2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
4 * Copyright (c) 2008 Ed Schouten <ed@FreeBSD.org>
7 * Portions of this software were developed under sponsorship from Snow
8 * B.V., the Netherlands.
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
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.
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
32 #include <sys/cdefs.h>
33 __FBSDID("$FreeBSD$");
35 #include <sys/param.h>
37 #include <sys/eventhandler.h>
38 #include <sys/fcntl.h>
39 #include <sys/kernel.h>
40 #include <sys/module.h>
42 #include <sys/sysctl.h>
43 #include <sys/syslog.h>
44 #include <sys/systm.h>
48 * This driver implements a BSD-style compatibility naming scheme for
49 * the pts(4) driver. We just call into pts(4) to create the actual PTY.
50 * To make sure we don't use the same PTY multiple times, we abuse
51 * si_drv1 inside the cdev to mark whether the PTY is in use.
53 * It also implements a /dev/ptmx device node, which is useful for Linux
57 static unsigned pty_warningcnt = 1;
58 SYSCTL_UINT(_kern, OID_AUTO, tty_pty_warningcnt, CTLFLAG_RW,
60 "Warnings that will be triggered upon legacy PTY allocation");
63 ptydev_fdopen(struct cdev *dev, int fflags, struct thread *td, struct file *fp)
66 char name[6]; /* "ttyXX" */
68 if (!atomic_cmpset_ptr((uintptr_t *)&dev->si_drv1, 0, 1))
71 /* Generate device name and create PTY. */
72 strlcpy(name, devtoname(dev), sizeof(name));
75 error = pts_alloc_external(fflags & (FREAD|FWRITE), td, fp, dev, name);
77 destroy_dev_sched(dev);
81 /* Raise a warning when a legacy PTY has been allocated. */
82 counted_warning(&pty_warningcnt, "is using legacy pty devices");
87 static struct cdevsw ptydev_cdevsw = {
88 .d_version = D_VERSION,
89 .d_fdopen = ptydev_fdopen,
94 pty_clone(void *arg, struct ucred *cr, char *name, int namelen,
97 struct make_dev_args mda;
100 /* Cloning is already satisfied. */
104 /* Only catch /dev/ptyXX. */
105 if (namelen != 5 || bcmp(name, "pty", 3) != 0)
108 /* Only catch /dev/pty[l-sL-S]X. */
109 if (!(name[3] >= 'l' && name[3] <= 's') &&
110 !(name[3] >= 'L' && name[3] <= 'S'))
113 /* Only catch /dev/pty[l-sL-S][0-9a-v]. */
114 if (!(name[4] >= '0' && name[4] <= '9') &&
115 !(name[4] >= 'a' && name[4] <= 'v'))
118 /* Create the controller device node. */
119 make_dev_args_init(&mda);
120 mda.mda_flags = MAKEDEV_CHECKNAME | MAKEDEV_REF;
121 mda.mda_devsw = &ptydev_cdevsw;
122 mda.mda_uid = UID_ROOT;
123 mda.mda_gid = GID_WHEEL;
125 error = make_dev_s(&mda, dev, "%s", name);
131 ptmx_fdopen(struct cdev *dev __unused, int fflags, struct thread *td,
135 return (pts_alloc(fflags & (FREAD|FWRITE), td, fp));
138 static struct cdevsw ptmx_cdevsw = {
139 .d_version = D_VERSION,
140 .d_fdopen = ptmx_fdopen,
145 pty_modevent(module_t mod, int type, void *data)
150 EVENTHANDLER_REGISTER(dev_clone, pty_clone, 0, 1000);
151 make_dev_credf(MAKEDEV_ETERNAL_KLD, &ptmx_cdevsw, 0, NULL,
152 UID_ROOT, GID_WHEEL, 0666, "ptmx");
157 /* XXX: No unloading support yet. */
166 DEV_MODULE(pty, pty_modevent, NULL);