summaryrefslogtreecommitdiffstats
path: root/libevent/poll.c
blob: c3c9aac52a85bd99ac6da38b6709b817c4810858 (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
/*	$OpenBSD: poll.c,v 1.2 2002/06/25 15:50:15 mickey Exp $	*/

/*
 * Copyright 2000-2007 Niels Provos <provos@citi.umich.edu>
 * Copyright 2007-2012 Niels Provos and Nick Mathewson
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
#include "event2/event-config.h"
#include "evconfig-private.h"

#ifdef EVENT__HAVE_POLL

#include <sys/types.h>
#ifdef EVENT__HAVE_SYS_TIME_H
#include <sys/time.h>
#endif
#include <sys/queue.h>
#include <poll.h>
#include <signal.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>

#include "event-internal.h"
#include "evsignal-internal.h"
#include "log-internal.h"
#include "evmap-internal.h"
#include "event2/thread.h"
#include "evthread-internal.h"
#include "time-internal.h"

/* Since Linux 2.6.17, poll is able to report about peer half-closed connection
   using special POLLRDHUP flag on a read event.
*/
#if !defined(POLLRDHUP)
#define POLLRDHUP 0
#define EARLY_CLOSE_IF_HAVE_RDHUP 0
#else
#define EARLY_CLOSE_IF_HAVE_RDHUP EV_FEATURE_EARLY_CLOSE
#endif


struct pollidx {
	int idxplus1;
};

struct pollop {
	int event_count;		/* Highest number alloc */
	int nfds;			/* Highest number used */
	int realloc_copy;		/* True iff we must realloc
					 * event_set_copy */
	struct pollfd *event_set;
	struct pollfd *event_set_copy;
};

static void *poll_init(struct event_base *);
static int poll_add(struct event_base *, int, short old, short events, void *idx);
static int poll_del(struct event_base *, int, short old, short events, void *idx);
static int poll_dispatch(struct event_base *, struct timeval *);
static void poll_dealloc(struct event_base *);

const struct eventop pollops = {
	"poll",
	poll_init,
	poll_add,
	poll_del,
	poll_dispatch,
	poll_dealloc,
	1, /* need_reinit */
	EV_FEATURE_FDS|EARLY_CLOSE_IF_HAVE_RDHUP,
	sizeof(struct pollidx),
};

static void *
poll_init(struct event_base *base)
{
	struct pollop *pollop;

	if (!(pollop = mm_calloc(1, sizeof(struct pollop))))
		return (NULL);

	evsig_init_(base);

	evutil_weakrand_seed_(&base->weakrand_seed, 0);

	return (pollop);
}

#ifdef CHECK_INVARIANTS
static void
poll_check_ok(struct pollop *pop)
{
	int i, idx;
	struct event *ev;

	for (i = 0; i < pop->fd_count; ++i) {
		idx = pop->idxplus1_by_fd[i]-1;
		if (idx < 0)
			continue;
		EVUTIL_ASSERT(pop->event_set[idx].fd == i);
	}
	for (i = 0; i < pop->nfds; ++i) {
		struct pollfd *pfd = &pop->event_set[i];
		EVUTIL_ASSERT(pop->idxplus1_by_fd[pfd->fd] == i+1);
	}
}
#else
#define poll_check_ok(pop)
#endif

static int
poll_dispatch(struct event_base *base, struct timeval *tv)
{
	int res, i, j, nfds;
	long msec = -1;
	struct pollop *pop = base->evbase;
	struct pollfd *event_set;

	poll_check_ok(pop);

	nfds = pop->nfds;

#ifndef EVENT__DISABLE_THREAD_SUPPORT
	if (base->th_base_lock) {
		/* If we're using this backend in a multithreaded setting,
		 * then we need to work on a copy of event_set, so that we can
		 * let other threads modify the main event_set while we're
		 * polling. If we're not multithreaded, then we'll skip the
		 * copy step here to save memory and time. */
		if (pop->realloc_copy) {
			struct pollfd *tmp = mm_realloc(pop->event_set_copy,
			    pop->event_count * sizeof(struct pollfd));
			if (tmp == NULL) {
				event_warn("realloc");
				return -1;
			}
			pop->event_set_copy = tmp;
			pop->realloc_copy = 0;
		}
		memcpy(pop->event_set_copy, pop->event_set,
		    sizeof(struct pollfd)*nfds);
		event_set = pop->event_set_copy;
	} else {
		event_set = pop->event_set;
	}
#else
	event_set = pop->event_set;
#endif

	if (tv != NULL) {
		msec = evutil_tv_to_msec_(tv);
		if (msec < 0 || msec > INT_MAX)
			msec = INT_MAX;
	}

	EVBASE_RELEASE_LOCK(base, th_base_lock);

	res = poll(event_set, nfds, msec);

	EVBASE_ACQUIRE_LOCK(base, th_base_lock);

	if (res == -1) {
		if (errno != EINTR) {
			event_warn("poll");
			return (-1);
		}

		return (0);
	}

	event_debug(("%s: poll reports %d", __func__, res));

	if (res == 0 || nfds == 0)
		return (0);

	i = evutil_weakrand_range_(&base->weakrand_seed, nfds);
	for (j = 0; j < nfds; j++) {
		int what;
		if (++i == nfds)
			i = 0;
		what = event_set[i].revents;
		if (!what)
			continue;

		res = 0;

		/* If the file gets closed notify */
		if (what & (POLLHUP|POLLERR|POLLNVAL))
			what |= POLLIN|POLLOUT;
		if (what & POLLIN)
			res |= EV_READ;
		if (what & POLLOUT)
			res |= EV_WRITE;
		if (what & POLLRDHUP)
			res |= EV_CLOSED;
		if (res == 0)
			continue;

		evmap_io_active_(base, event_set[i].fd, res);
	}

	return (0);
}

static int
poll_add(struct event_base *base, int fd, short old, short events, void *idx_)
{
	struct pollop *pop = base->evbase;
	struct pollfd *pfd = NULL;
	struct pollidx *idx = idx_;
	int i;

	EVUTIL_ASSERT((events & EV_SIGNAL) == 0);
	if (!(events & (EV_READ|EV_WRITE|EV_CLOSED)))
		return (0);

	poll_check_ok(pop);
	if (pop->nfds + 1 >= pop->event_count) {
		struct pollfd *tmp_event_set;
		int tmp_event_count;

		if (pop->event_count < 32)
			tmp_event_count = 32;
		else
			tmp_event_count = pop->event_count * 2;

		/* We need more file descriptors */
		tmp_event_set = mm_realloc(pop->event_set,
				 tmp_event_count * sizeof(struct pollfd));
		if (tmp_event_set == NULL) {
			event_warn("realloc");
			return (-1);
		}
		pop->event_set = tmp_event_set;

		pop->event_count = tmp_event_count;
		pop->realloc_copy = 1;
	}

	i = idx->idxplus1 - 1;

	if (i >= 0) {
		pfd = &pop->event_set[i];
	} else {
		i = pop->nfds++;
		pfd = &pop->event_set[i];
		pfd->events = 0;
		pfd->fd = fd;
		idx->idxplus1 = i + 1;
	}

	pfd->revents = 0;
	if (events & EV_WRITE)
		pfd->events |= POLLOUT;
	if (events & EV_READ)
		pfd->events |= POLLIN;
	if (events & EV_CLOSED)
		pfd->events |= POLLRDHUP;
	poll_check_ok(pop);

	return (0);
}

/*
 * Nothing to be done here.
 */

static int
poll_del(struct event_base *base, int fd, short old, short events, void *idx_)
{
	struct pollop *pop = base->evbase;
	struct pollfd *pfd = NULL;
	struct pollidx *idx = idx_;
	int i;

	EVUTIL_ASSERT((events & EV_SIGNAL) == 0);
	if (!(events & (EV_READ|EV_WRITE|EV_CLOSED)))
		return (0);

	poll_check_ok(pop);
	i = idx->idxplus1 - 1;
	if (i < 0)
		return (-1);

	/* Do we still want to read or write? */
	pfd = &pop->event_set[i];
	if (events & EV_READ)
		pfd->events &= ~POLLIN;
	if (events & EV_WRITE)
		pfd->events &= ~POLLOUT;
	if (events & EV_CLOSED)
		pfd->events &= ~POLLRDHUP;
	poll_check_ok(pop);
	if (pfd->events)
		/* Another event cares about that fd. */
		return (0);

	/* Okay, so we aren't interested in that fd anymore. */
	idx->idxplus1 = 0;

	--pop->nfds;
	if (i != pop->nfds) {
		/*
		 * Shift the last pollfd down into the now-unoccupied
		 * position.
		 */
		memcpy(&pop->event_set[i], &pop->event_set[pop->nfds],
		       sizeof(struct pollfd));
		idx = evmap_io_get_fdinfo_(&base->io, pop->event_set[i].fd);
		EVUTIL_ASSERT(idx);
		EVUTIL_ASSERT(idx->idxplus1 == pop->nfds + 1);
		idx->idxplus1 = i + 1;
	}

	poll_check_ok(pop);
	return (0);
}

static void
poll_dealloc(struct event_base *base)
{
	struct pollop *pop = base->evbase;

	evsig_dealloc_(base);
	if (pop->event_set)
		mm_free(pop->event_set);
	if (pop->event_set_copy)
		mm_free(pop->event_set_copy);

	memset(pop, 0, sizeof(struct pollop));
	mm_free(pop);
}

#endif /* EVENT__HAVE_POLL */