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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: sel.c,v 1.11 2003/05/17 10:34:04 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 1.11 2003/05/17 10:34:04 mdw |
34 | * Tidying and bugfixing. |
35 | * |
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36 | * Revision 1.10 2001/06/22 19:35:58 mdw |
37 | * Fix a large number of bugs. |
38 | * |
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39 | * Revision 1.9 2001/02/03 19:07:08 mdw |
40 | * Ensure that timers set to go off in the past don't case a problem. |
41 | * |
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42 | * Revision 1.8 2000/03/23 20:42:08 mdw |
43 | * Rearrange timeout handling to avoid list corruptions. |
44 | * |
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45 | * Revision 1.7 1999/12/11 11:12:17 mdw |
46 | * Fix comment formatting error. |
47 | * |
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48 | * Revision 1.6 1999/09/26 14:28:11 mdw |
49 | * (sel_select): Almost pointless efficiency tweak. |
50 | * |
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51 | * Revision 1.5 1999/08/31 17:42:22 mdw |
52 | * New function `sel_force' to force a descriptor to be `selected'. |
53 | * |
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54 | * Revision 1.4 1999/08/19 18:30:26 mdw |
55 | * Implement hooks for foreign select-using systems (currently not well |
56 | * tested). |
57 | * |
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58 | * Revision 1.3 1999/05/21 22:13:59 mdw |
59 | * Use new `tv' macros. Fix ordering bug for timeout selectors. |
60 | * |
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61 | * Revision 1.2 1999/05/15 10:33:32 mdw |
62 | * Fix copyright notices. |
63 | * |
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64 | * Revision 1.1 1999/05/14 21:01:14 mdw |
65 | * Integrated `select' handling bits from the background resolver project. |
66 | * |
67 | */ |
68 | |
69 | /*----- Header files ------------------------------------------------------*/ |
70 | |
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71 | #include <assert.h> |
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72 | #include <stdio.h> |
73 | #include <stdlib.h> |
74 | #include <string.h> |
75 | |
76 | #include <sys/types.h> |
77 | #include <sys/time.h> |
78 | #include <unistd.h> |
79 | |
80 | #include "sel.h" |
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81 | #include "sub.h" |
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82 | #include "tv.h" |
83 | |
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84 | /*----- Data structures ---------------------------------------------------*/ |
85 | |
86 | typedef struct sel_pendfile { |
87 | struct sel_pendfile *next; |
88 | sel_file *f; |
89 | } pfile; |
90 | |
91 | typedef struct sel_pendtimer { |
92 | struct sel_pendtimer *next; |
93 | sel_timer *t; |
94 | } ptimer; |
95 | |
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96 | /*----- Main code ---------------------------------------------------------*/ |
97 | |
98 | /* --- @sel_init@ --- * |
99 | * |
100 | * Arguments: @sel_state *s@ = pointer to a state block to initialize |
101 | * |
102 | * Returns: --- |
103 | * |
104 | * Use: Initializes a select state block. |
105 | */ |
106 | |
107 | void sel_init(sel_state *s) |
108 | { |
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109 | int i; |
110 | |
111 | for (i = 0; i < SEL_MODES; i++) { |
112 | s->files[i] = 0; |
113 | FD_ZERO(&s->fd[i]); |
114 | } |
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115 | s->timers = 0; |
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116 | s->hooks = 0; |
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117 | s->args = 0; |
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118 | } |
119 | |
120 | /* --- @sel_initfile@ --- * |
121 | * |
122 | * Arguments: @sel_state *s@ = select state to attach to |
123 | * @sel_file *f@ = pointer to a file block to initialize |
124 | * @int fd@ = the file descriptor to listen to |
125 | * @unsigned mode@ = what to listen for |
126 | * @void (*func)(int fd, unsigned mode, void *p)@ = handler |
127 | * @void *p@ = argument to pass to handler |
128 | * |
129 | * Returns: --- |
130 | * |
131 | * Use: Initializes a file block ready for use. The file block |
132 | * isn't added to the list of things to do until a call to |
133 | * @sel_addfile@. |
134 | */ |
135 | |
136 | void sel_initfile(sel_state *s, sel_file *f, |
137 | int fd, unsigned mode, |
138 | void (*func)(int /*fd*/, unsigned /*mode*/, void */*p*/), |
139 | void *p) |
140 | { |
141 | f->s = s; |
142 | f->fd = fd; |
143 | f->mode = mode; |
144 | f->func = func; |
145 | f->p = p; |
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146 | f->pend = 0; |
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147 | } |
148 | |
149 | /* --- @sel_addfile@ --- * |
150 | * |
151 | * Arguments: @sel_file *f@ = pointer to a file block |
152 | * |
153 | * Returns: --- |
154 | * |
155 | * Use: Adds a file block into the list of things to listen to. |
156 | */ |
157 | |
158 | void sel_addfile(sel_file *f) |
159 | { |
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160 | sel_file **ff = &f->s->files[f->mode]; |
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161 | |
162 | /* --- This little dance looks like line-noise, but it does the job --- */ |
163 | |
164 | while (*ff && (*ff)->fd > f->fd) |
165 | ff = &(*ff)->next; |
166 | f->next = *ff; |
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167 | f->prev = ff; |
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168 | if (*ff) |
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169 | (*ff)->prev = &f->next; |
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170 | *ff = f; |
171 | FD_SET(f->fd, f->s->fd + f->mode); |
172 | } |
173 | |
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174 | /* --- @sel_force@ --- * |
175 | * |
176 | * Arguments: @sel_file *f@ = pointer to file selector |
177 | * |
178 | * Returns: --- |
179 | * |
180 | * Use: Forces a file selector to be considered ready. This is only |
181 | * useful during a call to @sel_select@. Of particular use is |
182 | * forcing a write selector when there's something interesting |
183 | * ready for it. |
184 | */ |
185 | |
186 | void sel_force(sel_file *f) |
187 | { |
188 | if (f->s->args) |
189 | FD_SET(f->fd, &f->s->args->fd[f->mode]); |
190 | } |
191 | |
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192 | /* --- @sel_rmfile@ --- * |
193 | * |
194 | * Arguments: @sel_file *f@ = pointer to a file block |
195 | * |
196 | * Returns: --- |
197 | * |
198 | * Use: Removes a file block from the list of things to listen to. |
199 | */ |
200 | |
201 | void sel_rmfile(sel_file *f) |
202 | { |
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203 | *f->prev = f->next; |
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204 | if (f->next) |
205 | f->next->prev = f->prev; |
206 | FD_CLR(f->fd, f->s->fd + f->mode); |
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207 | if (f->pend) { |
208 | f->pend->f = 0; |
209 | f->pend = 0; |
210 | } |
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211 | } |
212 | |
213 | /* --- @sel_addtimer@ --- * |
214 | * |
215 | * Arguments: @sel_state *s@ = pointer to a state block |
216 | * @sel_timer *t@ = pointer to a timer block |
217 | * @struct timeval *tv@ = pointer to time to activate |
218 | * @void (*func)(struct timeval *tv, void *p)@ = handler |
219 | * @void *p@ = argument for handler function |
220 | * |
221 | * Returns: --- |
222 | * |
223 | * Use: Registers and sets up a timer. |
224 | */ |
225 | |
226 | void sel_addtimer(sel_state *s, sel_timer *t, |
227 | struct timeval *tv, |
228 | void (*func)(struct timeval */*tv*/, void */*p*/), |
229 | void *p) |
230 | { |
231 | sel_timer **tt = &s->timers; |
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232 | { sel_timer *q; for (q = s->timers; q; q = q->next) assert(q != t); } |
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233 | |
234 | /* --- Set up the timer block --- */ |
235 | |
236 | t->tv = *tv; |
237 | t->func = func; |
238 | t->p = p; |
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239 | t->pend = 0; |
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240 | |
241 | /* --- More line noise --- */ |
242 | |
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243 | while (*tt && TV_CMP(&(*tt)->tv, <, tv)) |
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244 | tt = &(*tt)->next; |
245 | t->next = *tt; |
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246 | t->prev = tt; |
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247 | if (*tt) |
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248 | (*tt)->prev = &t->next; |
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249 | *tt = t; |
250 | } |
251 | |
252 | /* --- @sel_rmtimer@ --- * |
253 | * |
254 | * Arguments: @sel_timer *t@ = pointer to timer block |
255 | * |
256 | * Returns: --- |
257 | * |
258 | * Use: Removes a timer from the list of timers. |
259 | */ |
260 | |
261 | void sel_rmtimer(sel_timer *t) |
262 | { |
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263 | if (t->pend) { |
264 | t->pend->t = 0; |
265 | t->pend = 0; |
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266 | } else { |
267 | *t->prev = t->next; |
268 | if (t->next) |
269 | t->next->prev = t->prev; |
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270 | } |
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271 | } |
272 | |
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273 | /* --- @sel_addhook@ --- * |
274 | * |
275 | * Arguments: @sel_state *s@ = pointer to state block |
276 | * @sel_hook *h@ = pointer to hook block |
277 | * @sel_hookfn before, after@ = hook functions |
278 | * @void *p@ = pointer argument to pass to hook functions |
279 | * |
280 | * Returns: --- |
281 | * |
282 | * Use: Registers hook functions to be called on each select call. |
283 | */ |
284 | |
285 | void sel_addhook(sel_state *s, sel_hook *h, |
286 | sel_hookfn before, sel_hookfn after, |
287 | void *p) |
288 | { |
289 | h->before = before; |
290 | h->after = after; |
291 | h->p = p; |
292 | h->next = s->hooks; |
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293 | h->prev = &s->hooks; |
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294 | if (s->hooks) |
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295 | s->hooks->prev = &h->next; |
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296 | s->hooks = h; |
297 | } |
298 | |
299 | /* --- @sel_rmhook@ --- * |
300 | * |
301 | * Arguments: @sel_hook *h@ = pointer to hook block |
302 | * |
303 | * Returns: --- |
304 | * |
305 | * Use: Removes hook functions. |
306 | */ |
307 | |
308 | void sel_rmhook(sel_hook *h) |
309 | { |
310 | if (h->next) |
311 | h->next->prev = h->prev; |
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312 | *h->prev = h->next; |
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313 | } |
314 | |
315 | /* --- @sel_fdmerge@ --- * |
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316 | * |
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317 | * Arguments: @fd_set *dest@ = destination FD set |
318 | * @fd_set *fd@ = pointer to set to merge |
319 | * @int maxfd@ = highest numbered descriptor in @fd@ + 1 |
320 | * |
321 | * Returns: Actual highest numbered descriptor. |
322 | * |
323 | * Use: Merges file descriptor sets, and returns an accurate @maxfd@ |
324 | * value. |
325 | */ |
326 | |
327 | int sel_fdmerge(fd_set *dest, fd_set *fd, int maxfd) |
328 | { |
329 | int i, m = -1; |
330 | |
331 | for (i = 0; i < maxfd; i++) { |
332 | if (FD_ISSET(i, fd)) { |
333 | FD_SET(i, dest); |
334 | m = i; |
335 | } |
336 | } |
337 | |
338 | return (m + 1); |
339 | } |
340 | |
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341 | /* --- @sel_select@ --- * |
342 | * |
343 | * Arguments: @sel_state *s@ = pointer to state block |
344 | * |
345 | * Returns: Zero if all OK, -1 on error. |
346 | * |
347 | * Use: Does a @select@ call (or equivalent @poll@). |
348 | */ |
349 | |
350 | int sel_select(sel_state *s) |
351 | { |
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352 | sel_args a; |
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353 | int err; |
354 | |
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355 | /* --- Initialize the argument block --- */ |
356 | |
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357 | { |
358 | int i; |
359 | a.maxfd = 0; |
360 | for (i = 0; i < SEL_MODES; i++) { |
361 | if (s->files[i] && s->files[i]->fd >= a.maxfd) |
362 | a.maxfd = s->files[i]->fd + 1; |
363 | } |
364 | } |
365 | |
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366 | memcpy(a.fd, s->fd, sizeof(a.fd)); |
367 | if (s->timers || s->hooks) |
368 | gettimeofday(&a.now, 0); |
369 | if (!s->timers) |
370 | a.tvp = 0; |
371 | else { |
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372 | if (TV_CMP(&s->timers->tv, >, &a.now)) |
373 | TV_SUB(&a.tv, &s->timers->tv, &a.now); |
374 | else { |
375 | a.tv.tv_sec = 0; |
376 | a.tv.tv_usec = 0; |
377 | } |
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378 | a.tvp = &a.tv; |
379 | } |
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380 | s->args = &a; |
1226c514 |
381 | |
382 | /* --- Grind through the pre hooks --- */ |
383 | |
384 | { |
385 | sel_hook *h = s->hooks; |
386 | while (h) { |
387 | sel_hook *hh = h; |
388 | h = h->next; |
389 | if (hh->before) |
390 | hh->before(s, &a, hh->p); |
391 | } |
392 | } |
393 | |
394 | /* --- Run the @select@ call --- */ |
395 | |
396 | if ((err = select(a.maxfd, |
397 | &a.fd[SEL_READ], &a.fd[SEL_WRITE], &a.fd[SEL_EXC], |
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398 | a.tvp)) < 0) { |
399 | s->args = 0; |
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400 | return (err); |
1101f87a |
401 | } |
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402 | |
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403 | if (a.tvp) |
404 | gettimeofday(&a.now, 0); |
405 | |
406 | /* --- Run through the hooks again --- */ |
407 | |
408 | { |
409 | sel_hook *h = s->hooks; |
410 | while (h) { |
411 | sel_hook *hh = h; |
412 | h = h->next; |
413 | if (hh->after) |
414 | hh->after(s, &a, hh->p); |
415 | } |
416 | } |
417 | |
418 | /* --- Run through the timers --- */ |
419 | |
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420 | if (s->timers) { |
421 | ptimer *pthead, *pt, **ptt = &pthead; |
422 | sel_timer *t; |
423 | |
424 | for (t = s->timers; t && TV_CMP(&t->tv, <=, &a.now); t = t->next) { |
425 | pt = CREATE(ptimer); |
426 | pt->t = t; |
427 | t->pend = pt; |
428 | *ptt = pt; |
429 | ptt = &pt->next; |
430 | } |
431 | *ptt = 0; |
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432 | if (t) { |
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433 | *t->prev = 0; |
434 | t->prev = &s->timers; |
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435 | } |
436 | s->timers = t; |
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437 | while (pthead) { |
438 | pt = pthead; |
439 | pthead = pt->next; |
440 | t = pt->t; |
441 | if (t) { |
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442 | t->pend = 0; |
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443 | t->next = 0; |
444 | t->prev = &t->next; |
445 | t->func(&a.now, t->p); |
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446 | } |
447 | DESTROY(pt); |
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448 | } |
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449 | } |
450 | |
1101f87a |
451 | /* --- And finally run through the files --- * |
452 | * |
453 | * Do reads first. It's quite possible that a read might prompt a write, |
454 | * but the other way around is less likely. Fortunately, the modes are |
455 | * in the right order for this. |
456 | */ |
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457 | |
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458 | { |
1101f87a |
459 | int i; |
460 | |
461 | for (i = 0; i < SEL_MODES; i++) { |
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462 | pfile *pfhead, *pf, **pff = &pfhead; |
463 | sel_file *f; |
464 | |
465 | for (f = s->files[i]; f; f = f->next) { |
466 | if (!FD_ISSET(f->fd, &a.fd[i])) |
467 | continue; |
468 | pf = CREATE(pfile); |
469 | pf->f = f; |
470 | f->pend = pf; |
471 | *pff = pf; |
472 | pff = &pf->next; |
473 | } |
474 | *pff = 0; |
475 | while (pfhead) { |
476 | pf = pfhead; |
477 | pfhead = pf->next; |
478 | f = pf->f; |
479 | if (f) { |
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480 | f->pend = 0; |
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481 | f->func(f->fd, i, f->p); |
0a2a19b4 |
482 | } |
1101f87a |
483 | } |
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484 | } |
485 | } |
486 | |
1101f87a |
487 | s->args = 0; |
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488 | return (0); |
489 | } |
490 | |
491 | /*----- That's all, folks -------------------------------------------------*/ |