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