1 /* $NetBSD: poll.c,v 1.1.1.2 2013/04/11 16:43:26 christos Exp $ */
2 /* $OpenBSD: poll.c,v 1.2 2002/06/25 15:50:15 mickey Exp $ */
3
4 /*
5 * Copyright 2000-2007 Niels Provos <provos@citi.umich.edu>
6 * Copyright 2007-2012 Niels Provos and Nick Mathewson
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. The name of the author may not be used to endorse or promote products
17 * derived from this software without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
20 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
21 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
22 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
23 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
24 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
28 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 */
30 #include "event2/event-config.h"
31 #include <sys/cdefs.h>
32 __RCSID("$NetBSD: poll.c,v 1.1.1.2 2013/04/11 16:43:26 christos Exp $");
33
34 #include <sys/types.h>
35 #ifdef _EVENT_HAVE_SYS_TIME_H
36 #include <sys/time.h>
37 #endif
38 #include <sys/queue.h>
39 #include <poll.h>
40 #include <signal.h>
41 #include <limits.h>
42 #include <stdio.h>
43 #include <stdlib.h>
44 #include <string.h>
45 #include <unistd.h>
46 #include <errno.h>
47
48 #include "event-internal.h"
49 #include "evsignal-internal.h"
50 #include "log-internal.h"
51 #include "evmap-internal.h"
52 #include "event2/thread.h"
53 #include "evthread-internal.h"
54
55 struct pollidx {
56 int idxplus1;
57 };
58
59 struct pollop {
60 int event_count; /* Highest number alloc */
61 int nfds; /* Highest number used */
62 int realloc_copy; /* True iff we must realloc
63 * event_set_copy */
64 struct pollfd *event_set;
65 struct pollfd *event_set_copy;
66 };
67
68 static void *poll_init(struct event_base *);
69 static int poll_add(struct event_base *, int, short old, short events, void *_idx);
70 static int poll_del(struct event_base *, int, short old, short events, void *_idx);
71 static int poll_dispatch(struct event_base *, struct timeval *);
72 static void poll_dealloc(struct event_base *);
73
74 const struct eventop pollops = {
75 "poll",
76 poll_init,
77 poll_add,
78 poll_del,
79 poll_dispatch,
80 poll_dealloc,
81 0, /* doesn't need_reinit */
82 EV_FEATURE_FDS,
83 sizeof(struct pollidx),
84 };
85
86 static void *
poll_init(struct event_base * base)87 poll_init(struct event_base *base)
88 {
89 struct pollop *pollop;
90
91 if (!(pollop = mm_calloc(1, sizeof(struct pollop))))
92 return (NULL);
93
94 evsig_init(base);
95
96 return (pollop);
97 }
98
99 #ifdef CHECK_INVARIANTS
100 static void
poll_check_ok(struct pollop * pop)101 poll_check_ok(struct pollop *pop)
102 {
103 int i, idx;
104 struct event *ev;
105
106 for (i = 0; i < pop->fd_count; ++i) {
107 idx = pop->idxplus1_by_fd[i]-1;
108 if (idx < 0)
109 continue;
110 EVUTIL_ASSERT(pop->event_set[idx].fd == i);
111 }
112 for (i = 0; i < pop->nfds; ++i) {
113 struct pollfd *pfd = &pop->event_set[i];
114 EVUTIL_ASSERT(pop->idxplus1_by_fd[pfd->fd] == i+1);
115 }
116 }
117 #else
118 #define poll_check_ok(pop)
119 #endif
120
121 static int
poll_dispatch(struct event_base * base,struct timeval * tv)122 poll_dispatch(struct event_base *base, struct timeval *tv)
123 {
124 int res, i, j, nfds;
125 long msec = -1;
126 struct pollop *pop = base->evbase;
127 struct pollfd *event_set;
128
129 poll_check_ok(pop);
130
131 nfds = pop->nfds;
132
133 #ifndef _EVENT_DISABLE_THREAD_SUPPORT
134 if (base->th_base_lock) {
135 /* If we're using this backend in a multithreaded setting,
136 * then we need to work on a copy of event_set, so that we can
137 * let other threads modify the main event_set while we're
138 * polling. If we're not multithreaded, then we'll skip the
139 * copy step here to save memory and time. */
140 if (pop->realloc_copy) {
141 struct pollfd *tmp = mm_realloc(pop->event_set_copy,
142 pop->event_count * sizeof(struct pollfd));
143 if (tmp == NULL) {
144 event_warn("realloc");
145 return -1;
146 }
147 pop->event_set_copy = tmp;
148 pop->realloc_copy = 0;
149 }
150 memcpy(pop->event_set_copy, pop->event_set,
151 sizeof(struct pollfd)*nfds);
152 event_set = pop->event_set_copy;
153 } else {
154 event_set = pop->event_set;
155 }
156 #else
157 event_set = pop->event_set;
158 #endif
159
160 if (tv != NULL) {
161 msec = evutil_tv_to_msec(tv);
162 if (msec < 0 || msec > INT_MAX)
163 msec = INT_MAX;
164 }
165
166 EVBASE_RELEASE_LOCK(base, th_base_lock);
167
168 res = poll(event_set, nfds, msec);
169
170 EVBASE_ACQUIRE_LOCK(base, th_base_lock);
171
172 if (res == -1) {
173 if (errno != EINTR) {
174 event_warn("poll");
175 return (-1);
176 }
177
178 return (0);
179 }
180
181 event_debug(("%s: poll reports %d", __func__, res));
182
183 if (res == 0 || nfds == 0)
184 return (0);
185
186 i = random() % nfds;
187 for (j = 0; j < nfds; j++) {
188 int what;
189 if (++i == nfds)
190 i = 0;
191 what = event_set[i].revents;
192 if (!what)
193 continue;
194
195 res = 0;
196
197 /* If the file gets closed notify */
198 if (what & (POLLHUP|POLLERR))
199 what |= POLLIN|POLLOUT;
200 if (what & POLLIN)
201 res |= EV_READ;
202 if (what & POLLOUT)
203 res |= EV_WRITE;
204 if (res == 0)
205 continue;
206
207 evmap_io_active(base, event_set[i].fd, res);
208 }
209
210 return (0);
211 }
212
213 static int
poll_add(struct event_base * base,int fd,short old,short events,void * _idx)214 poll_add(struct event_base *base, int fd, short old, short events, void *_idx)
215 {
216 struct pollop *pop = base->evbase;
217 struct pollfd *pfd = NULL;
218 struct pollidx *idx = _idx;
219 int i;
220
221 EVUTIL_ASSERT((events & EV_SIGNAL) == 0);
222 if (!(events & (EV_READ|EV_WRITE)))
223 return (0);
224
225 poll_check_ok(pop);
226 if (pop->nfds + 1 >= pop->event_count) {
227 struct pollfd *tmp_event_set;
228 int tmp_event_count;
229
230 if (pop->event_count < 32)
231 tmp_event_count = 32;
232 else
233 tmp_event_count = pop->event_count * 2;
234
235 /* We need more file descriptors */
236 tmp_event_set = mm_realloc(pop->event_set,
237 tmp_event_count * sizeof(struct pollfd));
238 if (tmp_event_set == NULL) {
239 event_warn("realloc");
240 return (-1);
241 }
242 pop->event_set = tmp_event_set;
243
244 pop->event_count = tmp_event_count;
245 pop->realloc_copy = 1;
246 }
247
248 i = idx->idxplus1 - 1;
249
250 if (i >= 0) {
251 pfd = &pop->event_set[i];
252 } else {
253 i = pop->nfds++;
254 pfd = &pop->event_set[i];
255 pfd->events = 0;
256 pfd->fd = fd;
257 idx->idxplus1 = i + 1;
258 }
259
260 pfd->revents = 0;
261 if (events & EV_WRITE)
262 pfd->events |= POLLOUT;
263 if (events & EV_READ)
264 pfd->events |= POLLIN;
265 poll_check_ok(pop);
266
267 return (0);
268 }
269
270 /*
271 * Nothing to be done here.
272 */
273
274 static int
poll_del(struct event_base * base,int fd,short old,short events,void * _idx)275 poll_del(struct event_base *base, int fd, short old, short events, void *_idx)
276 {
277 struct pollop *pop = base->evbase;
278 struct pollfd *pfd = NULL;
279 struct pollidx *idx = _idx;
280 int i;
281
282 EVUTIL_ASSERT((events & EV_SIGNAL) == 0);
283 if (!(events & (EV_READ|EV_WRITE)))
284 return (0);
285
286 poll_check_ok(pop);
287 i = idx->idxplus1 - 1;
288 if (i < 0)
289 return (-1);
290
291 /* Do we still want to read or write? */
292 pfd = &pop->event_set[i];
293 if (events & EV_READ)
294 pfd->events &= ~POLLIN;
295 if (events & EV_WRITE)
296 pfd->events &= ~POLLOUT;
297 poll_check_ok(pop);
298 if (pfd->events)
299 /* Another event cares about that fd. */
300 return (0);
301
302 /* Okay, so we aren't interested in that fd anymore. */
303 idx->idxplus1 = 0;
304
305 --pop->nfds;
306 if (i != pop->nfds) {
307 /*
308 * Shift the last pollfd down into the now-unoccupied
309 * position.
310 */
311 memcpy(&pop->event_set[i], &pop->event_set[pop->nfds],
312 sizeof(struct pollfd));
313 idx = evmap_io_get_fdinfo(&base->io, pop->event_set[i].fd);
314 EVUTIL_ASSERT(idx);
315 EVUTIL_ASSERT(idx->idxplus1 == pop->nfds + 1);
316 idx->idxplus1 = i + 1;
317 }
318
319 poll_check_ok(pop);
320 return (0);
321 }
322
323 static void
poll_dealloc(struct event_base * base)324 poll_dealloc(struct event_base *base)
325 {
326 struct pollop *pop = base->evbase;
327
328 evsig_dealloc(base);
329 if (pop->event_set)
330 mm_free(pop->event_set);
331 if (pop->event_set_copy)
332 mm_free(pop->event_set_copy);
333
334 memset(pop, 0, sizeof(struct pollop));
335 mm_free(pop);
336 }
337