1 /* $OpenBSD: poll.c,v 1.15 2010/04/21 20:02:40 nicm Exp $ */
2
3 /*
4 * Copyright 2000-2003 Niels Provos <provos@citi.umich.edu>
5 * All rights reserved.
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 #ifdef HAVE_CONFIG_H
30 #include "config.h"
31 #endif
32
33 #include <sys/types.h>
34 #ifdef HAVE_SYS_TIME_H
35 #include <sys/time.h>
36 #else
37 #include <sys/_libevent_time.h>
38 #endif
39 #include <sys/queue.h>
40 #include <poll.h>
41 #include <signal.h>
42 #include <stdio.h>
43 #include <stdlib.h>
44 #include <string.h>
45 #include <unistd.h>
46 #include <errno.h>
47 #ifdef CHECK_INVARIANTS
48 #include <assert.h>
49 #endif
50
51 #include "event.h"
52 #include "event-internal.h"
53 #include "evsignal.h"
54 #include "log.h"
55
56 __RCSID("$MirOS: src/lib/libevent/poll.c,v 1.4 2014/03/12 23:45:11 tg Exp $");
57
58 struct pollop {
59 int event_count; /* Highest number alloc */
60 int nfds; /* Size of event_* */
61 int fd_count; /* Size of idxplus1_by_fd */
62 struct pollfd *event_set;
63 struct event **event_r_back;
64 struct event **event_w_back;
65 int *idxplus1_by_fd; /* Index into event_set by fd; we add 1 so
66 * that 0 (which is easy to memset) can mean
67 * "no entry." */
68 };
69
70 static void *poll_init (struct event_base *);
71 static int poll_add (void *, struct event *);
72 static int poll_del (void *, struct event *);
73 static int poll_dispatch (struct event_base *, void *, struct timeval *);
74 static void poll_dealloc (struct event_base *, void *);
75
76 const struct eventop pollops = {
77 "poll",
78 poll_init,
79 poll_add,
80 poll_del,
81 poll_dispatch,
82 poll_dealloc,
83 0
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 /* Disable poll when this environment variable is set */
92 if (evutil_getenv("EVENT_NOPOLL"))
93 return (NULL);
94
95 if (!(pollop = calloc(1, sizeof(struct pollop))))
96 return (NULL);
97
98 evsignal_init(base);
99
100 return (pollop);
101 }
102
103 #ifdef CHECK_INVARIANTS
104 static void
poll_check_ok(struct pollop * pop)105 poll_check_ok(struct pollop *pop)
106 {
107 int i, idx;
108 struct event *ev;
109
110 for (i = 0; i < pop->fd_count; ++i) {
111 idx = pop->idxplus1_by_fd[i]-1;
112 if (idx < 0)
113 continue;
114 assert(pop->event_set[idx].fd == i);
115 if (pop->event_set[idx].events & POLLIN) {
116 ev = pop->event_r_back[idx];
117 assert(ev);
118 assert(ev->ev_events & EV_READ);
119 assert(ev->ev_fd == i);
120 }
121 if (pop->event_set[idx].events & POLLOUT) {
122 ev = pop->event_w_back[idx];
123 assert(ev);
124 assert(ev->ev_events & EV_WRITE);
125 assert(ev->ev_fd == i);
126 }
127 }
128 for (i = 0; i < pop->nfds; ++i) {
129 struct pollfd *pfd = &pop->event_set[i];
130 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,void * arg,struct timeval * tv)138 poll_dispatch(struct event_base *base, void *arg, struct timeval *tv)
139 {
140 int res, i, j, msec = -1, nfds;
141 struct pollop *pop = arg;
142
143 poll_check_ok(pop);
144
145 if (tv != NULL)
146 msec = tv->tv_sec * 1000 + (tv->tv_usec + 999) / 1000;
147
148 nfds = pop->nfds;
149 res = poll(pop->event_set, nfds, msec);
150
151 if (res == -1) {
152 if (errno != EINTR) {
153 event_warn("poll");
154 return (-1);
155 }
156
157 evsignal_process(base);
158 return (0);
159 } else if (base->sig.evsignal_caught) {
160 evsignal_process(base);
161 }
162
163 event_debug(("%s: poll reports %d", __func__, res));
164
165 if (res == 0 || nfds == 0)
166 return (0);
167
168 i = arc4random_uniform(nfds);
169 for (j = 0; j < nfds; j++) {
170 struct event *r_ev = NULL, *w_ev = NULL;
171 int what;
172 if (++i == nfds)
173 i = 0;
174 what = pop->event_set[i].revents;
175
176 if (!what)
177 continue;
178
179 res = 0;
180
181 /* If the file gets closed notify */
182 if (what & (POLLHUP|POLLERR))
183 what |= POLLIN|POLLOUT;
184 if (what & POLLIN) {
185 res |= EV_READ;
186 r_ev = pop->event_r_back[i];
187 }
188 if (what & POLLOUT) {
189 res |= EV_WRITE;
190 w_ev = pop->event_w_back[i];
191 }
192 if (res == 0)
193 continue;
194
195 if (r_ev && (res & r_ev->ev_events)) {
196 event_active(r_ev, res & r_ev->ev_events, 1);
197 }
198 if (w_ev && w_ev != r_ev && (res & w_ev->ev_events)) {
199 event_active(w_ev, res & w_ev->ev_events, 1);
200 }
201 }
202
203 return (0);
204 }
205
206 static int
poll_add(void * arg,struct event * ev)207 poll_add(void *arg, struct event *ev)
208 {
209 struct pollop *pop = arg;
210 struct pollfd *pfd = NULL;
211 int i;
212
213 if (ev->ev_events & EV_SIGNAL)
214 return (evsignal_add(ev));
215 if (!(ev->ev_events & (EV_READ|EV_WRITE)))
216 return (0);
217
218 poll_check_ok(pop);
219 if (pop->nfds + 1 >= pop->event_count) {
220 struct pollfd *tmp_event_set;
221 struct event **tmp_event_r_back;
222 struct event **tmp_event_w_back;
223 int tmp_event_count;
224
225 if (pop->event_count < 32)
226 tmp_event_count = 32;
227 else
228 tmp_event_count = pop->event_count * 2;
229
230 /* We need more file descriptors */
231 tmp_event_set = realloc(pop->event_set,
232 tmp_event_count * sizeof(struct pollfd));
233 if (tmp_event_set == NULL) {
234 event_warn("realloc");
235 return (-1);
236 }
237 pop->event_set = tmp_event_set;
238
239 tmp_event_r_back = realloc(pop->event_r_back,
240 tmp_event_count * sizeof(struct event *));
241 if (tmp_event_r_back == NULL) {
242 /* event_set overallocated; that's okay. */
243 event_warn("realloc");
244 return (-1);
245 }
246 pop->event_r_back = tmp_event_r_back;
247
248 tmp_event_w_back = realloc(pop->event_w_back,
249 tmp_event_count * sizeof(struct event *));
250 if (tmp_event_w_back == NULL) {
251 /* event_set and event_r_back overallocated; that's
252 * okay. */
253 event_warn("realloc");
254 return (-1);
255 }
256 pop->event_w_back = tmp_event_w_back;
257
258 pop->event_count = tmp_event_count;
259 }
260 if (ev->ev_fd >= pop->fd_count) {
261 int *tmp_idxplus1_by_fd;
262 int new_count;
263 if (pop->fd_count < 32)
264 new_count = 32;
265 else
266 new_count = pop->fd_count * 2;
267 while (new_count <= ev->ev_fd)
268 new_count *= 2;
269 tmp_idxplus1_by_fd =
270 realloc(pop->idxplus1_by_fd, new_count * sizeof(int));
271 if (tmp_idxplus1_by_fd == NULL) {
272 event_warn("realloc");
273 return (-1);
274 }
275 pop->idxplus1_by_fd = tmp_idxplus1_by_fd;
276 memset(pop->idxplus1_by_fd + pop->fd_count,
277 0, sizeof(int)*(new_count - pop->fd_count));
278 pop->fd_count = new_count;
279 }
280
281 i = pop->idxplus1_by_fd[ev->ev_fd] - 1;
282 if (i >= 0) {
283 pfd = &pop->event_set[i];
284 } else {
285 i = pop->nfds++;
286 pfd = &pop->event_set[i];
287 pfd->events = 0;
288 pfd->fd = ev->ev_fd;
289 pop->event_w_back[i] = pop->event_r_back[i] = NULL;
290 pop->idxplus1_by_fd[ev->ev_fd] = i + 1;
291 }
292
293 pfd->revents = 0;
294 if (ev->ev_events & EV_WRITE) {
295 pfd->events |= POLLOUT;
296 pop->event_w_back[i] = ev;
297 }
298 if (ev->ev_events & EV_READ) {
299 pfd->events |= POLLIN;
300 pop->event_r_back[i] = ev;
301 }
302 poll_check_ok(pop);
303
304 return (0);
305 }
306
307 /*
308 * Nothing to be done here.
309 */
310
311 static int
poll_del(void * arg,struct event * ev)312 poll_del(void *arg, struct event *ev)
313 {
314 struct pollop *pop = arg;
315 struct pollfd *pfd = NULL;
316 int i;
317
318 if (ev->ev_events & EV_SIGNAL)
319 return (evsignal_del(ev));
320
321 if (!(ev->ev_events & (EV_READ|EV_WRITE)))
322 return (0);
323
324 poll_check_ok(pop);
325 i = pop->idxplus1_by_fd[ev->ev_fd] - 1;
326 if (i < 0)
327 return (-1);
328
329 /* Do we still want to read or write? */
330 pfd = &pop->event_set[i];
331 if (ev->ev_events & EV_READ) {
332 pfd->events &= ~POLLIN;
333 pop->event_r_back[i] = NULL;
334 }
335 if (ev->ev_events & EV_WRITE) {
336 pfd->events &= ~POLLOUT;
337 pop->event_w_back[i] = NULL;
338 }
339 poll_check_ok(pop);
340 if (pfd->events)
341 /* Another event cares about that fd. */
342 return (0);
343
344 /* Okay, so we aren't interested in that fd anymore. */
345 pop->idxplus1_by_fd[ev->ev_fd] = 0;
346
347 --pop->nfds;
348 if (i != pop->nfds) {
349 /*
350 * Shift the last pollfd down into the now-unoccupied
351 * position.
352 */
353 memcpy(&pop->event_set[i], &pop->event_set[pop->nfds],
354 sizeof(struct pollfd));
355 pop->event_r_back[i] = pop->event_r_back[pop->nfds];
356 pop->event_w_back[i] = pop->event_w_back[pop->nfds];
357 pop->idxplus1_by_fd[pop->event_set[i].fd] = i + 1;
358 }
359
360 poll_check_ok(pop);
361 return (0);
362 }
363
364 static void
poll_dealloc(struct event_base * base,void * arg)365 poll_dealloc(struct event_base *base, void *arg)
366 {
367 struct pollop *pop = arg;
368
369 evsignal_dealloc(base);
370 if (pop->event_set)
371 free(pop->event_set);
372 if (pop->event_r_back)
373 free(pop->event_r_back);
374 if (pop->event_w_back)
375 free(pop->event_w_back);
376 if (pop->idxplus1_by_fd)
377 free(pop->idxplus1_by_fd);
378
379 memset(pop, 0, sizeof(struct pollop));
380 free(pop);
381 }
382