1 /* $OpenBSD: select.c,v 1.16 2010/04/21 21:02:47 nicm Exp $ */
2
3 /*
4 * Copyright 2000-2002 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 #ifdef HAVE_SYS_SELECT_H
40 #include <sys/select.h>
41 #endif
42 #include <sys/queue.h>
43 #include <signal.h>
44 #include <stdio.h>
45 #include <stdlib.h>
46 #include <string.h>
47 #include <unistd.h>
48 #include <errno.h>
49 #ifdef CHECK_INVARIANTS
50 #include <assert.h>
51 #endif
52
53 #include "event.h"
54 #include "evutil.h"
55 #include "event-internal.h"
56 #include "evsignal.h"
57 #include "log.h"
58
59 __RCSID("$MirOS: src/lib/libevent/select.c,v 1.8 2014/03/12 23:45:11 tg Exp $");
60
61 #ifndef howmany
62 #define howmany(x, y) (((x)+((y)-1))/(y))
63 #endif
64
65 #ifndef HAVE_FD_MASK
66 /* This type is mandatory, but Android doesn't define it. */
67 #undef NFDBITS
68 #define NFDBITS (sizeof(long)*8)
69 typedef unsigned long fd_mask;
70 #endif
71
72 struct selectop {
73 fd_set *event_readset_in;
74 fd_set *event_writeset_in;
75 fd_set *event_readset_out;
76 fd_set *event_writeset_out;
77 struct event **event_r_by_fd;
78 struct event **event_w_by_fd;
79 size_t event_fdsz;
80 int event_fds; /* Highest fd in fd set */
81 };
82
83 static void *select_init (struct event_base *);
84 static int select_add (void *, struct event *);
85 static int select_del (void *, struct event *);
86 static int select_dispatch (struct event_base *, void *, struct timeval *);
87 static void select_dealloc (struct event_base *, void *);
88
89 const struct eventop selectops = {
90 "select",
91 select_init,
92 select_add,
93 select_del,
94 select_dispatch,
95 select_dealloc,
96 0
97 };
98
99 static int select_resize(struct selectop *sop, size_t fdsz);
100
101 static void *
select_init(struct event_base * base)102 select_init(struct event_base *base)
103 {
104 struct selectop *sop;
105
106 /* Disable select when this environment variable is set */
107 if (evutil_getenv("EVENT_NOSELECT"))
108 return (NULL);
109
110 if (!(sop = calloc(1, sizeof(struct selectop))))
111 return (NULL);
112
113 select_resize(sop, howmany(32 + 1, NFDBITS)*sizeof(fd_mask));
114
115 evsignal_init(base);
116
117 return (sop);
118 }
119
120 #ifdef CHECK_INVARIANTS
121 static void
check_selectop(struct selectop * sop)122 check_selectop(struct selectop *sop)
123 {
124 int i;
125 for (i = 0; i <= sop->event_fds; ++i) {
126 if (FD_ISSET(i, sop->event_readset_in)) {
127 assert(sop->event_r_by_fd[i]);
128 assert(sop->event_r_by_fd[i]->ev_events & EV_READ);
129 assert(sop->event_r_by_fd[i]->ev_fd == i);
130 } else {
131 assert(! sop->event_r_by_fd[i]);
132 }
133 if (FD_ISSET(i, sop->event_writeset_in)) {
134 assert(sop->event_w_by_fd[i]);
135 assert(sop->event_w_by_fd[i]->ev_events & EV_WRITE);
136 assert(sop->event_w_by_fd[i]->ev_fd == i);
137 } else {
138 assert(! sop->event_w_by_fd[i]);
139 }
140 }
141
142 }
143 #else
144 #define check_selectop(sop) do { (void) sop; } while (0)
145 #endif
146
147 static int
select_dispatch(struct event_base * base,void * arg,struct timeval * tv)148 select_dispatch(struct event_base *base, void *arg, struct timeval *tv)
149 {
150 int res, i, j;
151 struct selectop *sop = arg;
152
153 check_selectop(sop);
154
155 memcpy(sop->event_readset_out, sop->event_readset_in,
156 sop->event_fdsz);
157 memcpy(sop->event_writeset_out, sop->event_writeset_in,
158 sop->event_fdsz);
159
160 res = select(sop->event_fds + 1, sop->event_readset_out,
161 sop->event_writeset_out, NULL, tv);
162
163 check_selectop(sop);
164
165 if (res == -1) {
166 if (errno != EINTR) {
167 event_warn("select");
168 return (-1);
169 }
170
171 evsignal_process(base);
172 return (0);
173 } else if (base->sig.evsignal_caught) {
174 evsignal_process(base);
175 }
176
177 event_debug(("%s: select reports %d", __func__, res));
178
179 check_selectop(sop);
180 i = arc4random_uniform(sop->event_fds + 1);
181 for (j = 0; j <= sop->event_fds; ++j) {
182 struct event *r_ev = NULL, *w_ev = NULL;
183 if (++i >= sop->event_fds+1)
184 i = 0;
185
186 res = 0;
187 if (FD_ISSET(i, sop->event_readset_out)) {
188 r_ev = sop->event_r_by_fd[i];
189 res |= EV_READ;
190 }
191 if (FD_ISSET(i, sop->event_writeset_out)) {
192 w_ev = sop->event_w_by_fd[i];
193 res |= EV_WRITE;
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 check_selectop(sop);
203
204 return (0);
205 }
206
207
208 static int
select_resize(struct selectop * sop,size_t fdsz)209 select_resize(struct selectop *sop, size_t fdsz)
210 {
211 int n_events, n_events_old;
212
213 fd_set *readset_in = NULL;
214 fd_set *writeset_in = NULL;
215 fd_set *readset_out = NULL;
216 fd_set *writeset_out = NULL;
217 struct event **r_by_fd = NULL;
218 struct event **w_by_fd = NULL;
219
220 n_events = (fdsz/sizeof(fd_mask)) * NFDBITS;
221 n_events_old = (sop->event_fdsz/sizeof(fd_mask)) * NFDBITS;
222
223 if (sop->event_readset_in)
224 check_selectop(sop);
225
226 if ((readset_in = realloc(sop->event_readset_in, fdsz)) == NULL)
227 goto error;
228 sop->event_readset_in = readset_in;
229 if ((readset_out = realloc(sop->event_readset_out, fdsz)) == NULL)
230 goto error;
231 sop->event_readset_out = readset_out;
232 if ((writeset_in = realloc(sop->event_writeset_in, fdsz)) == NULL)
233 goto error;
234 sop->event_writeset_in = writeset_in;
235 if ((writeset_out = realloc(sop->event_writeset_out, fdsz)) == NULL)
236 goto error;
237 sop->event_writeset_out = writeset_out;
238 if ((r_by_fd = realloc(sop->event_r_by_fd,
239 n_events*sizeof(struct event*))) == NULL)
240 goto error;
241 sop->event_r_by_fd = r_by_fd;
242 if ((w_by_fd = realloc(sop->event_w_by_fd,
243 n_events * sizeof(struct event*))) == NULL)
244 goto error;
245 sop->event_w_by_fd = w_by_fd;
246
247 memset((char *)sop->event_readset_in + sop->event_fdsz, 0,
248 fdsz - sop->event_fdsz);
249 memset((char *)sop->event_writeset_in + sop->event_fdsz, 0,
250 fdsz - sop->event_fdsz);
251 memset(sop->event_r_by_fd + n_events_old, 0,
252 (n_events-n_events_old) * sizeof(struct event*));
253 memset(sop->event_w_by_fd + n_events_old, 0,
254 (n_events-n_events_old) * sizeof(struct event*));
255
256 sop->event_fdsz = fdsz;
257 check_selectop(sop);
258
259 return (0);
260
261 error:
262 event_warn("malloc");
263 return (-1);
264 }
265
266
267 static int
select_add(void * arg,struct event * ev)268 select_add(void *arg, struct event *ev)
269 {
270 struct selectop *sop = arg;
271
272 if (ev->ev_events & EV_SIGNAL)
273 return (evsignal_add(ev));
274
275 check_selectop(sop);
276 /*
277 * Keep track of the highest fd, so that we can calculate the size
278 * of the fd_sets for select(2)
279 */
280 if (sop->event_fds < ev->ev_fd) {
281 size_t fdsz = sop->event_fdsz;
282
283 if (fdsz < sizeof(fd_mask))
284 fdsz = sizeof(fd_mask);
285
286 while (fdsz <
287 (howmany(ev->ev_fd + 1, NFDBITS) * sizeof(fd_mask)))
288 fdsz *= 2;
289
290 if (fdsz != sop->event_fdsz) {
291 if (select_resize(sop, fdsz)) {
292 check_selectop(sop);
293 return (-1);
294 }
295 }
296
297 sop->event_fds = ev->ev_fd;
298 }
299
300 if (ev->ev_events & EV_READ) {
301 FD_SET(ev->ev_fd, sop->event_readset_in);
302 sop->event_r_by_fd[ev->ev_fd] = ev;
303 }
304 if (ev->ev_events & EV_WRITE) {
305 FD_SET(ev->ev_fd, sop->event_writeset_in);
306 sop->event_w_by_fd[ev->ev_fd] = ev;
307 }
308 check_selectop(sop);
309
310 return (0);
311 }
312
313 /*
314 * Nothing to be done here.
315 */
316
317 static int
select_del(void * arg,struct event * ev)318 select_del(void *arg, struct event *ev)
319 {
320 struct selectop *sop = arg;
321
322 check_selectop(sop);
323 if (ev->ev_events & EV_SIGNAL)
324 return (evsignal_del(ev));
325
326 if (sop->event_fds < ev->ev_fd) {
327 check_selectop(sop);
328 return (0);
329 }
330
331 if (ev->ev_events & EV_READ) {
332 FD_CLR(ev->ev_fd, sop->event_readset_in);
333 sop->event_r_by_fd[ev->ev_fd] = NULL;
334 }
335
336 if (ev->ev_events & EV_WRITE) {
337 FD_CLR(ev->ev_fd, sop->event_writeset_in);
338 sop->event_w_by_fd[ev->ev_fd] = NULL;
339 }
340
341 check_selectop(sop);
342 return (0);
343 }
344
345 static void
select_dealloc(struct event_base * base,void * arg)346 select_dealloc(struct event_base *base, void *arg)
347 {
348 struct selectop *sop = arg;
349
350 evsignal_dealloc(base);
351 if (sop->event_readset_in)
352 free(sop->event_readset_in);
353 if (sop->event_writeset_in)
354 free(sop->event_writeset_in);
355 if (sop->event_readset_out)
356 free(sop->event_readset_out);
357 if (sop->event_writeset_out)
358 free(sop->event_writeset_out);
359 if (sop->event_r_by_fd)
360 free(sop->event_r_by_fd);
361 if (sop->event_w_by_fd)
362 free(sop->event_w_by_fd);
363
364 memset(sop, 0, sizeof(struct selectop));
365 free(sop);
366 }
367