3 * $Id: sel.c,v 1.12 2003/05/18 15:10:29 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 1.12 2003/05/18 15:10:29 mdw
36 * Revision 1.11 2003/05/17 10:34:04 mdw
37 * Tidying and bugfixing.
39 * Revision 1.10 2001/06/22 19:35:58 mdw
40 * Fix a large number of bugs.
42 * Revision 1.9 2001/02/03 19:07:08 mdw
43 * Ensure that timers set to go off in the past don't case a problem.
45 * Revision 1.8 2000/03/23 20:42:08 mdw
46 * Rearrange timeout handling to avoid list corruptions.
48 * Revision 1.7 1999/12/11 11:12:17 mdw
49 * Fix comment formatting error.
51 * Revision 1.6 1999/09/26 14:28:11 mdw
52 * (sel_select): Almost pointless efficiency tweak.
54 * Revision 1.5 1999/08/31 17:42:22 mdw
55 * New function `sel_force' to force a descriptor to be `selected'.
57 * Revision 1.4 1999/08/19 18:30:26 mdw
58 * Implement hooks for foreign select-using systems (currently not well
61 * Revision 1.3 1999/05/21 22:13:59 mdw
62 * Use new `tv' macros. Fix ordering bug for timeout selectors.
64 * Revision 1.2 1999/05/15 10:33:32 mdw
65 * Fix copyright notices.
67 * Revision 1.1 1999/05/14 21:01:14 mdw
68 * Integrated `select' handling bits from the background resolver project.
72 /*----- Header files ------------------------------------------------------*/
79 #include <sys/types.h>
87 /*----- Data structures ---------------------------------------------------*/
89 typedef struct sel_pendfile {
90 struct sel_pendfile *next;
94 typedef struct sel_pendtimer {
95 struct sel_pendtimer *next;
99 /*----- Main code ---------------------------------------------------------*/
101 /* --- @sel_init@ --- *
103 * Arguments: @sel_state *s@ = pointer to a state block to initialize
107 * Use: Initializes a select state block.
110 void sel_init(sel_state *s)
114 for (i = 0; i < SEL_MODES; i++) {
123 /* --- @sel_initfile@ --- *
125 * Arguments: @sel_state *s@ = select state to attach to
126 * @sel_file *f@ = pointer to a file block to initialize
127 * @int fd@ = the file descriptor to listen to
128 * @unsigned mode@ = what to listen for
129 * @void (*func)(int fd, unsigned mode, void *p)@ = handler
130 * @void *p@ = argument to pass to handler
134 * Use: Initializes a file block ready for use. The file block
135 * isn't added to the list of things to do until a call to
139 void sel_initfile(sel_state *s, sel_file *f,
140 int fd, unsigned mode,
141 void (*func)(int /*fd*/, unsigned /*mode*/, void */*p*/),
152 /* --- @sel_addfile@ --- *
154 * Arguments: @sel_file *f@ = pointer to a file block
158 * Use: Adds a file block into the list of things to listen to.
161 void sel_addfile(sel_file *f)
163 sel_file **ff = &f->s->files[f->mode];
165 /* --- This little dance looks like line-noise, but it does the job --- */
167 while (*ff && (*ff)->fd > f->fd)
172 (*ff)->prev = &f->next;
174 FD_SET(f->fd, f->s->fd + f->mode);
177 /* --- @sel_force@ --- *
179 * Arguments: @sel_file *f@ = pointer to file selector
183 * Use: Forces a file selector to be considered ready. This is only
184 * useful during a call to @sel_select@. Of particular use is
185 * forcing a write selector when there's something interesting
189 void sel_force(sel_file *f)
192 FD_SET(f->fd, &f->s->args->fd[f->mode]);
195 /* --- @sel_rmfile@ --- *
197 * Arguments: @sel_file *f@ = pointer to a file block
201 * Use: Removes a file block from the list of things to listen to.
204 void sel_rmfile(sel_file *f)
208 f->next->prev = f->prev;
209 FD_CLR(f->fd, f->s->fd + f->mode);
216 /* --- @sel_addtimer@ --- *
218 * Arguments: @sel_state *s@ = pointer to a state block
219 * @sel_timer *t@ = pointer to a timer block
220 * @struct timeval *tv@ = pointer to time to activate
221 * @void (*func)(struct timeval *tv, void *p)@ = handler
222 * @void *p@ = argument for handler function
226 * Use: Registers and sets up a timer.
229 void sel_addtimer(sel_state *s, sel_timer *t,
231 void (*func)(struct timeval */*tv*/, void */*p*/),
234 sel_timer **tt = &s->timers;
235 { sel_timer *q; for (q = s->timers; q; q = q->next) assert(q != t); }
237 /* --- Set up the timer block --- */
244 /* --- More line noise --- */
246 while (*tt && TV_CMP(&(*tt)->tv, <, tv))
251 (*tt)->prev = &t->next;
255 /* --- @sel_rmtimer@ --- *
257 * Arguments: @sel_timer *t@ = pointer to timer block
261 * Use: Removes a timer from the list of timers.
264 void sel_rmtimer(sel_timer *t)
272 t->next->prev = t->prev;
276 /* --- @sel_addhook@ --- *
278 * Arguments: @sel_state *s@ = pointer to state block
279 * @sel_hook *h@ = pointer to hook block
280 * @sel_hookfn before, after@ = hook functions
281 * @void *p@ = pointer argument to pass to hook functions
285 * Use: Registers hook functions to be called on each select call.
288 void sel_addhook(sel_state *s, sel_hook *h,
289 sel_hookfn before, sel_hookfn after,
298 s->hooks->prev = &h->next;
302 /* --- @sel_rmhook@ --- *
304 * Arguments: @sel_hook *h@ = pointer to hook block
308 * Use: Removes hook functions.
311 void sel_rmhook(sel_hook *h)
314 h->next->prev = h->prev;
318 /* --- @sel_fdmerge@ --- *
320 * Arguments: @fd_set *dest@ = destination FD set
321 * @fd_set *fd@ = pointer to set to merge
322 * @int maxfd@ = highest numbered descriptor in @fd@ + 1
324 * Returns: Actual highest numbered descriptor.
326 * Use: Merges file descriptor sets, and returns an accurate @maxfd@
330 int sel_fdmerge(fd_set *dest, fd_set *fd, int maxfd)
334 for (i = 0; i < maxfd; i++) {
335 if (FD_ISSET(i, fd)) {
344 /* --- @sel_select@ --- *
346 * Arguments: @sel_state *s@ = pointer to state block
348 * Returns: Zero if all OK, -1 on error.
350 * Use: Does a @select@ call (or equivalent @poll@).
353 int sel_select(sel_state *s)
358 /* --- Initialize the argument block --- */
363 for (i = 0; i < SEL_MODES; i++) {
364 if (s->files[i] && s->files[i]->fd >= a.maxfd)
365 a.maxfd = s->files[i]->fd + 1;
369 memcpy(a.fd, s->fd, sizeof(a.fd));
370 if (s->timers || s->hooks)
371 gettimeofday(&a.now, 0);
375 if (TV_CMP(&s->timers->tv, >, &a.now))
376 TV_SUB(&a.tv, &s->timers->tv, &a.now);
385 /* --- Grind through the pre hooks --- */
388 sel_hook *h = s->hooks;
393 hh->before(s, &a, hh->p);
397 /* --- Run the @select@ call --- */
399 if ((err = select(a.maxfd,
400 &a.fd[SEL_READ], &a.fd[SEL_WRITE], &a.fd[SEL_EXC],
407 gettimeofday(&a.now, 0);
409 /* --- Run through the hooks again --- */
412 sel_hook *h = s->hooks;
417 hh->after(s, &a, hh->p);
421 /* --- Run through the timers --- */
424 ptimer *pthead, *pt, **ptt = &pthead;
427 for (t = s->timers; t && TV_CMP(&t->tv, <=, &a.now); t = t->next) {
437 t->prev = &s->timers;
448 t->func(&a.now, t->p);
454 /* --- And finally run through the files --- *
456 * Do reads first. It's quite possible that a read might prompt a write,
457 * but the other way around is less likely. Fortunately, the modes are
458 * in the right order for this.
464 for (i = 0; i < SEL_MODES; i++) {
465 pfile *pfhead, *pf, **pff = &pfhead;
468 for (f = s->files[i]; f; f = f->next) {
469 if (!FD_ISSET(f->fd, &a.fd[i]))
484 f->func(f->fd, i, f->p);
495 /*----- That's all, folks -------------------------------------------------*/