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("$FreeBSD$");
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 .d_flags = D_TTY | D_NEEDGIANT,
47 };
48
49 static struct cdev *ctty;
50
51 static int
52 cttyopen(struct cdev *dev, int flag, int mode, struct thread *td)
53 {
54
55 return (ENXIO);
56 }
57
58 static void
59 ctty_clone(void *arg, struct ucred *cred, char *name, int namelen,
60 struct cdev **dev)
61 {
62
63 if (*dev != NULL)
64 return;
65 if (strcmp(name, "tty"))
66 return;
67 sx_sunlock(&clone_drain_lock);
68 mtx_lock(&Giant);
69 sx_slock(&proctree_lock);
70 sx_slock(&clone_drain_lock);
71 dev_lock();
72 if (!(curthread->td_proc->p_flag & P_CONTROLT))
73 *dev = ctty;
74 else if (curthread->td_proc->p_session->s_ttyvp == NULL)
75 *dev = ctty;
76 else if (curthread->td_proc->p_session->s_ttyvp->v_type == VBAD ||
77 curthread->td_proc->p_session->s_ttyvp->v_rdev == NULL) {
78 /* e.g. s_ttyvp was revoked */
79 *dev = ctty;
80 } else
81 *dev = curthread->td_proc->p_session->s_ttyvp->v_rdev;
82 dev_refl(*dev);
83 dev_unlock();
84 sx_sunlock(&proctree_lock);
85 mtx_unlock(&Giant);
86 }
87
88 static void
89 ctty_drvinit(void *unused)
90 {
91
92 EVENTHANDLER_REGISTER(dev_clone, ctty_clone, 0, 1000);
93 ctty = make_dev(&ctty_cdevsw, 0, 0, 0, 0666, "ctty");
94 }
95
96 SYSINIT(cttydev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE,ctty_drvinit,NULL)
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