1 /* $OpenBSD: select.c,v 1.2 2002/06/25 15:50:15 mickey Exp $ */ 2 3 /* 4 * Copyright 2000-2007 Niels Provos <provos@citi.umich.edu> 5 * Copyright 2007-2012 Niels Provos and Nick Mathewson 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 #include "event2/event-config.h" 30 #include "evconfig-private.h" 31 32 #ifdef EVENT__HAVE_SELECT 33 34 #ifdef __APPLE__ 35 /* Apple wants us to define this if we might ever pass more than 36 * FD_SETSIZE bits to select(). */ 37 #define _DARWIN_UNLIMITED_SELECT 38 #endif 39 40 #include <sys/types.h> 41 #ifdef EVENT__HAVE_SYS_TIME_H 42 #include <sys/time.h> 43 #endif 44 #ifdef EVENT__HAVE_SYS_SELECT_H 45 #include <sys/select.h> 46 #endif 47 #include <sys/queue.h> 48 #include <signal.h> 49 #include <stdio.h> 50 #include <stdlib.h> 51 #include <string.h> 52 #include <unistd.h> 53 #include <errno.h> 54 55 #include "event-internal.h" 56 #include "evsignal-internal.h" 57 #include "event2/thread.h" 58 #include "evthread-internal.h" 59 #include "log-internal.h" 60 #include "evmap-internal.h" 61 62 #ifndef EVENT__HAVE_FD_MASK 63 /* This type is mandatory, but Android doesn't define it. */ 64 typedef unsigned long fd_mask; 65 #endif 66 67 #ifndef NFDBITS 68 #define NFDBITS (sizeof(fd_mask)*8) 69 #endif 70 71 /* Divide positive x by y, rounding up. */ 72 #define DIV_ROUNDUP(x, y) (((x)+((y)-1))/(y)) 73 74 /* How many bytes to allocate for N fds? */ 75 #define SELECT_ALLOC_SIZE(n) \ 76 (DIV_ROUNDUP(n, NFDBITS) * sizeof(fd_mask)) 77 78 struct selectop { 79 int event_fds; /* Highest fd in fd set */ 80 int event_fdsz; 81 int resize_out_sets; 82 fd_set *event_readset_in; 83 fd_set *event_writeset_in; 84 fd_set *event_readset_out; 85 fd_set *event_writeset_out; 86 }; 87 88 static void *select_init(struct event_base *); 89 static int select_add(struct event_base *, int, short old, short events, void*); 90 static int select_del(struct event_base *, int, short old, short events, void*); 91 static int select_dispatch(struct event_base *, struct timeval *); 92 static void select_dealloc(struct event_base *); 93 94 const struct eventop selectops = { 95 "select", 96 select_init, 97 select_add, 98 select_del, 99 select_dispatch, 100 select_dealloc, 101 0, /* doesn't need reinit. */ 102 EV_FEATURE_FDS, 103 0, 104 }; 105 106 static int select_resize(struct selectop *sop, int fdsz); 107 static void select_free_selectop(struct selectop *sop); 108 109 static void * 110 select_init(struct event_base *base) 111 { 112 struct selectop *sop; 113 114 if (!(sop = mm_calloc(1, sizeof(struct selectop)))) 115 return (NULL); 116 117 if (select_resize(sop, SELECT_ALLOC_SIZE(32 + 1))) { 118 select_free_selectop(sop); 119 return (NULL); 120 } 121 122 evsig_init_(base); 123 124 evutil_weakrand_seed_(&base->weakrand_seed, 0); 125 126 return (sop); 127 } 128 129 #ifdef CHECK_INVARIANTS 130 static void 131 check_selectop(struct selectop *sop) 132 { 133 /* nothing to be done here */ 134 } 135 #else 136 #define check_selectop(sop) do { (void) sop; } while (0) 137 #endif 138 139 static int 140 select_dispatch(struct event_base *base, struct timeval *tv) 141 { 142 int res=0, i, j, nfds; 143 struct selectop *sop = base->evbase; 144 145 check_selectop(sop); 146 if (sop->resize_out_sets) { 147 fd_set *readset_out=NULL, *writeset_out=NULL; 148 size_t sz = sop->event_fdsz; 149 if (!(readset_out = mm_realloc(sop->event_readset_out, sz))) 150 return (-1); 151 sop->event_readset_out = readset_out; 152 if (!(writeset_out = mm_realloc(sop->event_writeset_out, sz))) { 153 /* We don't free readset_out here, since it was 154 * already successfully reallocated. The next time 155 * we call select_dispatch, the realloc will be a 156 * no-op. */ 157 return (-1); 158 } 159 sop->event_writeset_out = writeset_out; 160 sop->resize_out_sets = 0; 161 } 162 163 memcpy(sop->event_readset_out, sop->event_readset_in, 164 sop->event_fdsz); 165 memcpy(sop->event_writeset_out, sop->event_writeset_in, 166 sop->event_fdsz); 167 168 nfds = sop->event_fds+1; 169 170 EVBASE_RELEASE_LOCK(base, th_base_lock); 171 172 res = select(nfds, sop->event_readset_out, 173 sop->event_writeset_out, NULL, tv); 174 175 EVBASE_ACQUIRE_LOCK(base, th_base_lock); 176 177 check_selectop(sop); 178 179 if (res == -1) { 180 if (errno != EINTR) { 181 event_warn("select"); 182 return (-1); 183 } 184 185 return (0); 186 } 187 188 event_debug(("%s: select reports %d", __func__, res)); 189 190 check_selectop(sop); 191 i = evutil_weakrand_range_(&base->weakrand_seed, nfds); 192 for (j = 0; j < nfds; ++j) { 193 if (++i >= nfds) 194 i = 0; 195 res = 0; 196 if (FD_ISSET(i, sop->event_readset_out)) 197 res |= EV_READ; 198 if (FD_ISSET(i, sop->event_writeset_out)) 199 res |= EV_WRITE; 200 201 if (res == 0) 202 continue; 203 204 evmap_io_active_(base, i, res); 205 } 206 check_selectop(sop); 207 208 return (0); 209 } 210 211 static int 212 select_resize(struct selectop *sop, int fdsz) 213 { 214 fd_set *readset_in = NULL; 215 fd_set *writeset_in = NULL; 216 217 if (sop->event_readset_in) 218 check_selectop(sop); 219 220 if ((readset_in = mm_realloc(sop->event_readset_in, fdsz)) == NULL) 221 goto error; 222 sop->event_readset_in = readset_in; 223 if ((writeset_in = mm_realloc(sop->event_writeset_in, fdsz)) == NULL) { 224 /* Note that this will leave event_readset_in expanded. 225 * That's okay; we wouldn't want to free it, since that would 226 * change the semantics of select_resize from "expand the 227 * readset_in and writeset_in, or return -1" to "expand the 228 * *set_in members, or trash them and return -1." 229 */ 230 goto error; 231 } 232 sop->event_writeset_in = writeset_in; 233 sop->resize_out_sets = 1; 234 235 memset((char *)sop->event_readset_in + sop->event_fdsz, 0, 236 fdsz - sop->event_fdsz); 237 memset((char *)sop->event_writeset_in + sop->event_fdsz, 0, 238 fdsz - sop->event_fdsz); 239 240 sop->event_fdsz = fdsz; 241 check_selectop(sop); 242 243 return (0); 244 245 error: 246 event_warn("malloc"); 247 return (-1); 248 } 249 250 251 static int 252 select_add(struct event_base *base, int fd, short old, short events, void *p) 253 { 254 struct selectop *sop = base->evbase; 255 (void) p; 256 257 EVUTIL_ASSERT((events & EV_SIGNAL) == 0); 258 check_selectop(sop); 259 /* 260 * Keep track of the highest fd, so that we can calculate the size 261 * of the fd_sets for select(2) 262 */ 263 if (sop->event_fds < fd) { 264 int fdsz = sop->event_fdsz; 265 266 if (fdsz < (int)sizeof(fd_mask)) 267 fdsz = (int)sizeof(fd_mask); 268 269 /* In theory we should worry about overflow here. In 270 * reality, though, the highest fd on a unixy system will 271 * not overflow here. XXXX */ 272 while (fdsz < (int) SELECT_ALLOC_SIZE(fd + 1)) 273 fdsz *= 2; 274 275 if (fdsz != sop->event_fdsz) { 276 if (select_resize(sop, fdsz)) { 277 check_selectop(sop); 278 return (-1); 279 } 280 } 281 282 sop->event_fds = fd; 283 } 284 285 if (events & EV_READ) 286 FD_SET(fd, sop->event_readset_in); 287 if (events & EV_WRITE) 288 FD_SET(fd, sop->event_writeset_in); 289 check_selectop(sop); 290 291 return (0); 292 } 293 294 /* 295 * Nothing to be done here. 296 */ 297 298 static int 299 select_del(struct event_base *base, int fd, short old, short events, void *p) 300 { 301 struct selectop *sop = base->evbase; 302 (void)p; 303 304 EVUTIL_ASSERT((events & EV_SIGNAL) == 0); 305 check_selectop(sop); 306 307 if (sop->event_fds < fd) { 308 check_selectop(sop); 309 return (0); 310 } 311 312 if (events & EV_READ) 313 FD_CLR(fd, sop->event_readset_in); 314 315 if (events & EV_WRITE) 316 FD_CLR(fd, sop->event_writeset_in); 317 318 check_selectop(sop); 319 return (0); 320 } 321 322 static void 323 select_free_selectop(struct selectop *sop) 324 { 325 if (sop->event_readset_in) 326 mm_free(sop->event_readset_in); 327 if (sop->event_writeset_in) 328 mm_free(sop->event_writeset_in); 329 if (sop->event_readset_out) 330 mm_free(sop->event_readset_out); 331 if (sop->event_writeset_out) 332 mm_free(sop->event_writeset_out); 333 334 memset(sop, 0, sizeof(struct selectop)); 335 mm_free(sop); 336 } 337 338 static void 339 select_dealloc(struct event_base *base) 340 { 341 evsig_dealloc_(base); 342 343 select_free_selectop(base->evbase); 344 } 345 346 #endif /* EVENT__HAVE_SELECT */ 347