tty_pts.c

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    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/sysent.h>
   64 #include <sys/sysproto.h>
   65 #include <sys/systm.h>
   66 #include <sys/tty.h>
   67 #include <sys/ttycom.h>
   68 #include <sys/uio.h>
   69 #include <sys/user.h>
   70 
   71 #include <machine/stdarg.h>
   72 
   73 /*
   74  * Our utmp(5) format is limited to 8-byte TTY line names.  This means
   75  * we can at most allocate 1000 pseudo-terminals ("pts/999").  Allow
   76  * users to increase this number, assuming they have manually increased
   77  * UT_LINESIZE.
   78  */
   79 static struct unrhdr *pts_pool;
   80 
   81 static MALLOC_DEFINE(M_PTS, "pts", "pseudo tty device");
   82 
   83 /*
   84  * Per-PTS structure.
   85  *
   86  * List of locks
   87  * (t)  locked by tty_lock()
   88  * (c)  const until freeing
   89  */
   90 struct pts_softc {
   91         int             pts_unit;       /* (c) Device unit number. */
   92         unsigned int    pts_flags;      /* (t) Device flags. */
   93 #define PTS_PKT         0x1     /* Packet mode. */
   94 #define PTS_FINISHED    0x2     /* Return errors on read()/write(). */
   95         char            pts_pkt;        /* (t) Unread packet mode data. */
   96 
   97         struct cv       pts_inwait;     /* (t) Blocking write() on master. */
   98         struct selinfo  pts_inpoll;     /* (t) Select queue for write(). */
   99         struct cv       pts_outwait;    /* (t) Blocking read() on master. */
  100         struct selinfo  pts_outpoll;    /* (t) Select queue for read(). */
  101 
  102 #ifdef PTS_EXTERNAL
  103         struct cdev     *pts_cdev;      /* (c) Master device node. */
  104 #endif /* PTS_EXTERNAL */
  105 
  106         struct ucred    *pts_cred;      /* (c) Resource limit. */
  107 };
  108 
  109 /*
  110  * Controller-side file operations.
  111  */
  112 
  113 static int
  114 ptsdev_read(struct file *fp, struct uio *uio, struct ucred *active_cred,
  115     int flags, struct thread *td)
  116 {
  117         struct tty *tp = fp->f_data;
  118         struct pts_softc *psc = tty_softc(tp);
  119         int error = 0;
  120         char pkt;
  121 
  122         if (uio->uio_resid == 0)
  123                 return (0);
  124 
  125         tty_lock(tp);
  126 
  127         for (;;) {
  128                 /*
  129                  * Implement packet mode. When packet mode is turned on,
  130                  * the first byte contains a bitmask of events that
  131                  * occurred (start, stop, flush, window size, etc).
  132                  */
  133                 if (psc->pts_flags & PTS_PKT && psc->pts_pkt) {
  134                         pkt = psc->pts_pkt;
  135                         psc->pts_pkt = 0;
  136                         tty_unlock(tp);
  137 
  138                         error = ureadc(pkt, uio);
  139                         return (error);
  140                 }
  141 
  142                 /*
  143                  * Transmit regular data.
  144                  *
  145                  * XXX: We shouldn't use ttydisc_getc_poll()! Even
  146                  * though in this implementation, there is likely going
  147                  * to be data, we should just call ttydisc_getc_uio()
  148                  * and use its return value to sleep.
  149                  */
  150                 if (ttydisc_getc_poll(tp)) {
  151                         if (psc->pts_flags & PTS_PKT) {
  152                                 /*
  153                                  * XXX: Small race. Fortunately PTY
  154                                  * consumers aren't multithreaded.
  155                                  */
  156 
  157                                 tty_unlock(tp);
  158                                 error = ureadc(TIOCPKT_DATA, uio);
  159                                 if (error)
  160                                         return (error);
  161                                 tty_lock(tp);
  162                         }
  163 
  164                         error = ttydisc_getc_uio(tp, uio);
  165                         break;
  166                 }
  167 
  168                 /* Maybe the device isn't used anyway. */
  169                 if (psc->pts_flags & PTS_FINISHED)
  170                         break;
  171 
  172                 /* Wait for more data. */
  173                 if (fp->f_flag & O_NONBLOCK) {
  174                         error = EWOULDBLOCK;
  175                         break;
  176                 }
  177                 error = cv_wait_sig(&psc->pts_outwait, tp->t_mtx);
  178                 if (error != 0)
  179                         break;
  180         }
  181 
  182         tty_unlock(tp);
  183 
  184         return (error);
  185 }
  186 
  187 static int
  188 ptsdev_write(struct file *fp, struct uio *uio, struct ucred *active_cred,
  189     int flags, struct thread *td)
  190 {
  191         struct tty *tp = fp->f_data;
  192         struct pts_softc *psc = tty_softc(tp);
  193         char ib[256], *ibstart;
  194         size_t iblen, rintlen;
  195         int error = 0;
  196 
  197         if (uio->uio_resid == 0)
  198                 return (0);
  199 
  200         for (;;) {
  201                 ibstart = ib;
  202                 iblen = MIN(uio->uio_resid, sizeof ib);
  203                 error = uiomove(ib, iblen, uio);
  204 
  205                 tty_lock(tp);
  206                 if (error != 0) {
  207                         iblen = 0;
  208                         goto done;
  209                 }
  210 
  211                 /*
  212                  * When possible, avoid the slow path. rint_bypass()
  213                  * copies all input to the input queue at once.
  214                  */
  215                 MPASS(iblen > 0);
  216                 do {
  217                         rintlen = ttydisc_rint_simple(tp, ibstart, iblen);
  218                         ibstart += rintlen;
  219                         iblen -= rintlen;
  220                         if (iblen == 0) {
  221                                 /* All data written. */
  222                                 break;
  223                         }
  224 
  225                         /* Maybe the device isn't used anyway. */
  226                         if (psc->pts_flags & PTS_FINISHED) {
  227                                 error = EIO;
  228                                 goto done;
  229                         }
  230 
  231                         /* Wait for more data. */
  232                         if (fp->f_flag & O_NONBLOCK) {
  233                                 error = EWOULDBLOCK;
  234                                 goto done;
  235                         }
  236 
  237                         /* Wake up users on the slave side. */
  238                         ttydisc_rint_done(tp);
  239                         error = cv_wait_sig(&psc->pts_inwait, tp->t_mtx);
  240                         if (error != 0)
  241                                 goto done;
  242                 } while (iblen > 0);
  243 
  244                 if (uio->uio_resid == 0)
  245                         break;
  246                 tty_unlock(tp);
  247         }
  248 
  249 done:   ttydisc_rint_done(tp);
  250         tty_unlock(tp);
  251 
  252         /*
  253          * Don't account for the part of the buffer that we couldn't
  254          * pass to the TTY.
  255          */
  256         uio->uio_resid += iblen;
  257         return (error);
  258 }
  259 
  260 static int
  261 ptsdev_ioctl(struct file *fp, u_long cmd, void *data,
  262     struct ucred *active_cred, struct thread *td)
  263 {
  264         struct tty *tp = fp->f_data;
  265         struct pts_softc *psc = tty_softc(tp);
  266         int error = 0, sig;
  267 
  268         switch (cmd) {
  269         case FIODTYPE:
  270                 *(int *)data = D_TTY;
  271                 return (0);
  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 #ifdef COMPAT_FREEBSD32
  287         case FIODGNAME_32:
  288 #endif
  289         {
  290                 struct fiodgname_arg *fgn;
  291                 const char *p;
  292                 int i;
  293 
  294                 /* Reverse device name lookups, for ptsname() and ttyname(). */
  295                 fgn = data;
  296                 p = tty_devname(tp);
  297                 i = strlen(p) + 1;
  298                 if (i > fgn->len)
  299                         return (EINVAL);
  300                 return (copyout(p, fiodgname_buf_get_ptr(fgn, cmd), i));
  301         }
  302 
  303         /*
  304          * We need to implement TIOCGPGRP and TIOCGSID here again. When
  305          * called on the pseudo-terminal master, it should not check if
  306          * the terminal is the foreground terminal of the calling
  307          * process.
  308          *
  309          * TIOCGETA is also implemented here. Various Linux PTY routines
  310          * often call isatty(), which is implemented by tcgetattr().
  311          */
  312 #ifdef PTS_LINUX
  313         case TIOCGETA:
  314                 /* Obtain terminal flags through tcgetattr(). */
  315                 tty_lock(tp);
  316                 *(struct termios*)data = tp->t_termios;
  317                 tty_unlock(tp);
  318                 return (0);
  319 #endif /* PTS_LINUX */
  320         case TIOCSETAF:
  321         case TIOCSETAW:
  322                 /*
  323                  * We must make sure we turn tcsetattr() calls of TCSAFLUSH and
  324                  * TCSADRAIN into something different. If an application would
  325                  * call TCSAFLUSH or TCSADRAIN on the master descriptor, it may
  326                  * deadlock waiting for all data to be read.
  327                  */
  328                 cmd = TIOCSETA;
  329                 break;
  330 #if defined(PTS_COMPAT) || defined(PTS_LINUX)
  331         case TIOCGPTN:
  332                 /*
  333                  * Get the device unit number.
  334                  */
  335                 if (psc->pts_unit < 0)
  336                         return (ENOTTY);
  337                 *(unsigned int *)data = psc->pts_unit;
  338                 return (0);
  339 #endif /* PTS_COMPAT || PTS_LINUX */
  340         case TIOCGPGRP:
  341                 /* Get the foreground process group ID. */
  342                 tty_lock(tp);
  343                 if (tp->t_pgrp != NULL)
  344                         *(int *)data = tp->t_pgrp->pg_id;
  345                 else
  346                         *(int *)data = NO_PID;
  347                 tty_unlock(tp);
  348                 return (0);
  349         case TIOCGSID:
  350                 /* Get the session leader process ID. */
  351                 tty_lock(tp);
  352                 if (tp->t_session == NULL)
  353                         error = ENOTTY;
  354                 else
  355                         *(int *)data = tp->t_session->s_sid;
  356                 tty_unlock(tp);
  357                 return (error);
  358         case TIOCPTMASTER:
  359                 /* Yes, we are a pseudo-terminal master. */
  360                 return (0);
  361         case TIOCSIG:
  362                 /* Signal the foreground process group. */
  363                 sig = *(int *)data;
  364                 if (sig < 1 || sig >= NSIG)
  365                         return (EINVAL);
  366 
  367                 tty_lock(tp);
  368                 tty_signal_pgrp(tp, sig);
  369                 tty_unlock(tp);
  370                 return (0);
  371         case TIOCPKT:
  372                 /* Enable/disable packet mode. */
  373                 tty_lock(tp);
  374                 if (*(int *)data)
  375                         psc->pts_flags |= PTS_PKT;
  376                 else
  377                         psc->pts_flags &= ~PTS_PKT;
  378                 tty_unlock(tp);
  379                 return (0);
  380         }
  381 
  382         /* Just redirect this ioctl to the slave device. */
  383         tty_lock(tp);
  384         error = tty_ioctl(tp, cmd, data, fp->f_flag, td);
  385         tty_unlock(tp);
  386         if (error == ENOIOCTL)
  387                 error = ENOTTY;
  388 
  389         return (error);
  390 }
  391 
  392 static int
  393 ptsdev_poll(struct file *fp, int events, struct ucred *active_cred,
  394     struct thread *td)
  395 {
  396         struct tty *tp = fp->f_data;
  397         struct pts_softc *psc = tty_softc(tp);
  398         int revents = 0;
  399 
  400         tty_lock(tp);
  401 
  402         if (psc->pts_flags & PTS_FINISHED) {
  403                 /* Slave device is not opened. */
  404                 tty_unlock(tp);
  405                 return ((events & (POLLIN|POLLRDNORM)) | POLLHUP);
  406         }
  407 
  408         if (events & (POLLIN|POLLRDNORM)) {
  409                 /* See if we can getc something. */
  410                 if (ttydisc_getc_poll(tp) ||
  411                     (psc->pts_flags & PTS_PKT && psc->pts_pkt))
  412                         revents |= events & (POLLIN|POLLRDNORM);
  413         }
  414         if (events & (POLLOUT|POLLWRNORM)) {
  415                 /* See if we can rint something. */
  416                 if (ttydisc_rint_poll(tp))
  417                         revents |= events & (POLLOUT|POLLWRNORM);
  418         }
  419 
  420         /*
  421          * No need to check for POLLHUP here. This device cannot be used
  422          * as a callout device, which means we always have a carrier,
  423          * because the master is.
  424          */
  425 
  426         if (revents == 0) {
  427                 /*
  428                  * This code might look misleading, but the naming of
  429                  * poll events on this side is the opposite of the slave
  430                  * device.
  431                  */
  432                 if (events & (POLLIN|POLLRDNORM))
  433                         selrecord(td, &psc->pts_outpoll);
  434                 if (events & (POLLOUT|POLLWRNORM))
  435                         selrecord(td, &psc->pts_inpoll);
  436         }
  437 
  438         tty_unlock(tp);
  439 
  440         return (revents);
  441 }
  442 
  443 /*
  444  * kqueue support.
  445  */
  446 
  447 static void
  448 pts_kqops_read_detach(struct knote *kn)
  449 {
  450         struct file *fp = kn->kn_fp;
  451         struct tty *tp = fp->f_data;
  452         struct pts_softc *psc = tty_softc(tp);
  453 
  454         knlist_remove(&psc->pts_outpoll.si_note, kn, 0);
  455 }
  456 
  457 static int
  458 pts_kqops_read_event(struct knote *kn, long hint)
  459 {
  460         struct file *fp = kn->kn_fp;
  461         struct tty *tp = fp->f_data;
  462         struct pts_softc *psc = tty_softc(tp);
  463 
  464         if (psc->pts_flags & PTS_FINISHED) {
  465                 kn->kn_flags |= EV_EOF;
  466                 return (1);
  467         } else {
  468                 kn->kn_data = ttydisc_getc_poll(tp);
  469                 return (kn->kn_data > 0);
  470         }
  471 }
  472 
  473 static void
  474 pts_kqops_write_detach(struct knote *kn)
  475 {
  476         struct file *fp = kn->kn_fp;
  477         struct tty *tp = fp->f_data;
  478         struct pts_softc *psc = tty_softc(tp);
  479 
  480         knlist_remove(&psc->pts_inpoll.si_note, kn, 0);
  481 }
  482 
  483 static int
  484 pts_kqops_write_event(struct knote *kn, long hint)
  485 {
  486         struct file *fp = kn->kn_fp;
  487         struct tty *tp = fp->f_data;
  488         struct pts_softc *psc = tty_softc(tp);
  489 
  490         if (psc->pts_flags & PTS_FINISHED) {
  491                 kn->kn_flags |= EV_EOF;
  492                 return (1);
  493         } else {
  494                 kn->kn_data = ttydisc_rint_poll(tp);
  495                 return (kn->kn_data > 0);
  496         }
  497 }
  498 
  499 static struct filterops pts_kqops_read = {
  500         .f_isfd = 1,
  501         .f_detach = pts_kqops_read_detach,
  502         .f_event = pts_kqops_read_event,
  503 };
  504 static struct filterops pts_kqops_write = {
  505         .f_isfd = 1,
  506         .f_detach = pts_kqops_write_detach,
  507         .f_event = pts_kqops_write_event,
  508 };
  509 
  510 static int
  511 ptsdev_kqfilter(struct file *fp, struct knote *kn)
  512 {
  513         struct tty *tp = fp->f_data;
  514         struct pts_softc *psc = tty_softc(tp);
  515         int error = 0;
  516 
  517         tty_lock(tp);
  518 
  519         switch (kn->kn_filter) {
  520         case EVFILT_READ:
  521                 kn->kn_fop = &pts_kqops_read;
  522                 knlist_add(&psc->pts_outpoll.si_note, kn, 1);
  523                 break;
  524         case EVFILT_WRITE:
  525                 kn->kn_fop = &pts_kqops_write;
  526                 knlist_add(&psc->pts_inpoll.si_note, kn, 1);
  527                 break;
  528         default:
  529                 error = EINVAL;
  530                 break;
  531         }
  532 
  533         tty_unlock(tp);
  534         return (error);
  535 }
  536 
  537 static int
  538 ptsdev_stat(struct file *fp, struct stat *sb, struct ucred *active_cred,
  539     struct thread *td)
  540 {
  541         struct tty *tp = fp->f_data;
  542 #ifdef PTS_EXTERNAL
  543         struct pts_softc *psc = tty_softc(tp);
  544 #endif /* PTS_EXTERNAL */
  545         struct cdev *dev = tp->t_dev;
  546 
  547         /*
  548          * According to POSIX, we must implement an fstat(). This also
  549          * makes this implementation compatible with Linux binaries,
  550          * because Linux calls fstat() on the pseudo-terminal master to
  551          * obtain st_rdev.
  552          *
  553          * XXX: POSIX also mentions we must fill in st_dev, but how?
  554          */
  555 
  556         bzero(sb, sizeof *sb);
  557 #ifdef PTS_EXTERNAL
  558         if (psc->pts_cdev != NULL)
  559                 sb->st_ino = sb->st_rdev = dev2udev(psc->pts_cdev);
  560         else
  561 #endif /* PTS_EXTERNAL */
  562                 sb->st_ino = sb->st_rdev = tty_udev(tp);
  563 
  564         sb->st_atim = dev->si_atime;
  565         sb->st_ctim = dev->si_ctime;
  566         sb->st_mtim = dev->si_mtime;
  567         sb->st_uid = dev->si_uid;
  568         sb->st_gid = dev->si_gid;
  569         sb->st_mode = dev->si_mode | S_IFCHR;
  570 
  571         return (0);
  572 }
  573 
  574 static int
  575 ptsdev_close(struct file *fp, struct thread *td)
  576 {
  577         struct tty *tp = fp->f_data;
  578 
  579         /* Deallocate TTY device. */
  580         tty_lock(tp);
  581         tty_rel_gone(tp);
  582 
  583         /*
  584          * Open of /dev/ptmx or /dev/ptyXX changes the type of file
  585          * from DTYPE_VNODE to DTYPE_PTS. vn_open() increases vnode
  586          * use count, we need to decrement it, and possibly do other
  587          * required cleanup.
  588          */
  589         if (fp->f_vnode != NULL)
  590                 return (vnops.fo_close(fp, td));
  591 
  592         return (0);
  593 }
  594 
  595 static int
  596 ptsdev_fill_kinfo(struct file *fp, struct kinfo_file *kif, struct filedesc *fdp)
  597 {
  598         struct tty *tp;
  599 
  600         kif->kf_type = KF_TYPE_PTS;
  601         tp = fp->f_data;
  602         kif->kf_un.kf_pts.kf_pts_dev = tty_udev(tp);
  603         kif->kf_un.kf_pts.kf_pts_dev_freebsd11 =
  604             kif->kf_un.kf_pts.kf_pts_dev; /* truncate */
  605         strlcpy(kif->kf_path, tty_devname(tp), sizeof(kif->kf_path));
  606         return (0);
  607 }
  608 
  609 static struct fileops ptsdev_ops = {
  610         .fo_read        = ptsdev_read,
  611         .fo_write       = ptsdev_write,
  612         .fo_truncate    = invfo_truncate,
  613         .fo_ioctl       = ptsdev_ioctl,
  614         .fo_poll        = ptsdev_poll,
  615         .fo_kqfilter    = ptsdev_kqfilter,
  616         .fo_stat        = ptsdev_stat,
  617         .fo_close       = ptsdev_close,
  618         .fo_chmod       = invfo_chmod,
  619         .fo_chown       = invfo_chown,
  620         .fo_sendfile    = invfo_sendfile,
  621         .fo_fill_kinfo  = ptsdev_fill_kinfo,
  622         .fo_flags       = DFLAG_PASSABLE,
  623 };
  624 
  625 /*
  626  * Driver-side hooks.
  627  */
  628 
  629 static void
  630 ptsdrv_outwakeup(struct tty *tp)
  631 {
  632         struct pts_softc *psc = tty_softc(tp);
  633 
  634         cv_broadcast(&psc->pts_outwait);
  635         selwakeup(&psc->pts_outpoll);
  636         KNOTE_LOCKED(&psc->pts_outpoll.si_note, 0);
  637 }
  638 
  639 static void
  640 ptsdrv_inwakeup(struct tty *tp)
  641 {
  642         struct pts_softc *psc = tty_softc(tp);
  643 
  644         cv_broadcast(&psc->pts_inwait);
  645         selwakeup(&psc->pts_inpoll);
  646         KNOTE_LOCKED(&psc->pts_inpoll.si_note, 0);
  647 }
  648 
  649 static int
  650 ptsdrv_open(struct tty *tp)
  651 {
  652         struct pts_softc *psc = tty_softc(tp);
  653 
  654         psc->pts_flags &= ~PTS_FINISHED;
  655 
  656         return (0);
  657 }
  658 
  659 static void
  660 ptsdrv_close(struct tty *tp)
  661 {
  662         struct pts_softc *psc = tty_softc(tp);
  663 
  664         /* Wake up any blocked readers/writers. */
  665         psc->pts_flags |= PTS_FINISHED;
  666         ptsdrv_outwakeup(tp);
  667         ptsdrv_inwakeup(tp);
  668 }
  669 
  670 static void
  671 ptsdrv_pktnotify(struct tty *tp, char event)
  672 {
  673         struct pts_softc *psc = tty_softc(tp);
  674 
  675         /*
  676          * Clear conflicting flags.
  677          */
  678 
  679         switch (event) {
  680         case TIOCPKT_STOP:
  681                 psc->pts_pkt &= ~TIOCPKT_START;
  682                 break;
  683         case TIOCPKT_START:
  684                 psc->pts_pkt &= ~TIOCPKT_STOP;
  685                 break;
  686         case TIOCPKT_NOSTOP:
  687                 psc->pts_pkt &= ~TIOCPKT_DOSTOP;
  688                 break;
  689         case TIOCPKT_DOSTOP:
  690                 psc->pts_pkt &= ~TIOCPKT_NOSTOP;
  691                 break;
  692         }
  693 
  694         psc->pts_pkt |= event;
  695         ptsdrv_outwakeup(tp);
  696 }
  697 
  698 static void
  699 ptsdrv_free(void *softc)
  700 {
  701         struct pts_softc *psc = softc;
  702 
  703         /* Make device number available again. */
  704         if (psc->pts_unit >= 0)
  705                 free_unr(pts_pool, psc->pts_unit);
  706 
  707         chgptscnt(psc->pts_cred->cr_ruidinfo, -1, 0);
  708         racct_sub_cred(psc->pts_cred, RACCT_NPTS, 1);
  709         crfree(psc->pts_cred);
  710 
  711         seldrain(&psc->pts_inpoll);
  712         seldrain(&psc->pts_outpoll);
  713         knlist_destroy(&psc->pts_inpoll.si_note);
  714         knlist_destroy(&psc->pts_outpoll.si_note);
  715 
  716 #ifdef PTS_EXTERNAL
  717         /* Destroy master device as well. */
  718         if (psc->pts_cdev != NULL)
  719                 destroy_dev_sched(psc->pts_cdev);
  720 #endif /* PTS_EXTERNAL */
  721 
  722         free(psc, M_PTS);
  723 }
  724 
  725 static struct ttydevsw pts_class = {
  726         .tsw_flags      = TF_NOPREFIX,
  727         .tsw_outwakeup  = ptsdrv_outwakeup,
  728         .tsw_inwakeup   = ptsdrv_inwakeup,
  729         .tsw_open       = ptsdrv_open,
  730         .tsw_close      = ptsdrv_close,
  731         .tsw_pktnotify  = ptsdrv_pktnotify,
  732         .tsw_free       = ptsdrv_free,
  733 };
  734 
  735 #ifndef PTS_EXTERNAL
  736 static
  737 #endif /* !PTS_EXTERNAL */
  738 int
  739 pts_alloc(int fflags, struct thread *td, struct file *fp)
  740 {
  741         int unit, ok, error;
  742         struct tty *tp;
  743         struct pts_softc *psc;
  744         struct proc *p = td->td_proc;
  745         struct ucred *cred = td->td_ucred;
  746 
  747         /* Resource limiting. */
  748         PROC_LOCK(p);
  749         error = racct_add(p, RACCT_NPTS, 1);
  750         if (error != 0) {
  751                 PROC_UNLOCK(p);
  752                 return (EAGAIN);
  753         }
  754         ok = chgptscnt(cred->cr_ruidinfo, 1, lim_cur(td, RLIMIT_NPTS));
  755         if (!ok) {
  756                 racct_sub(p, RACCT_NPTS, 1);
  757                 PROC_UNLOCK(p);
  758                 return (EAGAIN);
  759         }
  760         PROC_UNLOCK(p);
  761 
  762         /* Try to allocate a new pts unit number. */
  763         unit = alloc_unr(pts_pool);
  764         if (unit < 0) {
  765                 racct_sub(p, RACCT_NPTS, 1);
  766                 chgptscnt(cred->cr_ruidinfo, -1, 0);
  767                 return (EAGAIN);
  768         }
  769 
  770         /* Allocate TTY and softc. */
  771         psc = malloc(sizeof(struct pts_softc), M_PTS, M_WAITOK|M_ZERO);
  772         cv_init(&psc->pts_inwait, "ptsin");
  773         cv_init(&psc->pts_outwait, "ptsout");
  774 
  775         psc->pts_unit = unit;
  776         psc->pts_cred = crhold(cred);
  777 
  778         tp = tty_alloc(&pts_class, psc);
  779         knlist_init_mtx(&psc->pts_inpoll.si_note, tp->t_mtx);
  780         knlist_init_mtx(&psc->pts_outpoll.si_note, tp->t_mtx);
  781 
  782         /* Expose the slave device as well. */
  783         tty_makedev(tp, td->td_ucred, "pts/%u", psc->pts_unit);
  784 
  785         finit(fp, fflags, DTYPE_PTS, tp, &ptsdev_ops);
  786 
  787         return (0);
  788 }
  789 
  790 #ifdef PTS_EXTERNAL
  791 int
  792 pts_alloc_external(int fflags, struct thread *td, struct file *fp,
  793     struct cdev *dev, const char *name)
  794 {
  795         int ok, error;
  796         struct tty *tp;
  797         struct pts_softc *psc;
  798         struct proc *p = td->td_proc;
  799         struct ucred *cred = td->td_ucred;
  800 
  801         /* Resource limiting. */
  802         PROC_LOCK(p);
  803         error = racct_add(p, RACCT_NPTS, 1);
  804         if (error != 0) {
  805                 PROC_UNLOCK(p);
  806                 return (EAGAIN);
  807         }
  808         ok = chgptscnt(cred->cr_ruidinfo, 1, lim_cur(td, RLIMIT_NPTS));
  809         if (!ok) {
  810                 racct_sub(p, RACCT_NPTS, 1);
  811                 PROC_UNLOCK(p);
  812                 return (EAGAIN);
  813         }
  814         PROC_UNLOCK(p);
  815 
  816         /* Allocate TTY and softc. */
  817         psc = malloc(sizeof(struct pts_softc), M_PTS, M_WAITOK|M_ZERO);
  818         cv_init(&psc->pts_inwait, "ptsin");
  819         cv_init(&psc->pts_outwait, "ptsout");
  820 
  821         psc->pts_unit = -1;
  822         psc->pts_cdev = dev;
  823         psc->pts_cred = crhold(cred);
  824 
  825         tp = tty_alloc(&pts_class, psc);
  826         knlist_init_mtx(&psc->pts_inpoll.si_note, tp->t_mtx);
  827         knlist_init_mtx(&psc->pts_outpoll.si_note, tp->t_mtx);
  828 
  829         /* Expose the slave device as well. */
  830         tty_makedev(tp, td->td_ucred, "%s", name);
  831 
  832         finit(fp, fflags, DTYPE_PTS, tp, &ptsdev_ops);
  833 
  834         return (0);
  835 }
  836 #endif /* PTS_EXTERNAL */
  837 
  838 int
  839 sys_posix_openpt(struct thread *td, struct posix_openpt_args *uap)
  840 {
  841         int error, fd;
  842         struct file *fp;
  843 
  844         /*
  845          * POSIX states it's unspecified when other flags are passed. We
  846          * don't allow this.
  847          */
  848         if (uap->flags & ~(O_RDWR|O_NOCTTY|O_CLOEXEC))
  849                 return (EINVAL);
  850 
  851         error = falloc(td, &fp, &fd, uap->flags);
  852         if (error)
  853                 return (error);
  854 
  855         /* Allocate the actual pseudo-TTY. */
  856         error = pts_alloc(FFLAGS(uap->flags & O_ACCMODE), td, fp);
  857         if (error != 0) {
  858                 fdclose(td, fp, fd);
  859                 fdrop(fp, td);
  860                 return (error);
  861         }
  862 
  863         /* Pass it back to userspace. */
  864         td->td_retval[0] = fd;
  865         fdrop(fp, td);
  866 
  867         return (0);
  868 }
  869 
  870 static void
  871 pts_init(void *unused)
  872 {
  873 
  874         pts_pool = new_unrhdr(0, INT_MAX, NULL);
  875 }
  876 
  877 SYSINIT(pts, SI_SUB_DRIVERS, SI_ORDER_MIDDLE, pts_init, NULL);
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FreeBSD/Linux Kernel Cross Reference sys/kern/tty_pts.c

FreeBSD/Linux Kernel Cross Reference
sys/kern/tty_pts.c
