FreeBSD/Linux Kernel Cross Reference
sys/kern/tty_tty.c
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: releng/8.3/sys/kern/tty_tty.c 217532 2011-01-18 10:42:13Z kib $");
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/sx.h>
35 #include <sys/vnode.h>
36
37 #include <fs/devfs/devfs.h>
38 #include <fs/devfs/devfs_int.h>
39
40 static d_open_t cttyopen;
41
42 static struct cdevsw ctty_cdevsw = {
43 .d_version = D_VERSION,
44 .d_open = cttyopen,
45 .d_name = "ctty",
46 };
47
48 static struct cdev *ctty;
49
50 static int
51 cttyopen(struct cdev *dev, int flag, int mode, struct thread *td)
52 {
53
54 return (ENXIO);
55 }
56
57 static void
58 ctty_clone(void *arg, struct ucred *cred, char *name, int namelen,
59 struct cdev **dev)
60 {
61
62 if (*dev != NULL)
63 return;
64 if (strcmp(name, "tty"))
65 return;
66 sx_sunlock(&clone_drain_lock);
67 sx_slock(&proctree_lock);
68 sx_slock(&clone_drain_lock);
69 dev_lock();
70 if (!(curthread->td_proc->p_flag & P_CONTROLT))
71 *dev = ctty;
72 else if (curthread->td_proc->p_session->s_ttyvp == NULL)
73 *dev = ctty;
74 else if (curthread->td_proc->p_session->s_ttyvp->v_type == VBAD ||
75 curthread->td_proc->p_session->s_ttyvp->v_rdev == NULL) {
76 /* e.g. s_ttyvp was revoked */
77 *dev = ctty;
78 } else
79 *dev = curthread->td_proc->p_session->s_ttyvp->v_rdev;
80 dev_refl(*dev);
81 dev_unlock();
82 sx_sunlock(&proctree_lock);
83 }
84
85 static void
86 ctty_drvinit(void *unused)
87 {
88
89 EVENTHANDLER_REGISTER(dev_clone, ctty_clone, 0, 1000);
90 ctty = make_dev_credf(MAKEDEV_ETERNAL, &ctty_cdevsw, 0, NULL, UID_ROOT,
91 GID_WHEEL, 0666, "ctty");
92 }
93
94 SYSINIT(cttydev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE,ctty_drvinit,NULL);
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