3 * $Id: sel.c,v 1.10 2001/06/22 19:35:58 mdw Exp $
5 * I/O multiplexing support
7 * (c) 1999 Straylight/Edgeware
10 /*----- Licensing notice --------------------------------------------------*
12 * This file is part of the mLib utilities library.
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.
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.
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,
30 /*----- Revision history --------------------------------------------------*
33 * Revision 1.10 2001/06/22 19:35:58 mdw
34 * Fix a large number of bugs.
36 * Revision 1.9 2001/02/03 19:07:08 mdw
37 * Ensure that timers set to go off in the past don't case a problem.
39 * Revision 1.8 2000/03/23 20:42:08 mdw
40 * Rearrange timeout handling to avoid list corruptions.
42 * Revision 1.7 1999/12/11 11:12:17 mdw
43 * Fix comment formatting error.
45 * Revision 1.6 1999/09/26 14:28:11 mdw
46 * (sel_select): Almost pointless efficiency tweak.
48 * Revision 1.5 1999/08/31 17:42:22 mdw
49 * New function `sel_force' to force a descriptor to be `selected'.
51 * Revision 1.4 1999/08/19 18:30:26 mdw
52 * Implement hooks for foreign select-using systems (currently not well
55 * Revision 1.3 1999/05/21 22:13:59 mdw
56 * Use new `tv' macros. Fix ordering bug for timeout selectors.
58 * Revision 1.2 1999/05/15 10:33:32 mdw
59 * Fix copyright notices.
61 * Revision 1.1 1999/05/14 21:01:14 mdw
62 * Integrated `select' handling bits from the background resolver project.
66 /*----- Header files ------------------------------------------------------*/
73 #include <sys/types.h>
81 /*----- Data structures ---------------------------------------------------*/
83 typedef struct sel_pendfile {
84 struct sel_pendfile *next;
88 typedef struct sel_pendtimer {
89 struct sel_pendtimer *next;
93 /*----- Main code ---------------------------------------------------------*/
95 /* --- @sel_init@ --- *
97 * Arguments: @sel_state *s@ = pointer to a state block to initialize
101 * Use: Initializes a select state block.
104 void sel_init(sel_state *s)
108 for (i = 0; i < SEL_MODES; i++) {
117 /* --- @sel_initfile@ --- *
119 * Arguments: @sel_state *s@ = select state to attach to
120 * @sel_file *f@ = pointer to a file block to initialize
121 * @int fd@ = the file descriptor to listen to
122 * @unsigned mode@ = what to listen for
123 * @void (*func)(int fd, unsigned mode, void *p)@ = handler
124 * @void *p@ = argument to pass to handler
128 * Use: Initializes a file block ready for use. The file block
129 * isn't added to the list of things to do until a call to
133 void sel_initfile(sel_state *s, sel_file *f,
134 int fd, unsigned mode,
135 void (*func)(int /*fd*/, unsigned /*mode*/, void */*p*/),
146 /* --- @sel_addfile@ --- *
148 * Arguments: @sel_file *f@ = pointer to a file block
152 * Use: Adds a file block into the list of things to listen to.
155 void sel_addfile(sel_file *f)
157 sel_file **ff = &f->s->files[f->mode];
159 /* --- This little dance looks like line-noise, but it does the job --- */
161 while (*ff && (*ff)->fd > f->fd)
164 f->prev = (sel_file *)ff;
168 FD_SET(f->fd, f->s->fd + f->mode);
171 /* --- @sel_force@ --- *
173 * Arguments: @sel_file *f@ = pointer to file selector
177 * Use: Forces a file selector to be considered ready. This is only
178 * useful during a call to @sel_select@. Of particular use is
179 * forcing a write selector when there's something interesting
183 void sel_force(sel_file *f)
186 FD_SET(f->fd, &f->s->args->fd[f->mode]);
189 /* --- @sel_rmfile@ --- *
191 * Arguments: @sel_file *f@ = pointer to a file block
195 * Use: Removes a file block from the list of things to listen to.
198 void sel_rmfile(sel_file *f)
200 f->prev->next = f->next;
202 f->next->prev = f->prev;
203 FD_CLR(f->fd, f->s->fd + f->mode);
210 /* --- @sel_addtimer@ --- *
212 * Arguments: @sel_state *s@ = pointer to a state block
213 * @sel_timer *t@ = pointer to a timer block
214 * @struct timeval *tv@ = pointer to time to activate
215 * @void (*func)(struct timeval *tv, void *p)@ = handler
216 * @void *p@ = argument for handler function
220 * Use: Registers and sets up a timer.
223 void sel_addtimer(sel_state *s, sel_timer *t,
225 void (*func)(struct timeval */*tv*/, void */*p*/),
228 sel_timer **tt = &s->timers;
229 { sel_timer *q; for (q = s->timers; q; q = q->next) assert(q != t); }
231 /* --- Set up the timer block --- */
238 /* --- More line noise --- */
240 while (*tt && TV_CMP(&(*tt)->tv, <, tv))
243 t->prev = (sel_timer *)tt;
249 /* --- @sel_rmtimer@ --- *
251 * Arguments: @sel_timer *t@ = pointer to timer block
255 * Use: Removes a timer from the list of timers.
258 void sel_rmtimer(sel_timer *t)
260 t->prev->next = t->next;
262 t->next->prev = t->prev;
269 /* --- @sel_addhook@ --- *
271 * Arguments: @sel_state *s@ = pointer to state block
272 * @sel_hook *h@ = pointer to hook block
273 * @sel_hookfn before, after@ = hook functions
274 * @void *p@ = pointer argument to pass to hook functions
278 * Use: Registers hook functions to be called on each select call.
281 void sel_addhook(sel_state *s, sel_hook *h,
282 sel_hookfn before, sel_hookfn after,
289 h->prev = (sel_hook *)&s->hooks;
295 /* --- @sel_rmhook@ --- *
297 * Arguments: @sel_hook *h@ = pointer to hook block
301 * Use: Removes hook functions.
304 void sel_rmhook(sel_hook *h)
307 h->next->prev = h->prev;
308 h->prev->next = h->next;
311 /* --- @sel_fdmerge@ --- *
313 * Arguments: @fd_set *dest@ = destination FD set
314 * @fd_set *fd@ = pointer to set to merge
315 * @int maxfd@ = highest numbered descriptor in @fd@ + 1
317 * Returns: Actual highest numbered descriptor.
319 * Use: Merges file descriptor sets, and returns an accurate @maxfd@
323 int sel_fdmerge(fd_set *dest, fd_set *fd, int maxfd)
327 for (i = 0; i < maxfd; i++) {
328 if (FD_ISSET(i, fd)) {
337 /* --- @sel_select@ --- *
339 * Arguments: @sel_state *s@ = pointer to state block
341 * Returns: Zero if all OK, -1 on error.
343 * Use: Does a @select@ call (or equivalent @poll@).
346 int sel_select(sel_state *s)
351 /* --- Initialize the argument block --- */
356 for (i = 0; i < SEL_MODES; i++) {
357 if (s->files[i] && s->files[i]->fd >= a.maxfd)
358 a.maxfd = s->files[i]->fd + 1;
362 memcpy(a.fd, s->fd, sizeof(a.fd));
363 if (s->timers || s->hooks)
364 gettimeofday(&a.now, 0);
368 if (TV_CMP(&s->timers->tv, >, &a.now))
369 TV_SUB(&a.tv, &s->timers->tv, &a.now);
378 /* --- Grind through the pre hooks --- */
381 sel_hook *h = s->hooks;
386 hh->before(s, &a, hh->p);
390 /* --- Run the @select@ call --- */
392 if ((err = select(a.maxfd,
393 &a.fd[SEL_READ], &a.fd[SEL_WRITE], &a.fd[SEL_EXC],
400 gettimeofday(&a.now, 0);
402 /* --- Run through the hooks again --- */
405 sel_hook *h = s->hooks;
410 hh->after(s, &a, hh->p);
414 /* --- Run through the timers --- */
417 ptimer *pthead, *pt, **ptt = &pthead;
420 for (t = s->timers; t && TV_CMP(&t->tv, <=, &a.now); t = t->next) {
430 t->prev = (sel_timer *)&s->timers;
438 t->func(&a.now, t->p);
445 /* --- And finally run through the files --- *
447 * Do reads first. It's quite possible that a read might prompt a write,
448 * but the other way around is less likely. Fortunately, the modes are
449 * in the right order for this.
455 for (i = 0; i < SEL_MODES; i++) {
456 pfile *pfhead, *pf, **pff = &pfhead;
459 for (f = s->files[i]; f; f = f->next) {
460 if (!FD_ISSET(f->fd, &a.fd[i]))
474 f->func(f->fd, i, f->p);
485 /*----- That's all, folks -------------------------------------------------*/