sys/kern/tty_tty.c

   1 /*-
   2  * Copyright (c) 2003 Poul-Henning Kamp.  All rights reserved.
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions
   6  * are met:
   7  * 1. Redistributions of source code must retain the above copyright
   8  *    notice, this list of conditions and the following disclaimer.
   9  * 2. Redistributions in binary form must reproduce the above copyright
  10  *    notice, this list of conditions and the following disclaimer in the
  11  *    documentation and/or other materials provided with the distribution.
  12  *
  13  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  14  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  16  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  17  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  18  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  19  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  20  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  21  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  22  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  23  * SUCH DAMAGE.
  24  */
  25
  26 #include <sys/cdefs.h>
  27 __FBSDID("$FreeBSD$");
  28
  29 #include <sys/param.h>
  30 #include <sys/systm.h>
  31 #include <sys/conf.h>
  32 #include <sys/kernel.h>
  33 #include <sys/proc.h>
  34 #include <sys/sx.h>
  35 #include <sys/vnode.h>
  36
  37 #include <fs/devfs/devfs.h>
  38 #include <fs/devfs/devfs_int.h>
  39
  40 static  d_open_t        cttyopen;
  41
  42 static struct cdevsw ctty_cdevsw = {
  43         .d_version =    D_VERSION,
  44         .d_open =       cttyopen,
  45         .d_name =       "ctty",
  46 };
  47
  48 static struct cdev *ctty;
  49
  50 static  int
  51 cttyopen(struct cdev *dev, int flag, int mode, struct thread *td)
  52 {
  53
  54         return (ENXIO);
  55 }
  56
  57 static void
  58 ctty_clone(void *arg, struct ucred *cred, char *name, int namelen,
  59     struct cdev **dev)
  60 {
  61         struct proc *p;
  62
  63         if (*dev != NULL)
  64                 return;
  65         if (strcmp(name, "tty"))
  66                 return;
  67         p = curproc;
  68         sx_sunlock(&clone_drain_lock);
  69         sx_slock(&proctree_lock);
  70         sx_slock(&clone_drain_lock);
  71         dev_lock();
  72         if (!(p->p_flag & P_CONTROLT))
  73                 *dev = ctty;
  74         else if (p->p_session->s_ttyvp == NULL)
  75                 *dev = ctty;
  76         else if (p->p_session->s_ttyvp->v_type == VBAD ||
  77             p->p_session->s_ttyvp->v_rdev == NULL) {
  78                 /* e.g. s_ttyvp was revoked */
  79                 *dev = ctty;
  80         } else
  81                 *dev = p->p_session->s_ttyvp->v_rdev;
  82         dev_refl(*dev);
  83         dev_unlock();
  84         sx_sunlock(&proctree_lock);
  85 }
  86
  87 static void
  88 ctty_drvinit(void *unused)
  89 {
  90
  91         EVENTHANDLER_REGISTER(dev_clone, ctty_clone, 0, 1000);
  92         ctty = make_dev_credf(MAKEDEV_ETERNAL, &ctty_cdevsw, 0, NULL, UID_ROOT,
  93             GID_WHEEL, 0666, "ctty");
  94 }
  95
  96 SYSINIT(cttydev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE,ctty_drvinit,NULL);