jshn: properly support JSON "null" type
[project/libubox.git] / uloop.c
1 /*
2 * uloop - event loop implementation
3 *
4 * Copyright (C) 2010-2016 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 struct uloop_fd_event {
42 struct uloop_fd *fd;
43 unsigned int events;
44 };
45
46 struct uloop_fd_stack {
47 struct uloop_fd_stack *next;
48 struct uloop_fd *fd;
49 unsigned int events;
50 };
51
52 static struct uloop_fd_stack *fd_stack = NULL;
53
54 #define ULOOP_MAX_EVENTS 10
55
56 static struct list_head timeouts = LIST_HEAD_INIT(timeouts);
57 static struct list_head processes = LIST_HEAD_INIT(processes);
58
59 static int poll_fd = -1;
60 bool uloop_cancelled = false;
61 bool uloop_handle_sigchld = true;
62 static int uloop_status = 0;
63 static bool do_sigchld = false;
64
65 static struct uloop_fd_event cur_fds[ULOOP_MAX_EVENTS];
66 static int cur_fd, cur_nfds;
67 static int uloop_run_depth = 0;
68
69 int uloop_fd_add(struct uloop_fd *sock, unsigned int flags);
70
71 #ifdef USE_KQUEUE
72 #include "uloop-kqueue.c"
73 #endif
74
75 #ifdef USE_EPOLL
76 #include "uloop-epoll.c"
77 #endif
78
79 static void waker_consume(struct uloop_fd *fd, unsigned int events)
80 {
81 char buf[4];
82
83 while (read(fd->fd, buf, 4) > 0)
84 ;
85 }
86
87 static int waker_pipe = -1;
88 static struct uloop_fd waker_fd = {
89 .fd = -1,
90 .cb = waker_consume,
91 };
92
93 static void waker_init_fd(int fd)
94 {
95 fcntl(fd, F_SETFD, fcntl(fd, F_GETFD) | FD_CLOEXEC);
96 fcntl(fd, F_SETFL, fcntl(fd, F_GETFL) | O_NONBLOCK);
97 }
98
99 static int waker_init(void)
100 {
101 int fds[2];
102
103 if (waker_pipe >= 0)
104 return 0;
105
106 if (pipe(fds) < 0)
107 return -1;
108
109 waker_init_fd(fds[0]);
110 waker_init_fd(fds[1]);
111 waker_pipe = fds[1];
112
113 waker_fd.fd = fds[0];
114 waker_fd.cb = waker_consume;
115 uloop_fd_add(&waker_fd, ULOOP_READ);
116
117 return 0;
118 }
119
120 static void uloop_setup_signals(bool add);
121
122 int uloop_init(void)
123 {
124 if (uloop_init_pollfd() < 0)
125 return -1;
126
127 if (waker_init() < 0) {
128 uloop_done();
129 return -1;
130 }
131
132 uloop_setup_signals(true);
133
134 return 0;
135 }
136
137 static bool uloop_fd_stack_event(struct uloop_fd *fd, int events)
138 {
139 struct uloop_fd_stack *cur;
140
141 /*
142 * Do not buffer events for level-triggered fds, they will keep firing.
143 * Caller needs to take care of recursion issues.
144 */
145 if (!(fd->flags & ULOOP_EDGE_TRIGGER))
146 return false;
147
148 for (cur = fd_stack; cur; cur = cur->next) {
149 if (cur->fd != fd)
150 continue;
151
152 if (events < 0)
153 cur->fd = NULL;
154 else
155 cur->events |= events | ULOOP_EVENT_BUFFERED;
156
157 return true;
158 }
159
160 return false;
161 }
162
163 static void uloop_run_events(int timeout)
164 {
165 struct uloop_fd_event *cur;
166 struct uloop_fd *fd;
167
168 if (!cur_nfds) {
169 cur_fd = 0;
170 cur_nfds = uloop_fetch_events(timeout);
171 if (cur_nfds < 0)
172 cur_nfds = 0;
173 }
174
175 while (cur_nfds > 0) {
176 struct uloop_fd_stack stack_cur;
177 unsigned int events;
178
179 cur = &cur_fds[cur_fd++];
180 cur_nfds--;
181
182 fd = cur->fd;
183 events = cur->events;
184 if (!fd)
185 continue;
186
187 if (!fd->cb)
188 continue;
189
190 if (uloop_fd_stack_event(fd, cur->events))
191 continue;
192
193 stack_cur.next = fd_stack;
194 stack_cur.fd = fd;
195 fd_stack = &stack_cur;
196 do {
197 stack_cur.events = 0;
198 fd->cb(fd, events);
199 events = stack_cur.events & ULOOP_EVENT_MASK;
200 } while (stack_cur.fd && events);
201 fd_stack = stack_cur.next;
202
203 return;
204 }
205 }
206
207 int uloop_fd_add(struct uloop_fd *sock, unsigned int flags)
208 {
209 unsigned int fl;
210 int ret;
211
212 if (!(flags & (ULOOP_READ | ULOOP_WRITE)))
213 return uloop_fd_delete(sock);
214
215 if (!sock->registered && !(flags & ULOOP_BLOCKING)) {
216 fl = fcntl(sock->fd, F_GETFL, 0);
217 fl |= O_NONBLOCK;
218 fcntl(sock->fd, F_SETFL, fl);
219 }
220
221 ret = register_poll(sock, flags);
222 if (ret < 0)
223 goto out;
224
225 sock->registered = true;
226 sock->eof = false;
227 sock->error = false;
228
229 out:
230 return ret;
231 }
232
233 int uloop_fd_delete(struct uloop_fd *fd)
234 {
235 int i;
236
237 for (i = 0; i < cur_nfds; i++) {
238 if (cur_fds[cur_fd + i].fd != fd)
239 continue;
240
241 cur_fds[cur_fd + i].fd = NULL;
242 }
243
244 if (!fd->registered)
245 return 0;
246
247 fd->registered = false;
248 uloop_fd_stack_event(fd, -1);
249 return __uloop_fd_delete(fd);
250 }
251
252 static int tv_diff(struct timeval *t1, struct timeval *t2)
253 {
254 return
255 (t1->tv_sec - t2->tv_sec) * 1000 +
256 (t1->tv_usec - t2->tv_usec) / 1000;
257 }
258
259 int uloop_timeout_add(struct uloop_timeout *timeout)
260 {
261 struct uloop_timeout *tmp;
262 struct list_head *h = &timeouts;
263
264 if (timeout->pending)
265 return -1;
266
267 list_for_each_entry(tmp, &timeouts, list) {
268 if (tv_diff(&tmp->time, &timeout->time) > 0) {
269 h = &tmp->list;
270 break;
271 }
272 }
273
274 list_add_tail(&timeout->list, h);
275 timeout->pending = true;
276
277 return 0;
278 }
279
280 static void uloop_gettime(struct timeval *tv)
281 {
282 struct timespec ts;
283
284 clock_gettime(CLOCK_MONOTONIC, &ts);
285 tv->tv_sec = ts.tv_sec;
286 tv->tv_usec = ts.tv_nsec / 1000;
287 }
288
289 int uloop_timeout_set(struct uloop_timeout *timeout, int msecs)
290 {
291 struct timeval *time = &timeout->time;
292
293 if (timeout->pending)
294 uloop_timeout_cancel(timeout);
295
296 uloop_gettime(time);
297
298 time->tv_sec += msecs / 1000;
299 time->tv_usec += (msecs % 1000) * 1000;
300
301 if (time->tv_usec > 1000000) {
302 time->tv_sec++;
303 time->tv_usec -= 1000000;
304 }
305
306 return uloop_timeout_add(timeout);
307 }
308
309 int uloop_timeout_cancel(struct uloop_timeout *timeout)
310 {
311 if (!timeout->pending)
312 return -1;
313
314 list_del(&timeout->list);
315 timeout->pending = false;
316
317 return 0;
318 }
319
320 int uloop_timeout_remaining(struct uloop_timeout *timeout)
321 {
322 struct timeval now;
323
324 if (!timeout->pending)
325 return -1;
326
327 uloop_gettime(&now);
328
329 return tv_diff(&timeout->time, &now);
330 }
331
332 int uloop_process_add(struct uloop_process *p)
333 {
334 struct uloop_process *tmp;
335 struct list_head *h = &processes;
336
337 if (p->pending)
338 return -1;
339
340 list_for_each_entry(tmp, &processes, list) {
341 if (tmp->pid > p->pid) {
342 h = &tmp->list;
343 break;
344 }
345 }
346
347 list_add_tail(&p->list, h);
348 p->pending = true;
349
350 return 0;
351 }
352
353 int uloop_process_delete(struct uloop_process *p)
354 {
355 if (!p->pending)
356 return -1;
357
358 list_del(&p->list);
359 p->pending = false;
360
361 return 0;
362 }
363
364 static void uloop_handle_processes(void)
365 {
366 struct uloop_process *p, *tmp;
367 pid_t pid;
368 int ret;
369
370 do_sigchld = false;
371
372 while (1) {
373 pid = waitpid(-1, &ret, WNOHANG);
374 if (pid < 0 && errno == EINTR)
375 continue;
376
377 if (pid <= 0)
378 return;
379
380 list_for_each_entry_safe(p, tmp, &processes, list) {
381 if (p->pid < pid)
382 continue;
383
384 if (p->pid > pid)
385 break;
386
387 uloop_process_delete(p);
388 p->cb(p, ret);
389 }
390 }
391
392 }
393
394 static void uloop_signal_wake(void)
395 {
396 do {
397 if (write(waker_pipe, "w", 1) < 0) {
398 if (errno == EINTR)
399 continue;
400 }
401 break;
402 } while (1);
403 }
404
405 static void uloop_handle_sigint(int signo)
406 {
407 uloop_status = signo;
408 uloop_cancelled = true;
409 uloop_signal_wake();
410 }
411
412 static void uloop_sigchld(int signo)
413 {
414 do_sigchld = true;
415 uloop_signal_wake();
416 }
417
418 static void uloop_install_handler(int signum, void (*handler)(int), struct sigaction* old, bool add)
419 {
420 struct sigaction s;
421 struct sigaction *act;
422
423 act = NULL;
424 sigaction(signum, NULL, &s);
425
426 if (add) {
427 if (s.sa_handler == SIG_DFL) { /* Do not override existing custom signal handlers */
428 memcpy(old, &s, sizeof(struct sigaction));
429 s.sa_handler = handler;
430 s.sa_flags = 0;
431 act = &s;
432 }
433 }
434 else if (s.sa_handler == handler) { /* Do not restore if someone modified our handler */
435 act = old;
436 }
437
438 if (act != NULL)
439 sigaction(signum, act, NULL);
440 }
441
442 static void uloop_ignore_signal(int signum, bool ignore)
443 {
444 struct sigaction s;
445 void *new_handler = NULL;
446
447 sigaction(signum, NULL, &s);
448
449 if (ignore) {
450 if (s.sa_handler == SIG_DFL) /* Ignore only if there isn't any custom handler */
451 new_handler = SIG_IGN;
452 } else {
453 if (s.sa_handler == SIG_IGN) /* Restore only if noone modified our SIG_IGN */
454 new_handler = SIG_DFL;
455 }
456
457 if (new_handler) {
458 s.sa_handler = new_handler;
459 s.sa_flags = 0;
460 sigaction(signum, &s, NULL);
461 }
462 }
463
464 static void uloop_setup_signals(bool add)
465 {
466 static struct sigaction old_sigint, old_sigchld, old_sigterm;
467
468 uloop_install_handler(SIGINT, uloop_handle_sigint, &old_sigint, add);
469 uloop_install_handler(SIGTERM, uloop_handle_sigint, &old_sigterm, add);
470
471 if (uloop_handle_sigchld)
472 uloop_install_handler(SIGCHLD, uloop_sigchld, &old_sigchld, add);
473
474 uloop_ignore_signal(SIGPIPE, add);
475 }
476
477 static int uloop_get_next_timeout(struct timeval *tv)
478 {
479 struct uloop_timeout *timeout;
480 int diff;
481
482 if (list_empty(&timeouts))
483 return -1;
484
485 timeout = list_first_entry(&timeouts, struct uloop_timeout, list);
486 diff = tv_diff(&timeout->time, tv);
487 if (diff < 0)
488 return 0;
489
490 return diff;
491 }
492
493 static void uloop_process_timeouts(struct timeval *tv)
494 {
495 struct uloop_timeout *t;
496
497 while (!list_empty(&timeouts)) {
498 t = list_first_entry(&timeouts, struct uloop_timeout, list);
499
500 if (tv_diff(&t->time, tv) > 0)
501 break;
502
503 uloop_timeout_cancel(t);
504 if (t->cb)
505 t->cb(t);
506 }
507 }
508
509 static void uloop_clear_timeouts(void)
510 {
511 struct uloop_timeout *t, *tmp;
512
513 list_for_each_entry_safe(t, tmp, &timeouts, list)
514 uloop_timeout_cancel(t);
515 }
516
517 static void uloop_clear_processes(void)
518 {
519 struct uloop_process *p, *tmp;
520
521 list_for_each_entry_safe(p, tmp, &processes, list)
522 uloop_process_delete(p);
523 }
524
525 bool uloop_cancelling(void)
526 {
527 return uloop_run_depth > 0 && uloop_cancelled;
528 }
529
530 int uloop_run_timeout(int timeout)
531 {
532 int next_time = 0;
533 struct timeval tv;
534
535 uloop_run_depth++;
536
537 uloop_status = 0;
538 uloop_cancelled = false;
539 while (!uloop_cancelled)
540 {
541 uloop_gettime(&tv);
542 uloop_process_timeouts(&tv);
543
544 if (do_sigchld)
545 uloop_handle_processes();
546
547 if (uloop_cancelled)
548 break;
549
550 uloop_gettime(&tv);
551
552 next_time = uloop_get_next_timeout(&tv);
553 if (timeout >= 0 && timeout < next_time)
554 next_time = timeout;
555 uloop_run_events(next_time);
556 }
557
558 --uloop_run_depth;
559
560 return uloop_status;
561 }
562
563 void uloop_done(void)
564 {
565 uloop_setup_signals(false);
566
567 if (poll_fd >= 0) {
568 close(poll_fd);
569 poll_fd = -1;
570 }
571
572 if (waker_pipe >= 0) {
573 uloop_fd_delete(&waker_fd);
574 close(waker_pipe);
575 close(waker_fd.fd);
576 waker_pipe = -1;
577 }
578
579 uloop_clear_timeouts();
580 uloop_clear_processes();
581 }