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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: sel.c,v 1.13 2004/04/08 01:36:13 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 | |
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30 | /*----- Header files ------------------------------------------------------*/ |
31 | |
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32 | #include <assert.h> |
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33 | #include <stdio.h> |
34 | #include <stdlib.h> |
35 | #include <string.h> |
36 | |
37 | #include <sys/types.h> |
38 | #include <sys/time.h> |
39 | #include <unistd.h> |
40 | |
41 | #include "sel.h" |
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42 | #include "sub.h" |
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43 | #include "tv.h" |
44 | |
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45 | /*----- Data structures ---------------------------------------------------*/ |
46 | |
47 | typedef struct sel_pendfile { |
48 | struct sel_pendfile *next; |
49 | sel_file *f; |
50 | } pfile; |
51 | |
52 | typedef struct sel_pendtimer { |
53 | struct sel_pendtimer *next; |
54 | sel_timer *t; |
55 | } ptimer; |
56 | |
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57 | /*----- Main code ---------------------------------------------------------*/ |
58 | |
59 | /* --- @sel_init@ --- * |
60 | * |
61 | * Arguments: @sel_state *s@ = pointer to a state block to initialize |
62 | * |
63 | * Returns: --- |
64 | * |
65 | * Use: Initializes a select state block. |
66 | */ |
67 | |
68 | void sel_init(sel_state *s) |
69 | { |
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70 | int i; |
71 | |
72 | for (i = 0; i < SEL_MODES; i++) { |
73 | s->files[i] = 0; |
74 | FD_ZERO(&s->fd[i]); |
75 | } |
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76 | s->timers = 0; |
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77 | s->hooks = 0; |
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78 | s->args = 0; |
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79 | } |
80 | |
81 | /* --- @sel_initfile@ --- * |
82 | * |
83 | * Arguments: @sel_state *s@ = select state to attach to |
84 | * @sel_file *f@ = pointer to a file block to initialize |
85 | * @int fd@ = the file descriptor to listen to |
86 | * @unsigned mode@ = what to listen for |
87 | * @void (*func)(int fd, unsigned mode, void *p)@ = handler |
88 | * @void *p@ = argument to pass to handler |
89 | * |
90 | * Returns: --- |
91 | * |
92 | * Use: Initializes a file block ready for use. The file block |
93 | * isn't added to the list of things to do until a call to |
94 | * @sel_addfile@. |
95 | */ |
96 | |
97 | void sel_initfile(sel_state *s, sel_file *f, |
98 | int fd, unsigned mode, |
99 | void (*func)(int /*fd*/, unsigned /*mode*/, void */*p*/), |
100 | void *p) |
101 | { |
102 | f->s = s; |
103 | f->fd = fd; |
104 | f->mode = mode; |
105 | f->func = func; |
106 | f->p = p; |
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107 | f->pend = 0; |
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108 | } |
109 | |
110 | /* --- @sel_addfile@ --- * |
111 | * |
112 | * Arguments: @sel_file *f@ = pointer to a file block |
113 | * |
114 | * Returns: --- |
115 | * |
116 | * Use: Adds a file block into the list of things to listen to. |
117 | */ |
118 | |
119 | void sel_addfile(sel_file *f) |
120 | { |
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121 | sel_file **ff = &f->s->files[f->mode]; |
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122 | |
123 | /* --- This little dance looks like line-noise, but it does the job --- */ |
124 | |
125 | while (*ff && (*ff)->fd > f->fd) |
126 | ff = &(*ff)->next; |
127 | f->next = *ff; |
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128 | f->prev = ff; |
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129 | if (*ff) |
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130 | (*ff)->prev = &f->next; |
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131 | *ff = f; |
132 | FD_SET(f->fd, f->s->fd + f->mode); |
133 | } |
134 | |
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135 | /* --- @sel_force@ --- * |
136 | * |
137 | * Arguments: @sel_file *f@ = pointer to file selector |
138 | * |
139 | * Returns: --- |
140 | * |
141 | * Use: Forces a file selector to be considered ready. This is only |
142 | * useful during a call to @sel_select@. Of particular use is |
143 | * forcing a write selector when there's something interesting |
144 | * ready for it. |
145 | */ |
146 | |
147 | void sel_force(sel_file *f) |
148 | { |
149 | if (f->s->args) |
150 | FD_SET(f->fd, &f->s->args->fd[f->mode]); |
151 | } |
152 | |
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153 | /* --- @sel_rmfile@ --- * |
154 | * |
155 | * Arguments: @sel_file *f@ = pointer to a file block |
156 | * |
157 | * Returns: --- |
158 | * |
159 | * Use: Removes a file block from the list of things to listen to. |
160 | */ |
161 | |
162 | void sel_rmfile(sel_file *f) |
163 | { |
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164 | *f->prev = f->next; |
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165 | if (f->next) |
166 | f->next->prev = f->prev; |
167 | FD_CLR(f->fd, f->s->fd + f->mode); |
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168 | if (f->pend) { |
169 | f->pend->f = 0; |
170 | f->pend = 0; |
171 | } |
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172 | } |
173 | |
174 | /* --- @sel_addtimer@ --- * |
175 | * |
176 | * Arguments: @sel_state *s@ = pointer to a state block |
177 | * @sel_timer *t@ = pointer to a timer block |
178 | * @struct timeval *tv@ = pointer to time to activate |
179 | * @void (*func)(struct timeval *tv, void *p)@ = handler |
180 | * @void *p@ = argument for handler function |
181 | * |
182 | * Returns: --- |
183 | * |
184 | * Use: Registers and sets up a timer. |
185 | */ |
186 | |
187 | void sel_addtimer(sel_state *s, sel_timer *t, |
188 | struct timeval *tv, |
189 | void (*func)(struct timeval */*tv*/, void */*p*/), |
190 | void *p) |
191 | { |
192 | sel_timer **tt = &s->timers; |
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193 | { sel_timer *q; for (q = s->timers; q; q = q->next) assert(q != t); } |
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194 | |
195 | /* --- Set up the timer block --- */ |
196 | |
197 | t->tv = *tv; |
198 | t->func = func; |
199 | t->p = p; |
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200 | t->pend = 0; |
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201 | |
202 | /* --- More line noise --- */ |
203 | |
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204 | while (*tt && TV_CMP(&(*tt)->tv, <, tv)) |
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205 | tt = &(*tt)->next; |
206 | t->next = *tt; |
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207 | t->prev = tt; |
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208 | if (*tt) |
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209 | (*tt)->prev = &t->next; |
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210 | *tt = t; |
211 | } |
212 | |
213 | /* --- @sel_rmtimer@ --- * |
214 | * |
215 | * Arguments: @sel_timer *t@ = pointer to timer block |
216 | * |
217 | * Returns: --- |
218 | * |
219 | * Use: Removes a timer from the list of timers. |
220 | */ |
221 | |
222 | void sel_rmtimer(sel_timer *t) |
223 | { |
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224 | if (t->pend) { |
225 | t->pend->t = 0; |
226 | t->pend = 0; |
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227 | } else { |
228 | *t->prev = t->next; |
229 | if (t->next) |
230 | t->next->prev = t->prev; |
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231 | } |
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232 | } |
233 | |
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234 | /* --- @sel_addhook@ --- * |
235 | * |
236 | * Arguments: @sel_state *s@ = pointer to state block |
237 | * @sel_hook *h@ = pointer to hook block |
238 | * @sel_hookfn before, after@ = hook functions |
239 | * @void *p@ = pointer argument to pass to hook functions |
240 | * |
241 | * Returns: --- |
242 | * |
243 | * Use: Registers hook functions to be called on each select call. |
244 | */ |
245 | |
246 | void sel_addhook(sel_state *s, sel_hook *h, |
247 | sel_hookfn before, sel_hookfn after, |
248 | void *p) |
249 | { |
250 | h->before = before; |
251 | h->after = after; |
252 | h->p = p; |
253 | h->next = s->hooks; |
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254 | h->prev = &s->hooks; |
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255 | if (s->hooks) |
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256 | s->hooks->prev = &h->next; |
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257 | s->hooks = h; |
258 | } |
259 | |
260 | /* --- @sel_rmhook@ --- * |
261 | * |
262 | * Arguments: @sel_hook *h@ = pointer to hook block |
263 | * |
264 | * Returns: --- |
265 | * |
266 | * Use: Removes hook functions. |
267 | */ |
268 | |
269 | void sel_rmhook(sel_hook *h) |
270 | { |
271 | if (h->next) |
272 | h->next->prev = h->prev; |
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273 | *h->prev = h->next; |
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274 | } |
275 | |
276 | /* --- @sel_fdmerge@ --- * |
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277 | * |
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278 | * Arguments: @fd_set *dest@ = destination FD set |
279 | * @fd_set *fd@ = pointer to set to merge |
280 | * @int maxfd@ = highest numbered descriptor in @fd@ + 1 |
281 | * |
282 | * Returns: Actual highest numbered descriptor. |
283 | * |
284 | * Use: Merges file descriptor sets, and returns an accurate @maxfd@ |
285 | * value. |
286 | */ |
287 | |
288 | int sel_fdmerge(fd_set *dest, fd_set *fd, int maxfd) |
289 | { |
290 | int i, m = -1; |
291 | |
292 | for (i = 0; i < maxfd; i++) { |
293 | if (FD_ISSET(i, fd)) { |
294 | FD_SET(i, dest); |
295 | m = i; |
296 | } |
297 | } |
298 | |
299 | return (m + 1); |
300 | } |
301 | |
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302 | /* --- @sel_select@ --- * |
303 | * |
304 | * Arguments: @sel_state *s@ = pointer to state block |
305 | * |
306 | * Returns: Zero if all OK, -1 on error. |
307 | * |
308 | * Use: Does a @select@ call (or equivalent @poll@). |
309 | */ |
310 | |
311 | int sel_select(sel_state *s) |
312 | { |
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313 | sel_args a; |
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314 | int err; |
315 | |
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316 | /* --- Initialize the argument block --- */ |
317 | |
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318 | { |
319 | int i; |
320 | a.maxfd = 0; |
321 | for (i = 0; i < SEL_MODES; i++) { |
322 | if (s->files[i] && s->files[i]->fd >= a.maxfd) |
323 | a.maxfd = s->files[i]->fd + 1; |
324 | } |
325 | } |
326 | |
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327 | memcpy(a.fd, s->fd, sizeof(a.fd)); |
328 | if (s->timers || s->hooks) |
329 | gettimeofday(&a.now, 0); |
330 | if (!s->timers) |
331 | a.tvp = 0; |
332 | else { |
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333 | if (TV_CMP(&s->timers->tv, >, &a.now)) |
334 | TV_SUB(&a.tv, &s->timers->tv, &a.now); |
335 | else { |
336 | a.tv.tv_sec = 0; |
337 | a.tv.tv_usec = 0; |
338 | } |
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339 | a.tvp = &a.tv; |
340 | } |
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341 | s->args = &a; |
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342 | |
343 | /* --- Grind through the pre hooks --- */ |
344 | |
345 | { |
346 | sel_hook *h = s->hooks; |
347 | while (h) { |
348 | sel_hook *hh = h; |
349 | h = h->next; |
350 | if (hh->before) |
351 | hh->before(s, &a, hh->p); |
352 | } |
353 | } |
354 | |
355 | /* --- Run the @select@ call --- */ |
356 | |
357 | if ((err = select(a.maxfd, |
358 | &a.fd[SEL_READ], &a.fd[SEL_WRITE], &a.fd[SEL_EXC], |
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359 | a.tvp)) < 0) { |
360 | s->args = 0; |
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361 | return (err); |
1101f87a |
362 | } |
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363 | |
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364 | if (a.tvp) |
365 | gettimeofday(&a.now, 0); |
366 | |
367 | /* --- Run through the hooks again --- */ |
368 | |
369 | { |
370 | sel_hook *h = s->hooks; |
371 | while (h) { |
372 | sel_hook *hh = h; |
373 | h = h->next; |
374 | if (hh->after) |
375 | hh->after(s, &a, hh->p); |
376 | } |
377 | } |
378 | |
379 | /* --- Run through the timers --- */ |
380 | |
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381 | if (s->timers) { |
382 | ptimer *pthead, *pt, **ptt = &pthead; |
383 | sel_timer *t; |
384 | |
385 | for (t = s->timers; t && TV_CMP(&t->tv, <=, &a.now); t = t->next) { |
386 | pt = CREATE(ptimer); |
387 | pt->t = t; |
388 | t->pend = pt; |
389 | *ptt = pt; |
390 | ptt = &pt->next; |
391 | } |
392 | *ptt = 0; |
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393 | if (t) { |
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394 | *t->prev = 0; |
395 | t->prev = &s->timers; |
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396 | } |
397 | s->timers = t; |
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398 | while (pthead) { |
399 | pt = pthead; |
400 | pthead = pt->next; |
401 | t = pt->t; |
402 | if (t) { |
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403 | t->pend = 0; |
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404 | t->next = 0; |
405 | t->prev = &t->next; |
406 | t->func(&a.now, t->p); |
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407 | } |
408 | DESTROY(pt); |
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409 | } |
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410 | } |
411 | |
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412 | /* --- And finally run through the files --- * |
413 | * |
414 | * Do reads first. It's quite possible that a read might prompt a write, |
415 | * but the other way around is less likely. Fortunately, the modes are |
416 | * in the right order for this. |
417 | */ |
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418 | |
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419 | { |
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420 | int i; |
421 | |
422 | for (i = 0; i < SEL_MODES; i++) { |
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423 | pfile *pfhead, *pf, **pff = &pfhead; |
424 | sel_file *f; |
425 | |
426 | for (f = s->files[i]; f; f = f->next) { |
427 | if (!FD_ISSET(f->fd, &a.fd[i])) |
428 | continue; |
429 | pf = CREATE(pfile); |
430 | pf->f = f; |
431 | f->pend = pf; |
432 | *pff = pf; |
433 | pff = &pf->next; |
434 | } |
435 | *pff = 0; |
436 | while (pfhead) { |
437 | pf = pfhead; |
438 | pfhead = pf->next; |
439 | f = pf->f; |
440 | if (f) { |
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441 | f->pend = 0; |
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442 | f->func(f->fd, i, f->p); |
0a2a19b4 |
443 | } |
35036742 |
444 | DESTROY(pf); |
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445 | } |
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446 | } |
447 | } |
448 | |
1101f87a |
449 | s->args = 0; |
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450 | return (0); |
451 | } |
452 | |
453 | /*----- That's all, folks -------------------------------------------------*/ |