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 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 161 ttyerrpoll(struct tty *tp, int events, struct lwp *l) 162 { 163 164 return (POLLERR); 165 } 166 167 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 * 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 * 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 * 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 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 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 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 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 * 355 ttyldisc_default(void) 356 { 357 358 return (&termios_disc); 359 } 360
Indexes created Sat Sep 20 22:09:52 GMT 2025