safe_list: add a new linked list variant
[project/libubox.git] / uloop.c
1 /*
2  * uloop - event loop implementation
3  *
4  * Copyright (C) 2010-2013 Felix Fietkau <nbd@openwrt.org>
5  *
6  * Permission to use, copy, modify, and/or distribute this software for any
7  * purpose with or without fee is hereby granted, provided that the above
8  * copyright notice and this permission notice appear in all copies.
9  *
10  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
11  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
12  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
13  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
14  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
15  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
16  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
17  */
18 #include <sys/time.h>
19 #include <sys/types.h>
20
21 #include <unistd.h>
22 #include <stdio.h>
23 #include <stdlib.h>
24 #include <errno.h>
25 #include <poll.h>
26 #include <string.h>
27 #include <fcntl.h>
28 #include <stdbool.h>
29
30 #include "uloop.h"
31 #include "utils.h"
32
33 #ifdef USE_KQUEUE
34 #include <sys/event.h>
35 #endif
36 #ifdef USE_EPOLL
37 #include <sys/epoll.h>
38 #endif
39 #include <sys/wait.h>
40
41 #define ULOOP_MAX_EVENTS 10
42
43 static struct list_head timeouts = LIST_HEAD_INIT(timeouts);
44 static struct list_head processes = LIST_HEAD_INIT(processes);
45
46 static int poll_fd = -1;
47 bool uloop_cancelled = false;
48 bool uloop_handle_sigchld = true;
49 static bool do_sigchld = false;
50 static int cur_fd, cur_nfds;
51
52 #ifdef USE_KQUEUE
53
54 int uloop_init(void)
55 {
56         struct timespec timeout = { 0, 0 };
57         struct kevent ev = {};
58
59         if (poll_fd >= 0)
60                 return 0;
61
62         poll_fd = kqueue();
63         if (poll_fd < 0)
64                 return -1;
65
66         EV_SET(&ev, SIGCHLD, EVFILT_SIGNAL, EV_ADD, 0, 0, 0);
67         kevent(poll_fd, &ev, 1, NULL, 0, &timeout);
68
69         return 0;
70 }
71
72
73 static uint16_t get_flags(unsigned int flags, unsigned int mask)
74 {
75         uint16_t kflags = 0;
76
77         if (!(flags & mask))
78                 return EV_DELETE;
79
80         kflags = EV_ADD;
81         if (flags & ULOOP_EDGE_TRIGGER)
82                 kflags |= EV_CLEAR;
83
84         return kflags;
85 }
86
87 static struct kevent events[ULOOP_MAX_EVENTS];
88
89 static int register_kevent(struct uloop_fd *fd, unsigned int flags)
90 {
91         struct timespec timeout = { 0, 0 };
92         struct kevent ev[2];
93         int nev = 0;
94         unsigned int fl = 0;
95         unsigned int changed;
96         uint16_t kflags;
97
98         if (flags & ULOOP_EDGE_DEFER)
99                 flags &= ~ULOOP_EDGE_TRIGGER;
100
101         changed = flags ^ fd->flags;
102         if (changed & ULOOP_EDGE_TRIGGER)
103                 changed |= flags;
104
105         if (changed & ULOOP_READ) {
106                 kflags = get_flags(flags, ULOOP_READ);
107                 EV_SET(&ev[nev++], fd->fd, EVFILT_READ, kflags, 0, 0, fd);
108         }
109
110         if (changed & ULOOP_WRITE) {
111                 kflags = get_flags(flags, ULOOP_WRITE);
112                 EV_SET(&ev[nev++], fd->fd, EVFILT_WRITE, kflags, 0, 0, fd);
113         }
114
115         if (!flags)
116                 fl |= EV_DELETE;
117
118         fd->flags = flags;
119         if (kevent(poll_fd, ev, nev, NULL, fl, &timeout) == -1)
120                 return -1;
121
122         return 0;
123 }
124
125 static int register_poll(struct uloop_fd *fd, unsigned int flags)
126 {
127         if (flags & ULOOP_EDGE_TRIGGER)
128                 flags |= ULOOP_EDGE_DEFER;
129         else
130                 flags &= ~ULOOP_EDGE_DEFER;
131
132         return register_kevent(fd, flags);
133 }
134
135 int uloop_fd_delete(struct uloop_fd *sock)
136 {
137         int i;
138
139         for (i = cur_fd + 1; i < cur_nfds; i++) {
140                 if (events[i].udata != sock)
141                         continue;
142
143                 events[i].udata = NULL;
144         }
145
146         sock->registered = false;
147         return register_poll(sock, 0);
148 }
149
150 static void uloop_run_events(int timeout)
151 {
152         struct timespec ts;
153         int nfds, n;
154
155         if (timeout >= 0) {
156                 ts.tv_sec = timeout / 1000;
157                 ts.tv_nsec = (timeout % 1000) * 1000000;
158         }
159
160         nfds = kevent(poll_fd, NULL, 0, events, ARRAY_SIZE(events), timeout >= 0 ? &ts : NULL);
161         for(n = 0; n < nfds; ++n)
162         {
163                 struct uloop_fd *u = events[n].udata;
164                 unsigned int ev = 0;
165
166                 if (!u)
167                         continue;
168
169                 if (events[n].flags & EV_ERROR) {
170                         u->error = true;
171                         uloop_fd_delete(u);
172                 }
173
174                 if(events[n].filter == EVFILT_READ)
175                         ev |= ULOOP_READ;
176                 else if (events[n].filter == EVFILT_WRITE)
177                         ev |= ULOOP_WRITE;
178
179                 if (events[n].flags & EV_EOF)
180                         u->eof = true;
181                 else if (!ev)
182                         continue;
183
184                 if (u->cb) {
185                         cur_fd = n;
186                         cur_nfds = nfds;
187                         u->cb(u, ev);
188                         if (u->flags & ULOOP_EDGE_DEFER) {
189                                 u->flags &= ~ULOOP_EDGE_DEFER;
190                                 register_kevent(u, u->flags);
191                         }
192                 }
193         }
194         cur_nfds = 0;
195 }
196
197 #endif
198
199 #ifdef USE_EPOLL
200
201 /**
202  * FIXME: uClibc < 0.9.30.3 does not define EPOLLRDHUP for Linux >= 2.6.17
203  */
204 #ifndef EPOLLRDHUP
205 #define EPOLLRDHUP 0x2000
206 #endif
207
208 int uloop_init(void)
209 {
210         if (poll_fd >= 0)
211                 return 0;
212
213         poll_fd = epoll_create(32);
214         if (poll_fd < 0)
215                 return -1;
216
217         fcntl(poll_fd, F_SETFD, fcntl(poll_fd, F_GETFD) | FD_CLOEXEC);
218         return 0;
219 }
220
221 static int register_poll(struct uloop_fd *fd, unsigned int flags)
222 {
223         struct epoll_event ev;
224         int op = fd->registered ? EPOLL_CTL_MOD : EPOLL_CTL_ADD;
225
226         memset(&ev, 0, sizeof(struct epoll_event));
227
228         if (flags & ULOOP_READ)
229                 ev.events |= EPOLLIN | EPOLLRDHUP;
230
231         if (flags & ULOOP_WRITE)
232                 ev.events |= EPOLLOUT;
233
234         if (flags & ULOOP_EDGE_TRIGGER)
235                 ev.events |= EPOLLET;
236
237         ev.data.fd = fd->fd;
238         ev.data.ptr = fd;
239
240         return epoll_ctl(poll_fd, op, fd->fd, &ev);
241 }
242
243 static struct epoll_event events[ULOOP_MAX_EVENTS];
244
245 int uloop_fd_delete(struct uloop_fd *sock)
246 {
247         int i;
248
249         if (!sock->registered)
250                 return 0;
251
252         for (i = cur_fd + 1; i < cur_nfds; i++) {
253                 if (events[i].data.ptr != sock)
254                         continue;
255
256                 events[i].data.ptr = NULL;
257         }
258         sock->registered = false;
259         return epoll_ctl(poll_fd, EPOLL_CTL_DEL, sock->fd, 0);
260 }
261
262 static void uloop_run_events(int timeout)
263 {
264         int n, nfds;
265
266         nfds = epoll_wait(poll_fd, events, ARRAY_SIZE(events), timeout);
267         for(n = 0; n < nfds; ++n)
268         {
269                 struct uloop_fd *u = events[n].data.ptr;
270                 unsigned int ev = 0;
271
272                 if (!u)
273                         continue;
274
275                 if(events[n].events & (EPOLLERR|EPOLLHUP)) {
276                         u->error = true;
277                         uloop_fd_delete(u);
278                 }
279
280                 if(!(events[n].events & (EPOLLRDHUP|EPOLLIN|EPOLLOUT|EPOLLERR|EPOLLHUP)))
281                         continue;
282
283                 if(events[n].events & EPOLLRDHUP)
284                         u->eof = true;
285
286                 if(events[n].events & EPOLLIN)
287                         ev |= ULOOP_READ;
288
289                 if(events[n].events & EPOLLOUT)
290                         ev |= ULOOP_WRITE;
291
292                 if(u->cb) {
293                         cur_fd = n;
294                         cur_nfds = nfds;
295                         u->cb(u, ev);
296                 }
297         }
298         cur_nfds = 0;
299 }
300
301 #endif
302
303 int uloop_fd_add(struct uloop_fd *sock, unsigned int flags)
304 {
305         unsigned int fl;
306         int ret;
307
308         if (!(flags & (ULOOP_READ | ULOOP_WRITE)))
309                 return uloop_fd_delete(sock);
310
311         if (!sock->registered && !(flags & ULOOP_BLOCKING)) {
312                 fl = fcntl(sock->fd, F_GETFL, 0);
313                 fl |= O_NONBLOCK;
314                 fcntl(sock->fd, F_SETFL, fl);
315         }
316
317         ret = register_poll(sock, flags);
318         if (ret < 0)
319                 goto out;
320
321         sock->registered = true;
322         sock->eof = false;
323
324 out:
325         return ret;
326 }
327
328 static int tv_diff(struct timeval *t1, struct timeval *t2)
329 {
330         return
331                 (t1->tv_sec - t2->tv_sec) * 1000 +
332                 (t1->tv_usec - t2->tv_usec) / 1000;
333 }
334
335 int uloop_timeout_add(struct uloop_timeout *timeout)
336 {
337         struct uloop_timeout *tmp;
338         struct list_head *h = &timeouts;
339
340         if (timeout->pending)
341                 return -1;
342
343         list_for_each_entry(tmp, &timeouts, list) {
344                 if (tv_diff(&tmp->time, &timeout->time) > 0) {
345                         h = &tmp->list;
346                         break;
347                 }
348         }
349
350         list_add_tail(&timeout->list, h);
351         timeout->pending = true;
352
353         return 0;
354 }
355
356 static void uloop_gettime(struct timeval *tv)
357 {
358         struct timespec ts;
359
360         clock_gettime(CLOCK_MONOTONIC, &ts);
361         tv->tv_sec = ts.tv_sec;
362         tv->tv_usec = ts.tv_nsec / 1000;
363 }
364
365 int uloop_timeout_set(struct uloop_timeout *timeout, int msecs)
366 {
367         struct timeval *time = &timeout->time;
368
369         if (timeout->pending)
370                 uloop_timeout_cancel(timeout);
371
372         uloop_gettime(&timeout->time);
373
374         time->tv_sec += msecs / 1000;
375         time->tv_usec += (msecs % 1000) * 1000;
376
377         if (time->tv_usec > 1000000) {
378                 time->tv_sec++;
379                 time->tv_usec %= 1000000;
380         }
381
382         return uloop_timeout_add(timeout);
383 }
384
385 int uloop_timeout_cancel(struct uloop_timeout *timeout)
386 {
387         if (!timeout->pending)
388                 return -1;
389
390         list_del(&timeout->list);
391         timeout->pending = false;
392
393         return 0;
394 }
395
396 int uloop_timeout_remaining(struct uloop_timeout *timeout)
397 {
398         struct timeval now;
399
400         if (!timeout->pending)
401                 return -1;
402
403         uloop_gettime(&now);
404
405         return tv_diff(&timeout->time, &now);
406 }
407
408 int uloop_process_add(struct uloop_process *p)
409 {
410         struct uloop_process *tmp;
411         struct list_head *h = &processes;
412
413         if (p->pending)
414                 return -1;
415
416         list_for_each_entry(tmp, &processes, list) {
417                 if (tmp->pid > p->pid) {
418                         h = &tmp->list;
419                         break;
420                 }
421         }
422
423         list_add_tail(&p->list, h);
424         p->pending = true;
425
426         return 0;
427 }
428
429 int uloop_process_delete(struct uloop_process *p)
430 {
431         if (!p->pending)
432                 return -1;
433
434         list_del(&p->list);
435         p->pending = false;
436
437         return 0;
438 }
439
440 static void uloop_handle_processes(void)
441 {
442         struct uloop_process *p, *tmp;
443         pid_t pid;
444         int ret;
445
446         do_sigchld = false;
447
448         while (1) {
449                 pid = waitpid(-1, &ret, WNOHANG);
450                 if (pid <= 0)
451                         return;
452
453                 list_for_each_entry_safe(p, tmp, &processes, list) {
454                         if (p->pid < pid)
455                                 continue;
456
457                         if (p->pid > pid)
458                                 break;
459
460                         uloop_process_delete(p);
461                         p->cb(p, ret);
462                 }
463         }
464
465 }
466
467 static void uloop_handle_sigint(int signo)
468 {
469         uloop_cancelled = true;
470 }
471
472 static void uloop_sigchld(int signo)
473 {
474         do_sigchld = true;
475 }
476
477 static void uloop_setup_signals(void)
478 {
479         struct sigaction s;
480
481         memset(&s, 0, sizeof(struct sigaction));
482         s.sa_handler = uloop_handle_sigint;
483         s.sa_flags = 0;
484         sigaction(SIGINT, &s, NULL);
485
486         if (uloop_handle_sigchld) {
487                 s.sa_handler = uloop_sigchld;
488                 sigaction(SIGCHLD, &s, NULL);
489         }
490 }
491
492 static int uloop_get_next_timeout(struct timeval *tv)
493 {
494         struct uloop_timeout *timeout;
495         int diff;
496
497         if (list_empty(&timeouts))
498                 return -1;
499
500         timeout = list_first_entry(&timeouts, struct uloop_timeout, list);
501         diff = tv_diff(&timeout->time, tv);
502         if (diff < 0)
503                 return 0;
504
505         return diff;
506 }
507
508 static void uloop_process_timeouts(struct timeval *tv)
509 {
510         struct uloop_timeout *t;
511
512         while (!list_empty(&timeouts)) {
513                 t = list_first_entry(&timeouts, struct uloop_timeout, list);
514
515                 if (tv_diff(&t->time, tv) > 0)
516                         break;
517
518                 uloop_timeout_cancel(t);
519                 if (t->cb)
520                         t->cb(t);
521         }
522 }
523
524 static void uloop_clear_timeouts(void)
525 {
526         struct uloop_timeout *t, *tmp;
527
528         list_for_each_entry_safe(t, tmp, &timeouts, list)
529                 uloop_timeout_cancel(t);
530 }
531
532 static void uloop_clear_processes(void)
533 {
534         struct uloop_process *p, *tmp;
535
536         list_for_each_entry_safe(p, tmp, &processes, list)
537                 uloop_process_delete(p);
538 }
539
540 void uloop_run(void)
541 {
542         struct timeval tv;
543
544         uloop_setup_signals();
545         while(!uloop_cancelled)
546         {
547                 uloop_gettime(&tv);
548                 uloop_process_timeouts(&tv);
549                 if (uloop_cancelled)
550                         break;
551
552                 if (do_sigchld)
553                         uloop_handle_processes();
554                 uloop_run_events(uloop_get_next_timeout(&tv));
555         }
556 }
557
558 void uloop_done(void)
559 {
560         if (poll_fd < 0)
561                 return;
562
563         close(poll_fd);
564         poll_fd = -1;
565
566         uloop_clear_timeouts();
567         uloop_clear_processes();
568 }