3 * $Id: sel.c,v 1.13 2004/04/08 01:36:13 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 /*----- Header files ------------------------------------------------------*/
37 #include <sys/types.h>
45 /*----- Data structures ---------------------------------------------------*/
47 typedef struct sel_pendfile {
48 struct sel_pendfile *next;
52 typedef struct sel_pendtimer {
53 struct sel_pendtimer *next;
57 /*----- Main code ---------------------------------------------------------*/
59 /* --- @sel_init@ --- *
61 * Arguments: @sel_state *s@ = pointer to a state block to initialize
65 * Use: Initializes a select state block.
68 void sel_init(sel_state *s)
72 for (i = 0; i < SEL_MODES; i++) {
81 /* --- @sel_initfile@ --- *
83 * Arguments: @sel_state *s@ = select state to attach to
84 * @sel_file *f@ = pointer to a file block to initialize
85 * @int fd@ = the file descriptor to listen to
86 * @unsigned mode@ = what to listen for
87 * @void (*func)(int fd, unsigned mode, void *p)@ = handler
88 * @void *p@ = argument to pass to handler
92 * Use: Initializes a file block ready for use. The file block
93 * isn't added to the list of things to do until a call to
97 void sel_initfile(sel_state *s, sel_file *f,
98 int fd, unsigned mode,
99 void (*func)(int /*fd*/, unsigned /*mode*/, void */*p*/),
110 /* --- @sel_addfile@ --- *
112 * Arguments: @sel_file *f@ = pointer to a file block
116 * Use: Adds a file block into the list of things to listen to.
119 void sel_addfile(sel_file *f)
121 sel_file **ff = &f->s->files[f->mode];
123 /* --- This little dance looks like line-noise, but it does the job --- */
125 while (*ff && (*ff)->fd > f->fd)
130 (*ff)->prev = &f->next;
132 FD_SET(f->fd, f->s->fd + f->mode);
135 /* --- @sel_force@ --- *
137 * Arguments: @sel_file *f@ = pointer to file selector
141 * Use: Forces a file selector to be considered ready. This is only
142 * useful during a call to @sel_select@. Of particular use is
143 * forcing a write selector when there's something interesting
147 void sel_force(sel_file *f)
150 FD_SET(f->fd, &f->s->args->fd[f->mode]);
153 /* --- @sel_rmfile@ --- *
155 * Arguments: @sel_file *f@ = pointer to a file block
159 * Use: Removes a file block from the list of things to listen to.
162 void sel_rmfile(sel_file *f)
166 f->next->prev = f->prev;
167 FD_CLR(f->fd, f->s->fd + f->mode);
174 /* --- @sel_addtimer@ --- *
176 * Arguments: @sel_state *s@ = pointer to a state block
177 * @sel_timer *t@ = pointer to a timer block
178 * @struct timeval *tv@ = pointer to time to activate
179 * @void (*func)(struct timeval *tv, void *p)@ = handler
180 * @void *p@ = argument for handler function
184 * Use: Registers and sets up a timer.
187 void sel_addtimer(sel_state *s, sel_timer *t,
189 void (*func)(struct timeval */*tv*/, void */*p*/),
192 sel_timer **tt = &s->timers;
193 { sel_timer *q; for (q = s->timers; q; q = q->next) assert(q != t); }
195 /* --- Set up the timer block --- */
202 /* --- More line noise --- */
204 while (*tt && TV_CMP(&(*tt)->tv, <, tv))
209 (*tt)->prev = &t->next;
213 /* --- @sel_rmtimer@ --- *
215 * Arguments: @sel_timer *t@ = pointer to timer block
219 * Use: Removes a timer from the list of timers.
222 void sel_rmtimer(sel_timer *t)
230 t->next->prev = t->prev;
234 /* --- @sel_addhook@ --- *
236 * Arguments: @sel_state *s@ = pointer to state block
237 * @sel_hook *h@ = pointer to hook block
238 * @sel_hookfn before, after@ = hook functions
239 * @void *p@ = pointer argument to pass to hook functions
243 * Use: Registers hook functions to be called on each select call.
246 void sel_addhook(sel_state *s, sel_hook *h,
247 sel_hookfn before, sel_hookfn after,
256 s->hooks->prev = &h->next;
260 /* --- @sel_rmhook@ --- *
262 * Arguments: @sel_hook *h@ = pointer to hook block
266 * Use: Removes hook functions.
269 void sel_rmhook(sel_hook *h)
272 h->next->prev = h->prev;
276 /* --- @sel_fdmerge@ --- *
278 * Arguments: @fd_set *dest@ = destination FD set
279 * @fd_set *fd@ = pointer to set to merge
280 * @int maxfd@ = highest numbered descriptor in @fd@ + 1
282 * Returns: Actual highest numbered descriptor.
284 * Use: Merges file descriptor sets, and returns an accurate @maxfd@
288 int sel_fdmerge(fd_set *dest, fd_set *fd, int maxfd)
292 for (i = 0; i < maxfd; i++) {
293 if (FD_ISSET(i, fd)) {
302 /* --- @sel_select@ --- *
304 * Arguments: @sel_state *s@ = pointer to state block
306 * Returns: Zero if all OK, -1 on error.
308 * Use: Does a @select@ call (or equivalent @poll@).
311 int sel_select(sel_state *s)
316 /* --- Initialize the argument block --- */
321 for (i = 0; i < SEL_MODES; i++) {
322 if (s->files[i] && s->files[i]->fd >= a.maxfd)
323 a.maxfd = s->files[i]->fd + 1;
327 memcpy(a.fd, s->fd, sizeof(a.fd));
328 if (s->timers || s->hooks)
329 gettimeofday(&a.now, 0);
333 if (TV_CMP(&s->timers->tv, >, &a.now))
334 TV_SUB(&a.tv, &s->timers->tv, &a.now);
343 /* --- Grind through the pre hooks --- */
346 sel_hook *h = s->hooks;
351 hh->before(s, &a, hh->p);
355 /* --- Run the @select@ call --- */
357 if ((err = select(a.maxfd,
358 &a.fd[SEL_READ], &a.fd[SEL_WRITE], &a.fd[SEL_EXC],
365 gettimeofday(&a.now, 0);
367 /* --- Run through the hooks again --- */
370 sel_hook *h = s->hooks;
375 hh->after(s, &a, hh->p);
379 /* --- Run through the timers --- */
382 ptimer *pthead, *pt, **ptt = &pthead;
385 for (t = s->timers; t && TV_CMP(&t->tv, <=, &a.now); t = t->next) {
395 t->prev = &s->timers;
406 t->func(&a.now, t->p);
412 /* --- And finally run through the files --- *
414 * Do reads first. It's quite possible that a read might prompt a write,
415 * but the other way around is less likely. Fortunately, the modes are
416 * in the right order for this.
422 for (i = 0; i < SEL_MODES; i++) {
423 pfile *pfhead, *pf, **pff = &pfhead;
426 for (f = s->files[i]; f; f = f->next) {
427 if (!FD_ISSET(f->fd, &a.fd[i]))
442 f->func(f->fd, i, f->p);
453 /*----- That's all, folks -------------------------------------------------*/