summaryrefslogtreecommitdiff
path: root/lib/tevent/tevent.c
blob: aa758de64037b35b2cd039119feaf869b08c63e5 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
/* 
   Unix SMB/CIFS implementation.
   main select loop and event handling
   Copyright (C) Andrew Tridgell 2003
   Copyright (C) Stefan Metzmacher 2009

     ** NOTE! The following LGPL license applies to the tevent
     ** library. This does NOT imply that all of Samba is released
     ** under the LGPL

   This library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 3 of the License, or (at your option) any later version.

   This library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with this library; if not, see <http://www.gnu.org/licenses/>.
*/

/*
  PLEASE READ THIS BEFORE MODIFYING!

  This module is a general abstraction for the main select loop and
  event handling. Do not ever put any localised hacks in here, instead
  register one of the possible event types and implement that event
  somewhere else.

  There are 2 types of event handling that are handled in this module:

  1) a file descriptor becoming readable or writeable. This is mostly
     used for network sockets, but can be used for any type of file
     descriptor. You may only register one handler for each file
     descriptor/io combination or you will get unpredictable results
     (this means that you can have a handler for read events, and a
     separate handler for write events, but not two handlers that are
     both handling read events)

  2) a timed event. You can register an event that happens at a
     specific time.  You can register as many of these as you
     like. They are single shot - add a new timed event in the event
     handler to get another event.

  To setup a set of events you first need to create a event_context
  structure using the function tevent_context_init(); This returns a
  'struct tevent_context' that you use in all subsequent calls.

  After that you can add/remove events that you are interested in
  using tevent_add_*() and talloc_free()

  Finally, you call tevent_loop_wait_once() to block waiting for one of the
  events to occor or tevent_loop_wait() which will loop
  forever.

*/
#include "replace.h"
#include "system/filesys.h"
#define TEVENT_DEPRECATED 1
#include "tevent.h"
#include "tevent_internal.h"
#include "tevent_util.h"

struct tevent_ops_list {
	struct tevent_ops_list *next, *prev;
	const char *name;
	const struct tevent_ops *ops;
};

/* list of registered event backends */
static struct tevent_ops_list *tevent_backends = NULL;
static char *tevent_default_backend = NULL;

/*
  register an events backend
*/
bool tevent_register_backend(const char *name, const struct tevent_ops *ops)
{
	struct tevent_ops_list *e;

	for (e = tevent_backends; e != NULL; e = e->next) {
		if (0 == strcmp(e->name, name)) {
			/* already registered, skip it */
			return true;
		}
	}

	e = talloc(NULL, struct tevent_ops_list);
	if (e == NULL) return false;

	e->name = name;
	e->ops = ops;
	DLIST_ADD(tevent_backends, e);

	return true;
}

/*
  set the default event backend
 */
void tevent_set_default_backend(const char *backend)
{
	talloc_free(tevent_default_backend);
	tevent_default_backend = talloc_strdup(NULL, backend);
}

/*
  initialise backends if not already done
*/
static void tevent_backend_init(void)
{
	static bool done;

	if (done) {
		return;
	}

	done = true;

	tevent_select_init();
	tevent_poll_init();
	tevent_poll_mt_init();
#ifdef HAVE_EPOLL
	tevent_epoll_init();
#endif
	tevent_standard_init();
}

_PRIVATE_ const struct tevent_ops *tevent_find_ops_byname(const char *name)
{
	struct tevent_ops_list *e;

	tevent_backend_init();

	if (name == NULL) {
		name = tevent_default_backend;
	}
	if (name == NULL) {
		name = "standard";
	}

	for (e = tevent_backends; e != NULL; e = e->next) {
		if (0 == strcmp(e->name, name)) {
			return e->ops;
		}
	}

	return NULL;
}

/*
  list available backends
*/
const char **tevent_backend_list(TALLOC_CTX *mem_ctx)
{
	const char **list = NULL;
	struct tevent_ops_list *e;

	tevent_backend_init();

	for (e=tevent_backends;e;e=e->next) {
		list = ev_str_list_add(list, e->name);
	}

	talloc_steal(mem_ctx, list);

	return list;
}

int tevent_common_context_destructor(struct tevent_context *ev)
{
	struct tevent_fd *fd, *fn;
	struct tevent_timer *te, *tn;
	struct tevent_immediate *ie, *in;
	struct tevent_signal *se, *sn;

	if (ev->pipe_fde) {
		talloc_free(ev->pipe_fde);
		close(ev->pipe_fds[0]);
		close(ev->pipe_fds[1]);
		ev->pipe_fde = NULL;
	}

	for (fd = ev->fd_events; fd; fd = fn) {
		fn = fd->next;
		fd->event_ctx = NULL;
		DLIST_REMOVE(ev->fd_events, fd);
	}

	for (te = ev->timer_events; te; te = tn) {
		tn = te->next;
		te->event_ctx = NULL;
		DLIST_REMOVE(ev->timer_events, te);
	}

	for (ie = ev->immediate_events; ie; ie = in) {
		in = ie->next;
		ie->event_ctx = NULL;
		ie->cancel_fn = NULL;
		DLIST_REMOVE(ev->immediate_events, ie);
	}

	for (se = ev->signal_events; se; se = sn) {
		sn = se->next;
		se->event_ctx = NULL;
		DLIST_REMOVE(ev->signal_events, se);
		/*
		 * This is important, Otherwise signals
		 * are handled twice in child. eg, SIGHUP.
		 * one added in parent, and another one in
		 * the child. -- BoYang
		 */
		tevent_cleanup_pending_signal_handlers(se);
	}

	/* removing nesting hook or we get an abort when nesting is
	 * not allowed. -- SSS
	 * Note that we need to leave the allowed flag at its current
	 * value, otherwise the use in tevent_re_initialise() will
	 * leave the event context with allowed forced to false, which
	 * will break users that expect nesting to be allowed
	 */
	ev->nesting.level = 0;
	ev->nesting.hook_fn = NULL;
	ev->nesting.hook_private = NULL;

	return 0;
}

/*
  create a event_context structure for a specific implemementation.
  This must be the first events call, and all subsequent calls pass
  this event_context as the first element. Event handlers also
  receive this as their first argument.

  This function is for allowing third-party-applications to hook in gluecode
  to their own event loop code, so that they can make async usage of our client libs

  NOTE: use tevent_context_init() inside of samba!
*/
struct tevent_context *tevent_context_init_ops(TALLOC_CTX *mem_ctx,
					       const struct tevent_ops *ops,
					       void *additional_data)
{
	struct tevent_context *ev;
	int ret;

	ev = talloc_zero(mem_ctx, struct tevent_context);
	if (!ev) return NULL;

	talloc_set_destructor(ev, tevent_common_context_destructor);

	ev->ops = ops;
	ev->additional_data = additional_data;

	ret = ev->ops->context_init(ev);
	if (ret != 0) {
		talloc_free(ev);
		return NULL;
	}

	return ev;
}

/*
  create a event_context structure. This must be the first events
  call, and all subsequent calls pass this event_context as the first
  element. Event handlers also receive this as their first argument.
*/
struct tevent_context *tevent_context_init_byname(TALLOC_CTX *mem_ctx,
						  const char *name)
{
	struct tevent_ops *ops;

	ops = tevent_find_ops_byname(name);
	if (ops == NULL) {
		return NULL;
	}

	return tevent_context_init_ops(mem_ctx, ops, NULL);
}


/*
  create a event_context structure. This must be the first events
  call, and all subsequent calls pass this event_context as the first
  element. Event handlers also receive this as their first argument.
*/
struct tevent_context *tevent_context_init(TALLOC_CTX *mem_ctx)
{
	return tevent_context_init_byname(mem_ctx, NULL);
}

/*
  add a fd based event
  return NULL on failure (memory allocation error)
*/
struct tevent_fd *_tevent_add_fd(struct tevent_context *ev,
				 TALLOC_CTX *mem_ctx,
				 int fd,
				 uint16_t flags,
				 tevent_fd_handler_t handler,
				 void *private_data,
				 const char *handler_name,
				 const char *location)
{
	return ev->ops->add_fd(ev, mem_ctx, fd, flags, handler, private_data,
			       handler_name, location);
}

/*
  set a close function on the fd event
*/
void tevent_fd_set_close_fn(struct tevent_fd *fde,
			    tevent_fd_close_fn_t close_fn)
{
	if (!fde) return;
	if (!fde->event_ctx) return;
	fde->event_ctx->ops->set_fd_close_fn(fde, close_fn);
}

static void tevent_fd_auto_close_fn(struct tevent_context *ev,
				    struct tevent_fd *fde,
				    int fd,
				    void *private_data)
{
	close(fd);
}

void tevent_fd_set_auto_close(struct tevent_fd *fde)
{
	tevent_fd_set_close_fn(fde, tevent_fd_auto_close_fn);
}

/*
  return the fd event flags
*/
uint16_t tevent_fd_get_flags(struct tevent_fd *fde)
{
	if (!fde) return 0;
	if (!fde->event_ctx) return 0;
	return fde->event_ctx->ops->get_fd_flags(fde);
}

/*
  set the fd event flags
*/
void tevent_fd_set_flags(struct tevent_fd *fde, uint16_t flags)
{
	if (!fde) return;
	if (!fde->event_ctx) return;
	fde->event_ctx->ops->set_fd_flags(fde, flags);
}

bool tevent_signal_support(struct tevent_context *ev)
{
	if (ev->ops->add_signal) {
		return true;
	}
	return false;
}

static void (*tevent_abort_fn)(const char *reason);

void tevent_set_abort_fn(void (*abort_fn)(const char *reason))
{
	tevent_abort_fn = abort_fn;
}

static void tevent_abort(struct tevent_context *ev, const char *reason)
{
	tevent_debug(ev, TEVENT_DEBUG_FATAL,
		     "abort: %s\n", reason);

	if (!tevent_abort_fn) {
		abort();
	}

	tevent_abort_fn(reason);
}

/*
  add a timer event
  return NULL on failure
*/
struct tevent_timer *_tevent_add_timer(struct tevent_context *ev,
				       TALLOC_CTX *mem_ctx,
				       struct timeval next_event,
				       tevent_timer_handler_t handler,
				       void *private_data,
				       const char *handler_name,
				       const char *location)
{
	return ev->ops->add_timer(ev, mem_ctx, next_event, handler, private_data,
				  handler_name, location);
}

/*
  allocate an immediate event
  return NULL on failure (memory allocation error)
*/
struct tevent_immediate *_tevent_create_immediate(TALLOC_CTX *mem_ctx,
						  const char *location)
{
	struct tevent_immediate *im;

	im = talloc(mem_ctx, struct tevent_immediate);
	if (im == NULL) return NULL;

	im->prev		= NULL;
	im->next		= NULL;
	im->event_ctx		= NULL;
	im->create_location	= location;
	im->handler		= NULL;
	im->private_data	= NULL;
	im->handler_name	= NULL;
	im->schedule_location	= NULL;
	im->cancel_fn		= NULL;
	im->additional_data	= NULL;

	return im;
}

/*
  schedule an immediate event
*/
void _tevent_schedule_immediate(struct tevent_immediate *im,
				struct tevent_context *ev,
				tevent_immediate_handler_t handler,
				void *private_data,
				const char *handler_name,
				const char *location)
{
	ev->ops->schedule_immediate(im, ev, handler, private_data,
				    handler_name, location);
}

/*
  add a signal event

  sa_flags are flags to sigaction(2)

  return NULL on failure
*/
struct tevent_signal *_tevent_add_signal(struct tevent_context *ev,
					 TALLOC_CTX *mem_ctx,
					 int signum,
					 int sa_flags,
					 tevent_signal_handler_t handler,
					 void *private_data,
					 const char *handler_name,
					 const char *location)
{
	return ev->ops->add_signal(ev, mem_ctx, signum, sa_flags, handler, private_data,
				   handler_name, location);
}

void tevent_loop_allow_nesting(struct tevent_context *ev)
{
	ev->nesting.allowed = true;
}

void tevent_loop_set_nesting_hook(struct tevent_context *ev,
				  tevent_nesting_hook hook,
				  void *private_data)
{
	if (ev->nesting.hook_fn && 
	    (ev->nesting.hook_fn != hook ||
	     ev->nesting.hook_private != private_data)) {
		/* the way the nesting hook code is currently written
		   we cannot support two different nesting hooks at the
		   same time. */
		tevent_abort(ev, "tevent: Violation of nesting hook rules\n");
	}
	ev->nesting.hook_fn = hook;
	ev->nesting.hook_private = private_data;
}

static void tevent_abort_nesting(struct tevent_context *ev, const char *location)
{
	const char *reason;

	reason = talloc_asprintf(NULL, "tevent_loop_once() nesting at %s",
				 location);
	if (!reason) {
		reason = "tevent_loop_once() nesting";
	}

	tevent_abort(ev, reason);
}

/*
  do a single event loop using the events defined in ev 
*/
int _tevent_loop_once(struct tevent_context *ev, const char *location)
{
	int ret;
	void *nesting_stack_ptr = NULL;

	ev->nesting.level++;

	if (ev->nesting.level > 1) {
		if (!ev->nesting.allowed) {
			tevent_abort_nesting(ev, location);
			errno = ELOOP;
			return -1;
		}
	}
	if (ev->nesting.level > 0) {
		if (ev->nesting.hook_fn) {
			int ret2;
			ret2 = ev->nesting.hook_fn(ev,
						   ev->nesting.hook_private,
						   ev->nesting.level,
						   true,
						   (void *)&nesting_stack_ptr,
						   location);
			if (ret2 != 0) {
				ret = ret2;
				goto done;
			}
		}
	}

	ret = ev->ops->loop_once(ev, location);

	if (ev->nesting.level > 0) {
		if (ev->nesting.hook_fn) {
			int ret2;
			ret2 = ev->nesting.hook_fn(ev,
						   ev->nesting.hook_private,
						   ev->nesting.level,
						   false,
						   (void *)&nesting_stack_ptr,
						   location);
			if (ret2 != 0) {
				ret = ret2;
				goto done;
			}
		}
	}

done:
	ev->nesting.level--;
	return ret;
}

/*
  this is a performance optimization for the samba4 nested event loop problems
*/
int _tevent_loop_until(struct tevent_context *ev,
		       bool (*finished)(void *private_data),
		       void *private_data,
		       const char *location)
{
	int ret = 0;
	void *nesting_stack_ptr = NULL;

	ev->nesting.level++;

	if (ev->nesting.level > 1) {
		if (!ev->nesting.allowed) {
			tevent_abort_nesting(ev, location);
			errno = ELOOP;
			return -1;
		}
	}
	if (ev->nesting.level > 0) {
		if (ev->nesting.hook_fn) {
			int ret2;
			ret2 = ev->nesting.hook_fn(ev,
						   ev->nesting.hook_private,
						   ev->nesting.level,
						   true,
						   (void *)&nesting_stack_ptr,
						   location);
			if (ret2 != 0) {
				ret = ret2;
				goto done;
			}
		}
	}

	while (!finished(private_data)) {
		ret = ev->ops->loop_once(ev, location);
		if (ret != 0) {
			break;
		}
	}

	if (ev->nesting.level > 0) {
		if (ev->nesting.hook_fn) {
			int ret2;
			ret2 = ev->nesting.hook_fn(ev,
						   ev->nesting.hook_private,
						   ev->nesting.level,
						   false,
						   (void *)&nesting_stack_ptr,
						   location);
			if (ret2 != 0) {
				ret = ret2;
				goto done;
			}
		}
	}

done:
	ev->nesting.level--;
	return ret;
}

/*
  return on failure or (with 0) if all fd events are removed
*/
int tevent_common_loop_wait(struct tevent_context *ev,
			    const char *location)
{
	/*
	 * loop as long as we have events pending
	 */
	while (ev->fd_events ||
	       ev->timer_events ||
	       ev->immediate_events ||
	       ev->signal_events) {
		int ret;
		ret = _tevent_loop_once(ev, location);
		if (ret != 0) {
			tevent_debug(ev, TEVENT_DEBUG_FATAL,
				     "_tevent_loop_once() failed: %d - %s\n",
				     ret, strerror(errno));
			return ret;
		}
	}

	tevent_debug(ev, TEVENT_DEBUG_WARNING,
		     "tevent_common_loop_wait() out of events\n");
	return 0;
}

/*
  return on failure or (with 0) if all fd events are removed
*/
int _tevent_loop_wait(struct tevent_context *ev, const char *location)
{
	return ev->ops->loop_wait(ev, location);
}


/*
  re-initialise a tevent context. This leaves you with the same
  event context, but all events are wiped and the structure is
  re-initialised. This is most useful after a fork()  

  zero is returned on success, non-zero on failure
*/
int tevent_re_initialise(struct tevent_context *ev)
{
	tevent_common_context_destructor(ev);

	return ev->ops->context_init(ev);
}