FreeBSD/Linux Kernel Cross Reference
sys/kern/tty_tty.c
1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 2003 Poul-Henning Kamp. All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * SUCH DAMAGE.
26 */
27
28 #include <sys/cdefs.h>
29 __FBSDID("$FreeBSD$");
30
31 #include <sys/param.h>
32 #include <sys/systm.h>
33 #include <sys/conf.h>
34 #include <sys/kernel.h>
35 #include <sys/proc.h>
36 #include <sys/sx.h>
37 #include <sys/vnode.h>
38
39 #include <fs/devfs/devfs.h>
40 #include <fs/devfs/devfs_int.h>
41
42 static d_open_t cttyopen;
43
44 static struct cdevsw ctty_cdevsw = {
45 .d_version = D_VERSION,
46 .d_open = cttyopen,
47 .d_name = "ctty",
48 };
49
50 static struct cdev *ctty;
51
52 static int
53 cttyopen(struct cdev *dev, int flag, int mode, struct thread *td)
54 {
55
56 return (ENXIO);
57 }
58
59 static void
60 ctty_clone(void *arg, struct ucred *cred, char *name, int namelen,
61 struct cdev **dev)
62 {
63 struct proc *p;
64
65 if (*dev != NULL)
66 return;
67 if (strcmp(name, "tty"))
68 return;
69 p = curproc;
70 sx_sunlock(&clone_drain_lock);
71 sx_slock(&proctree_lock);
72 sx_slock(&clone_drain_lock);
73 dev_lock();
74 if (!(p->p_flag & P_CONTROLT))
75 *dev = ctty;
76 else if (p->p_session->s_ttyvp == NULL)
77 *dev = ctty;
78 else if (p->p_session->s_ttyvp->v_type == VBAD ||
79 p->p_session->s_ttyvp->v_rdev == NULL) {
80 /* e.g. s_ttyvp was revoked */
81 *dev = ctty;
82 } else
83 *dev = p->p_session->s_ttyvp->v_rdev;
84 dev_refl(*dev);
85 dev_unlock();
86 sx_sunlock(&proctree_lock);
87 }
88
89 static void
90 ctty_drvinit(void *unused)
91 {
92
93 EVENTHANDLER_REGISTER(dev_clone, ctty_clone, 0, 1000);
94 ctty = make_dev_credf(MAKEDEV_ETERNAL, &ctty_cdevsw, 0, NULL, UID_ROOT,
95 GID_WHEEL, 0666, "ctty");
96 }
97
98 SYSINIT(cttydev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE,ctty_drvinit,NULL);
Cache object: 93af99497357c833808489c4dfe3c0ac
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