1 /* $NetBSD: tty_conf.c,v 1.57 2021/08/09 20:49:10 andvar Exp $ */
2
3 /*-
4 * Copyright (c) 2005, 2007 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 *
19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29 * POSSIBILITY OF SUCH DAMAGE.
30 */
31
32 /*-
33 * Copyright (c) 1982, 1986, 1991, 1993
34 * The Regents of the University of California. All rights reserved.
35 * (c) UNIX System Laboratories, Inc.
36 * All or some portions of this file are derived from material licensed
37 * to the University of California by American Telephone and Telegraph
38 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
39 * the permission of UNIX System Laboratories, Inc.
40 *
41 * Redistribution and use in source and binary forms, with or without
42 * modification, are permitted provided that the following conditions
43 * are met:
44 * 1. Redistributions of source code must retain the above copyright
45 * notice, this list of conditions and the following disclaimer.
46 * 2. Redistributions in binary form must reproduce the above copyright
47 * notice, this list of conditions and the following disclaimer in the
48 * documentation and/or other materials provided with the distribution.
49 * 3. Neither the name of the University nor the names of its contributors
50 * may be used to endorse or promote products derived from this software
51 * without specific prior written permission.
52 *
53 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
54 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
55 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
56 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
57 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
58 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
59 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
60 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
61 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
62 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
63 * SUCH DAMAGE.
64 *
65 * @(#)tty_conf.c 8.5 (Berkeley) 1/9/95
66 */
67
68 #include <sys/cdefs.h>
69 __KERNEL_RCSID(0, "$NetBSD: tty_conf.c,v 1.57 2021/08/09 20:49:10 andvar Exp $");
70
71 #define TTY_ALLOW_PRIVATE
72
73 #include <sys/param.h>
74 #include <sys/systm.h>
75 #include <sys/poll.h>
76 #include <sys/proc.h>
77 #include <sys/tty.h>
78 #include <sys/ttycom.h>
79 #include <sys/conf.h>
80 #include <sys/mutex.h>
81 #include <sys/queue.h>
82
83 static struct linesw termios_disc = {
84 .l_name = "termios",
85 .l_open = ttylopen,
86 .l_close = ttylclose,
87 .l_read = ttread,
88 .l_write = ttwrite,
89 .l_ioctl = ttynullioctl,
90 .l_rint = ttyinput,
91 .l_start = ttstart,
92 .l_modem = ttymodem,
93 .l_poll = ttpoll
94 };
95
96 /*
97 * This is for the benefit of old BSD TTY compatibility, but since it is
98 * identical to termios (except for the name), don't bother conditionalizing
99 * it.
100 */
101 static struct linesw ntty_disc = { /* old NTTYDISC */
102 .l_name = "ntty",
103 .l_open = ttylopen,
104 .l_close = ttylclose,
105 .l_read = ttread,
106 .l_write = ttwrite,
107 .l_ioctl = ttynullioctl,
108 .l_rint = ttyinput,
109 .l_start = ttstart,
110 .l_modem = ttymodem,
111 .l_poll = ttpoll
112 };
113
114 static LIST_HEAD(, linesw) ttyldisc_list = LIST_HEAD_INITIALIZER(ttyldisc_head);
115
116 /*
117 * Note: We don't bother refcounting termios_disc and ntty_disc; they can't
118 * be removed from the list, and termios_disc is likely to have very many
119 * references (could we overflow the count?).
120 */
121 #define TTYLDISC_ISSTATIC(disc) \
122 ((disc) == &termios_disc || (disc) == &ntty_disc)
123
124 #define TTYLDISC_HOLD(disc) \
125 do { \
126 if (! TTYLDISC_ISSTATIC(disc)) { \
127 KASSERT((disc)->l_refcnt != UINT_MAX); \
128 (disc)->l_refcnt++; \
129 } \
130 } while (/*CONSTCOND*/0)
131
132 #define TTYLDISC_RELE(disc) \
133 do { \
134 if (! TTYLDISC_ISSTATIC(disc)) { \
135 KASSERT((disc)->l_refcnt != 0); \
136 (disc)->l_refcnt--; \
137 } \
138 } while (/*CONSTCOND*/0)
139
140 #define TTYLDISC_ISINUSE(disc) \
141 (TTYLDISC_ISSTATIC(disc) || (disc)->l_refcnt != 0)
142
143 /*
144 * Do nothing specific version of line
145 * discipline specific ioctl command.
146 */
147 /*ARGSUSED*/
148 int
ttynullioctl(struct tty * tp,u_long cmd,void * data,int flags,struct lwp * l)149 ttynullioctl(struct tty *tp, u_long cmd, void *data, int flags, struct lwp *l)
150 {
151
152 return (EPASSTHROUGH);
153 }
154
155 /*
156 * Return error to line discipline
157 * specific poll call.
158 */
159 /*ARGSUSED*/
160 int
ttyerrpoll(struct tty * tp,int events,struct lwp * l)161 ttyerrpoll(struct tty *tp, int events, struct lwp *l)
162 {
163
164 return (POLLERR);
165 }
166
167 void
ttyldisc_init(void)168 ttyldisc_init(void)
169 {
170
171 if (ttyldisc_attach(&termios_disc) != 0)
172 panic("ttyldisc_init: termios_disc");
173 if (ttyldisc_attach(&ntty_disc) != 0)
174 panic("ttyldisc_init: ntty_disc");
175 }
176
177 static struct linesw *
ttyldisc_lookup_locked(const char * name)178 ttyldisc_lookup_locked(const char *name)
179 {
180 struct linesw *disc;
181
182 LIST_FOREACH(disc, &ttyldisc_list, l_list) {
183 if (strcmp(name, disc->l_name) == 0)
184 return (disc);
185 }
186
187 return (NULL);
188 }
189
190 /*
191 * Look up a line discipline by its name. Caller holds a reference on
192 * the returned line discipline.
193 */
194 struct linesw *
ttyldisc_lookup(const char * name)195 ttyldisc_lookup(const char *name)
196 {
197 struct linesw *disc;
198
199 mutex_spin_enter(&tty_lock);
200 disc = ttyldisc_lookup_locked(name);
201 if (disc != NULL)
202 TTYLDISC_HOLD(disc);
203 mutex_spin_exit(&tty_lock);
204
205 return (disc);
206 }
207
208 /*
209 * Look up a line discipline by its legacy number. Caller holds a
210 * reference on the returned line discipline.
211 */
212 struct linesw *
ttyldisc_lookup_bynum(int num)213 ttyldisc_lookup_bynum(int num)
214 {
215 struct linesw *disc;
216
217 mutex_spin_enter(&tty_lock);
218
219 LIST_FOREACH(disc, &ttyldisc_list, l_list) {
220 if (disc->l_no == num) {
221 TTYLDISC_HOLD(disc);
222 mutex_spin_exit(&tty_lock);
223 return (disc);
224 }
225 }
226
227 mutex_spin_exit(&tty_lock);
228 return (NULL);
229 }
230
231 /*
232 * Release a reference on a line discipline previously added by
233 * ttyldisc_lookup() or ttyldisc_lookup_bynum().
234 */
235 void
ttyldisc_release(struct linesw * disc)236 ttyldisc_release(struct linesw *disc)
237 {
238
239 if (disc == NULL)
240 return;
241
242 mutex_spin_enter(&tty_lock);
243 TTYLDISC_RELE(disc);
244 mutex_spin_exit(&tty_lock);
245 }
246
247 #define TTYLDISC_LEGACY_NUMBER_MIN 10
248 #define TTYLDISC_LEGACY_NUMBER_MAX INT_MAX
249
250 static void
ttyldisc_assign_legacy_number(struct linesw * disc)251 ttyldisc_assign_legacy_number(struct linesw *disc)
252 {
253 static const struct {
254 const char *name;
255 int num;
256 } table[] = {
257 { "termios", TTYDISC },
258 { "ntty", 2 /* XXX old NTTYDISC */ },
259 { "tablet", TABLDISC },
260 { "slip", SLIPDISC },
261 { "ppp", PPPDISC },
262 { "strip", STRIPDISC },
263 { "hdlc", HDLCDISC },
264 { NULL, 0 }
265 };
266 struct linesw *ldisc;
267 int i;
268
269 for (i = 0; table[i].name != NULL; i++) {
270 if (strcmp(disc->l_name, table[i].name) == 0) {
271 disc->l_no = table[i].num;
272 return;
273 }
274 }
275
276 disc->l_no = TTYLDISC_LEGACY_NUMBER_MIN;
277
278 LIST_FOREACH(ldisc, &ttyldisc_list, l_list) {
279 if (disc->l_no == ldisc->l_no) {
280 KASSERT(disc->l_no < TTYLDISC_LEGACY_NUMBER_MAX);
281 disc->l_no++;
282 }
283 }
284 }
285
286 /*
287 * Register a line discipline.
288 */
289 int
ttyldisc_attach(struct linesw * disc)290 ttyldisc_attach(struct linesw *disc)
291 {
292
293 KASSERT(disc->l_name != NULL);
294 KASSERT(disc->l_open != NULL);
295 KASSERT(disc->l_close != NULL);
296 KASSERT(disc->l_read != NULL);
297 KASSERT(disc->l_write != NULL);
298 KASSERT(disc->l_ioctl != NULL);
299 KASSERT(disc->l_rint != NULL);
300 KASSERT(disc->l_start != NULL);
301 KASSERT(disc->l_modem != NULL);
302 KASSERT(disc->l_poll != NULL);
303
304 /* You are not allowed to exceed TTLINEDNAMELEN */
305 if (strlen(disc->l_name) >= TTLINEDNAMELEN)
306 return (ENAMETOOLONG);
307
308 mutex_spin_enter(&tty_lock);
309
310 if (ttyldisc_lookup_locked(disc->l_name) != NULL) {
311 mutex_spin_exit(&tty_lock);
312 return (EEXIST);
313 }
314
315 ttyldisc_assign_legacy_number(disc);
316 LIST_INSERT_HEAD(&ttyldisc_list, disc, l_list);
317
318 mutex_spin_exit(&tty_lock);
319
320 return (0);
321 }
322
323 /*
324 * Remove a line discipline.
325 */
326 int
ttyldisc_detach(struct linesw * disc)327 ttyldisc_detach(struct linesw *disc)
328 {
329 #ifdef DIAGNOSTIC
330 struct linesw *ldisc = ttyldisc_lookup(disc->l_name);
331
332 KASSERT(ldisc != NULL);
333 KASSERT(ldisc == disc);
334 ttyldisc_release(ldisc);
335 #endif
336
337 mutex_spin_enter(&tty_lock);
338
339 if (TTYLDISC_ISINUSE(disc)) {
340 mutex_spin_exit(&tty_lock);
341 return (EBUSY);
342 }
343
344 LIST_REMOVE(disc, l_list);
345
346 mutex_spin_exit(&tty_lock);
347
348 return (0);
349 }
350
351 /*
352 * Return the default line discipline.
353 */
354 struct linesw *
ttyldisc_default(void)355 ttyldisc_default(void)
356 {
357
358 return (&termios_disc);
359 }
360