| 1 | /* -*-c-*- |
| 2 | * |
| 3 | * $Id: sel.c,v 1.10 2001/06/22 19:35:58 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 1.10 2001/06/22 19:35:58 mdw |
| 34 | * Fix a large number of bugs. |
| 35 | * |
| 36 | * Revision 1.9 2001/02/03 19:07:08 mdw |
| 37 | * Ensure that timers set to go off in the past don't case a problem. |
| 38 | * |
| 39 | * Revision 1.8 2000/03/23 20:42:08 mdw |
| 40 | * Rearrange timeout handling to avoid list corruptions. |
| 41 | * |
| 42 | * Revision 1.7 1999/12/11 11:12:17 mdw |
| 43 | * Fix comment formatting error. |
| 44 | * |
| 45 | * Revision 1.6 1999/09/26 14:28:11 mdw |
| 46 | * (sel_select): Almost pointless efficiency tweak. |
| 47 | * |
| 48 | * Revision 1.5 1999/08/31 17:42:22 mdw |
| 49 | * New function `sel_force' to force a descriptor to be `selected'. |
| 50 | * |
| 51 | * Revision 1.4 1999/08/19 18:30:26 mdw |
| 52 | * Implement hooks for foreign select-using systems (currently not well |
| 53 | * tested). |
| 54 | * |
| 55 | * Revision 1.3 1999/05/21 22:13:59 mdw |
| 56 | * Use new `tv' macros. Fix ordering bug for timeout selectors. |
| 57 | * |
| 58 | * Revision 1.2 1999/05/15 10:33:32 mdw |
| 59 | * Fix copyright notices. |
| 60 | * |
| 61 | * Revision 1.1 1999/05/14 21:01:14 mdw |
| 62 | * Integrated `select' handling bits from the background resolver project. |
| 63 | * |
| 64 | */ |
| 65 | |
| 66 | /*----- Header files ------------------------------------------------------*/ |
| 67 | |
| 68 | #include <assert.h> |
| 69 | #include <stdio.h> |
| 70 | #include <stdlib.h> |
| 71 | #include <string.h> |
| 72 | |
| 73 | #include <sys/types.h> |
| 74 | #include <sys/time.h> |
| 75 | #include <unistd.h> |
| 76 | |
| 77 | #include "sel.h" |
| 78 | #include "sub.h" |
| 79 | #include "tv.h" |
| 80 | |
| 81 | /*----- Data structures ---------------------------------------------------*/ |
| 82 | |
| 83 | typedef struct sel_pendfile { |
| 84 | struct sel_pendfile *next; |
| 85 | sel_file *f; |
| 86 | } pfile; |
| 87 | |
| 88 | typedef struct sel_pendtimer { |
| 89 | struct sel_pendtimer *next; |
| 90 | sel_timer *t; |
| 91 | } ptimer; |
| 92 | |
| 93 | /*----- Main code ---------------------------------------------------------*/ |
| 94 | |
| 95 | /* --- @sel_init@ --- * |
| 96 | * |
| 97 | * Arguments: @sel_state *s@ = pointer to a state block to initialize |
| 98 | * |
| 99 | * Returns: --- |
| 100 | * |
| 101 | * Use: Initializes a select state block. |
| 102 | */ |
| 103 | |
| 104 | void sel_init(sel_state *s) |
| 105 | { |
| 106 | int i; |
| 107 | |
| 108 | for (i = 0; i < SEL_MODES; i++) { |
| 109 | s->files[i] = 0; |
| 110 | FD_ZERO(&s->fd[i]); |
| 111 | } |
| 112 | s->timers = 0; |
| 113 | s->hooks = 0; |
| 114 | s->args = 0; |
| 115 | } |
| 116 | |
| 117 | /* --- @sel_initfile@ --- * |
| 118 | * |
| 119 | * Arguments: @sel_state *s@ = select state to attach to |
| 120 | * @sel_file *f@ = pointer to a file block to initialize |
| 121 | * @int fd@ = the file descriptor to listen to |
| 122 | * @unsigned mode@ = what to listen for |
| 123 | * @void (*func)(int fd, unsigned mode, void *p)@ = handler |
| 124 | * @void *p@ = argument to pass to handler |
| 125 | * |
| 126 | * Returns: --- |
| 127 | * |
| 128 | * Use: Initializes a file block ready for use. The file block |
| 129 | * isn't added to the list of things to do until a call to |
| 130 | * @sel_addfile@. |
| 131 | */ |
| 132 | |
| 133 | void sel_initfile(sel_state *s, sel_file *f, |
| 134 | int fd, unsigned mode, |
| 135 | void (*func)(int /*fd*/, unsigned /*mode*/, void */*p*/), |
| 136 | void *p) |
| 137 | { |
| 138 | f->s = s; |
| 139 | f->fd = fd; |
| 140 | f->mode = mode; |
| 141 | f->func = func; |
| 142 | f->p = p; |
| 143 | f->pend = 0; |
| 144 | } |
| 145 | |
| 146 | /* --- @sel_addfile@ --- * |
| 147 | * |
| 148 | * Arguments: @sel_file *f@ = pointer to a file block |
| 149 | * |
| 150 | * Returns: --- |
| 151 | * |
| 152 | * Use: Adds a file block into the list of things to listen to. |
| 153 | */ |
| 154 | |
| 155 | void sel_addfile(sel_file *f) |
| 156 | { |
| 157 | sel_file **ff = &f->s->files[f->mode]; |
| 158 | |
| 159 | /* --- This little dance looks like line-noise, but it does the job --- */ |
| 160 | |
| 161 | while (*ff && (*ff)->fd > f->fd) |
| 162 | ff = &(*ff)->next; |
| 163 | f->next = *ff; |
| 164 | f->prev = (sel_file *)ff; |
| 165 | if (*ff) |
| 166 | (*ff)->prev = f; |
| 167 | *ff = f; |
| 168 | FD_SET(f->fd, f->s->fd + f->mode); |
| 169 | } |
| 170 | |
| 171 | /* --- @sel_force@ --- * |
| 172 | * |
| 173 | * Arguments: @sel_file *f@ = pointer to file selector |
| 174 | * |
| 175 | * Returns: --- |
| 176 | * |
| 177 | * Use: Forces a file selector to be considered ready. This is only |
| 178 | * useful during a call to @sel_select@. Of particular use is |
| 179 | * forcing a write selector when there's something interesting |
| 180 | * ready for it. |
| 181 | */ |
| 182 | |
| 183 | void sel_force(sel_file *f) |
| 184 | { |
| 185 | if (f->s->args) |
| 186 | FD_SET(f->fd, &f->s->args->fd[f->mode]); |
| 187 | } |
| 188 | |
| 189 | /* --- @sel_rmfile@ --- * |
| 190 | * |
| 191 | * Arguments: @sel_file *f@ = pointer to a file block |
| 192 | * |
| 193 | * Returns: --- |
| 194 | * |
| 195 | * Use: Removes a file block from the list of things to listen to. |
| 196 | */ |
| 197 | |
| 198 | void sel_rmfile(sel_file *f) |
| 199 | { |
| 200 | f->prev->next = f->next; |
| 201 | if (f->next) |
| 202 | f->next->prev = f->prev; |
| 203 | FD_CLR(f->fd, f->s->fd + f->mode); |
| 204 | if (f->pend) { |
| 205 | f->pend->f = 0; |
| 206 | f->pend = 0; |
| 207 | } |
| 208 | } |
| 209 | |
| 210 | /* --- @sel_addtimer@ --- * |
| 211 | * |
| 212 | * Arguments: @sel_state *s@ = pointer to a state block |
| 213 | * @sel_timer *t@ = pointer to a timer block |
| 214 | * @struct timeval *tv@ = pointer to time to activate |
| 215 | * @void (*func)(struct timeval *tv, void *p)@ = handler |
| 216 | * @void *p@ = argument for handler function |
| 217 | * |
| 218 | * Returns: --- |
| 219 | * |
| 220 | * Use: Registers and sets up a timer. |
| 221 | */ |
| 222 | |
| 223 | void sel_addtimer(sel_state *s, sel_timer *t, |
| 224 | struct timeval *tv, |
| 225 | void (*func)(struct timeval */*tv*/, void */*p*/), |
| 226 | void *p) |
| 227 | { |
| 228 | sel_timer **tt = &s->timers; |
| 229 | { sel_timer *q; for (q = s->timers; q; q = q->next) assert(q != t); } |
| 230 | |
| 231 | /* --- Set up the timer block --- */ |
| 232 | |
| 233 | t->tv = *tv; |
| 234 | t->func = func; |
| 235 | t->p = p; |
| 236 | t->pend = 0; |
| 237 | |
| 238 | /* --- More line noise --- */ |
| 239 | |
| 240 | while (*tt && TV_CMP(&(*tt)->tv, <, tv)) |
| 241 | tt = &(*tt)->next; |
| 242 | t->next = *tt; |
| 243 | t->prev = (sel_timer *)tt; |
| 244 | if (*tt) |
| 245 | (*tt)->prev = t; |
| 246 | *tt = t; |
| 247 | } |
| 248 | |
| 249 | /* --- @sel_rmtimer@ --- * |
| 250 | * |
| 251 | * Arguments: @sel_timer *t@ = pointer to timer block |
| 252 | * |
| 253 | * Returns: --- |
| 254 | * |
| 255 | * Use: Removes a timer from the list of timers. |
| 256 | */ |
| 257 | |
| 258 | void sel_rmtimer(sel_timer *t) |
| 259 | { |
| 260 | t->prev->next = t->next; |
| 261 | if (t->next) |
| 262 | t->next->prev = t->prev; |
| 263 | if (t->pend) { |
| 264 | t->pend->t = 0; |
| 265 | t->pend = 0; |
| 266 | } |
| 267 | } |
| 268 | |
| 269 | /* --- @sel_addhook@ --- * |
| 270 | * |
| 271 | * Arguments: @sel_state *s@ = pointer to state block |
| 272 | * @sel_hook *h@ = pointer to hook block |
| 273 | * @sel_hookfn before, after@ = hook functions |
| 274 | * @void *p@ = pointer argument to pass to hook functions |
| 275 | * |
| 276 | * Returns: --- |
| 277 | * |
| 278 | * Use: Registers hook functions to be called on each select call. |
| 279 | */ |
| 280 | |
| 281 | void sel_addhook(sel_state *s, sel_hook *h, |
| 282 | sel_hookfn before, sel_hookfn after, |
| 283 | void *p) |
| 284 | { |
| 285 | h->before = before; |
| 286 | h->after = after; |
| 287 | h->p = p; |
| 288 | h->next = s->hooks; |
| 289 | h->prev = (sel_hook *)&s->hooks; |
| 290 | if (s->hooks) |
| 291 | s->hooks->prev = h; |
| 292 | s->hooks = h; |
| 293 | } |
| 294 | |
| 295 | /* --- @sel_rmhook@ --- * |
| 296 | * |
| 297 | * Arguments: @sel_hook *h@ = pointer to hook block |
| 298 | * |
| 299 | * Returns: --- |
| 300 | * |
| 301 | * Use: Removes hook functions. |
| 302 | */ |
| 303 | |
| 304 | void sel_rmhook(sel_hook *h) |
| 305 | { |
| 306 | if (h->next) |
| 307 | h->next->prev = h->prev; |
| 308 | h->prev->next = h->next; |
| 309 | } |
| 310 | |
| 311 | /* --- @sel_fdmerge@ --- * |
| 312 | * |
| 313 | * Arguments: @fd_set *dest@ = destination FD set |
| 314 | * @fd_set *fd@ = pointer to set to merge |
| 315 | * @int maxfd@ = highest numbered descriptor in @fd@ + 1 |
| 316 | * |
| 317 | * Returns: Actual highest numbered descriptor. |
| 318 | * |
| 319 | * Use: Merges file descriptor sets, and returns an accurate @maxfd@ |
| 320 | * value. |
| 321 | */ |
| 322 | |
| 323 | int sel_fdmerge(fd_set *dest, fd_set *fd, int maxfd) |
| 324 | { |
| 325 | int i, m = -1; |
| 326 | |
| 327 | for (i = 0; i < maxfd; i++) { |
| 328 | if (FD_ISSET(i, fd)) { |
| 329 | FD_SET(i, dest); |
| 330 | m = i; |
| 331 | } |
| 332 | } |
| 333 | |
| 334 | return (m + 1); |
| 335 | } |
| 336 | |
| 337 | /* --- @sel_select@ --- * |
| 338 | * |
| 339 | * Arguments: @sel_state *s@ = pointer to state block |
| 340 | * |
| 341 | * Returns: Zero if all OK, -1 on error. |
| 342 | * |
| 343 | * Use: Does a @select@ call (or equivalent @poll@). |
| 344 | */ |
| 345 | |
| 346 | int sel_select(sel_state *s) |
| 347 | { |
| 348 | sel_args a; |
| 349 | int err; |
| 350 | |
| 351 | /* --- Initialize the argument block --- */ |
| 352 | |
| 353 | { |
| 354 | int i; |
| 355 | a.maxfd = 0; |
| 356 | for (i = 0; i < SEL_MODES; i++) { |
| 357 | if (s->files[i] && s->files[i]->fd >= a.maxfd) |
| 358 | a.maxfd = s->files[i]->fd + 1; |
| 359 | } |
| 360 | } |
| 361 | |
| 362 | memcpy(a.fd, s->fd, sizeof(a.fd)); |
| 363 | if (s->timers || s->hooks) |
| 364 | gettimeofday(&a.now, 0); |
| 365 | if (!s->timers) |
| 366 | a.tvp = 0; |
| 367 | else { |
| 368 | if (TV_CMP(&s->timers->tv, >, &a.now)) |
| 369 | TV_SUB(&a.tv, &s->timers->tv, &a.now); |
| 370 | else { |
| 371 | a.tv.tv_sec = 0; |
| 372 | a.tv.tv_usec = 0; |
| 373 | } |
| 374 | a.tvp = &a.tv; |
| 375 | } |
| 376 | s->args = &a; |
| 377 | |
| 378 | /* --- Grind through the pre hooks --- */ |
| 379 | |
| 380 | { |
| 381 | sel_hook *h = s->hooks; |
| 382 | while (h) { |
| 383 | sel_hook *hh = h; |
| 384 | h = h->next; |
| 385 | if (hh->before) |
| 386 | hh->before(s, &a, hh->p); |
| 387 | } |
| 388 | } |
| 389 | |
| 390 | /* --- Run the @select@ call --- */ |
| 391 | |
| 392 | if ((err = select(a.maxfd, |
| 393 | &a.fd[SEL_READ], &a.fd[SEL_WRITE], &a.fd[SEL_EXC], |
| 394 | a.tvp)) < 0) { |
| 395 | s->args = 0; |
| 396 | return (err); |
| 397 | } |
| 398 | |
| 399 | if (a.tvp) |
| 400 | gettimeofday(&a.now, 0); |
| 401 | |
| 402 | /* --- Run through the hooks again --- */ |
| 403 | |
| 404 | { |
| 405 | sel_hook *h = s->hooks; |
| 406 | while (h) { |
| 407 | sel_hook *hh = h; |
| 408 | h = h->next; |
| 409 | if (hh->after) |
| 410 | hh->after(s, &a, hh->p); |
| 411 | } |
| 412 | } |
| 413 | |
| 414 | /* --- Run through the timers --- */ |
| 415 | |
| 416 | if (s->timers) { |
| 417 | ptimer *pthead, *pt, **ptt = &pthead; |
| 418 | sel_timer *t; |
| 419 | |
| 420 | for (t = s->timers; t && TV_CMP(&t->tv, <=, &a.now); t = t->next) { |
| 421 | pt = CREATE(ptimer); |
| 422 | pt->t = t; |
| 423 | t->pend = pt; |
| 424 | *ptt = pt; |
| 425 | ptt = &pt->next; |
| 426 | } |
| 427 | *ptt = 0; |
| 428 | if (t) { |
| 429 | t->prev->next = 0; |
| 430 | t->prev = (sel_timer *)&s->timers; |
| 431 | } |
| 432 | s->timers = t; |
| 433 | while (pthead) { |
| 434 | pt = pthead; |
| 435 | pthead = pt->next; |
| 436 | t = pt->t; |
| 437 | if (t) { |
| 438 | t->func(&a.now, t->p); |
| 439 | t->pend = 0; |
| 440 | } |
| 441 | DESTROY(pt); |
| 442 | } |
| 443 | } |
| 444 | |
| 445 | /* --- And finally run through the files --- * |
| 446 | * |
| 447 | * Do reads first. It's quite possible that a read might prompt a write, |
| 448 | * but the other way around is less likely. Fortunately, the modes are |
| 449 | * in the right order for this. |
| 450 | */ |
| 451 | |
| 452 | { |
| 453 | int i; |
| 454 | |
| 455 | for (i = 0; i < SEL_MODES; i++) { |
| 456 | pfile *pfhead, *pf, **pff = &pfhead; |
| 457 | sel_file *f; |
| 458 | |
| 459 | for (f = s->files[i]; f; f = f->next) { |
| 460 | if (!FD_ISSET(f->fd, &a.fd[i])) |
| 461 | continue; |
| 462 | pf = CREATE(pfile); |
| 463 | pf->f = f; |
| 464 | f->pend = pf; |
| 465 | *pff = pf; |
| 466 | pff = &pf->next; |
| 467 | } |
| 468 | *pff = 0; |
| 469 | while (pfhead) { |
| 470 | pf = pfhead; |
| 471 | pfhead = pf->next; |
| 472 | f = pf->f; |
| 473 | if (f) { |
| 474 | f->func(f->fd, i, f->p); |
| 475 | f->pend = 0; |
| 476 | } |
| 477 | } |
| 478 | } |
| 479 | } |
| 480 | |
| 481 | s->args = 0; |
| 482 | return (0); |
| 483 | } |
| 484 | |
| 485 | /*----- That's all, folks -------------------------------------------------*/ |