1 /* $OpenBSD: select.c,v 1.2 2002/06/25 15:50:15 mickey 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 #ifndef howmany
60 #define howmany(x, y) (((x)+((y)-1))/(y))
61 #endif
62
63 #ifndef _EVENT_HAVE_FD_MASK
64 /* This type is mandatory, but Android doesn't define it. */
65 #undef NFDBITS
66 #define NFDBITS (sizeof(long)*8)
67 typedef unsigned long fd_mask;
68 #endif
69
70 struct selectop {
71 int event_fds; /* Highest fd in fd set */
72 int event_fdsz;
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 };
80
81 static void *select_init (struct event_base *);
82 static int select_add (void *, struct event *);
83 static int select_del (void *, struct event *);
84 static int select_dispatch (struct event_base *, void *, struct timeval *);
85 static void select_dealloc (struct event_base *, void *);
86
87 const struct eventop selectops = {
88 "select",
89 select_init,
90 select_add,
91 select_del,
92 select_dispatch,
93 select_dealloc,
94 0
95 };
96
97 static int select_resize(struct selectop *sop, int fdsz);
98
99 static void *
select_init(struct event_base * base)100 select_init(struct event_base *base)
101 {
102 struct selectop *sop;
103
104 /* Disable select when this environment variable is set */
105 if (evutil_getenv("EVENT_NOSELECT"))
106 return (NULL);
107
108 if (!(sop = calloc(1, sizeof(struct selectop))))
109 return (NULL);
110
111 select_resize(sop, howmany(32 + 1, NFDBITS)*sizeof(fd_mask));
112
113 evsignal_init(base);
114
115 return (sop);
116 }
117
118 #ifdef CHECK_INVARIANTS
119 static void
check_selectop(struct selectop * sop)120 check_selectop(struct selectop *sop)
121 {
122 int i;
123 for (i = 0; i <= sop->event_fds; ++i) {
124 if (FD_ISSET(i, sop->event_readset_in)) {
125 assert(sop->event_r_by_fd[i]);
126 assert(sop->event_r_by_fd[i]->ev_events & EV_READ);
127 assert(sop->event_r_by_fd[i]->ev_fd == i);
128 } else {
129 assert(! sop->event_r_by_fd[i]);
130 }
131 if (FD_ISSET(i, sop->event_writeset_in)) {
132 assert(sop->event_w_by_fd[i]);
133 assert(sop->event_w_by_fd[i]->ev_events & EV_WRITE);
134 assert(sop->event_w_by_fd[i]->ev_fd == i);
135 } else {
136 assert(! sop->event_w_by_fd[i]);
137 }
138 }
139
140 }
141 #else
142 #define check_selectop(sop) do { (void) sop; } while (0)
143 #endif
144
145 static int
select_dispatch(struct event_base * base,void * arg,struct timeval * tv)146 select_dispatch(struct event_base *base, void *arg, struct timeval *tv)
147 {
148 int res, i, j;
149 struct selectop *sop = arg;
150
151 check_selectop(sop);
152
153 memcpy(sop->event_readset_out, sop->event_readset_in,
154 sop->event_fdsz);
155 memcpy(sop->event_writeset_out, sop->event_writeset_in,
156 sop->event_fdsz);
157
158 res = select(sop->event_fds + 1, sop->event_readset_out,
159 sop->event_writeset_out, NULL, tv);
160
161 check_selectop(sop);
162
163 if (res == -1) {
164 if (errno != EINTR) {
165 event_warn("select");
166 return (-1);
167 }
168
169 evsignal_process(base);
170 return (0);
171 } else if (base->sig.evsignal_caught) {
172 evsignal_process(base);
173 }
174
175 event_debug(("%s: select reports %d", __func__, res));
176
177 check_selectop(sop);
178 i = random() % (sop->event_fds+1);
179 for (j = 0; j <= sop->event_fds; ++j) {
180 struct event *r_ev = NULL, *w_ev = NULL;
181 if (++i >= sop->event_fds+1)
182 i = 0;
183
184 res = 0;
185 if (FD_ISSET(i, sop->event_readset_out)) {
186 r_ev = sop->event_r_by_fd[i];
187 res |= EV_READ;
188 }
189 if (FD_ISSET(i, sop->event_writeset_out)) {
190 w_ev = sop->event_w_by_fd[i];
191 res |= EV_WRITE;
192 }
193 if (r_ev && (res & r_ev->ev_events)) {
194 event_active(r_ev, res & r_ev->ev_events, 1);
195 }
196 if (w_ev && w_ev != r_ev && (res & w_ev->ev_events)) {
197 event_active(w_ev, res & w_ev->ev_events, 1);
198 }
199 }
200 check_selectop(sop);
201
202 return (0);
203 }
204
205
206 static int
select_resize(struct selectop * sop,int fdsz)207 select_resize(struct selectop *sop, int fdsz)
208 {
209 int n_events, n_events_old;
210
211 fd_set *readset_in = NULL;
212 fd_set *writeset_in = NULL;
213 fd_set *readset_out = NULL;
214 fd_set *writeset_out = NULL;
215 struct event **r_by_fd = NULL;
216 struct event **w_by_fd = NULL;
217
218 n_events = (fdsz/sizeof(fd_mask)) * NFDBITS;
219 n_events_old = (sop->event_fdsz/sizeof(fd_mask)) * NFDBITS;
220
221 if (sop->event_readset_in)
222 check_selectop(sop);
223
224 if ((readset_in = realloc(sop->event_readset_in, fdsz)) == NULL)
225 goto error;
226 sop->event_readset_in = readset_in;
227 if ((readset_out = realloc(sop->event_readset_out, fdsz)) == NULL)
228 goto error;
229 sop->event_readset_out = readset_out;
230 if ((writeset_in = realloc(sop->event_writeset_in, fdsz)) == NULL)
231 goto error;
232 sop->event_writeset_in = writeset_in;
233 if ((writeset_out = realloc(sop->event_writeset_out, fdsz)) == NULL)
234 goto error;
235 sop->event_writeset_out = writeset_out;
236 if ((r_by_fd = realloc(sop->event_r_by_fd,
237 n_events*sizeof(struct event*))) == NULL)
238 goto error;
239 sop->event_r_by_fd = r_by_fd;
240 if ((w_by_fd = realloc(sop->event_w_by_fd,
241 n_events * sizeof(struct event*))) == NULL)
242 goto error;
243 sop->event_w_by_fd = w_by_fd;
244
245 memset((char *)sop->event_readset_in + sop->event_fdsz, 0,
246 fdsz - sop->event_fdsz);
247 memset((char *)sop->event_writeset_in + sop->event_fdsz, 0,
248 fdsz - sop->event_fdsz);
249 memset(sop->event_r_by_fd + n_events_old, 0,
250 (n_events-n_events_old) * sizeof(struct event*));
251 memset(sop->event_w_by_fd + n_events_old, 0,
252 (n_events-n_events_old) * sizeof(struct event*));
253
254 sop->event_fdsz = fdsz;
255 check_selectop(sop);
256
257 return (0);
258
259 error:
260 event_warn("malloc");
261 return (-1);
262 }
263
264
265 static int
select_add(void * arg,struct event * ev)266 select_add(void *arg, struct event *ev)
267 {
268 struct selectop *sop = arg;
269
270 if (ev->ev_events & EV_SIGNAL)
271 return (evsignal_add(ev));
272
273 check_selectop(sop);
274 /*
275 * Keep track of the highest fd, so that we can calculate the size
276 * of the fd_sets for select(2)
277 */
278 if (sop->event_fds < ev->ev_fd) {
279 int fdsz = sop->event_fdsz;
280
281 if (fdsz < sizeof(fd_mask))
282 fdsz = sizeof(fd_mask);
283
284 while (fdsz <
285 (howmany(ev->ev_fd + 1, NFDBITS) * sizeof(fd_mask)))
286 fdsz *= 2;
287
288 if (fdsz != sop->event_fdsz) {
289 if (select_resize(sop, fdsz)) {
290 check_selectop(sop);
291 return (-1);
292 }
293 }
294
295 sop->event_fds = ev->ev_fd;
296 }
297
298 if (ev->ev_events & EV_READ) {
299 FD_SET(ev->ev_fd, sop->event_readset_in);
300 sop->event_r_by_fd[ev->ev_fd] = ev;
301 }
302 if (ev->ev_events & EV_WRITE) {
303 FD_SET(ev->ev_fd, sop->event_writeset_in);
304 sop->event_w_by_fd[ev->ev_fd] = ev;
305 }
306 check_selectop(sop);
307
308 return (0);
309 }
310
311 /*
312 * Nothing to be done here.
313 */
314
315 static int
select_del(void * arg,struct event * ev)316 select_del(void *arg, struct event *ev)
317 {
318 struct selectop *sop = arg;
319
320 check_selectop(sop);
321 if (ev->ev_events & EV_SIGNAL)
322 return (evsignal_del(ev));
323
324 if (sop->event_fds < ev->ev_fd) {
325 check_selectop(sop);
326 return (0);
327 }
328
329 if (ev->ev_events & EV_READ) {
330 FD_CLR(ev->ev_fd, sop->event_readset_in);
331 sop->event_r_by_fd[ev->ev_fd] = NULL;
332 }
333
334 if (ev->ev_events & EV_WRITE) {
335 FD_CLR(ev->ev_fd, sop->event_writeset_in);
336 sop->event_w_by_fd[ev->ev_fd] = NULL;
337 }
338
339 check_selectop(sop);
340 return (0);
341 }
342
343 static void
select_dealloc(struct event_base * base,void * arg)344 select_dealloc(struct event_base *base, void *arg)
345 {
346 struct selectop *sop = arg;
347
348 evsignal_dealloc(base);
349 if (sop->event_readset_in)
350 free(sop->event_readset_in);
351 if (sop->event_writeset_in)
352 free(sop->event_writeset_in);
353 if (sop->event_readset_out)
354 free(sop->event_readset_out);
355 if (sop->event_writeset_out)
356 free(sop->event_writeset_out);
357 if (sop->event_r_by_fd)
358 free(sop->event_r_by_fd);
359 if (sop->event_w_by_fd)
360 free(sop->event_w_by_fd);
361
362 memset(sop, 0, sizeof(struct selectop));
363 free(sop);
364 }
365