp);
641
642 cv_broadcast(&psc->pts_inwait);
643 selwakeup(&psc->pts_inpoll);
644 KNOTE_LOCKED(&psc->pts_inpoll.si_note, 0);
645 }
646
647 static int
648 ptsdrv_open(struct tty *tp)
649 {
650 struct pts_softc *psc = tty_softc(tp);
651
652 psc->pts_flags &= ~PTS_FINISHED;
653
654 return (0);
655 }
656
657 static void
658 ptsdrv_close(struct tty *tp)
659 {
660 struct pts_softc *psc = tty_softc(tp);
661
662 /* Wake up any blocked readers/writers. */
663 psc->pts_flags |= PTS_FINISHED;
664 ptsdrv_outwakeup(tp);
665 ptsdrv_inwakeup(tp);
666 }
667
668 static void
669 ptsdrv_pktnotify(struct tty *tp, char event)
670 {
671 struct pts_softc *psc = tty_softc(tp);
672
673 /*
674 * Clear conflicting flags.
675 */
676
677 switch (event) {
678 case TIOCPKT_STOP:
679 psc->pts_pkt &= ~TIOCPKT_START;
680 break;
681 case TIOCPKT_START:
682 psc->pts_pkt &= ~TIOCPKT_STOP;
683 break;
684 case TIOCPKT_NOSTOP:
685 psc->pts_pkt &= ~TIOCPKT_DOSTOP;
686 break;
687 case TIOCPKT_DOSTOP:
688 psc->pts_pkt &= ~TIOCPKT_NOSTOP;
689 break;
690 }
691
692 psc->pts_pkt |= event;
693 ptsdrv_outwakeup(tp);
694 }
695
696 static void
697 ptsdrv_free(void *softc)
698 {
699 struct pts_softc *psc = softc;
700
701 /* Make device number available again. */
702 if (psc->pts_unit >= 0)
703 free_unr(pts_pool, psc->pts_unit);
704
705 chgptscnt(psc->pts_cred->cr_ruidinfo, -1, 0);
706 racct_sub_cred(psc->pts_cred, RACCT_NPTS, 1);
707 crfree(psc->pts_cred);
708
709 seldrain(&psc->pts_inpoll);
710 seldrain(&psc->pts_outpoll);
711 knlist_destroy(&psc->pts_inpoll.si_note);
712 knlist_destroy(&psc->pts_outpoll.si_note);
713
714 #ifdef PTS_EXTERNAL
715 /* Destroy master device as well. */
716 if (psc->pts_cdev != NULL)
717 destroy_dev_sched(psc->pts_cdev);
718 #endif /* PTS_EXTERNAL */
719
720 free(psc, M_PTS);
721 }
722
723 static struct ttydevsw pts_class = {
724 .tsw_flags = TF_NOPREFIX,
725 .tsw_outwakeup = ptsdrv_outwakeup,
726 .tsw_inwakeup = ptsdrv_inwakeup,
727 .tsw_open = ptsdrv_open,
728 .tsw_close = ptsdrv_close,
729 .tsw_pktnotify = ptsdrv_pktnotify,
730 .tsw_free = ptsdrv_free,
731 };
732
733 #ifndef PTS_EXTERNAL
734 static
735 #endif /* !PTS_EXTERNAL */
736 int
737 pts_alloc(int fflags, struct thread *td, struct file *fp)
738 {
739 int unit, ok, error;
740 struct tty *tp;
741 struct pts_softc *psc;
742 struct proc *p = td->td_proc;
743 struct ucred *cred = td->td_ucred;
744
745 /* Resource limiting. */
746 PROC_LOCK(p);
747 error = racct_add(p, RACCT_NPTS, 1);
748 if (error != 0) {
749 PROC_UNLOCK(p);
750 return (EAGAIN);
751 }
752 ok = chgptscnt(cred->cr_ruidinfo, 1, lim_cur(td, RLIMIT_NPTS));
753 if (!ok) {
754 racct_sub(p, RACCT_NPTS, 1);
755 PROC_UNLOCK(p);
756 return (EAGAIN);
757 }
758 PROC_UNLOCK(p);
759
760 /* Try to allocate a new pts unit number. */
761 unit = alloc_unr(pts_pool);
762 if (unit < 0) {
763 racct_sub(p, RACCT_NPTS, 1);
764 chgptscnt(cred->cr_ruidinfo, -1, 0);
765 return (EAGAIN);
766 }
767
768 /* Allocate TTY and softc. */
769 psc = malloc(sizeof(struct pts_softc), M_PTS, M_WAITOK|M_ZERO);
770 cv_init(&psc->pts_inwait, "ptsin");
771 cv_init(&psc->pts_outwait, "ptsout");
772
773 psc->pts_unit = unit;
774 psc->pts_cred = crhold(cred);
775
776 tp = tty_alloc(&pts_class, psc);
777 knlist_init_mtx(&psc->pts_inpoll.si_note, tp->t_mtx);
778 knlist_init_mtx(&psc->pts_outpoll.si_note, tp->t_mtx);
779
780 /* Expose the slave device as well. */
781 tty_makedev(tp, td->td_ucred, "pts/%u", psc->pts_unit);
782
783 finit(fp, fflags, DTYPE_PTS, tp, &ptsdev_ops);
784
785 return (0);
786 }
787
788 #ifdef PTS_EXTERNAL
789 int
790 pts_alloc_external(int fflags, struct thread *td, struct file *fp,
791 struct cdev *dev, const char *name)
792 {
793 int ok, error;
794 struct tty *tp;
795 struct pts_softc *psc;
796 struct proc *p = td->td_proc;
797 struct ucred *cred = td->td_ucred;
798
799 /* Resource limiting. */
800 PROC_LOCK(p);
801 error = racct_add(p, RACCT_NPTS, 1);
802 if (error != 0) {
803 PROC_UNLOCK(p);
804 return (EAGAIN);
805 }
806 ok = chgptscnt(cred->cr_ruidinfo, 1, lim_cur(td, RLIMIT_NPTS));
807 if (!ok) {
808 racct_sub(p, RACCT_NPTS, 1);
809 PROC_UNLOCK(p);
810 return (EAGAIN);
811 }
812 PROC_UNLOCK(p);
813
814 /* Allocate TTY and softc. */
815 psc = malloc(sizeof(struct pts_softc), M_PTS, M_WAITOK|M_ZERO);
816 cv_init(&psc->pts_inwait, "ptsin");
817 cv_init(&psc->pts_outwait, "ptsout");
818
819 psc->pts_unit = -1;
820 psc->pts_cdev = dev;
821 psc->pts_cred = crhold(cred);
822
823 tp = tty_alloc(&pts_class, psc);
824 knlist_init_mtx(&psc->pts_inpoll.si_note, tp->t_mtx);
825 knlist_init_mtx(&psc->pts_outpoll.si_note, tp->t_mtx);
826
827 /* Expose the slave device as well. */
828 tty_makedev(tp, td->td_ucred, "%s", name);
829
830 finit(fp, fflags, DTYPE_PTS, tp, &ptsdev_ops);
831
832 return (0);
833 }
834 #endif /* PTS_EXTERNAL */
835
836 int
837 sys_posix_openpt(struct thread *td, struct posix_openpt_args *uap)
838 {
839 int error, fd;
840 struct file *fp;
841
842 /*
843 * POSIX states it's unspecified when other flags are passed. We
844 * don't allow this.
845 */
846 if (uap->flags & ~(O_RDWR|O_NOCTTY|O_CLOEXEC))
847 return (EINVAL);
848
849 error = falloc(td, &fp, &fd, uap->flags);
850 if (error)
851 return (error);
852
853 /* Allocate the actual pseudo-TTY. */
854 error = pts_alloc(FFLAGS(uap->flags & O_ACCMODE), td, fp);
855 if (error != 0) {
856 fdclose(td, fp, fd);
857 fdrop(fp, td);
858 return (error);
859 }
860
861 /* Pass it back to userspace. */
862 td->td_retval[0] = fd;
863 fdrop(fp, td);
864
865 return (0);
866 }
867
868 static void
869 pts_init(void *unused)
870 {
871
872 pts_pool = new_unrhdr(0, INT_MAX, NULL);
873 }
874
875 SYSINIT(pts, SI_SUB_DRIVERS, SI_ORDER_MIDDLE, pts_init, NULL);
Cache object: a40363ad66b7be9400795eb08fdd39b4
|