summaryrefslogtreecommitdiff
path: root/lib/tevent/tevent_poll.c
blob: cda028a964bf8c723eb211571af9f1762eac18d9 (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
/*
   Unix SMB/CIFS implementation.
   main select loop and event handling
   Copyright (C) Andrew Tridgell	2003-2005
   Copyright (C) Stefan Metzmacher	2005-2009

     ** 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/>.
*/

#include "replace.h"
#include "system/filesys.h"
#include "system/select.h"
#include "tevent.h"
#include "tevent_util.h"
#include "tevent_internal.h"

struct poll_event_context {
	/*
	 * These two arrays are maintained together.
	 */
	struct pollfd *fds;
	struct tevent_fd **fd_events;
	int num_fds;

	/* information for exiting from the event loop */
	int exit_code;
};

/*
  create a select_event_context structure.
*/
static int poll_event_context_init(struct tevent_context *ev)
{
	struct poll_event_context *poll_ev;

	poll_ev = talloc_zero(ev, struct poll_event_context);
	if (poll_ev == NULL) {
		return -1;
	}
	ev->additional_data = poll_ev;
	return 0;
}

/*
  destroy an fd_event
*/
static int poll_event_fd_destructor(struct tevent_fd *fde)
{
	struct tevent_context *ev = fde->event_ctx;
	struct poll_event_context *poll_ev = NULL;
	struct tevent_fd *moved_fde;
	long del_idx;

	if (ev == NULL) {
		goto done;
	}

	poll_ev = talloc_get_type_abort(
		ev->additional_data, struct poll_event_context);

	/*
	 * Assume a void * can carry enough bits to hold num_fds.
	 */
	del_idx = (long)(fde->additional_data);

	moved_fde = poll_ev->fd_events[poll_ev->num_fds-1];
	poll_ev->fd_events[del_idx] = moved_fde;
	poll_ev->fds[del_idx] = poll_ev->fds[poll_ev->num_fds-1];
	moved_fde->additional_data = (void *)del_idx;

	poll_ev->num_fds -= 1;
done:
	return tevent_common_fd_destructor(fde);
}

/*
  add a fd based event
  return NULL on failure (memory allocation error)
*/
static struct tevent_fd *poll_event_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)
{
	struct poll_event_context *poll_ev = talloc_get_type_abort(
		ev->additional_data, struct poll_event_context);
	struct pollfd *pfd;
	struct tevent_fd *fde;

	fde = tevent_common_add_fd(ev, mem_ctx, fd, flags,
				   handler, private_data,
				   handler_name, location);
	if (fde == NULL) {
		return NULL;
	}

	/* we allocate 16 slots to avoid a lot of reallocations */
	if (talloc_array_length(poll_ev->fds) == poll_ev->num_fds) {
		struct pollfd *tmp_fds;
		struct tevent_fd **tmp_fd_events;
		tmp_fds = talloc_realloc(
			poll_ev, poll_ev->fds, struct pollfd,
			poll_ev->num_fds + 16);
		if (tmp_fds == NULL) {
			TALLOC_FREE(fde);
			return NULL;
		}
		poll_ev->fds = tmp_fds;

		tmp_fd_events = talloc_realloc(
			poll_ev, poll_ev->fd_events, struct tevent_fd *,
			poll_ev->num_fds + 16);
		if (tmp_fd_events == NULL) {
			TALLOC_FREE(fde);
			return NULL;
		}
		poll_ev->fd_events = tmp_fd_events;
	}

	pfd = &poll_ev->fds[poll_ev->num_fds];

	pfd->fd = fd;

	pfd->events = 0;
	pfd->revents = 0;

	if (flags & TEVENT_FD_READ) {
		pfd->events |= (POLLIN|POLLHUP);
	}
	if (flags & TEVENT_FD_WRITE) {
		pfd->events |= (POLLOUT);
	}

	/*
	 * Assume a void * can carry enough bits to hold num_fds.
	 */
	fde->additional_data = (void *)(long)poll_ev->num_fds;
	poll_ev->fd_events[poll_ev->num_fds] = fde;

	poll_ev->num_fds += 1;

	talloc_set_destructor(fde, poll_event_fd_destructor);

	return fde;
}

/*
  set the fd event flags
*/
static void poll_event_set_fd_flags(struct tevent_fd *fde, uint16_t flags)
{
	struct poll_event_context *poll_ev = talloc_get_type_abort(
		fde->event_ctx->additional_data, struct poll_event_context);
	long idx;
	uint16_t pollflags = 0;

	if (flags & TEVENT_FD_READ) {
		pollflags |= (POLLIN|POLLHUP);
	}
	if (flags & TEVENT_FD_WRITE) {
		pollflags |= (POLLOUT);
	}

	idx = (long)(fde->additional_data);
	poll_ev->fds[idx].events = pollflags;

	fde->flags = flags;
}

/*
  event loop handling using select()
*/
static int poll_event_loop_poll(struct tevent_context *ev,
				struct timeval *tvalp)
{
	struct poll_event_context *poll_ev = talloc_get_type_abort(
		ev->additional_data, struct poll_event_context);
	struct tevent_fd *fde;
	int pollrtn;
	int timeout = -1;

	if (ev->signal_events && tevent_common_check_signal(ev)) {
		return 0;
	}

	if (tvalp != NULL) {
		timeout = tvalp->tv_sec * 1000;
		timeout += (tvalp->tv_usec + 999) / 1000;
	}

	pollrtn = poll(poll_ev->fds, poll_ev->num_fds, timeout);

	if (pollrtn == -1 && errno == EINTR && ev->signal_events) {
		tevent_common_check_signal(ev);
		return 0;
	}

	if (pollrtn == -1 && errno == EBADF) {
		/* the socket is dead! this should never
		   happen as the socket should have first been
		   made readable and that should have removed
		   the event, so this must be a bug. This is a
		   fatal error. */
		tevent_debug(ev, TEVENT_DEBUG_FATAL,
			     "ERROR: EBADF on poll_event_loop_once\n");
		poll_ev->exit_code = EBADF;
		return -1;
	}

	if (pollrtn == 0 && tvalp) {
		/* we don't care about a possible delay here */
		tevent_common_loop_timer_delay(ev);
		return 0;
	}

	if (pollrtn > 0) {
		/* at least one file descriptor is ready - check
		   which ones and call the handler, being careful to allow
		   the handler to remove itself when called */
		for (fde = ev->fd_events; fde; fde = fde->next) {
			struct pollfd *pfd;
			long pfd_idx;
			uint16_t flags = 0;

			pfd_idx = (long)(fde->additional_data);

			pfd = &poll_ev->fds[pfd_idx];

			if (pfd->revents & (POLLIN|POLLHUP|POLLERR)) {
				flags |= TEVENT_FD_READ;
			}
			if (pfd->revents & POLLOUT) {
				flags |= TEVENT_FD_WRITE;
			}
			if (flags != 0) {
				fde->handler(ev, fde, flags,
					     fde->private_data);
				break;
			}
		}
	}

	return 0;
}

/*
  do a single event loop using the events defined in ev
*/
static int poll_event_loop_once(struct tevent_context *ev,
				const char *location)
{
	struct timeval tval;

	if (ev->signal_events &&
	    tevent_common_check_signal(ev)) {
		return 0;
	}

	if (ev->immediate_events &&
	    tevent_common_loop_immediate(ev)) {
		return 0;
	}

	tval = tevent_common_loop_timer_delay(ev);
	if (tevent_timeval_is_zero(&tval)) {
		return 0;
	}

	return poll_event_loop_poll(ev, &tval);
}

static const struct tevent_ops poll_event_ops = {
	.context_init		= poll_event_context_init,
	.add_fd			= poll_event_add_fd,
	.set_fd_close_fn	= tevent_common_fd_set_close_fn,
	.get_fd_flags		= tevent_common_fd_get_flags,
	.set_fd_flags		= poll_event_set_fd_flags,
	.add_timer		= tevent_common_add_timer,
	.schedule_immediate	= tevent_common_schedule_immediate,
	.add_signal		= tevent_common_add_signal,
	.loop_once		= poll_event_loop_once,
	.loop_wait		= tevent_common_loop_wait,
};

_PRIVATE_ bool tevent_poll_init(void)
{
	return tevent_register_backend("poll", &poll_event_ops);
}