3 * $Id: sel.c,v 1.5 1999/08/31 17:42:22 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 1.5 1999/08/31 17:42:22 mdw
34 * New function `sel_force' to force a descriptor to be `selected'.
36 * Revision 1.4 1999/08/19 18:30:26 mdw
37 * Implement hooks for foreign select-using systems (currently not well
40 * Revision 1.3 1999/05/21 22:13:59 mdw
41 * Use new `tv' macros. Fix ordering bug for timeout selectors.
43 * Revision 1.2 1999/05/15 10:33:32 mdw
44 * Fix copyright notices.
46 * Revision 1.1 1999/05/14 21:01:14 mdw
47 * Integrated `select' handling bits from the background resolver project.
51 /*----- Header files ------------------------------------------------------*/
57 #include <sys/types.h>
64 /*----- Main code ---------------------------------------------------------*/
66 /* --- @sel_init@ --- *
68 * Arguments: @sel_state *s@ = pointer to a state block to initialize
72 * Use: Initializes a select state block.
75 void sel_init(sel_state
*s
)
79 for (i
= 0; i
< SEL_MODES
; i
++) {
88 /* --- @sel_initfile@ --- *
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
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
104 void sel_initfile(sel_state
*s
, sel_file
*f
,
105 int fd
, unsigned mode
,
106 void (*func
)(int /*fd*/, unsigned /*mode*/, void */
*p*/
),
116 /* --- @sel_addfile@ --- *
118 * Arguments: @sel_file *f@ = pointer to a file block
122 * Use: Adds a file block into the list of things to listen to.
125 void sel_addfile(sel_file
*f
)
127 sel_file
**ff
= &f
->s
->files
[f
->mode
];
129 /* --- This little dance looks like line-noise, but it does the job --- */
131 while (*ff
&& (*ff
)->fd
> f
->fd
)
134 f
->prev
= (sel_file
*)ff
;
138 FD_SET(f
->fd
, f
->s
->fd
+ f
->mode
);
141 /* --- @sel_force@ --- *
143 * Arguments: @sel_file *f@ = pointer to file selector
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
153 void sel_force(sel_file
*f
)
156 FD_SET(f
->fd
, &f
->s
->args
->fd
[f
->mode
]);
159 /* --- @sel_rmfile@ --- *
161 * Arguments: @sel_file *f@ = pointer to a file block
165 * Use: Removes a file block from the list of things to listen to.
168 void sel_rmfile(sel_file
*f
)
170 f
->prev
->next
= f
->next
;
172 f
->next
->prev
= f
->prev
;
173 FD_CLR(f
->fd
, f
->s
->fd
+ f
->mode
);
176 /* --- @sel_addtimer@ --- *
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
186 * Use: Registers and sets up a timer.
189 void sel_addtimer(sel_state
*s
, sel_timer
*t
,
191 void (*func
)(struct timeval */
*tv*/
, void */
*p*/
),
194 sel_timer
**tt
= &s
->timers
;
196 /* --- Set up the timer block --- */
202 /* --- More line noise --- */
204 while (*tt
&& TV_CMP(&(*tt
)->tv
, <, tv
))
207 t
->prev
= (sel_timer
*)tt
;
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
)
224 t
->prev
->next
= t
->next
;
226 t
->next
->prev
= t
->prev
;
229 /* --- @sel_addhook@ --- *
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
238 * Use: Registers hook functions to be called on each select call.
241 void sel_addhook(sel_state
*s
, sel_hook
*h
,
242 sel_hookfn before
, sel_hookfn after
,
249 h
->prev
= (sel_hook
*)&s
->hooks
;
255 /* --- @sel_rmhook@ --- *
257 * Arguments: @sel_hook *h@ = pointer to hook block
261 * Use: Removes hook functions.
264 void sel_rmhook(sel_hook
*h
)
267 h
->next
->prev
= h
->prev
;
268 h
->prev
->next
= h
->next
;
271 /* --- @sel_fdmerge@ --- *
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
277 * Returns: Actual highest numbered descriptor.
279 * Use: Merges file descriptor sets, and returns an accurate @maxfd@
283 int sel_fdmerge(fd_set
*dest
, fd_set
*fd
, int maxfd
)
287 for (i
= 0; i
< maxfd
; i
++) {
288 if (FD_ISSET(i
, fd
)) {
297 /* --- @sel_select@ --- *
299 * Arguments: @sel_state *s@ = pointer to state block
301 * Returns: Zero if all OK, -1 on error.
303 * Use: Does a @select@ call (or equivalent @poll@).
306 int sel_select(sel_state
*s
)
311 /* --- Initialize the argument block --- */
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;
322 memcpy(a
.fd
, s
->fd
, sizeof(a
.fd
));
323 if (s
->timers
|| s
->hooks
)
324 gettimeofday(&a
.now
, 0);
328 TV_SUB(&a
.tv
, &s
->timers
->tv
, &a
.now
);
333 /* --- Grind through the pre hooks --- */
336 sel_hook
*h
= s
->hooks
;
341 hh
->before(s
, &a
, hh
->p
);
345 /* --- Run the @select@ call --- */
347 if ((err
= select(a
.maxfd
,
348 &a
.fd
[SEL_READ
], &a
.fd
[SEL_WRITE
], &a
.fd
[SEL_EXC
],
355 gettimeofday(&a
.now
, 0);
357 /* --- Run through the hooks again --- */
360 sel_hook
*h
= s
->hooks
;
365 hh
->after(s
, &a
, hh
->p
);
369 /* --- Run through the timers --- */
373 for (t
= s
->timers
; t
&& TV_CMP(&t
->tv
, <=, &a
.now
); t
= tt
) {
375 t
->next
= t
->prev
= t
;
376 t
->func(&a
.now
, t
->p
);
380 t
->prev
= (sel_timer
*)&s
->timers
;
383 /* --- And finally run through the files --- *
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.
393 for (i
= 0; i
< SEL_MODES
; i
++) {
395 for (f
= s
->files
[i
]; f
; f
= ff
) {
397 if (FD_ISSET(f
->fd
, a
.fd
+ f
->mode
))
398 f
->func(f
->fd
, f
->mode
, f
->p
);
407 /*----- That's all, folks -------------------------------------------------*/