1/***
2  This file is part of avahi.
3
4  avahi is free software; you can redistribute it and/or modify it
5  under the terms of the GNU Lesser General Public License as
6  published by the Free Software Foundation; either version 2.1 of the
7  License, or (at your option) any later version.
8
9  avahi is distributed in the hope that it will be useful, but WITHOUT
10  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
11  or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General
12  Public License for more details.
13
14  You should have received a copy of the GNU Lesser General Public
15  License along with avahi; if not, write to the Free Software
16  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
17  USA.
18***/
19
20#ifdef HAVE_CONFIG_H
21#include <config.h>
22#endif
23
24#include <sys/poll.h>
25#include <assert.h>
26#include <string.h>
27#include <errno.h>
28#include <unistd.h>
29#include <fcntl.h>
30#include <stdio.h>
31
32#include "llist.h"
33#include "avahi-malloc.h"
34#include "timeval.h"
35#include "simple-watch.h"
36
37struct AvahiWatch {
38    AvahiSimplePoll *simple_poll;
39    int dead;
40
41    int idx;
42    struct pollfd pollfd;
43
44    AvahiWatchCallback callback;
45    void *userdata;
46
47    AVAHI_LLIST_FIELDS(AvahiWatch, watches);
48};
49
50struct AvahiTimeout {
51    AvahiSimplePoll *simple_poll;
52    int dead;
53
54    int enabled;
55    struct timeval expiry;
56
57    AvahiTimeoutCallback callback;
58    void  *userdata;
59
60    AVAHI_LLIST_FIELDS(AvahiTimeout, timeouts);
61};
62
63struct AvahiSimplePoll {
64    AvahiPoll api;
65    AvahiPollFunc poll_func;
66    void *poll_func_userdata;
67
68    struct pollfd* pollfds;
69    int n_pollfds, max_pollfds, rebuild_pollfds;
70
71    int watch_req_cleanup, timeout_req_cleanup;
72    int quit;
73    int events_valid;
74
75    int n_watches;
76    AVAHI_LLIST_HEAD(AvahiWatch, watches);
77    AVAHI_LLIST_HEAD(AvahiTimeout, timeouts);
78
79    int wakeup_pipe[2];
80    int wakeup_issued;
81
82    int prepared_timeout;
83
84    enum {
85        STATE_INIT,
86        STATE_PREPARING,
87        STATE_PREPARED,
88        STATE_RUNNING,
89        STATE_RAN,
90        STATE_DISPATCHING,
91        STATE_DISPATCHED,
92        STATE_QUIT,
93        STATE_FAILURE
94    } state;
95};
96
97void avahi_simple_poll_wakeup(AvahiSimplePoll *s) {
98    char c = 'W';
99    assert(s);
100
101    write(s->wakeup_pipe[1], &c, sizeof(c));
102    s->wakeup_issued = 1;
103}
104
105static void clear_wakeup(AvahiSimplePoll *s) {
106    char c[10]; /* Read ten at a time */
107
108    if (!s->wakeup_issued)
109        return;
110
111    s->wakeup_issued = 0;
112
113    for(;;)
114        if (read(s->wakeup_pipe[0], &c, sizeof(c)) != sizeof(c))
115            break;
116}
117
118static int set_nonblock(int fd) {
119    int n;
120
121    assert(fd >= 0);
122
123    if ((n = fcntl(fd, F_GETFL)) < 0)
124        return -1;
125
126    if (n & O_NONBLOCK)
127        return 0;
128
129    return fcntl(fd, F_SETFL, n|O_NONBLOCK);
130}
131
132static AvahiWatch* watch_new(const AvahiPoll *api, int fd, AvahiWatchEvent event, AvahiWatchCallback callback, void *userdata) {
133    AvahiWatch *w;
134    AvahiSimplePoll *s;
135
136    assert(api);
137    assert(fd >= 0);
138    assert(callback);
139
140    s = api->userdata;
141    assert(s);
142
143    if (!(w = avahi_new(AvahiWatch, 1)))
144        return NULL;
145
146    /* If there is a background thread running the poll() for us, tell it to exit the poll() */
147    avahi_simple_poll_wakeup(s);
148
149    w->simple_poll = s;
150    w->dead = 0;
151
152    w->pollfd.fd = fd;
153    w->pollfd.events = event;
154    w->pollfd.revents = 0;
155
156    w->callback = callback;
157    w->userdata = userdata;
158
159    w->idx = -1;
160    s->rebuild_pollfds = 1;
161
162    AVAHI_LLIST_PREPEND(AvahiWatch, watches, s->watches, w);
163    s->n_watches++;
164
165    return w;
166}
167
168static void watch_update(AvahiWatch *w, AvahiWatchEvent events) {
169    assert(w);
170    assert(!w->dead);
171
172    /* If there is a background thread running the poll() for us, tell it to exit the poll() */
173    avahi_simple_poll_wakeup(w->simple_poll);
174
175    w->pollfd.events = events;
176
177    if (w->idx != -1) {
178        assert(w->simple_poll);
179        w->simple_poll->pollfds[w->idx] = w->pollfd;
180    } else
181        w->simple_poll->rebuild_pollfds = 1;
182}
183
184static AvahiWatchEvent watch_get_events(AvahiWatch *w) {
185    assert(w);
186    assert(!w->dead);
187
188    if (w->idx != -1 && w->simple_poll->events_valid)
189        return w->simple_poll->pollfds[w->idx].revents;
190
191    return 0;
192}
193
194static void remove_pollfd(AvahiWatch *w) {
195    assert(w);
196
197    if (w->idx == -1)
198        return;
199
200    w->simple_poll->rebuild_pollfds = 1;
201}
202
203static void watch_free(AvahiWatch *w) {
204    assert(w);
205
206    assert(!w->dead);
207
208    /* If there is a background thread running the poll() for us, tell it to exit the poll() */
209    avahi_simple_poll_wakeup(w->simple_poll);
210
211    remove_pollfd(w);
212
213    w->dead = 1;
214    w->simple_poll->n_watches --;
215    w->simple_poll->watch_req_cleanup = 1;
216}
217
218static void destroy_watch(AvahiWatch *w) {
219    assert(w);
220
221    remove_pollfd(w);
222    AVAHI_LLIST_REMOVE(AvahiWatch, watches, w->simple_poll->watches, w);
223
224    if (!w->dead)
225        w->simple_poll->n_watches --;
226
227    avahi_free(w);
228}
229
230static void cleanup_watches(AvahiSimplePoll *s, int all) {
231    AvahiWatch *w, *next;
232    assert(s);
233
234    for (w = s->watches; w; w = next) {
235        next = w->watches_next;
236
237        if (all || w->dead)
238            destroy_watch(w);
239    }
240
241    s->timeout_req_cleanup = 0;
242}
243
244static AvahiTimeout* timeout_new(const AvahiPoll *api, const struct timeval *tv, AvahiTimeoutCallback callback, void *userdata) {
245    AvahiTimeout *t;
246    AvahiSimplePoll *s;
247
248    assert(api);
249    assert(callback);
250
251    s = api->userdata;
252    assert(s);
253
254    if (!(t = avahi_new(AvahiTimeout, 1)))
255        return NULL;
256
257    /* If there is a background thread running the poll() for us, tell it to exit the poll() */
258    avahi_simple_poll_wakeup(s);
259
260    t->simple_poll = s;
261    t->dead = 0;
262
263    if ((t->enabled = !!tv))
264        t->expiry = *tv;
265
266    t->callback = callback;
267    t->userdata = userdata;
268
269    AVAHI_LLIST_PREPEND(AvahiTimeout, timeouts, s->timeouts, t);
270    return t;
271}
272
273static void timeout_update(AvahiTimeout *t, const struct timeval *tv) {
274    assert(t);
275    assert(!t->dead);
276
277    /* If there is a background thread running the poll() for us, tell it to exit the poll() */
278    avahi_simple_poll_wakeup(t->simple_poll);
279
280    if ((t->enabled = !!tv))
281        t->expiry = *tv;
282}
283
284static void timeout_free(AvahiTimeout *t) {
285    assert(t);
286    assert(!t->dead);
287
288    /* If there is a background thread running the poll() for us, tell it to exit the poll() */
289    avahi_simple_poll_wakeup(t->simple_poll);
290
291    t->dead = 1;
292    t->simple_poll->timeout_req_cleanup = 1;
293}
294
295
296static void destroy_timeout(AvahiTimeout *t) {
297    assert(t);
298
299    AVAHI_LLIST_REMOVE(AvahiTimeout, timeouts, t->simple_poll->timeouts, t);
300
301    avahi_free(t);
302}
303
304static void cleanup_timeouts(AvahiSimplePoll *s, int all) {
305    AvahiTimeout *t, *next;
306    assert(s);
307
308    for (t = s->timeouts; t; t = next) {
309        next = t->timeouts_next;
310
311        if (all || t->dead)
312            destroy_timeout(t);
313    }
314
315    s->timeout_req_cleanup = 0;
316}
317
318AvahiSimplePoll *avahi_simple_poll_new(void) {
319    AvahiSimplePoll *s;
320
321    if (!(s = avahi_new(AvahiSimplePoll, 1)))
322        return NULL;
323
324    if (pipe(s->wakeup_pipe) < 0) {
325        avahi_free(s);
326        return NULL;
327    }
328
329    set_nonblock(s->wakeup_pipe[0]);
330    set_nonblock(s->wakeup_pipe[1]);
331
332    s->api.userdata = s;
333
334    s->api.watch_new = watch_new;
335    s->api.watch_free = watch_free;
336    s->api.watch_update = watch_update;
337    s->api.watch_get_events = watch_get_events;
338
339    s->api.timeout_new = timeout_new;
340    s->api.timeout_free = timeout_free;
341    s->api.timeout_update = timeout_update;
342
343    s->pollfds = NULL;
344    s->max_pollfds = s->n_pollfds = 0;
345    s->rebuild_pollfds = 1;
346    s->quit = 0;
347    s->n_watches = 0;
348    s->events_valid = 0;
349
350    s->watch_req_cleanup = 0;
351    s->timeout_req_cleanup = 0;
352
353    s->prepared_timeout = 0;
354
355    s->state = STATE_INIT;
356
357    s->wakeup_issued = 0;
358
359    avahi_simple_poll_set_func(s, NULL, NULL);
360
361    AVAHI_LLIST_HEAD_INIT(AvahiWatch, s->watches);
362    AVAHI_LLIST_HEAD_INIT(AvahiTimeout, s->timeouts);
363
364    return s;
365}
366
367void avahi_simple_poll_free(AvahiSimplePoll *s) {
368    assert(s);
369
370    cleanup_timeouts(s, 1);
371    cleanup_watches(s, 1);
372    assert(s->n_watches == 0);
373
374    avahi_free(s->pollfds);
375
376    if (s->wakeup_pipe[0] >= 0)
377        close(s->wakeup_pipe[0]);
378
379    if (s->wakeup_pipe[1] >= 0)
380        close(s->wakeup_pipe[1]);
381
382    avahi_free(s);
383}
384
385static int rebuild(AvahiSimplePoll *s) {
386    AvahiWatch *w;
387    int idx;
388
389    assert(s);
390
391    if (s->n_watches+1 > s->max_pollfds) {
392        struct pollfd *n;
393
394        s->max_pollfds = s->n_watches + 10;
395
396        if (!(n = avahi_realloc(s->pollfds, sizeof(struct pollfd) * s->max_pollfds)))
397            return -1;
398
399        s->pollfds = n;
400    }
401
402
403    s->pollfds[0].fd = s->wakeup_pipe[0];
404    s->pollfds[0].events = POLLIN;
405    s->pollfds[0].revents = 0;
406
407    idx = 1;
408
409    for (w = s->watches; w; w = w->watches_next) {
410
411        if(w->dead)
412            continue;
413
414        assert(w->idx < s->max_pollfds);
415        s->pollfds[w->idx = idx++] = w->pollfd;
416    }
417
418    s->n_pollfds = idx;
419    s->events_valid = 0;
420    s->rebuild_pollfds = 0;
421
422    return 0;
423}
424
425static AvahiTimeout* find_next_timeout(AvahiSimplePoll *s) {
426    AvahiTimeout *t, *n = NULL;
427    assert(s);
428
429    for (t = s->timeouts; t; t = t->timeouts_next) {
430
431        if (t->dead || !t->enabled)
432            continue;
433
434        if (!n || avahi_timeval_compare(&t->expiry, &n->expiry) < 0)
435            n = t;
436    }
437
438    return n;
439}
440
441static void timeout_callback(AvahiTimeout *t) {
442    assert(t);
443    assert(!t->dead);
444    assert(t->enabled);
445
446    t->enabled = 0;
447    t->callback(t, t->userdata);
448}
449
450int avahi_simple_poll_prepare(AvahiSimplePoll *s, int timeout) {
451    AvahiTimeout *next_timeout;
452
453    assert(s);
454    assert(s->state == STATE_INIT || s->state == STATE_DISPATCHED || s->state == STATE_FAILURE);
455    s->state = STATE_PREPARING;
456
457    /* Clear pending wakeup requests */
458    clear_wakeup(s);
459
460    /* Cleanup things first */
461    if (s->watch_req_cleanup)
462        cleanup_watches(s, 0);
463
464    if (s->timeout_req_cleanup)
465        cleanup_timeouts(s, 0);
466
467    /* Check whether a quit was requested */
468    if (s->quit) {
469        s->state = STATE_QUIT;
470        return 1;
471    }
472
473    /* Do we need to rebuild our array of pollfds? */
474    if (s->rebuild_pollfds)
475        if (rebuild(s) < 0) {
476            s->state = STATE_FAILURE;
477            return -1;
478        }
479
480    /* Calculate the wakeup time */
481    if ((next_timeout = find_next_timeout(s))) {
482        struct timeval now;
483        int t;
484        AvahiUsec usec;
485
486        if (next_timeout->expiry.tv_sec == 0 &&
487            next_timeout->expiry.tv_usec == 0) {
488
489            /* Just a shortcut so that we don't need to call gettimeofday() */
490            timeout = 0;
491            goto finish;
492        }
493
494        gettimeofday(&now, NULL);
495        usec = avahi_timeval_diff(&next_timeout->expiry, &now);
496
497        if (usec <= 0) {
498            /* Timeout elapsed */
499
500            timeout = 0;
501            goto finish;
502        }
503
504        /* Calculate sleep time. We add 1ms because otherwise we'd
505         * wake up too early most of the time */
506        t = (int) (usec / 1000) + 1;
507
508        if (timeout < 0 || timeout > t)
509            timeout = t;
510    }
511
512finish:
513    s->prepared_timeout = timeout;
514    s->state = STATE_PREPARED;
515    return 0;
516}
517
518int avahi_simple_poll_run(AvahiSimplePoll *s) {
519    assert(s);
520    assert(s->state == STATE_PREPARED || s->state == STATE_FAILURE);
521
522    s->state = STATE_RUNNING;
523
524    for (;;) {
525        errno = 0;
526
527        if (s->poll_func(s->pollfds, s->n_pollfds, s->prepared_timeout, s->poll_func_userdata) < 0) {
528
529            if (errno == EINTR)
530                continue;
531
532            s->state = STATE_FAILURE;
533            return -1;
534        }
535
536        break;
537    }
538
539    /* The poll events are now valid again */
540    s->events_valid = 1;
541
542    /* Update state */
543    s->state = STATE_RAN;
544    return 0;
545}
546
547int avahi_simple_poll_dispatch(AvahiSimplePoll *s) {
548    AvahiTimeout *next_timeout;
549    AvahiWatch *w;
550
551    assert(s);
552    assert(s->state == STATE_RAN);
553    s->state = STATE_DISPATCHING;
554
555    /* We execute only on callback in every iteration */
556
557    /* Check whether the wakeup time has been reached now */
558    if ((next_timeout = find_next_timeout(s))) {
559
560        if (next_timeout->expiry.tv_sec == 0 && next_timeout->expiry.tv_usec == 0) {
561
562            /* Just a shortcut so that we don't need to call gettimeofday() */
563            timeout_callback(next_timeout);
564            goto finish;
565        }
566
567        if (avahi_age(&next_timeout->expiry) >= 0) {
568
569            /* Timeout elapsed */
570            timeout_callback(next_timeout);
571            goto finish;
572        }
573    }
574
575    /* Look for some kind of I/O event */
576    for (w = s->watches; w; w = w->watches_next) {
577
578        if (w->dead)
579            continue;
580
581        assert(w->idx >= 0);
582        assert(w->idx < s->n_pollfds);
583
584        if (s->pollfds[w->idx].revents != 0) {
585            w->callback(w, w->pollfd.fd, s->pollfds[w->idx].revents, w->userdata);
586            goto finish;
587        }
588    }
589
590finish:
591
592    s->state = STATE_DISPATCHED;
593    return 0;
594}
595
596int avahi_simple_poll_iterate(AvahiSimplePoll *s, int timeout) {
597    int r;
598
599    if ((r = avahi_simple_poll_prepare(s, timeout)) != 0)
600        return r;
601
602    if ((r = avahi_simple_poll_run(s)) != 0)
603        return r;
604
605    if ((r = avahi_simple_poll_dispatch(s)) != 0)
606        return r;
607
608    return 0;
609}
610
611void avahi_simple_poll_quit(AvahiSimplePoll *s) {
612    assert(s);
613
614    s->quit = 1;
615
616    /* If there is a background thread running the poll() for us, tell it to exit the poll() */
617    avahi_simple_poll_wakeup(s);
618}
619
620const AvahiPoll* avahi_simple_poll_get(AvahiSimplePoll *s) {
621    assert(s);
622
623    return &s->api;
624}
625
626static int system_poll(struct pollfd *ufds, unsigned int nfds, int timeout, AVAHI_GCC_UNUSED void *userdata) {
627    return poll(ufds, nfds, timeout);
628}
629
630void avahi_simple_poll_set_func(AvahiSimplePoll *s, AvahiPollFunc func, void *userdata) {
631    assert(s);
632
633    s->poll_func = func ? func : system_poll;
634    s->poll_func_userdata = func ? userdata : NULL;
635
636    /* If there is a background thread running the poll() for us, tell it to exit the poll() */
637    avahi_simple_poll_wakeup(s);
638}
639
640int avahi_simple_poll_loop(AvahiSimplePoll *s) {
641    int r;
642
643    assert(s);
644
645    for (;;)
646        if ((r = avahi_simple_poll_iterate(s, -1)) != 0)
647            if (r >= 0 || errno != EINTR)
648                return r;
649}
650