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