FreeBSD/Linux Kernel Cross Reference
sys/kern/tty_conf.c
1 /* $NetBSD: tty_conf.c,v 1.52 2006/11/01 10:17:59 yamt Exp $ */
2
3 /*-
4 * Copyright (c) 2005 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Jason R. Thorpe.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. All advertising materials mentioning features or use of this software
19 * must display the following acknowledgement:
20 * This product includes software developed by the NetBSD
21 * Foundation, Inc. and its contributors.
22 * 4. Neither the name of The NetBSD Foundation nor the names of its
23 * contributors may be used to endorse or promote products derived
24 * from this software without specific prior written permission.
25 *
26 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
27 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
28 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
29 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
30 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
31 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
32 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
33 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
34 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
35 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
36 * POSSIBILITY OF SUCH DAMAGE.
37 */
38
39 /*-
40 * Copyright (c) 1982, 1986, 1991, 1993
41 * The Regents of the University of California. All rights reserved.
42 * (c) UNIX System Laboratories, Inc.
43 * All or some portions of this file are derived from material licensed
44 * to the University of California by American Telephone and Telegraph
45 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
46 * the permission of UNIX System Laboratories, Inc.
47 *
48 * Redistribution and use in source and binary forms, with or without
49 * modification, are permitted provided that the following conditions
50 * are met:
51 * 1. Redistributions of source code must retain the above copyright
52 * notice, this list of conditions and the following disclaimer.
53 * 2. Redistributions in binary form must reproduce the above copyright
54 * notice, this list of conditions and the following disclaimer in the
55 * documentation and/or other materials provided with the distribution.
56 * 3. Neither the name of the University nor the names of its contributors
57 * may be used to endorse or promote products derived from this software
58 * without specific prior written permission.
59 *
60 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
61 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
62 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
63 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
64 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
65 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
66 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
67 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
68 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
69 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
70 * SUCH DAMAGE.
71 *
72 * @(#)tty_conf.c 8.5 (Berkeley) 1/9/95
73 */
74
75 #include <sys/cdefs.h>
76 __KERNEL_RCSID(0, "$NetBSD: tty_conf.c,v 1.52 2006/11/01 10:17:59 yamt Exp $");
77
78 #include <sys/param.h>
79 #include <sys/systm.h>
80 #include <sys/poll.h>
81 #include <sys/proc.h>
82 #include <sys/tty.h>
83 #include <sys/ttycom.h>
84 #include <sys/conf.h>
85 #include <sys/once.h>
86 #include <sys/lock.h>
87 #include <sys/queue.h>
88
89 static struct linesw termios_disc = {
90 .l_name = "termios",
91 .l_open = ttylopen,
92 .l_close = ttylclose,
93 .l_read = ttread,
94 .l_write = ttwrite,
95 .l_ioctl = ttynullioctl,
96 .l_rint = ttyinput,
97 .l_start = ttstart,
98 .l_modem = ttymodem,
99 .l_poll = ttpoll
100 };
101
102 /*
103 * This is for the benefit of old BSD TTY compatbility, but since it is
104 * identical to termios (except for the name), don't bother conditionalizing
105 * it.
106 */
107 static struct linesw ntty_disc = { /* old NTTYDISC */
108 .l_name = "ntty",
109 .l_open = ttylopen,
110 .l_close = ttylclose,
111 .l_read = ttread,
112 .l_write = ttwrite,
113 .l_ioctl = ttynullioctl,
114 .l_rint = ttyinput,
115 .l_start = ttstart,
116 .l_modem = ttymodem,
117 .l_poll = ttpoll
118 };
119
120 static LIST_HEAD(, linesw) ttyldisc_list = LIST_HEAD_INITIALIZER(ttyldisc_head);
121 static struct simplelock ttyldisc_list_slock = SIMPLELOCK_INITIALIZER;
122
123 /*
124 * Note: We don't bother refcounting termios_disc and ntty_disc; they can't
125 * be removed from the list, and termios_disc is likely to have very many
126 * references (could we overflow the count?).
127 */
128 #define TTYLDISC_ISSTATIC(disc) \
129 ((disc) == &termios_disc || (disc) == &ntty_disc)
130
131 #define TTYLDISC_HOLD(disc) \
132 do { \
133 if (! TTYLDISC_ISSTATIC(disc)) { \
134 KASSERT((disc)->l_refcnt != UINT_MAX); \
135 (disc)->l_refcnt++; \
136 } \
137 } while (/*CONSTCOND*/0)
138
139 #define TTYLDISC_RELE(disc) \
140 do { \
141 if (! TTYLDISC_ISSTATIC(disc)) { \
142 KASSERT((disc)->l_refcnt != 0); \
143 (disc)->l_refcnt--; \
144 } \
145 } while (/*CONSTCOND*/0)
146
147 #define TTYLDISC_ISINUSE(disc) \
148 (TTYLDISC_ISSTATIC(disc) || (disc)->l_refcnt != 0)
149
150 /*
151 * Do nothing specific version of line
152 * discipline specific ioctl command.
153 */
154 /*ARGSUSED*/
155 int
156 ttynullioctl(struct tty *tp, u_long cmd, char *data, int flags, struct lwp *l)
157 {
158
159 return (EPASSTHROUGH);
160 }
161
162 /*
163 * Return error to line discipline
164 * specific poll call.
165 */
166 /*ARGSUSED*/
167 int
168 ttyerrpoll(struct tty *tp, int events, struct lwp *l)
169 {
170
171 return (POLLERR);
172 }
173
174 static ONCE_DECL(ttyldisc_init_once);
175
176 static int
177 ttyldisc_init(void)
178 {
179
180 if (ttyldisc_attach(&termios_disc) != 0)
181 panic("ttyldisc_init: termios_disc");
182 if (ttyldisc_attach(&ntty_disc) != 0)
183 panic("ttyldisc_init: ntty_disc");
184
185 return 0;
186 }
187
188 static struct linesw *
189 ttyldisc_lookup_locked(const char *name)
190 {
191 struct linesw *disc;
192
193 LIST_FOREACH(disc, &ttyldisc_list, l_list) {
194 if (strcmp(name, disc->l_name) == 0)
195 return (disc);
196 }
197
198 return (NULL);
199 }
200
201 /*
202 * Look up a line discipline by its name. Caller holds a reference on
203 * the returned line discipline.
204 */
205 struct linesw *
206 ttyldisc_lookup(const char *name)
207 {
208 struct linesw *disc;
209
210 RUN_ONCE(&ttyldisc_init_once, ttyldisc_init);
211
212 simple_lock(&ttyldisc_list_slock);
213 disc = ttyldisc_lookup_locked(name);
214 if (disc != NULL)
215 TTYLDISC_HOLD(disc);
216 simple_unlock(&ttyldisc_list_slock);
217
218 return (disc);
219 }
220
221 /*
222 * Look up a line discipline by its legacy number. Caller holds a
223 * reference on the returned line discipline.
224 */
225 struct linesw *
226 ttyldisc_lookup_bynum(int num)
227 {
228 struct linesw *disc;
229
230 RUN_ONCE(&ttyldisc_init_once, ttyldisc_init);
231
232 simple_lock(&ttyldisc_list_slock);
233
234 LIST_FOREACH(disc, &ttyldisc_list, l_list) {
235 if (disc->l_no == num) {
236 TTYLDISC_HOLD(disc);
237 simple_unlock(&ttyldisc_list_slock);
238 return (disc);
239 }
240 }
241
242 simple_unlock(&ttyldisc_list_slock);
243 return (NULL);
244 }
245
246 /*
247 * Release a reference on a line discipline previously added by
248 * ttyldisc_lookup() or ttyldisc_lookup_bynum().
249 */
250 void
251 ttyldisc_release(struct linesw *disc)
252 {
253
254 if (disc == NULL)
255 return;
256
257 simple_lock(&ttyldisc_list_slock);
258 TTYLDISC_RELE(disc);
259 simple_unlock(&ttyldisc_list_slock);
260 }
261
262 #define TTYLDISC_LEGACY_NUMBER_MIN 10
263 #define TTYLDISC_LEGACY_NUMBER_MAX INT_MAX
264
265 static void
266 ttyldisc_assign_legacy_number(struct linesw *disc)
267 {
268 static const struct {
269 const char *name;
270 int num;
271 } table[] = {
272 { "termios", TTYDISC },
273 { "ntty", 2 /* XXX old NTTYDISC */ },
274 { "tablet", TABLDISC },
275 { "slip", SLIPDISC },
276 { "ppp", PPPDISC },
277 { "strip", STRIPDISC },
278 { "hdlc", HDLCDISC },
279 { NULL, 0 }
280 };
281 struct linesw *ldisc;
282 int i;
283
284 for (i = 0; table[i].name != NULL; i++) {
285 if (strcmp(disc->l_name, table[i].name) == 0) {
286 disc->l_no = table[i].num;
287 return;
288 }
289 }
290
291 disc->l_no = TTYLDISC_LEGACY_NUMBER_MIN;
292
293 LIST_FOREACH(ldisc, &ttyldisc_list, l_list) {
294 if (disc->l_no == ldisc->l_no) {
295 KASSERT(disc->l_no < TTYLDISC_LEGACY_NUMBER_MAX);
296 disc->l_no++;
297 }
298 }
299 }
300
301 /*
302 * Register a line discipline.
303 */
304 int
305 ttyldisc_attach(struct linesw *disc)
306 {
307
308 KASSERT(disc->l_name != NULL);
309 KASSERT(disc->l_open != NULL);
310 KASSERT(disc->l_close != NULL);
311 KASSERT(disc->l_read != NULL);
312 KASSERT(disc->l_write != NULL);
313 KASSERT(disc->l_ioctl != NULL);
314 KASSERT(disc->l_rint != NULL);
315 KASSERT(disc->l_start != NULL);
316 KASSERT(disc->l_modem != NULL);
317 KASSERT(disc->l_poll != NULL);
318
319 /* You are not allowed to exceed TTLINEDNAMELEN */
320 if (strlen(disc->l_name) >= TTLINEDNAMELEN)
321 return (ENAMETOOLONG);
322
323 simple_lock(&ttyldisc_list_slock);
324
325 if (ttyldisc_lookup_locked(disc->l_name) != NULL) {
326 simple_unlock(&ttyldisc_list_slock);
327 return (EEXIST);
328 }
329
330 ttyldisc_assign_legacy_number(disc);
331 LIST_INSERT_HEAD(&ttyldisc_list, disc, l_list);
332
333 simple_unlock(&ttyldisc_list_slock);
334
335 return (0);
336 }
337
338 /*
339 * Remove a line discipline.
340 */
341 int
342 ttyldisc_detach(struct linesw *disc)
343 {
344 #ifdef DIAGNOSTIC
345 struct linesw *ldisc = ttyldisc_lookup(disc->l_name);
346
347 KASSERT(ldisc != NULL);
348 KASSERT(ldisc == disc);
349 ttyldisc_release(ldisc);
350 #endif
351
352 simple_lock(&ttyldisc_list_slock);
353
354 if (TTYLDISC_ISINUSE(disc)) {
355 simple_unlock(&ttyldisc_list_slock);
356 return (EBUSY);
357 }
358
359 LIST_REMOVE(disc, l_list);
360
361 simple_unlock(&ttyldisc_list_slock);
362
363 return (0);
364 }
365
366 /*
367 * Return the default line discipline.
368 */
369 struct linesw *
370 ttyldisc_default(void)
371 {
372
373 return (&termios_disc);
374 }
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