| 1 | /* -*-c-*- |
| 2 | * |
| 3 | * $Id: sel.c,v 1.8 2000/03/23 20:42:08 mdw Exp $ |
| 4 | * |
| 5 | * I/O multiplexing support |
| 6 | * |
| 7 | * (c) 1999 Straylight/Edgeware |
| 8 | */ |
| 9 | |
| 10 | /*----- Licensing notice --------------------------------------------------* |
| 11 | * |
| 12 | * This file is part of the mLib utilities library. |
| 13 | * |
| 14 | * mLib is free software; you can redistribute it and/or modify |
| 15 | * it under the terms of the GNU Library General Public License as |
| 16 | * published by the Free Software Foundation; either version 2 of the |
| 17 | * License, or (at your option) any later version. |
| 18 | * |
| 19 | * mLib is distributed in the hope that it will be useful, |
| 20 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 21 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 22 | * GNU Library General Public License for more details. |
| 23 | * |
| 24 | * You should have received a copy of the GNU Library General Public |
| 25 | * License along with mLib; if not, write to the Free |
| 26 | * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, |
| 27 | * MA 02111-1307, USA. |
| 28 | */ |
| 29 | |
| 30 | /*----- Revision history --------------------------------------------------* |
| 31 | * |
| 32 | * $Log: sel.c,v $ |
| 33 | * Revision 1.8 2000/03/23 20:42:08 mdw |
| 34 | * Rearrange timeout handling to avoid list corruptions. |
| 35 | * |
| 36 | * Revision 1.7 1999/12/11 11:12:17 mdw |
| 37 | * Fix comment formatting error. |
| 38 | * |
| 39 | * Revision 1.6 1999/09/26 14:28:11 mdw |
| 40 | * (sel_select): Almost pointless efficiency tweak. |
| 41 | * |
| 42 | * Revision 1.5 1999/08/31 17:42:22 mdw |
| 43 | * New function `sel_force' to force a descriptor to be `selected'. |
| 44 | * |
| 45 | * Revision 1.4 1999/08/19 18:30:26 mdw |
| 46 | * Implement hooks for foreign select-using systems (currently not well |
| 47 | * tested). |
| 48 | * |
| 49 | * Revision 1.3 1999/05/21 22:13:59 mdw |
| 50 | * Use new `tv' macros. Fix ordering bug for timeout selectors. |
| 51 | * |
| 52 | * Revision 1.2 1999/05/15 10:33:32 mdw |
| 53 | * Fix copyright notices. |
| 54 | * |
| 55 | * Revision 1.1 1999/05/14 21:01:14 mdw |
| 56 | * Integrated `select' handling bits from the background resolver project. |
| 57 | * |
| 58 | */ |
| 59 | |
| 60 | /*----- Header files ------------------------------------------------------*/ |
| 61 | |
| 62 | #include <stdio.h> |
| 63 | #include <stdlib.h> |
| 64 | #include <string.h> |
| 65 | |
| 66 | #include <sys/types.h> |
| 67 | #include <sys/time.h> |
| 68 | #include <unistd.h> |
| 69 | |
| 70 | #include "sel.h" |
| 71 | #include "tv.h" |
| 72 | |
| 73 | /*----- Main code ---------------------------------------------------------*/ |
| 74 | |
| 75 | /* --- @sel_init@ --- * |
| 76 | * |
| 77 | * Arguments: @sel_state *s@ = pointer to a state block to initialize |
| 78 | * |
| 79 | * Returns: --- |
| 80 | * |
| 81 | * Use: Initializes a select state block. |
| 82 | */ |
| 83 | |
| 84 | void sel_init(sel_state *s) |
| 85 | { |
| 86 | int i; |
| 87 | |
| 88 | for (i = 0; i < SEL_MODES; i++) { |
| 89 | s->files[i] = 0; |
| 90 | FD_ZERO(&s->fd[i]); |
| 91 | } |
| 92 | s->timers = 0; |
| 93 | s->hooks = 0; |
| 94 | s->args = 0; |
| 95 | } |
| 96 | |
| 97 | /* --- @sel_initfile@ --- * |
| 98 | * |
| 99 | * Arguments: @sel_state *s@ = select state to attach to |
| 100 | * @sel_file *f@ = pointer to a file block to initialize |
| 101 | * @int fd@ = the file descriptor to listen to |
| 102 | * @unsigned mode@ = what to listen for |
| 103 | * @void (*func)(int fd, unsigned mode, void *p)@ = handler |
| 104 | * @void *p@ = argument to pass to handler |
| 105 | * |
| 106 | * Returns: --- |
| 107 | * |
| 108 | * Use: Initializes a file block ready for use. The file block |
| 109 | * isn't added to the list of things to do until a call to |
| 110 | * @sel_addfile@. |
| 111 | */ |
| 112 | |
| 113 | void sel_initfile(sel_state *s, sel_file *f, |
| 114 | int fd, unsigned mode, |
| 115 | void (*func)(int /*fd*/, unsigned /*mode*/, void */*p*/), |
| 116 | void *p) |
| 117 | { |
| 118 | f->s = s; |
| 119 | f->fd = fd; |
| 120 | f->mode = mode; |
| 121 | f->func = func; |
| 122 | f->p = p; |
| 123 | } |
| 124 | |
| 125 | /* --- @sel_addfile@ --- * |
| 126 | * |
| 127 | * Arguments: @sel_file *f@ = pointer to a file block |
| 128 | * |
| 129 | * Returns: --- |
| 130 | * |
| 131 | * Use: Adds a file block into the list of things to listen to. |
| 132 | */ |
| 133 | |
| 134 | void sel_addfile(sel_file *f) |
| 135 | { |
| 136 | sel_file **ff = &f->s->files[f->mode]; |
| 137 | |
| 138 | /* --- This little dance looks like line-noise, but it does the job --- */ |
| 139 | |
| 140 | while (*ff && (*ff)->fd > f->fd) |
| 141 | ff = &(*ff)->next; |
| 142 | f->next = *ff; |
| 143 | f->prev = (sel_file *)ff; |
| 144 | if (*ff) |
| 145 | (*ff)->prev = f; |
| 146 | *ff = f; |
| 147 | FD_SET(f->fd, f->s->fd + f->mode); |
| 148 | } |
| 149 | |
| 150 | /* --- @sel_force@ --- * |
| 151 | * |
| 152 | * Arguments: @sel_file *f@ = pointer to file selector |
| 153 | * |
| 154 | * Returns: --- |
| 155 | * |
| 156 | * Use: Forces a file selector to be considered ready. This is only |
| 157 | * useful during a call to @sel_select@. Of particular use is |
| 158 | * forcing a write selector when there's something interesting |
| 159 | * ready for it. |
| 160 | */ |
| 161 | |
| 162 | void sel_force(sel_file *f) |
| 163 | { |
| 164 | if (f->s->args) |
| 165 | FD_SET(f->fd, &f->s->args->fd[f->mode]); |
| 166 | } |
| 167 | |
| 168 | /* --- @sel_rmfile@ --- * |
| 169 | * |
| 170 | * Arguments: @sel_file *f@ = pointer to a file block |
| 171 | * |
| 172 | * Returns: --- |
| 173 | * |
| 174 | * Use: Removes a file block from the list of things to listen to. |
| 175 | */ |
| 176 | |
| 177 | void sel_rmfile(sel_file *f) |
| 178 | { |
| 179 | f->prev->next = f->next; |
| 180 | if (f->next) |
| 181 | f->next->prev = f->prev; |
| 182 | FD_CLR(f->fd, f->s->fd + f->mode); |
| 183 | } |
| 184 | |
| 185 | /* --- @sel_addtimer@ --- * |
| 186 | * |
| 187 | * Arguments: @sel_state *s@ = pointer to a state block |
| 188 | * @sel_timer *t@ = pointer to a timer block |
| 189 | * @struct timeval *tv@ = pointer to time to activate |
| 190 | * @void (*func)(struct timeval *tv, void *p)@ = handler |
| 191 | * @void *p@ = argument for handler function |
| 192 | * |
| 193 | * Returns: --- |
| 194 | * |
| 195 | * Use: Registers and sets up a timer. |
| 196 | */ |
| 197 | |
| 198 | void sel_addtimer(sel_state *s, sel_timer *t, |
| 199 | struct timeval *tv, |
| 200 | void (*func)(struct timeval */*tv*/, void */*p*/), |
| 201 | void *p) |
| 202 | { |
| 203 | sel_timer **tt = &s->timers; |
| 204 | |
| 205 | /* --- Set up the timer block --- */ |
| 206 | |
| 207 | t->tv = *tv; |
| 208 | t->func = func; |
| 209 | t->p = p; |
| 210 | |
| 211 | /* --- More line noise --- */ |
| 212 | |
| 213 | while (*tt && TV_CMP(&(*tt)->tv, <, tv)) |
| 214 | tt = &(*tt)->next; |
| 215 | t->next = *tt; |
| 216 | t->prev = (sel_timer *)tt; |
| 217 | if (*tt) |
| 218 | (*tt)->prev = t; |
| 219 | *tt = t; |
| 220 | } |
| 221 | |
| 222 | /* --- @sel_rmtimer@ --- * |
| 223 | * |
| 224 | * Arguments: @sel_timer *t@ = pointer to timer block |
| 225 | * |
| 226 | * Returns: --- |
| 227 | * |
| 228 | * Use: Removes a timer from the list of timers. |
| 229 | */ |
| 230 | |
| 231 | void sel_rmtimer(sel_timer *t) |
| 232 | { |
| 233 | t->prev->next = t->next; |
| 234 | if (t->next) |
| 235 | t->next->prev = t->prev; |
| 236 | } |
| 237 | |
| 238 | /* --- @sel_addhook@ --- * |
| 239 | * |
| 240 | * Arguments: @sel_state *s@ = pointer to state block |
| 241 | * @sel_hook *h@ = pointer to hook block |
| 242 | * @sel_hookfn before, after@ = hook functions |
| 243 | * @void *p@ = pointer argument to pass to hook functions |
| 244 | * |
| 245 | * Returns: --- |
| 246 | * |
| 247 | * Use: Registers hook functions to be called on each select call. |
| 248 | */ |
| 249 | |
| 250 | void sel_addhook(sel_state *s, sel_hook *h, |
| 251 | sel_hookfn before, sel_hookfn after, |
| 252 | void *p) |
| 253 | { |
| 254 | h->before = before; |
| 255 | h->after = after; |
| 256 | h->p = p; |
| 257 | h->next = s->hooks; |
| 258 | h->prev = (sel_hook *)&s->hooks; |
| 259 | if (s->hooks) |
| 260 | s->hooks->prev = h; |
| 261 | s->hooks = h; |
| 262 | } |
| 263 | |
| 264 | /* --- @sel_rmhook@ --- * |
| 265 | * |
| 266 | * Arguments: @sel_hook *h@ = pointer to hook block |
| 267 | * |
| 268 | * Returns: --- |
| 269 | * |
| 270 | * Use: Removes hook functions. |
| 271 | */ |
| 272 | |
| 273 | void sel_rmhook(sel_hook *h) |
| 274 | { |
| 275 | if (h->next) |
| 276 | h->next->prev = h->prev; |
| 277 | h->prev->next = h->next; |
| 278 | } |
| 279 | |
| 280 | /* --- @sel_fdmerge@ --- * |
| 281 | * |
| 282 | * Arguments: @fd_set *dest@ = destination FD set |
| 283 | * @fd_set *fd@ = pointer to set to merge |
| 284 | * @int maxfd@ = highest numbered descriptor in @fd@ + 1 |
| 285 | * |
| 286 | * Returns: Actual highest numbered descriptor. |
| 287 | * |
| 288 | * Use: Merges file descriptor sets, and returns an accurate @maxfd@ |
| 289 | * value. |
| 290 | */ |
| 291 | |
| 292 | int sel_fdmerge(fd_set *dest, fd_set *fd, int maxfd) |
| 293 | { |
| 294 | int i, m = -1; |
| 295 | |
| 296 | for (i = 0; i < maxfd; i++) { |
| 297 | if (FD_ISSET(i, fd)) { |
| 298 | FD_SET(i, dest); |
| 299 | m = i; |
| 300 | } |
| 301 | } |
| 302 | |
| 303 | return (m + 1); |
| 304 | } |
| 305 | |
| 306 | /* --- @sel_select@ --- * |
| 307 | * |
| 308 | * Arguments: @sel_state *s@ = pointer to state block |
| 309 | * |
| 310 | * Returns: Zero if all OK, -1 on error. |
| 311 | * |
| 312 | * Use: Does a @select@ call (or equivalent @poll@). |
| 313 | */ |
| 314 | |
| 315 | int sel_select(sel_state *s) |
| 316 | { |
| 317 | sel_args a; |
| 318 | int err; |
| 319 | |
| 320 | /* --- Initialize the argument block --- */ |
| 321 | |
| 322 | { |
| 323 | int i; |
| 324 | a.maxfd = 0; |
| 325 | for (i = 0; i < SEL_MODES; i++) { |
| 326 | if (s->files[i] && s->files[i]->fd >= a.maxfd) |
| 327 | a.maxfd = s->files[i]->fd + 1; |
| 328 | } |
| 329 | } |
| 330 | |
| 331 | memcpy(a.fd, s->fd, sizeof(a.fd)); |
| 332 | if (s->timers || s->hooks) |
| 333 | gettimeofday(&a.now, 0); |
| 334 | if (!s->timers) |
| 335 | a.tvp = 0; |
| 336 | else { |
| 337 | TV_SUB(&a.tv, &s->timers->tv, &a.now); |
| 338 | a.tvp = &a.tv; |
| 339 | } |
| 340 | s->args = &a; |
| 341 | |
| 342 | /* --- Grind through the pre hooks --- */ |
| 343 | |
| 344 | { |
| 345 | sel_hook *h = s->hooks; |
| 346 | while (h) { |
| 347 | sel_hook *hh = h; |
| 348 | h = h->next; |
| 349 | if (hh->before) |
| 350 | hh->before(s, &a, hh->p); |
| 351 | } |
| 352 | } |
| 353 | |
| 354 | /* --- Run the @select@ call --- */ |
| 355 | |
| 356 | if ((err = select(a.maxfd, |
| 357 | &a.fd[SEL_READ], &a.fd[SEL_WRITE], &a.fd[SEL_EXC], |
| 358 | a.tvp)) < 0) { |
| 359 | s->args = 0; |
| 360 | return (err); |
| 361 | } |
| 362 | |
| 363 | if (a.tvp) |
| 364 | gettimeofday(&a.now, 0); |
| 365 | |
| 366 | /* --- Run through the hooks again --- */ |
| 367 | |
| 368 | { |
| 369 | sel_hook *h = s->hooks; |
| 370 | while (h) { |
| 371 | sel_hook *hh = h; |
| 372 | h = h->next; |
| 373 | if (hh->after) |
| 374 | hh->after(s, &a, hh->p); |
| 375 | } |
| 376 | } |
| 377 | |
| 378 | /* --- Run through the timers --- */ |
| 379 | |
| 380 | if (s->timers && TV_CMP(&s->timers->tv, <=, &a.now)) { |
| 381 | sel_timer *t, *tt; |
| 382 | tt = s->timers; |
| 383 | for (t = tt; t && TV_CMP(&t->tv, <=, &a.now); t = t->next) |
| 384 | ; |
| 385 | if (t) { |
| 386 | t->prev->next = 0; |
| 387 | t->prev = (sel_timer *)&s->timers; |
| 388 | } |
| 389 | s->timers = t; |
| 390 | for (t = tt; t; t = tt) { |
| 391 | tt = t->next; |
| 392 | t->func(&a.now, t->p); |
| 393 | } |
| 394 | } |
| 395 | |
| 396 | /* --- And finally run through the files --- * |
| 397 | * |
| 398 | * Do reads first. It's quite possible that a read might prompt a write, |
| 399 | * but the other way around is less likely. Fortunately, the modes are |
| 400 | * in the right order for this. |
| 401 | */ |
| 402 | |
| 403 | { |
| 404 | int i; |
| 405 | |
| 406 | for (i = 0; i < SEL_MODES; i++) { |
| 407 | sel_file *f, *ff; |
| 408 | for (f = s->files[i]; f; f = ff) { |
| 409 | ff = f->next; |
| 410 | if (FD_ISSET(f->fd, a.fd + i)) |
| 411 | f->func(f->fd, i, f->p); |
| 412 | } |
| 413 | } |
| 414 | } |
| 415 | |
| 416 | s->args = 0; |
| 417 | return (0); |
| 418 | } |
| 419 | |
| 420 | /*----- That's all, folks -------------------------------------------------*/ |