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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: sel.c,v 1.10 2001/06/22 19:35:58 mdw Exp $ |
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4 | * |
5 | * I/O multiplexing support |
6 | * |
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7 | * (c) 1999 Straylight/Edgeware |
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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 $ |
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33 | * Revision 1.10 2001/06/22 19:35:58 mdw |
34 | * Fix a large number of bugs. |
35 | * |
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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 | * |
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39 | * Revision 1.8 2000/03/23 20:42:08 mdw |
40 | * Rearrange timeout handling to avoid list corruptions. |
41 | * |
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42 | * Revision 1.7 1999/12/11 11:12:17 mdw |
43 | * Fix comment formatting error. |
44 | * |
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45 | * Revision 1.6 1999/09/26 14:28:11 mdw |
46 | * (sel_select): Almost pointless efficiency tweak. |
47 | * |
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48 | * Revision 1.5 1999/08/31 17:42:22 mdw |
49 | * New function `sel_force' to force a descriptor to be `selected'. |
50 | * |
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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 | * |
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55 | * Revision 1.3 1999/05/21 22:13:59 mdw |
56 | * Use new `tv' macros. Fix ordering bug for timeout selectors. |
57 | * |
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58 | * Revision 1.2 1999/05/15 10:33:32 mdw |
59 | * Fix copyright notices. |
60 | * |
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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 | |
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68 | #include <assert.h> |
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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" |
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78 | #include "sub.h" |
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79 | #include "tv.h" |
80 | |
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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 | |
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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 | { |
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106 | int i; |
107 | |
108 | for (i = 0; i < SEL_MODES; i++) { |
109 | s->files[i] = 0; |
110 | FD_ZERO(&s->fd[i]); |
111 | } |
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112 | s->timers = 0; |
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113 | s->hooks = 0; |
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114 | s->args = 0; |
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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; |
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143 | f->pend = 0; |
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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 | { |
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157 | sel_file **ff = &f->s->files[f->mode]; |
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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 | |
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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 | |
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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); |
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204 | if (f->pend) { |
205 | f->pend->f = 0; |
206 | f->pend = 0; |
207 | } |
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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; |
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229 | { sel_timer *q; for (q = s->timers; q; q = q->next) assert(q != t); } |
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230 | |
231 | /* --- Set up the timer block --- */ |
232 | |
233 | t->tv = *tv; |
234 | t->func = func; |
235 | t->p = p; |
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236 | t->pend = 0; |
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237 | |
238 | /* --- More line noise --- */ |
239 | |
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240 | while (*tt && TV_CMP(&(*tt)->tv, <, tv)) |
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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; |
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263 | if (t->pend) { |
264 | t->pend->t = 0; |
265 | t->pend = 0; |
266 | } |
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267 | } |
268 | |
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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@ --- * |
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312 | * |
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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 | |
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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 | { |
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348 | sel_args a; |
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349 | int err; |
350 | |
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351 | /* --- Initialize the argument block --- */ |
352 | |
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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 | |
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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 { |
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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 | } |
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374 | a.tvp = &a.tv; |
375 | } |
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376 | s->args = &a; |
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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], |
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394 | a.tvp)) < 0) { |
395 | s->args = 0; |
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396 | return (err); |
1101f87a |
397 | } |
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398 | |
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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 | |
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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; |
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428 | if (t) { |
429 | t->prev->next = 0; |
430 | t->prev = (sel_timer *)&s->timers; |
431 | } |
432 | s->timers = t; |
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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); |
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442 | } |
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443 | } |
444 | |
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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 | */ |
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451 | |
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452 | { |
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453 | int i; |
454 | |
455 | for (i = 0; i < SEL_MODES; i++) { |
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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) { |
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474 | f->func(f->fd, i, f->p); |
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475 | f->pend = 0; |
476 | } |
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477 | } |
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478 | } |
479 | } |
480 | |
1101f87a |
481 | s->args = 0; |
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482 | return (0); |
483 | } |
484 | |
485 | /*----- That's all, folks -------------------------------------------------*/ |