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