kernel - Major signal path adjustments to fix races, tsleep race fixes, +more
[dragonfly.git] / sys / kern / tty_tty.c
CommitLineData
984263bc 1/*-
22ff886e
AH
2 * (MPSAFE)
3 *
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4 * Copyright (c) 1982, 1986, 1991, 1993
5 * The Regents of the University of California. All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. All advertising materials mentioning features or use of this software
16 * must display the following acknowledgement:
17 * This product includes software developed by the University of
18 * California, Berkeley and its contributors.
19 * 4. Neither the name of the University nor the names of its contributors
20 * may be used to endorse or promote products derived from this software
21 * without specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * SUCH DAMAGE.
34 *
35 * @(#)tty_tty.c 8.2 (Berkeley) 9/23/93
36 * $FreeBSD: src/sys/kern/tty_tty.c,v 1.30 1999/09/25 18:24:24 phk Exp $
37 */
38
39/*
40 * Indirect driver for controlling tty.
41 */
42
43#include <sys/param.h>
44#include <sys/systm.h>
45#include <sys/conf.h>
fef8985e 46#include <sys/device.h>
984263bc 47#include <sys/lock.h>
84cca6ec 48#include <sys/fcntl.h>
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49#include <sys/proc.h>
50#include <sys/ttycom.h>
51#include <sys/vnode.h>
52#include <sys/kernel.h>
163625b9 53#include <sys/poll.h> /* XXX: poll args used in KQ filters */
7d1f168a 54#include <sys/event.h>
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55
56static d_open_t cttyopen;
e4c9c0c8 57static d_close_t cttyclose;
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58static d_read_t cttyread;
59static d_write_t cttywrite;
60static d_ioctl_t cttyioctl;
7d1f168a
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61static d_kqfilter_t cttykqfilter;
62
63static void cttyfilt_detach(struct knote *);
64static int cttyfilt_read(struct knote *, long);
65static int cttyfilt_write(struct knote *, long);
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66
67#define CDEV_MAJOR 1
f49c57cd 68static struct dev_ops ctty_ops = {
88abd8b5 69 { "ctty", 0, D_TTY },
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70 .d_open = cttyopen,
71 .d_close = cttyclose,
72 .d_read = cttyread,
73 .d_write = cttywrite,
74 .d_ioctl = cttyioctl,
7d1f168a 75 .d_kqfilter = cttykqfilter
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76};
77
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78#define cttyvp(p) (((p)->p_flags & P_CONTROLT) ? \
79 (p)->p_session->s_ttyvp : NULL)
984263bc 80
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81/*
82 * This opens /dev/tty. Because multiple opens of /dev/tty only
83 * generate a single open to the actual tty, the file modes are
84 * locked to FREAD|FWRITE.
85 */
984263bc 86static int
fef8985e 87cttyopen(struct dev_open_args *ap)
984263bc 88{
fef8985e 89 struct proc *p = curproc;
41c20dac 90 struct vnode *ttyvp;
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91 int error;
92
dadab5e9 93 KKASSERT(p);
f1aeb0c0
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94retry:
95 if ((ttyvp = cttyvp(p)) == NULL)
96 return (ENXIO);
97 if (ttyvp->v_flag & VCTTYISOPEN)
98 return (0);
99
100 /*
101 * Messy interlock, don't let the vnode go away while we try to
102 * lock it and check for race after we might have blocked.
103 */
104 vhold(ttyvp);
105 vn_lock(ttyvp, LK_EXCLUSIVE | LK_RETRY);
106 if (ttyvp != cttyvp(p) || (ttyvp->v_flag & VCTTYISOPEN)) {
107 kprintf("Warning: cttyopen: race avoided\n");
108 vn_unlock(ttyvp);
109 vdrop(ttyvp);
110 goto retry;
e4c9c0c8 111 }
f1aeb0c0
MD
112 vsetflags(ttyvp, VCTTYISOPEN);
113 error = VOP_OPEN(ttyvp, FREAD|FWRITE, ap->a_cred, NULL);
114 if (error)
115 vclrflags(ttyvp, VCTTYISOPEN);
116 vn_unlock(ttyvp);
117 vdrop(ttyvp);
118 return(error);
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119}
120
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121/*
122 * This closes /dev/tty. Because multiple opens of /dev/tty only
123 * generate a single open to the actual tty, the file modes are
124 * locked to FREAD|FWRITE.
125 */
e4c9c0c8 126static int
fef8985e 127cttyclose(struct dev_close_args *ap)
e4c9c0c8 128{
fef8985e 129 struct proc *p = curproc;
e4c9c0c8
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130 struct vnode *ttyvp;
131 int error;
132
133 KKASSERT(p);
f1aeb0c0
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134retry:
135 /*
136 * The tty may have been TIOCNOTTY'd, don't return an
137 * error on close. We just have nothing to do.
138 */
139 if ((ttyvp = cttyvp(p)) == NULL)
140 return(0);
141 if (ttyvp->v_flag & VCTTYISOPEN) {
5fd012e0 142 /*
f1aeb0c0 143 * Avoid a nasty race if we block while getting the lock.
5fd012e0 144 */
8e73fd39 145 vref(ttyvp);
ca466bae 146 error = vn_lock(ttyvp, LK_EXCLUSIVE | LK_RETRY);
f1aeb0c0 147 if (error) {
8e73fd39 148 vrele(ttyvp);
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149 goto retry;
150 }
151 if (ttyvp != cttyvp(p) || (ttyvp->v_flag & VCTTYISOPEN) == 0) {
152 kprintf("Warning: cttyclose: race avoided\n");
a11aaa81 153 vn_unlock(ttyvp);
8e73fd39 154 vrele(ttyvp);
f1aeb0c0 155 goto retry;
5fd012e0 156 }
f1aeb0c0
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157 vclrflags(ttyvp, VCTTYISOPEN);
158 error = VOP_CLOSE(ttyvp, FREAD|FWRITE);
159 vn_unlock(ttyvp);
8e73fd39 160 vrele(ttyvp);
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161 } else {
162 error = 0;
163 }
e4c9c0c8
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164 return(error);
165}
166
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167/*
168 * Read from the controlling terminal (/dev/tty). The tty is refed as
169 * of the cttyvp(), but the ref can get ripped out from under us if
170 * the controlling terminal is revoked while we are blocked on the lock,
a11aaa81 171 * so use vget() instead of vn_lock().
84cca6ec 172 */
984263bc 173static int
fef8985e 174cttyread(struct dev_read_args *ap)
984263bc 175{
fef8985e 176 struct proc *p = curproc;
dadab5e9 177 struct vnode *ttyvp;
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178 int error;
179
dadab5e9
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180 KKASSERT(p);
181 ttyvp = cttyvp(p);
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182 if (ttyvp == NULL)
183 return (EIO);
87de5057 184 if ((error = vget(ttyvp, LK_EXCLUSIVE | LK_RETRY)) == 0) {
fef8985e 185 error = VOP_READ(ttyvp, ap->a_uio, ap->a_ioflag, NOCRED);
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186 vput(ttyvp);
187 }
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188 return (error);
189}
190
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191/*
192 * Read from the controlling terminal (/dev/tty). The tty is refed as
193 * of the cttyvp(), but the ref can get ripped out from under us if
194 * the controlling terminal is revoked while we are blocked on the lock,
a11aaa81 195 * so use vget() instead of vn_lock().
84cca6ec 196 */
984263bc 197static int
fef8985e 198cttywrite(struct dev_write_args *ap)
984263bc 199{
fef8985e 200 struct proc *p = curproc;
dadab5e9 201 struct vnode *ttyvp;
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202 int error;
203
dadab5e9
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204 KKASSERT(p);
205 ttyvp = cttyvp(p);
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206 if (ttyvp == NULL)
207 return (EIO);
87de5057 208 if ((error = vget(ttyvp, LK_EXCLUSIVE | LK_RETRY)) == 0) {
fef8985e 209 error = VOP_WRITE(ttyvp, ap->a_uio, ap->a_ioflag, NOCRED);
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210 vput(ttyvp);
211 }
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212 return (error);
213}
214
215/*ARGSUSED*/
216static int
fef8985e 217cttyioctl(struct dev_ioctl_args *ap)
984263bc 218{
41c20dac 219 struct vnode *ttyvp;
fef8985e 220 struct proc *p = curproc;
984263bc 221
dadab5e9 222 KKASSERT(p);
616516c8 223 lwkt_gettoken(&p->p_token);
22ff886e 224 lwkt_gettoken(&proc_token);
dadab5e9 225 ttyvp = cttyvp(p);
22ff886e
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226 if (ttyvp == NULL) {
227 lwkt_reltoken(&proc_token);
f303603c 228 lwkt_reltoken(&p->p_token);
984263bc 229 return (EIO);
22ff886e 230 }
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231 /*
232 * Don't allow controlling tty to be set to the controlling tty
233 * (infinite recursion).
234 */
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235 if (ap->a_cmd == TIOCSCTTY) {
236 lwkt_reltoken(&proc_token);
f303603c 237 lwkt_reltoken(&p->p_token);
fef8985e 238 return EINVAL;
22ff886e 239 }
fef8985e 240 if (ap->a_cmd == TIOCNOTTY) {
dadab5e9 241 if (!SESS_LEADER(p)) {
4643740a 242 p->p_flags &= ~P_CONTROLT;
22ff886e 243 lwkt_reltoken(&proc_token);
f303603c 244 lwkt_reltoken(&p->p_token);
984263bc 245 return (0);
fef8985e 246 } else {
22ff886e 247 lwkt_reltoken(&proc_token);
f303603c 248 lwkt_reltoken(&p->p_token);
984263bc 249 return (EINVAL);
fef8985e 250 }
984263bc 251 }
22ff886e 252 lwkt_reltoken(&proc_token);
f303603c 253 lwkt_reltoken(&p->p_token);
22ff886e 254
87baaf0c
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255 return (VOP_IOCTL(ttyvp, ap->a_cmd, ap->a_data, ap->a_fflag,
256 ap->a_cred, ap->a_sysmsg));
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257}
258
7d1f168a 259static struct filterops cttyfiltops_read =
4c91dbc9 260 { FILTEROP_ISFD, NULL, cttyfilt_detach, cttyfilt_read };
7d1f168a 261static struct filterops cttyfiltops_write =
4c91dbc9 262 { FILTEROP_ISFD, NULL, cttyfilt_detach, cttyfilt_write };
7d1f168a
SG
263
264static int
265cttykqfilter(struct dev_kqfilter_args *ap)
266{
267 cdev_t dev = ap->a_head.a_dev;
268 struct proc *p = curproc;
269 struct knote *kn = ap->a_kn;
270 struct vnode *ttyvp;
271
272 KKASSERT(p);
273 ttyvp = cttyvp(p);
274
275 if (ttyvp != NULL)
276 return (VOP_KQFILTER(ttyvp, kn));
277
278 ap->a_result = 0;
279
280 switch (kn->kn_filter) {
281 case EVFILT_READ:
282 kn->kn_fop = &cttyfiltops_read;
283 kn->kn_hook = (caddr_t)dev;
284 break;
285 case EVFILT_WRITE:
286 kn->kn_fop = &cttyfiltops_write;
287 kn->kn_hook = (caddr_t)dev;
288 break;
289 default:
b287d649 290 ap->a_result = EOPNOTSUPP;
7d1f168a
SG
291 return (0);
292 }
293
294 return (0);
295}
296
297static void
298cttyfilt_detach(struct knote *kn) {}
299
300static int
301cttyfilt_read(struct knote *kn, long hint)
302{
303 cdev_t dev = (cdev_t)kn->kn_hook;
304
305 if (seltrue(dev, POLLIN | POLLRDNORM))
306 return (1);
307
308 return (0);
309}
310
311static int
312cttyfilt_write(struct knote *kn, long hint)
313{
314 cdev_t dev = (cdev_t)kn->kn_hook;
315
316 if (seltrue(dev, POLLOUT | POLLWRNORM))
317 return (1);
318
319 return (0);
320}
321
984263bc 322static void
fef8985e 323ctty_drvinit(void *unused __unused)
984263bc 324{
fef8985e 325 make_dev(&ctty_ops, 0, 0, 0, 0666, "tty");
984263bc
MD
326}
327
328SYSINIT(cttydev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE+CDEV_MAJOR,ctty_drvinit,NULL)