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