1 /* $NetBSD: poll.c,v 1.6 2024/08/18 20:47:21 christos Exp $ */
2
3 /* $OpenBSD: poll.c,v 1.2 2002/06/25 15:50:15 mickey Exp $ */
4
5 /*
6 * Copyright 2000-2007 Niels Provos <provos@citi.umich.edu>
7 * Copyright 2007-2012 Niels Provos and Nick Mathewson
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 * 3. The name of the author may not be used to endorse or promote products
18 * derived from this software without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
21 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
22 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
23 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
24 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
25 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
26 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
27 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
28 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
29 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30 */
31 #include "event2/event-config.h"
32 #include "evconfig-private.h"
33
34 #ifdef EVENT__HAVE_POLL
35
36 #include <sys/types.h>
37 #ifdef EVENT__HAVE_SYS_TIME_H
38 #include <sys/time.h>
39 #endif
40 #include <sys/queue.h>
41 #include <poll.h>
42 #include <signal.h>
43 #include <limits.h>
44 #include <stdio.h>
45 #include <stdlib.h>
46 #include <string.h>
47 #include <unistd.h>
48 #include <errno.h>
49
50 #include "event-internal.h"
51 #include "evsignal-internal.h"
52 #include "log-internal.h"
53 #include "evmap-internal.h"
54 #include "event2/thread.h"
55 #include "evthread-internal.h"
56 #include "time-internal.h"
57
58 /* Since Linux 2.6.17, poll is able to report about peer half-closed connection
59 using special POLLRDHUP flag on a read event.
60 */
61 #if !defined(POLLRDHUP)
62 #define POLLRDHUP 0
63 #define EARLY_CLOSE_IF_HAVE_RDHUP 0
64 #else
65 #define EARLY_CLOSE_IF_HAVE_RDHUP EV_FEATURE_EARLY_CLOSE
66 #endif
67
68
69 struct pollidx {
70 int idxplus1;
71 };
72
73 struct pollop {
74 int event_count; /* Highest number alloc */
75 int nfds; /* Highest number used */
76 int realloc_copy; /* True iff we must realloc
77 * event_set_copy */
78 struct pollfd *event_set;
79 struct pollfd *event_set_copy;
80 };
81
82 static void *poll_init(struct event_base *);
83 static int poll_add(struct event_base *, int, short old, short events, void *idx);
84 static int poll_del(struct event_base *, int, short old, short events, void *idx);
85 static int poll_dispatch(struct event_base *, struct timeval *);
86 static void poll_dealloc(struct event_base *);
87
88 const struct eventop pollops = {
89 "poll",
90 poll_init,
91 poll_add,
92 poll_del,
93 poll_dispatch,
94 poll_dealloc,
95 1, /* need_reinit */
96 EV_FEATURE_FDS|EARLY_CLOSE_IF_HAVE_RDHUP,
97 sizeof(struct pollidx),
98 };
99
100 static void *
poll_init(struct event_base * base)101 poll_init(struct event_base *base)
102 {
103 struct pollop *pollop;
104
105 if (!(pollop = mm_calloc(1, sizeof(struct pollop))))
106 return (NULL);
107
108 evsig_init_(base);
109
110 evutil_weakrand_seed_(&base->weakrand_seed, 0);
111
112 return (pollop);
113 }
114
115 #ifdef CHECK_INVARIANTS
116 static void
poll_check_ok(struct pollop * pop)117 poll_check_ok(struct pollop *pop)
118 {
119 int i, idx;
120 struct event *ev;
121
122 for (i = 0; i < pop->fd_count; ++i) {
123 idx = pop->idxplus1_by_fd[i]-1;
124 if (idx < 0)
125 continue;
126 EVUTIL_ASSERT(pop->event_set[idx].fd == i);
127 }
128 for (i = 0; i < pop->nfds; ++i) {
129 struct pollfd *pfd = &pop->event_set[i];
130 EVUTIL_ASSERT(pop->idxplus1_by_fd[pfd->fd] == i+1);
131 }
132 }
133 #else
134 #define poll_check_ok(pop)
135 #endif
136
137 static int
poll_dispatch(struct event_base * base,struct timeval * tv)138 poll_dispatch(struct event_base *base, struct timeval *tv)
139 {
140 int res, i, j, nfds;
141 long msec = -1;
142 struct pollop *pop = base->evbase;
143 struct pollfd *event_set;
144
145 poll_check_ok(pop);
146
147 nfds = pop->nfds;
148
149 #ifndef EVENT__DISABLE_THREAD_SUPPORT
150 if (base->th_base_lock) {
151 /* If we're using this backend in a multithreaded setting,
152 * then we need to work on a copy of event_set, so that we can
153 * let other threads modify the main event_set while we're
154 * polling. If we're not multithreaded, then we'll skip the
155 * copy step here to save memory and time. */
156 if (pop->realloc_copy) {
157 struct pollfd *tmp = mm_realloc(pop->event_set_copy,
158 pop->event_count * sizeof(struct pollfd));
159 if (tmp == NULL) {
160 event_warn("realloc");
161 return -1;
162 }
163 pop->event_set_copy = tmp;
164 pop->realloc_copy = 0;
165 }
166 memcpy(pop->event_set_copy, pop->event_set,
167 sizeof(struct pollfd)*nfds);
168 event_set = pop->event_set_copy;
169 } else {
170 event_set = pop->event_set;
171 }
172 #else
173 event_set = pop->event_set;
174 #endif
175
176 if (tv != NULL) {
177 msec = evutil_tv_to_msec_(tv);
178 if (msec < 0 || msec > INT_MAX)
179 msec = INT_MAX;
180 }
181
182 EVBASE_RELEASE_LOCK(base, th_base_lock);
183
184 res = poll(event_set, nfds, msec);
185
186 EVBASE_ACQUIRE_LOCK(base, th_base_lock);
187
188 if (res == -1) {
189 if (errno != EINTR) {
190 event_warn("poll");
191 return (-1);
192 }
193
194 return (0);
195 }
196
197 event_debug(("%s: poll reports %d", __func__, res));
198
199 if (res == 0 || nfds == 0)
200 return (0);
201
202 i = evutil_weakrand_range_(&base->weakrand_seed, nfds);
203 for (j = 0; j < nfds; j++) {
204 int what;
205 if (++i == nfds)
206 i = 0;
207 what = event_set[i].revents;
208 if (!what)
209 continue;
210
211 res = 0;
212
213 /* If the file gets closed notify */
214 if (what & (POLLHUP|POLLERR|POLLNVAL))
215 what |= POLLIN|POLLOUT;
216 if (what & POLLIN)
217 res |= EV_READ;
218 if (what & POLLOUT)
219 res |= EV_WRITE;
220 if (what & POLLRDHUP)
221 res |= EV_CLOSED;
222 if (res == 0)
223 continue;
224
225 evmap_io_active_(base, event_set[i].fd, res);
226 }
227
228 return (0);
229 }
230
231 static int
poll_add(struct event_base * base,int fd,short old,short events,void * idx_)232 poll_add(struct event_base *base, int fd, short old, short events, void *idx_)
233 {
234 struct pollop *pop = base->evbase;
235 struct pollfd *pfd = NULL;
236 struct pollidx *idx = idx_;
237 int i;
238
239 EVUTIL_ASSERT((events & EV_SIGNAL) == 0);
240 if (!(events & (EV_READ|EV_WRITE|EV_CLOSED)))
241 return (0);
242
243 poll_check_ok(pop);
244 if (pop->nfds + 1 >= pop->event_count) {
245 struct pollfd *tmp_event_set;
246 int tmp_event_count;
247
248 if (pop->event_count < 32)
249 tmp_event_count = 32;
250 else
251 tmp_event_count = pop->event_count * 2;
252
253 /* We need more file descriptors */
254 tmp_event_set = mm_realloc(pop->event_set,
255 tmp_event_count * sizeof(struct pollfd));
256 if (tmp_event_set == NULL) {
257 event_warn("realloc");
258 return (-1);
259 }
260 pop->event_set = tmp_event_set;
261
262 pop->event_count = tmp_event_count;
263 pop->realloc_copy = 1;
264 }
265
266 i = idx->idxplus1 - 1;
267
268 if (i >= 0) {
269 pfd = &pop->event_set[i];
270 } else {
271 i = pop->nfds++;
272 pfd = &pop->event_set[i];
273 pfd->events = 0;
274 pfd->fd = fd;
275 idx->idxplus1 = i + 1;
276 }
277
278 pfd->revents = 0;
279 if (events & EV_WRITE)
280 pfd->events |= POLLOUT;
281 if (events & EV_READ)
282 pfd->events |= POLLIN;
283 if (events & EV_CLOSED)
284 pfd->events |= POLLRDHUP;
285 poll_check_ok(pop);
286
287 return (0);
288 }
289
290 /*
291 * Nothing to be done here.
292 */
293
294 static int
poll_del(struct event_base * base,int fd,short old,short events,void * idx_)295 poll_del(struct event_base *base, int fd, short old, short events, void *idx_)
296 {
297 struct pollop *pop = base->evbase;
298 struct pollfd *pfd = NULL;
299 struct pollidx *idx = idx_;
300 int i;
301
302 EVUTIL_ASSERT((events & EV_SIGNAL) == 0);
303 if (!(events & (EV_READ|EV_WRITE|EV_CLOSED)))
304 return (0);
305
306 poll_check_ok(pop);
307 i = idx->idxplus1 - 1;
308 if (i < 0)
309 return (-1);
310
311 /* Do we still want to read or write? */
312 pfd = &pop->event_set[i];
313 if (events & EV_READ)
314 pfd->events &= ~POLLIN;
315 if (events & EV_WRITE)
316 pfd->events &= ~POLLOUT;
317 if (events & EV_CLOSED)
318 pfd->events &= ~POLLRDHUP;
319 poll_check_ok(pop);
320 if (pfd->events)
321 /* Another event cares about that fd. */
322 return (0);
323
324 /* Okay, so we aren't interested in that fd anymore. */
325 idx->idxplus1 = 0;
326
327 --pop->nfds;
328 if (i != pop->nfds) {
329 /*
330 * Shift the last pollfd down into the now-unoccupied
331 * position.
332 */
333 memcpy(&pop->event_set[i], &pop->event_set[pop->nfds],
334 sizeof(struct pollfd));
335 idx = evmap_io_get_fdinfo_(&base->io, pop->event_set[i].fd);
336 EVUTIL_ASSERT(idx);
337 EVUTIL_ASSERT(idx->idxplus1 == pop->nfds + 1);
338 idx->idxplus1 = i + 1;
339 }
340
341 poll_check_ok(pop);
342 return (0);
343 }
344
345 static void
poll_dealloc(struct event_base * base)346 poll_dealloc(struct event_base *base)
347 {
348 struct pollop *pop = base->evbase;
349
350 evsig_dealloc_(base);
351 if (pop->event_set)
352 mm_free(pop->event_set);
353 if (pop->event_set_copy)
354 mm_free(pop->event_set_copy);
355
356 memset(pop, 0, sizeof(struct pollop));
357 mm_free(pop);
358 }
359
360 #endif /* EVENT__HAVE_POLL */
361