xref: /freebsd/sys/dev/pty/pty.c (revision 23b70c1ae21553acc791d61475afa4708977ad9c)
1bfdaa523SEd Schouten /*-
2bfdaa523SEd Schouten  * Copyright (c) 2008 Ed Schouten <ed@FreeBSD.org>
3bfdaa523SEd Schouten  * All rights reserved.
4bfdaa523SEd Schouten  *
5bfdaa523SEd Schouten  * Portions of this software were developed under sponsorship from Snow
6bfdaa523SEd Schouten  * B.V., the Netherlands.
7bfdaa523SEd Schouten  *
8bfdaa523SEd Schouten  * Redistribution and use in source and binary forms, with or without
9bfdaa523SEd Schouten  * modification, are permitted provided that the following conditions
10bfdaa523SEd Schouten  * are met:
11bfdaa523SEd Schouten  * 1. Redistributions of source code must retain the above copyright
12bfdaa523SEd Schouten  *    notice, this list of conditions and the following disclaimer.
13bfdaa523SEd Schouten  * 2. Redistributions in binary form must reproduce the above copyright
14bfdaa523SEd Schouten  *    notice, this list of conditions and the following disclaimer in the
15bfdaa523SEd Schouten  *    documentation and/or other materials provided with the distribution.
16bfdaa523SEd Schouten  *
17bfdaa523SEd Schouten  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18bfdaa523SEd Schouten  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19bfdaa523SEd Schouten  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20bfdaa523SEd Schouten  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21bfdaa523SEd Schouten  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22bfdaa523SEd Schouten  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23bfdaa523SEd Schouten  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24bfdaa523SEd Schouten  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25bfdaa523SEd Schouten  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26bfdaa523SEd Schouten  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27bfdaa523SEd Schouten  * SUCH DAMAGE.
28bfdaa523SEd Schouten  */
29bfdaa523SEd Schouten 
30bfdaa523SEd Schouten #include <sys/cdefs.h>
31bfdaa523SEd Schouten __FBSDID("$FreeBSD$");
32bfdaa523SEd Schouten 
33bfdaa523SEd Schouten #include <sys/param.h>
34bfdaa523SEd Schouten #include <sys/conf.h>
35bfdaa523SEd Schouten #include <sys/eventhandler.h>
36bfdaa523SEd Schouten #include <sys/fcntl.h>
37bfdaa523SEd Schouten #include <sys/kernel.h>
38bfdaa523SEd Schouten #include <sys/module.h>
39bfdaa523SEd Schouten #include <sys/proc.h>
40bfdaa523SEd Schouten #include <sys/sysctl.h>
41bfdaa523SEd Schouten #include <sys/syslog.h>
42bfdaa523SEd Schouten #include <sys/systm.h>
43bfdaa523SEd Schouten #include <sys/tty.h>
44bfdaa523SEd Schouten 
45bfdaa523SEd Schouten /*
46bfdaa523SEd Schouten  * This driver implements a BSD-style compatibility naming scheme for
47bfdaa523SEd Schouten  * the pts(4) driver. We just call into pts(4) to create the actual PTY.
48bfdaa523SEd Schouten  * To make sure we don't use the same PTY multiple times, we abuse
49bfdaa523SEd Schouten  * si_drv1 inside the cdev to mark whether the PTY is in use.
504d3b1aacSEd Schouten  *
514d3b1aacSEd Schouten  * It also implements a /dev/ptmx device node, which is useful for Linux
524d3b1aacSEd Schouten  * binary emulation.
53bfdaa523SEd Schouten  */
54bfdaa523SEd Schouten 
55bfdaa523SEd Schouten static unsigned int pty_warningcnt = 1;
56bfdaa523SEd Schouten SYSCTL_UINT(_kern, OID_AUTO, tty_pty_warningcnt, CTLFLAG_RW,
57bfdaa523SEd Schouten 	&pty_warningcnt, 0,
58bfdaa523SEd Schouten 	"Warnings that will be triggered upon legacy PTY allocation");
59bfdaa523SEd Schouten 
60bfdaa523SEd Schouten static int
61bfdaa523SEd Schouten ptydev_fdopen(struct cdev *dev, int fflags, struct thread *td, struct file *fp)
62bfdaa523SEd Schouten {
63bfdaa523SEd Schouten 	int error;
64bfdaa523SEd Schouten 	char name[6]; /* "ttyXX" */
65bfdaa523SEd Schouten 
66bfdaa523SEd Schouten 	if (!atomic_cmpset_ptr((uintptr_t *)&dev->si_drv1, 0, 1))
67bfdaa523SEd Schouten 		return (EBUSY);
68bfdaa523SEd Schouten 
69bfdaa523SEd Schouten 	/* Generate device name and create PTY. */
70bfdaa523SEd Schouten 	strcpy(name, devtoname(dev));
71bfdaa523SEd Schouten 	name[0] = 't';
72bfdaa523SEd Schouten 
73bfdaa523SEd Schouten 	error = pts_alloc_external(fflags & (FREAD|FWRITE), td, fp, dev, name);
74bfdaa523SEd Schouten 	if (error != 0) {
75bfdaa523SEd Schouten 		destroy_dev_sched(dev);
76bfdaa523SEd Schouten 		return (error);
77bfdaa523SEd Schouten 	}
78bfdaa523SEd Schouten 
79bfdaa523SEd Schouten 	/* Raise a warning when a legacy PTY has been allocated. */
80bfdaa523SEd Schouten 	if (pty_warningcnt > 0) {
81bfdaa523SEd Schouten 		pty_warningcnt--;
82bfdaa523SEd Schouten 		log(LOG_INFO, "pid %d (%s) is using legacy pty devices%s\n",
83bfdaa523SEd Schouten 		    td->td_proc->p_pid, td->td_name,
84bfdaa523SEd Schouten 		    pty_warningcnt ? "" : " - not logging anymore");
85bfdaa523SEd Schouten 	}
86bfdaa523SEd Schouten 
87bfdaa523SEd Schouten 	return (0);
88bfdaa523SEd Schouten }
89bfdaa523SEd Schouten 
90bfdaa523SEd Schouten static struct cdevsw ptydev_cdevsw = {
91bfdaa523SEd Schouten 	.d_version	= D_VERSION,
92bfdaa523SEd Schouten 	.d_fdopen	= ptydev_fdopen,
93bfdaa523SEd Schouten 	.d_name		= "ptydev",
94bfdaa523SEd Schouten };
95bfdaa523SEd Schouten 
96bfdaa523SEd Schouten static void
97bfdaa523SEd Schouten pty_clone(void *arg, struct ucred *cr, char *name, int namelen,
98bfdaa523SEd Schouten     struct cdev **dev)
99bfdaa523SEd Schouten {
100bfdaa523SEd Schouten 
101bfdaa523SEd Schouten 	/* Cloning is already satisfied. */
102bfdaa523SEd Schouten 	if (*dev != NULL)
103bfdaa523SEd Schouten 		return;
104bfdaa523SEd Schouten 
105bfdaa523SEd Schouten 	/* Only catch /dev/ptyXX. */
106bfdaa523SEd Schouten 	if (namelen != 5 || bcmp(name, "pty", 3) != 0)
107bfdaa523SEd Schouten 		return;
108bfdaa523SEd Schouten 
109bfdaa523SEd Schouten 	/* Only catch /dev/pty[l-sL-S]X. */
110bfdaa523SEd Schouten 	if (!(name[3] >= 'l' && name[3] <= 's') &&
111bfdaa523SEd Schouten 	    !(name[3] >= 'L' && name[3] <= 'S'))
112bfdaa523SEd Schouten 		return;
113bfdaa523SEd Schouten 
114bfdaa523SEd Schouten 	/* Only catch /dev/pty[l-sL-S][0-9a-v]. */
115bfdaa523SEd Schouten 	if (!(name[4] >= '0' && name[4] <= '9') &&
116bfdaa523SEd Schouten 	    !(name[4] >= 'a' && name[4] <= 'v'))
117bfdaa523SEd Schouten 		return;
118bfdaa523SEd Schouten 
119bfdaa523SEd Schouten 	/* Create the controller device node. */
120bfdaa523SEd Schouten 	*dev = make_dev_credf(MAKEDEV_REF, &ptydev_cdevsw, 0,
121bfdaa523SEd Schouten 	    NULL, UID_ROOT, GID_WHEEL, 0666, "%s", name);
122bfdaa523SEd Schouten }
123bfdaa523SEd Schouten 
124bfdaa523SEd Schouten static int
1254d3b1aacSEd Schouten ptmx_fdopen(struct cdev *dev __unused, int fflags, struct thread *td,
1264d3b1aacSEd Schouten     struct file *fp)
1274d3b1aacSEd Schouten {
1284d3b1aacSEd Schouten 
1294d3b1aacSEd Schouten 	return (pts_alloc(fflags & (FREAD|FWRITE), td, fp));
1304d3b1aacSEd Schouten }
1314d3b1aacSEd Schouten 
1324d3b1aacSEd Schouten static struct cdevsw ptmx_cdevsw = {
1334d3b1aacSEd Schouten 	.d_version	= D_VERSION,
1344d3b1aacSEd Schouten 	.d_fdopen	= ptmx_fdopen,
1354d3b1aacSEd Schouten 	.d_name		= "ptmx",
1364d3b1aacSEd Schouten };
1374d3b1aacSEd Schouten 
1384d3b1aacSEd Schouten static int
139bfdaa523SEd Schouten pty_modevent(module_t mod, int type, void *data)
140bfdaa523SEd Schouten {
141bfdaa523SEd Schouten 
142bfdaa523SEd Schouten         switch(type) {
143bfdaa523SEd Schouten         case MOD_LOAD:
144bfdaa523SEd Schouten 		EVENTHANDLER_REGISTER(dev_clone, pty_clone, 0, 1000);
145*23b70c1aSKonstantin Belousov 		make_dev_credf(MAKEDEV_ETERNAL_KLD, &ptmx_cdevsw, 0, NULL,
146*23b70c1aSKonstantin Belousov 		    UID_ROOT, GID_WHEEL, 0666, "ptmx");
147bfdaa523SEd Schouten 		break;
148bfdaa523SEd Schouten 	case MOD_SHUTDOWN:
149bfdaa523SEd Schouten 		break;
150bfdaa523SEd Schouten 	case MOD_UNLOAD:
151bfdaa523SEd Schouten 		/* XXX: No unloading support yet. */
152bfdaa523SEd Schouten 		return (EBUSY);
153bfdaa523SEd Schouten 	default:
154bfdaa523SEd Schouten 		return (EOPNOTSUPP);
155bfdaa523SEd Schouten 	}
156bfdaa523SEd Schouten 
157bfdaa523SEd Schouten 	return (0);
158bfdaa523SEd Schouten }
159bfdaa523SEd Schouten 
160bfdaa523SEd Schouten DEV_MODULE(pty, pty_modevent, NULL);
161