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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: sel.c,v 1.12 2003/05/18 15:10:29 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 1.12 2003/05/18 15:10:29 mdw |
34 | * Remove memory leak. |
35 | * |
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36 | * Revision 1.11 2003/05/17 10:34:04 mdw |
37 | * Tidying and bugfixing. |
38 | * |
0a2a19b4 |
39 | * Revision 1.10 2001/06/22 19:35:58 mdw |
40 | * Fix a large number of bugs. |
41 | * |
c1f23e99 |
42 | * Revision 1.9 2001/02/03 19:07:08 mdw |
43 | * Ensure that timers set to go off in the past don't case a problem. |
44 | * |
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45 | * Revision 1.8 2000/03/23 20:42:08 mdw |
46 | * Rearrange timeout handling to avoid list corruptions. |
47 | * |
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48 | * Revision 1.7 1999/12/11 11:12:17 mdw |
49 | * Fix comment formatting error. |
50 | * |
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51 | * Revision 1.6 1999/09/26 14:28:11 mdw |
52 | * (sel_select): Almost pointless efficiency tweak. |
53 | * |
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54 | * Revision 1.5 1999/08/31 17:42:22 mdw |
55 | * New function `sel_force' to force a descriptor to be `selected'. |
56 | * |
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57 | * Revision 1.4 1999/08/19 18:30:26 mdw |
58 | * Implement hooks for foreign select-using systems (currently not well |
59 | * tested). |
60 | * |
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61 | * Revision 1.3 1999/05/21 22:13:59 mdw |
62 | * Use new `tv' macros. Fix ordering bug for timeout selectors. |
63 | * |
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64 | * Revision 1.2 1999/05/15 10:33:32 mdw |
65 | * Fix copyright notices. |
66 | * |
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67 | * Revision 1.1 1999/05/14 21:01:14 mdw |
68 | * Integrated `select' handling bits from the background resolver project. |
69 | * |
70 | */ |
71 | |
72 | /*----- Header files ------------------------------------------------------*/ |
73 | |
0a2a19b4 |
74 | #include <assert.h> |
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75 | #include <stdio.h> |
76 | #include <stdlib.h> |
77 | #include <string.h> |
78 | |
79 | #include <sys/types.h> |
80 | #include <sys/time.h> |
81 | #include <unistd.h> |
82 | |
83 | #include "sel.h" |
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84 | #include "sub.h" |
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85 | #include "tv.h" |
86 | |
0a2a19b4 |
87 | /*----- Data structures ---------------------------------------------------*/ |
88 | |
89 | typedef struct sel_pendfile { |
90 | struct sel_pendfile *next; |
91 | sel_file *f; |
92 | } pfile; |
93 | |
94 | typedef struct sel_pendtimer { |
95 | struct sel_pendtimer *next; |
96 | sel_timer *t; |
97 | } ptimer; |
98 | |
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99 | /*----- Main code ---------------------------------------------------------*/ |
100 | |
101 | /* --- @sel_init@ --- * |
102 | * |
103 | * Arguments: @sel_state *s@ = pointer to a state block to initialize |
104 | * |
105 | * Returns: --- |
106 | * |
107 | * Use: Initializes a select state block. |
108 | */ |
109 | |
110 | void sel_init(sel_state *s) |
111 | { |
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112 | int i; |
113 | |
114 | for (i = 0; i < SEL_MODES; i++) { |
115 | s->files[i] = 0; |
116 | FD_ZERO(&s->fd[i]); |
117 | } |
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118 | s->timers = 0; |
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119 | s->hooks = 0; |
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120 | s->args = 0; |
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121 | } |
122 | |
123 | /* --- @sel_initfile@ --- * |
124 | * |
125 | * Arguments: @sel_state *s@ = select state to attach to |
126 | * @sel_file *f@ = pointer to a file block to initialize |
127 | * @int fd@ = the file descriptor to listen to |
128 | * @unsigned mode@ = what to listen for |
129 | * @void (*func)(int fd, unsigned mode, void *p)@ = handler |
130 | * @void *p@ = argument to pass to handler |
131 | * |
132 | * Returns: --- |
133 | * |
134 | * Use: Initializes a file block ready for use. The file block |
135 | * isn't added to the list of things to do until a call to |
136 | * @sel_addfile@. |
137 | */ |
138 | |
139 | void sel_initfile(sel_state *s, sel_file *f, |
140 | int fd, unsigned mode, |
141 | void (*func)(int /*fd*/, unsigned /*mode*/, void */*p*/), |
142 | void *p) |
143 | { |
144 | f->s = s; |
145 | f->fd = fd; |
146 | f->mode = mode; |
147 | f->func = func; |
148 | f->p = p; |
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149 | f->pend = 0; |
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150 | } |
151 | |
152 | /* --- @sel_addfile@ --- * |
153 | * |
154 | * Arguments: @sel_file *f@ = pointer to a file block |
155 | * |
156 | * Returns: --- |
157 | * |
158 | * Use: Adds a file block into the list of things to listen to. |
159 | */ |
160 | |
161 | void sel_addfile(sel_file *f) |
162 | { |
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163 | sel_file **ff = &f->s->files[f->mode]; |
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164 | |
165 | /* --- This little dance looks like line-noise, but it does the job --- */ |
166 | |
167 | while (*ff && (*ff)->fd > f->fd) |
168 | ff = &(*ff)->next; |
169 | f->next = *ff; |
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170 | f->prev = ff; |
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171 | if (*ff) |
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172 | (*ff)->prev = &f->next; |
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173 | *ff = f; |
174 | FD_SET(f->fd, f->s->fd + f->mode); |
175 | } |
176 | |
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177 | /* --- @sel_force@ --- * |
178 | * |
179 | * Arguments: @sel_file *f@ = pointer to file selector |
180 | * |
181 | * Returns: --- |
182 | * |
183 | * Use: Forces a file selector to be considered ready. This is only |
184 | * useful during a call to @sel_select@. Of particular use is |
185 | * forcing a write selector when there's something interesting |
186 | * ready for it. |
187 | */ |
188 | |
189 | void sel_force(sel_file *f) |
190 | { |
191 | if (f->s->args) |
192 | FD_SET(f->fd, &f->s->args->fd[f->mode]); |
193 | } |
194 | |
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195 | /* --- @sel_rmfile@ --- * |
196 | * |
197 | * Arguments: @sel_file *f@ = pointer to a file block |
198 | * |
199 | * Returns: --- |
200 | * |
201 | * Use: Removes a file block from the list of things to listen to. |
202 | */ |
203 | |
204 | void sel_rmfile(sel_file *f) |
205 | { |
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206 | *f->prev = f->next; |
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207 | if (f->next) |
208 | f->next->prev = f->prev; |
209 | FD_CLR(f->fd, f->s->fd + f->mode); |
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210 | if (f->pend) { |
211 | f->pend->f = 0; |
212 | f->pend = 0; |
213 | } |
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214 | } |
215 | |
216 | /* --- @sel_addtimer@ --- * |
217 | * |
218 | * Arguments: @sel_state *s@ = pointer to a state block |
219 | * @sel_timer *t@ = pointer to a timer block |
220 | * @struct timeval *tv@ = pointer to time to activate |
221 | * @void (*func)(struct timeval *tv, void *p)@ = handler |
222 | * @void *p@ = argument for handler function |
223 | * |
224 | * Returns: --- |
225 | * |
226 | * Use: Registers and sets up a timer. |
227 | */ |
228 | |
229 | void sel_addtimer(sel_state *s, sel_timer *t, |
230 | struct timeval *tv, |
231 | void (*func)(struct timeval */*tv*/, void */*p*/), |
232 | void *p) |
233 | { |
234 | sel_timer **tt = &s->timers; |
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235 | { sel_timer *q; for (q = s->timers; q; q = q->next) assert(q != t); } |
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236 | |
237 | /* --- Set up the timer block --- */ |
238 | |
239 | t->tv = *tv; |
240 | t->func = func; |
241 | t->p = p; |
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242 | t->pend = 0; |
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243 | |
244 | /* --- More line noise --- */ |
245 | |
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246 | while (*tt && TV_CMP(&(*tt)->tv, <, tv)) |
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247 | tt = &(*tt)->next; |
248 | t->next = *tt; |
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249 | t->prev = tt; |
97f65b00 |
250 | if (*tt) |
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251 | (*tt)->prev = &t->next; |
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252 | *tt = t; |
253 | } |
254 | |
255 | /* --- @sel_rmtimer@ --- * |
256 | * |
257 | * Arguments: @sel_timer *t@ = pointer to timer block |
258 | * |
259 | * Returns: --- |
260 | * |
261 | * Use: Removes a timer from the list of timers. |
262 | */ |
263 | |
264 | void sel_rmtimer(sel_timer *t) |
265 | { |
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266 | if (t->pend) { |
267 | t->pend->t = 0; |
268 | t->pend = 0; |
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269 | } else { |
270 | *t->prev = t->next; |
271 | if (t->next) |
272 | t->next->prev = t->prev; |
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273 | } |
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274 | } |
275 | |
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276 | /* --- @sel_addhook@ --- * |
277 | * |
278 | * Arguments: @sel_state *s@ = pointer to state block |
279 | * @sel_hook *h@ = pointer to hook block |
280 | * @sel_hookfn before, after@ = hook functions |
281 | * @void *p@ = pointer argument to pass to hook functions |
282 | * |
283 | * Returns: --- |
284 | * |
285 | * Use: Registers hook functions to be called on each select call. |
286 | */ |
287 | |
288 | void sel_addhook(sel_state *s, sel_hook *h, |
289 | sel_hookfn before, sel_hookfn after, |
290 | void *p) |
291 | { |
292 | h->before = before; |
293 | h->after = after; |
294 | h->p = p; |
295 | h->next = s->hooks; |
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296 | h->prev = &s->hooks; |
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297 | if (s->hooks) |
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298 | s->hooks->prev = &h->next; |
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299 | s->hooks = h; |
300 | } |
301 | |
302 | /* --- @sel_rmhook@ --- * |
303 | * |
304 | * Arguments: @sel_hook *h@ = pointer to hook block |
305 | * |
306 | * Returns: --- |
307 | * |
308 | * Use: Removes hook functions. |
309 | */ |
310 | |
311 | void sel_rmhook(sel_hook *h) |
312 | { |
313 | if (h->next) |
314 | h->next->prev = h->prev; |
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315 | *h->prev = h->next; |
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316 | } |
317 | |
318 | /* --- @sel_fdmerge@ --- * |
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319 | * |
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320 | * Arguments: @fd_set *dest@ = destination FD set |
321 | * @fd_set *fd@ = pointer to set to merge |
322 | * @int maxfd@ = highest numbered descriptor in @fd@ + 1 |
323 | * |
324 | * Returns: Actual highest numbered descriptor. |
325 | * |
326 | * Use: Merges file descriptor sets, and returns an accurate @maxfd@ |
327 | * value. |
328 | */ |
329 | |
330 | int sel_fdmerge(fd_set *dest, fd_set *fd, int maxfd) |
331 | { |
332 | int i, m = -1; |
333 | |
334 | for (i = 0; i < maxfd; i++) { |
335 | if (FD_ISSET(i, fd)) { |
336 | FD_SET(i, dest); |
337 | m = i; |
338 | } |
339 | } |
340 | |
341 | return (m + 1); |
342 | } |
343 | |
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344 | /* --- @sel_select@ --- * |
345 | * |
346 | * Arguments: @sel_state *s@ = pointer to state block |
347 | * |
348 | * Returns: Zero if all OK, -1 on error. |
349 | * |
350 | * Use: Does a @select@ call (or equivalent @poll@). |
351 | */ |
352 | |
353 | int sel_select(sel_state *s) |
354 | { |
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355 | sel_args a; |
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356 | int err; |
357 | |
1226c514 |
358 | /* --- Initialize the argument block --- */ |
359 | |
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360 | { |
361 | int i; |
362 | a.maxfd = 0; |
363 | for (i = 0; i < SEL_MODES; i++) { |
364 | if (s->files[i] && s->files[i]->fd >= a.maxfd) |
365 | a.maxfd = s->files[i]->fd + 1; |
366 | } |
367 | } |
368 | |
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369 | memcpy(a.fd, s->fd, sizeof(a.fd)); |
370 | if (s->timers || s->hooks) |
371 | gettimeofday(&a.now, 0); |
372 | if (!s->timers) |
373 | a.tvp = 0; |
374 | else { |
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375 | if (TV_CMP(&s->timers->tv, >, &a.now)) |
376 | TV_SUB(&a.tv, &s->timers->tv, &a.now); |
377 | else { |
378 | a.tv.tv_sec = 0; |
379 | a.tv.tv_usec = 0; |
380 | } |
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381 | a.tvp = &a.tv; |
382 | } |
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383 | s->args = &a; |
1226c514 |
384 | |
385 | /* --- Grind through the pre hooks --- */ |
386 | |
387 | { |
388 | sel_hook *h = s->hooks; |
389 | while (h) { |
390 | sel_hook *hh = h; |
391 | h = h->next; |
392 | if (hh->before) |
393 | hh->before(s, &a, hh->p); |
394 | } |
395 | } |
396 | |
397 | /* --- Run the @select@ call --- */ |
398 | |
399 | if ((err = select(a.maxfd, |
400 | &a.fd[SEL_READ], &a.fd[SEL_WRITE], &a.fd[SEL_EXC], |
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401 | a.tvp)) < 0) { |
402 | s->args = 0; |
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403 | return (err); |
1101f87a |
404 | } |
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405 | |
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406 | if (a.tvp) |
407 | gettimeofday(&a.now, 0); |
408 | |
409 | /* --- Run through the hooks again --- */ |
410 | |
411 | { |
412 | sel_hook *h = s->hooks; |
413 | while (h) { |
414 | sel_hook *hh = h; |
415 | h = h->next; |
416 | if (hh->after) |
417 | hh->after(s, &a, hh->p); |
418 | } |
419 | } |
420 | |
421 | /* --- Run through the timers --- */ |
422 | |
0a2a19b4 |
423 | if (s->timers) { |
424 | ptimer *pthead, *pt, **ptt = &pthead; |
425 | sel_timer *t; |
426 | |
427 | for (t = s->timers; t && TV_CMP(&t->tv, <=, &a.now); t = t->next) { |
428 | pt = CREATE(ptimer); |
429 | pt->t = t; |
430 | t->pend = pt; |
431 | *ptt = pt; |
432 | ptt = &pt->next; |
433 | } |
434 | *ptt = 0; |
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435 | if (t) { |
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436 | *t->prev = 0; |
437 | t->prev = &s->timers; |
38472b8e |
438 | } |
439 | s->timers = t; |
0a2a19b4 |
440 | while (pthead) { |
441 | pt = pthead; |
442 | pthead = pt->next; |
443 | t = pt->t; |
444 | if (t) { |
0a2a19b4 |
445 | t->pend = 0; |
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446 | t->next = 0; |
447 | t->prev = &t->next; |
448 | t->func(&a.now, t->p); |
0a2a19b4 |
449 | } |
450 | DESTROY(pt); |
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451 | } |
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452 | } |
453 | |
1101f87a |
454 | /* --- And finally run through the files --- * |
455 | * |
456 | * Do reads first. It's quite possible that a read might prompt a write, |
457 | * but the other way around is less likely. Fortunately, the modes are |
458 | * in the right order for this. |
459 | */ |
1226c514 |
460 | |
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461 | { |
1101f87a |
462 | int i; |
463 | |
464 | for (i = 0; i < SEL_MODES; i++) { |
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465 | pfile *pfhead, *pf, **pff = &pfhead; |
466 | sel_file *f; |
467 | |
468 | for (f = s->files[i]; f; f = f->next) { |
469 | if (!FD_ISSET(f->fd, &a.fd[i])) |
470 | continue; |
471 | pf = CREATE(pfile); |
472 | pf->f = f; |
473 | f->pend = pf; |
474 | *pff = pf; |
475 | pff = &pf->next; |
476 | } |
477 | *pff = 0; |
478 | while (pfhead) { |
479 | pf = pfhead; |
480 | pfhead = pf->next; |
481 | f = pf->f; |
482 | if (f) { |
0a2a19b4 |
483 | f->pend = 0; |
4790f418 |
484 | f->func(f->fd, i, f->p); |
0a2a19b4 |
485 | } |
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486 | DESTROY(pf); |
1101f87a |
487 | } |
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488 | } |
489 | } |
490 | |
1101f87a |
491 | s->args = 0; |
97f65b00 |
492 | return (0); |
493 | } |
494 | |
495 | /*----- That's all, folks -------------------------------------------------*/ |