1 /* $NetBSD: select.c,v 1.2 2013/04/11 16:56:41 christos Exp $ */
2 /* $OpenBSD: select.c,v 1.2 2002/06/25 15:50:15 mickey Exp $ */
3
4 /*
5 * Copyright 2000-2007 Niels Provos <provos@citi.umich.edu>
6 * Copyright 2007-2012 Niels Provos and Nick Mathewson
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. The name of the author may not be used to endorse or promote products
17 * derived from this software without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
20 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
21 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
22 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
23 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
24 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
28 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 */
30 #include "event2/event-config.h"
31 #include <sys/cdefs.h>
32 __RCSID("$NetBSD: select.c,v 1.2 2013/04/11 16:56:41 christos Exp $");
33
34 #include <sys/types.h>
35 #ifdef _EVENT_HAVE_SYS_TIME_H
36 #include <sys/time.h>
37 #endif
38 #ifdef _EVENT_HAVE_SYS_SELECT_H
39 #include <sys/select.h>
40 #endif
41 #include <sys/queue.h>
42 #include <signal.h>
43 #include <stdio.h>
44 #include <stdlib.h>
45 #include <string.h>
46 #include <unistd.h>
47 #include <errno.h>
48
49 #include "event-internal.h"
50 #include "evsignal-internal.h"
51 #include "event2/thread.h"
52 #include "evthread-internal.h"
53 #include "log-internal.h"
54 #include "evmap-internal.h"
55
56 #ifndef _EVENT_HAVE_FD_MASK
57 /* This type is mandatory, but Android doesn't define it. */
58 typedef unsigned long fd_mask;
59 #endif
60
61 #ifndef NFDBITS
62 #define NFDBITS (sizeof(fd_mask)*8)
63 #endif
64
65 /* Divide positive x by y, rounding up. */
66 #define DIV_ROUNDUP(x, y) (((x)+((y)-1))/(y))
67
68 /* How many bytes to allocate for N fds? */
69 #define SELECT_ALLOC_SIZE(n) \
70 (DIV_ROUNDUP(n, NFDBITS) * sizeof(fd_mask))
71
72 struct selectop {
73 int event_fds; /* Highest fd in fd set */
74 int event_fdsz;
75 int resize_out_sets;
76 fd_set *event_readset_in;
77 fd_set *event_writeset_in;
78 fd_set *event_readset_out;
79 fd_set *event_writeset_out;
80 };
81
82 static void *select_init(struct event_base *);
83 static int select_add(struct event_base *, int, short old, short events, void*);
84 static int select_del(struct event_base *, int, short old, short events, void*);
85 static int select_dispatch(struct event_base *, struct timeval *);
86 static void select_dealloc(struct event_base *);
87
88 const struct eventop selectops = {
89 "select",
90 select_init,
91 select_add,
92 select_del,
93 select_dispatch,
94 select_dealloc,
95 0, /* doesn't need reinit. */
96 EV_FEATURE_FDS,
97 0,
98 };
99
100 static int select_resize(struct selectop *sop, int fdsz);
101 static void select_free_selectop(struct selectop *sop);
102
103 static void *
select_init(struct event_base * base)104 select_init(struct event_base *base)
105 {
106 struct selectop *sop;
107
108 if (!(sop = mm_calloc(1, sizeof(struct selectop))))
109 return (NULL);
110
111 if (select_resize(sop, SELECT_ALLOC_SIZE(32 + 1))) {
112 select_free_selectop(sop);
113 return (NULL);
114 }
115
116 evsig_init(base);
117
118 return (sop);
119 }
120
121 #ifdef CHECK_INVARIANTS
122 static void
check_selectop(struct selectop * sop)123 check_selectop(struct selectop *sop)
124 {
125 /* nothing to be done here */
126 }
127 #else
128 #define check_selectop(sop) do { (void) sop; } while (/*CONSTCOND*/0)
129 #endif
130
131 static int
select_dispatch(struct event_base * base,struct timeval * tv)132 select_dispatch(struct event_base *base, struct timeval *tv)
133 {
134 int res=0, i, j, nfds;
135 struct selectop *sop = base->evbase;
136
137 check_selectop(sop);
138 if (sop->resize_out_sets) {
139 fd_set *readset_out=NULL, *writeset_out=NULL;
140 size_t sz = sop->event_fdsz;
141 if (!(readset_out = mm_realloc(sop->event_readset_out, sz)))
142 return (-1);
143 sop->event_readset_out = readset_out;
144 if (!(writeset_out = mm_realloc(sop->event_writeset_out, sz))) {
145 /* We don't free readset_out here, since it was
146 * already successfully reallocated. The next time
147 * we call select_dispatch, the realloc will be a
148 * no-op. */
149 return (-1);
150 }
151 sop->event_writeset_out = writeset_out;
152 sop->resize_out_sets = 0;
153 }
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 nfds = sop->event_fds+1;
161
162 EVBASE_RELEASE_LOCK(base, th_base_lock);
163
164 res = select(nfds, sop->event_readset_out,
165 sop->event_writeset_out, NULL, tv);
166
167 EVBASE_ACQUIRE_LOCK(base, th_base_lock);
168
169 check_selectop(sop);
170
171 if (res == -1) {
172 if (errno != EINTR) {
173 event_warn("select");
174 return (-1);
175 }
176
177 return (0);
178 }
179
180 event_debug(("%s: select reports %d", __func__, res));
181
182 check_selectop(sop);
183 i = random() % nfds;
184 for (j = 0; j < nfds; ++j) {
185 if (++i >= nfds)
186 i = 0;
187 res = 0;
188 if (FD_ISSET(i, sop->event_readset_out))
189 res |= EV_READ;
190 if (FD_ISSET(i, sop->event_writeset_out))
191 res |= EV_WRITE;
192
193 if (res == 0)
194 continue;
195
196 evmap_io_active(base, i, res);
197 }
198 check_selectop(sop);
199
200 return (0);
201 }
202
203 static int
select_resize(struct selectop * sop,int fdsz)204 select_resize(struct selectop *sop, int fdsz)
205 {
206 fd_set *readset_in = NULL;
207 fd_set *writeset_in = NULL;
208
209 if (sop->event_readset_in)
210 check_selectop(sop);
211
212 if ((readset_in = mm_realloc(sop->event_readset_in, fdsz)) == NULL)
213 goto error;
214 sop->event_readset_in = readset_in;
215 if ((writeset_in = mm_realloc(sop->event_writeset_in, fdsz)) == NULL) {
216 /* Note that this will leave event_readset_in expanded.
217 * That's okay; we wouldn't want to free it, since that would
218 * change the semantics of select_resize from "expand the
219 * readset_in and writeset_in, or return -1" to "expand the
220 * *set_in members, or trash them and return -1."
221 */
222 goto error;
223 }
224 sop->event_writeset_in = writeset_in;
225 sop->resize_out_sets = 1;
226
227 memset((char *)sop->event_readset_in + sop->event_fdsz, 0,
228 fdsz - sop->event_fdsz);
229 memset((char *)sop->event_writeset_in + sop->event_fdsz, 0,
230 fdsz - sop->event_fdsz);
231
232 sop->event_fdsz = fdsz;
233 check_selectop(sop);
234
235 return (0);
236
237 error:
238 event_warn("malloc");
239 return (-1);
240 }
241
242
243 static int
select_add(struct event_base * base,int fd,short old,short events,void * p)244 select_add(struct event_base *base, int fd, short old, short events, void *p)
245 {
246 struct selectop *sop = base->evbase;
247 (void) p;
248
249 EVUTIL_ASSERT((events & EV_SIGNAL) == 0);
250 check_selectop(sop);
251 /*
252 * Keep track of the highest fd, so that we can calculate the size
253 * of the fd_sets for select(2)
254 */
255 if (sop->event_fds < fd) {
256 int fdsz = sop->event_fdsz;
257
258 if (fdsz < (int)sizeof(fd_mask))
259 fdsz = (int)sizeof(fd_mask);
260
261 /* In theory we should worry about overflow here. In
262 * reality, though, the highest fd on a unixy system will
263 * not overflow here. XXXX */
264 while (fdsz < (int) SELECT_ALLOC_SIZE(fd + 1))
265 fdsz *= 2;
266
267 if (fdsz != sop->event_fdsz) {
268 if (select_resize(sop, fdsz)) {
269 check_selectop(sop);
270 return (-1);
271 }
272 }
273
274 sop->event_fds = fd;
275 }
276
277 if (events & EV_READ)
278 FD_SET(fd, sop->event_readset_in);
279 if (events & EV_WRITE)
280 FD_SET(fd, sop->event_writeset_in);
281 check_selectop(sop);
282
283 return (0);
284 }
285
286 /*
287 * Nothing to be done here.
288 */
289
290 static int
select_del(struct event_base * base,int fd,short old,short events,void * p)291 select_del(struct event_base *base, int fd, short old, short events, void *p)
292 {
293 struct selectop *sop = base->evbase;
294 (void)p;
295
296 EVUTIL_ASSERT((events & EV_SIGNAL) == 0);
297 check_selectop(sop);
298
299 if (sop->event_fds < fd) {
300 check_selectop(sop);
301 return (0);
302 }
303
304 if (events & EV_READ)
305 FD_CLR(fd, sop->event_readset_in);
306
307 if (events & EV_WRITE)
308 FD_CLR(fd, sop->event_writeset_in);
309
310 check_selectop(sop);
311 return (0);
312 }
313
314 static void
select_free_selectop(struct selectop * sop)315 select_free_selectop(struct selectop *sop)
316 {
317 if (sop->event_readset_in)
318 mm_free(sop->event_readset_in);
319 if (sop->event_writeset_in)
320 mm_free(sop->event_writeset_in);
321 if (sop->event_readset_out)
322 mm_free(sop->event_readset_out);
323 if (sop->event_writeset_out)
324 mm_free(sop->event_writeset_out);
325
326 memset(sop, 0, sizeof(struct selectop));
327 mm_free(sop);
328 }
329
330 static void
select_dealloc(struct event_base * base)331 select_dealloc(struct event_base *base)
332 {
333 evsig_dealloc(base);
334
335 select_free_selectop(base->evbase);
336 }
337