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