The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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

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

Cache object: 297d1bca866c46522569dd3e835c38df


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