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