snp.c

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    1 /*-
    2  * Copyright (c) 2008 Ed Schouten <ed@FreeBSD.org>
    3  * All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  * 1. Redistributions of source code must retain the above copyright
    9  *    notice, this list of conditions and the following disclaimer.
   10  * 2. Redistributions in binary form must reproduce the above copyright
   11  *    notice, this list of conditions and the following disclaimer in the
   12  *    documentation and/or other materials provided with the distribution.
   13  *
   14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   24  * SUCH DAMAGE.
   25  */
   26 
   27 #include <sys/cdefs.h>
   28 __FBSDID("$FreeBSD: releng/9.0/sys/dev/snp/snp.c 224778 2011-08-11 12:30:23Z rwatson $");
   29 
   30 #include <sys/param.h>
   31 #include <sys/conf.h>
   32 #include <sys/fcntl.h>
   33 #include <sys/filio.h>
   34 #include <sys/kernel.h>
   35 #include <sys/malloc.h>
   36 #include <sys/module.h>
   37 #include <sys/poll.h>
   38 #include <sys/proc.h>
   39 #include <sys/snoop.h>
   40 #include <sys/sx.h>
   41 #include <sys/systm.h>
   42 #include <sys/tty.h>
   43 #include <sys/uio.h>
   44 
   45 static struct cdev      *snp_dev;
   46 static MALLOC_DEFINE(M_SNP, "snp", "tty snoop device");
   47 
   48 /* XXX: should be mtx, but TTY can be locked by Giant. */
   49 #if 0
   50 static struct mtx       snp_register_lock;
   51 MTX_SYSINIT(snp_register_lock, &snp_register_lock,
   52     "tty snoop registration", MTX_DEF);
   53 #define SNP_LOCK()      mtx_lock(&snp_register_lock)
   54 #define SNP_UNLOCK()    mtx_unlock(&snp_register_lock)
   55 #else
   56 static struct sx        snp_register_lock;
   57 SX_SYSINIT(snp_register_lock, &snp_register_lock,
   58     "tty snoop registration");
   59 #define SNP_LOCK()      sx_xlock(&snp_register_lock)
   60 #define SNP_UNLOCK()    sx_xunlock(&snp_register_lock)
   61 #endif
   62 
   63 /*
   64  * There is no need to have a big input buffer. In most typical setups,
   65  * we won't inject much data into the TTY, because users can't type
   66  * really fast.
   67  */
   68 #define SNP_INPUT_BUFSIZE       16
   69 /*
   70  * The output buffer has to be really big. Right now we don't support
   71  * any form of flow control, which means we lost any data we can't
   72  * accept. We set the output buffer size to about twice the size of a
   73  * pseudo-terminal/virtual console's output buffer.
   74  */
   75 #define SNP_OUTPUT_BUFSIZE      16384
   76 
   77 static d_open_t         snp_open;
   78 static d_read_t         snp_read;
   79 static d_write_t        snp_write;
   80 static d_ioctl_t        snp_ioctl;
   81 static d_poll_t         snp_poll;
   82 
   83 static struct cdevsw snp_cdevsw = {
   84         .d_version      = D_VERSION,
   85         .d_open         = snp_open,
   86         .d_read         = snp_read,
   87         .d_write        = snp_write,
   88         .d_ioctl        = snp_ioctl,
   89         .d_poll         = snp_poll,
   90         .d_name         = "snp",
   91 };
   92 
   93 static th_getc_capture_t        snp_getc_capture;
   94 
   95 static struct ttyhook snp_hook = {
   96         .th_getc_capture        = snp_getc_capture,
   97 };
   98 
   99 /*
  100  * Per-instance structure.
  101  *
  102  * List of locks
  103  * (r)  locked by snp_register_lock on assignment
  104  * (t)  locked by tty_lock
  105  */
  106 struct snp_softc {
  107         struct tty      *snp_tty;       /* (r) TTY we're snooping. */
  108         struct ttyoutq  snp_outq;       /* (t) Output queue. */
  109         struct cv       snp_outwait;    /* (t) Output wait queue. */
  110         struct selinfo  snp_outpoll;    /* (t) Output polling. */
  111 };
  112 
  113 static void
  114 snp_dtor(void *data)
  115 {
  116         struct snp_softc *ss = data;
  117         struct tty *tp;
  118 
  119         tp = ss->snp_tty;
  120         if (tp != NULL) {
  121                 tty_lock(tp);
  122                 ttyoutq_free(&ss->snp_outq);
  123                 ttyhook_unregister(tp);
  124         }
  125 
  126         cv_destroy(&ss->snp_outwait);
  127         free(ss, M_SNP);
  128 }
  129 
  130 /*
  131  * Snoop device node routines.
  132  */
  133 
  134 static int
  135 snp_open(struct cdev *dev, int flag, int mode, struct thread *td)
  136 {
  137         struct snp_softc *ss;
  138 
  139         /* Allocate per-snoop data. */
  140         ss = malloc(sizeof(struct snp_softc), M_SNP, M_WAITOK|M_ZERO);
  141         cv_init(&ss->snp_outwait, "snp out");
  142 
  143         devfs_set_cdevpriv(ss, snp_dtor);
  144 
  145         return (0);
  146 }
  147 
  148 static int
  149 snp_read(struct cdev *dev, struct uio *uio, int flag)
  150 {
  151         int error, oresid = uio->uio_resid;
  152         struct snp_softc *ss;
  153         struct tty *tp;
  154 
  155         if (uio->uio_resid == 0)
  156                 return (0);
  157 
  158         error = devfs_get_cdevpriv((void **)&ss);
  159         if (error != 0)
  160                 return (error);
  161 
  162         tp = ss->snp_tty;
  163         if (tp == NULL || tty_gone(tp))
  164                 return (EIO);
  165 
  166         tty_lock(tp);
  167         for (;;) {
  168                 error = ttyoutq_read_uio(&ss->snp_outq, tp, uio);
  169                 if (error != 0 || uio->uio_resid != oresid)
  170                         break;
  171 
  172                 /* Wait for more data. */
  173                 if (flag & O_NONBLOCK) {
  174                         error = EWOULDBLOCK;
  175                         break;
  176                 }
  177                 error = cv_wait_sig(&ss->snp_outwait, tp->t_mtx);
  178                 if (error != 0)
  179                         break;
  180                 if (tty_gone(tp)) {
  181                         error = EIO;
  182                         break;
  183                 }
  184         }
  185         tty_unlock(tp);
  186 
  187         return (error);
  188 }
  189 
  190 static int
  191 snp_write(struct cdev *dev, struct uio *uio, int flag)
  192 {
  193         struct snp_softc *ss;
  194         struct tty *tp;
  195         int error, len;
  196         char in[SNP_INPUT_BUFSIZE];
  197 
  198         error = devfs_get_cdevpriv((void **)&ss);
  199         if (error != 0)
  200                 return (error);
  201 
  202         tp = ss->snp_tty;
  203         if (tp == NULL || tty_gone(tp))
  204                 return (EIO);
  205 
  206         while (uio->uio_resid > 0) {
  207                 /* Read new data. */
  208                 len = imin(uio->uio_resid, sizeof in);
  209                 error = uiomove(in, len, uio);
  210                 if (error != 0)
  211                         return (error);
  212 
  213                 tty_lock(tp);
  214 
  215                 /* Driver could have abandoned the TTY in the mean time. */
  216                 if (tty_gone(tp)) {
  217                         tty_unlock(tp);
  218                         return (ENXIO);
  219                 }
  220 
  221                 /*
  222                  * Deliver data to the TTY. Ignore errors for now,
  223                  * because we shouldn't bail out when we're running
  224                  * close to the watermarks.
  225                  */
  226                 ttydisc_rint_simple(tp, in, len);
  227                 ttydisc_rint_done(tp);
  228 
  229                 tty_unlock(tp);
  230         }
  231 
  232         return (0);
  233 }
  234 
  235 static int
  236 snp_ioctl(struct cdev *dev, u_long cmd, caddr_t data, int flags,
  237     struct thread *td)
  238 {
  239         struct snp_softc *ss;
  240         struct tty *tp;
  241         int error;
  242 
  243         error = devfs_get_cdevpriv((void **)&ss);
  244         if (error != 0)
  245                 return (error);
  246 
  247         switch (cmd) {
  248         case SNPSTTY:
  249                 /* Bind TTY to snoop instance. */
  250                 SNP_LOCK();
  251                 if (ss->snp_tty != NULL) {
  252                         SNP_UNLOCK();
  253                         return (EBUSY);
  254                 }
  255                 /*
  256                  * XXXRW / XXXJA: no capability check here.
  257                  */
  258                 error = ttyhook_register(&ss->snp_tty, td->td_proc,
  259                     *(int *)data, &snp_hook, ss);
  260                 SNP_UNLOCK();
  261                 if (error != 0)
  262                         return (error);
  263 
  264                 /* Now that went okay, allocate a buffer for the queue. */
  265                 tp = ss->snp_tty;
  266                 tty_lock(tp);
  267                 ttyoutq_setsize(&ss->snp_outq, tp, SNP_OUTPUT_BUFSIZE);
  268                 tty_unlock(tp);
  269 
  270                 return (0);
  271         case SNPGTTY:
  272                 /* Obtain device number of associated TTY. */
  273                 if (ss->snp_tty == NULL)
  274                         *(dev_t *)data = NODEV;
  275                 else
  276                         *(dev_t *)data = tty_udev(ss->snp_tty);
  277                 return (0);
  278         case FIONREAD:
  279                 tp = ss->snp_tty;
  280                 if (tp != NULL) {
  281                         tty_lock(tp);
  282                         *(int *)data = ttyoutq_bytesused(&ss->snp_outq);
  283                         tty_unlock(tp);
  284                 } else {
  285                         *(int *)data = 0;
  286                 }
  287                 return (0);
  288         default:
  289                 return (ENOTTY);
  290         }
  291 }
  292 
  293 static int
  294 snp_poll(struct cdev *dev, int events, struct thread *td)
  295 {
  296         struct snp_softc *ss;
  297         struct tty *tp;
  298         int revents;
  299 
  300         if (devfs_get_cdevpriv((void **)&ss) != 0)
  301                 return (events &
  302                     (POLLHUP|POLLIN|POLLRDNORM|POLLOUT|POLLWRNORM));
  303 
  304         revents = 0;
  305 
  306         if (events & (POLLIN | POLLRDNORM)) {
  307                 tp = ss->snp_tty;
  308                 if (tp != NULL) {
  309                         tty_lock(tp);
  310                         if (ttyoutq_bytesused(&ss->snp_outq) > 0)
  311                                 revents |= events & (POLLIN | POLLRDNORM);
  312                         tty_unlock(tp);
  313                 }
  314         }
  315 
  316         if (revents == 0)
  317                 selrecord(td, &ss->snp_outpoll);
  318 
  319         return (revents);
  320 }
  321 
  322 /*
  323  * TTY hook events.
  324  */
  325 
  326 static int
  327 snp_modevent(module_t mod, int type, void *data)
  328 {
  329 
  330         switch (type) {
  331         case MOD_LOAD:
  332                 snp_dev = make_dev(&snp_cdevsw, 0,
  333                     UID_ROOT, GID_WHEEL, 0600, "snp");
  334                 return (0);
  335         case MOD_UNLOAD:
  336                 /* XXX: Make existing users leave. */
  337                 destroy_dev(snp_dev);
  338                 return (0);
  339         default:
  340                 return (EOPNOTSUPP);
  341         }
  342 }
  343 
  344 static void
  345 snp_getc_capture(struct tty *tp, const void *buf, size_t len)
  346 {
  347         struct snp_softc *ss = ttyhook_softc(tp);
  348 
  349         ttyoutq_write(&ss->snp_outq, buf, len);
  350 
  351         cv_broadcast(&ss->snp_outwait);
  352         selwakeup(&ss->snp_outpoll);
  353 }
  354 
  355 static moduledata_t snp_mod = {
  356         "snp",
  357         snp_modevent,
  358         NULL
  359 };
  360 
  361 DECLARE_MODULE(snp, snp_mod, SI_SUB_DRIVERS, SI_ORDER_MIDDLE);
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FreeBSD/Linux Kernel Cross Reference sys/dev/snp/snp.c

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sys/dev/snp/snp.c
