tty_tty.c revision 148868 
1/*-
2 * Copyright (c) 2003 Poul-Henning Kamp.  All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 *    notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 *    notice, this list of conditions and the following disclaimer in the
11 *    documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
14 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
16 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
17 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
18 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
19 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
20 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
21 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
22 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
23 * SUCH DAMAGE.
24 */
25
26#include <sys/cdefs.h>
27__FBSDID("$FreeBSD: head/sys/kern/tty_tty.c 148868 2005-08-08 19:55:32Z rwatson $");
28
29#include <sys/param.h>
30#include <sys/systm.h>
31#include <sys/conf.h>
32#include <sys/kernel.h>
33#include <sys/proc.h>
34#include <sys/vnode.h>
35
36static	d_open_t	cttyopen;
37
38static struct cdevsw ctty_cdevsw = {
39	.d_version =	D_VERSION,
40	.d_open =	cttyopen,
41	.d_name =	"ctty",
42	.d_flags =	D_TTY | D_NEEDGIANT,
43};
44
45static struct cdev *ctty;
46
47static	int
48cttyopen(struct cdev *dev, int flag, int mode, struct thread *td)
49{
50
51	return (ENXIO);
52}
53
54static void
55ctty_clone(void *arg, struct ucred *cred, char *name, int namelen,
56    struct cdev **dev)
57{
58
59	if (*dev != NULL)
60		return;
61	if (strcmp(name, "tty"))
62		return;
63	if (!(curthread->td_proc->p_flag & P_CONTROLT))
64		*dev = ctty;
65	else if (curthread->td_proc->p_session->s_ttyvp == NULL)
66		*dev = ctty;
67	else
68		*dev = curthread->td_proc->p_session->s_ttyvp->v_rdev;
69	dev_ref(*dev);
70}
71
72static void
73ctty_drvinit(void *unused)
74{
75
76	EVENTHANDLER_REGISTER(dev_clone, ctty_clone, 0, 1000);
77	ctty = make_dev(&ctty_cdevsw, 0, 0, 0, 0666, "ctty");
78}
79
80SYSINIT(cttydev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE,ctty_drvinit,NULL)
81