1 /*	$NetBSD: tty_conf.c,v 1.56 2014/05/22 16:28:06 dholland 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 1.56 2014/05/22 16:28:06 dholland 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 compatbility, 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