FreeBSD/Linux Kernel Cross Reference
sys/dev/pty/pty.c

     /*-
      * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
      *
      * Copyright (c) 2008 Ed Schouten <ed@FreeBSD.org>
      * All rights reserved.
      *
      * Portions of this software were developed under sponsorship from Snow
      * B.V., the Netherlands.
      *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     */
    
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD$");
    
    #include <sys/param.h>
    #include <sys/conf.h>
    #include <sys/eventhandler.h>
    #include <sys/fcntl.h>
    #include <sys/kernel.h>
    #include <sys/module.h>
    #include <sys/proc.h>
    #include <sys/sysctl.h>
    #include <sys/syslog.h>
    #include <sys/systm.h>
    #include <sys/tty.h>
    
    /*
     * This driver implements a BSD-style compatibility naming scheme for
     * the pts(4) driver. We just call into pts(4) to create the actual PTY.
     * To make sure we don't use the same PTY multiple times, we abuse
     * si_drv1 inside the cdev to mark whether the PTY is in use.
     *
     * It also implements a /dev/ptmx device node, which is useful for Linux
     * binary emulation.
     */
    
    static unsigned pty_warningcnt = 1;
    SYSCTL_UINT(_kern, OID_AUTO, tty_pty_warningcnt, CTLFLAG_RW,
        &pty_warningcnt, 0,
        "Warnings that will be triggered upon legacy PTY allocation");
    
    static int
    ptydev_fdopen(struct cdev *dev, int fflags, struct thread *td, struct file *fp)
    {
            int error;
            char name[6]; /* "ttyXX" */
    
            if (!atomic_cmpset_ptr((uintptr_t *)&dev->si_drv1, 0, 1))
                    return (EBUSY);
    
            /* Generate device name and create PTY. */
            strlcpy(name, devtoname(dev), sizeof(name));
            name[0] = 't';
    
            error = pts_alloc_external(fflags & (FREAD|FWRITE), td, fp, dev, name);
            if (error != 0) {
                    destroy_dev_sched(dev);
                    return (error);
            }
    
            /* Raise a warning when a legacy PTY has been allocated. */
            counted_warning(&pty_warningcnt, "is using legacy pty devices");
    
            return (0);
    }
    
    static struct cdevsw ptydev_cdevsw = {
            .d_version      = D_VERSION,
            .d_fdopen       = ptydev_fdopen,
            .d_name         = "ptydev",
    };
    
    static void
    pty_clone(void *arg, struct ucred *cr, char *name, int namelen,
        struct cdev **dev)
    {
            struct make_dev_args mda;
            int error;
    
           /* Cloning is already satisfied. */
           if (*dev != NULL)
                   return;
   
           /* Only catch /dev/ptyXX. */
           if (namelen != 5 || bcmp(name, "pty", 3) != 0)
                   return;
   
           /* Only catch /dev/pty[l-sL-S]X. */
           if (!(name[3] >= 'l' && name[3] <= 's') &&
               !(name[3] >= 'L' && name[3] <= 'S'))
                   return;
   
           /* Only catch /dev/pty[l-sL-S][0-9a-v]. */
           if (!(name[4] >= '' && name[4] <= '9') &&
               !(name[4] >= 'a' && name[4] <= 'v'))
                   return;
   
           /* Create the controller device node. */
           make_dev_args_init(&mda);
           mda.mda_flags =  MAKEDEV_CHECKNAME | MAKEDEV_REF;
           mda.mda_devsw = &ptydev_cdevsw;
           mda.mda_uid = UID_ROOT;
           mda.mda_gid = GID_WHEEL;
           mda.mda_mode = 0666;
           error = make_dev_s(&mda, dev, "%s", name);
           if (error != 0)
                   *dev = NULL;
   }
   
   static int
   ptmx_fdopen(struct cdev *dev __unused, int fflags, struct thread *td,
       struct file *fp)
   {
   
           return (pts_alloc(fflags & (FREAD|FWRITE), td, fp));
   }
   
   static struct cdevsw ptmx_cdevsw = {
           .d_version      = D_VERSION,
           .d_fdopen       = ptmx_fdopen,
           .d_name         = "ptmx",
   };
   
   static int
   pty_modevent(module_t mod, int type, void *data)
   {
   
           switch(type) {
           case MOD_LOAD:
                   EVENTHANDLER_REGISTER(dev_clone, pty_clone, 0, 1000);
                   make_dev_credf(MAKEDEV_ETERNAL_KLD, &ptmx_cdevsw, 0, NULL,
                       UID_ROOT, GID_WHEEL, 0666, "ptmx");
                   break;
           case MOD_SHUTDOWN:
                   break;
           case MOD_UNLOAD:
                   /* XXX: No unloading support yet. */
                   return (EBUSY);
           default:
                   return (EOPNOTSUPP);
           }
   
           return (0);
   }
   
   DEV_MODULE(pty, pty_modevent, NULL);

Cache object: e3697e3c4169d1f70709c53b66bd037f