1178825Sdfr/*-
2233294Sstas * Copyright (c) 2003 Poul-Henning Kamp.  All rights reserved.
3233294Sstas *
4233294Sstas * Redistribution and use in source and binary forms, with or without
5178825Sdfr * modification, are permitted provided that the following conditions
6233294Sstas * are met:
7233294Sstas * 1. Redistributions of source code must retain the above copyright
8233294Sstas *    notice, this list of conditions and the following disclaimer.
9178825Sdfr * 2. Redistributions in binary form must reproduce the above copyright
10233294Sstas *    notice, this list of conditions and the following disclaimer in the
11233294Sstas *    documentation and/or other materials provided with the distribution.
12178825Sdfr *
13233294Sstas * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
14233294Sstas * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15233294Sstas * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
16178825Sdfr * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
17233294Sstas * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
18233294Sstas * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
19233294Sstas * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
20178825Sdfr * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
21233294Sstas * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
22233294Sstas * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
23233294Sstas * SUCH DAMAGE.
24233294Sstas */
25233294Sstas
26233294Sstas#include <sys/cdefs.h>
27233294Sstas__FBSDID("$FreeBSD$");
28233294Sstas
29233294Sstas#include <sys/param.h>
30233294Sstas#include <sys/systm.h>
31233294Sstas#include <sys/conf.h>
32178825Sdfr#include <sys/kernel.h>
33178825Sdfr#include <sys/proc.h>
34178825Sdfr#include <sys/sx.h>
35178825Sdfr#include <sys/vnode.h>
36178825Sdfr
37178825Sdfr#include <fs/devfs/devfs.h>
38178825Sdfr#include <fs/devfs/devfs_int.h>
39178825Sdfr
40178825Sdfrstatic	d_open_t	cttyopen;
41178825Sdfr
42178825Sdfrstatic struct cdevsw ctty_cdevsw = {
43178825Sdfr	.d_version =	D_VERSION,
44178825Sdfr	.d_open =	cttyopen,
45178825Sdfr	.d_name =	"ctty",
46178825Sdfr};
47178825Sdfr
48178825Sdfrstatic struct cdev *ctty;
49178825Sdfr
50178825Sdfrstatic	int
51178825Sdfrcttyopen(struct cdev *dev, int flag, int mode, struct thread *td)
52{
53
54	return (ENXIO);
55}
56
57static void
58ctty_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
87static void
88ctty_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
96SYSINIT(cttydev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE,ctty_drvinit,NULL);
97