1 /* $NetBSD: select.c,v 1.5 2020/05/25 20:47:33 christos Exp $ */ 2 3 /* $OpenBSD: select.c,v 1.2 2002/06/25 15:50:15 mickey Exp $ */ 4 5 /* 6 * Copyright 2000-2007 Niels Provos <provos@citi.umich.edu> 7 * Copyright 2007-2012 Niels Provos and Nick Mathewson 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 3. The name of the author may not be used to endorse or promote products 18 * derived from this software without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 21 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 22 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 23 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 24 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 25 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 26 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 27 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 28 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 29 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 30 */ 31 #include "event2/event-config.h" 32 #include "evconfig-private.h" 33 34 #ifdef EVENT__HAVE_SELECT 35 36 #ifdef __APPLE__ 37 /* Apple wants us to define this if we might ever pass more than 38 * FD_SETSIZE bits to select(). */ 39 #define _DARWIN_UNLIMITED_SELECT 40 #endif 41 42 #include <sys/types.h> 43 #ifdef EVENT__HAVE_SYS_TIME_H 44 #include <sys/time.h> 45 #endif 46 #ifdef EVENT__HAVE_SYS_SELECT_H 47 #include <sys/select.h> 48 #endif 49 #include <sys/queue.h> 50 #include <signal.h> 51 #include <stdio.h> 52 #include <stdlib.h> 53 #include <string.h> 54 #include <unistd.h> 55 #include <errno.h> 56 57 #include "event-internal.h" 58 #include "evsignal-internal.h" 59 #include "event2/thread.h" 60 #include "evthread-internal.h" 61 #include "log-internal.h" 62 #include "evmap-internal.h" 63 64 #ifndef EVENT__HAVE_FD_MASK 65 /* This type is mandatory, but Android doesn't define it. */ 66 typedef unsigned long fd_mask; 67 #endif 68 69 #ifndef NFDBITS 70 #define NFDBITS (sizeof(fd_mask)*8) 71 #endif 72 73 /* Divide positive x by y, rounding up. */ 74 #define DIV_ROUNDUP(x, y) (((x)+((y)-1))/(y)) 75 76 /* How many bytes to allocate for N fds? */ 77 #define SELECT_ALLOC_SIZE(n) \ 78 (DIV_ROUNDUP(n, NFDBITS) * sizeof(fd_mask)) 79 80 struct selectop { 81 int event_fds; /* Highest fd in fd set */ 82 int event_fdsz; 83 int resize_out_sets; 84 fd_set *event_readset_in; 85 fd_set *event_writeset_in; 86 fd_set *event_readset_out; 87 fd_set *event_writeset_out; 88 }; 89 90 static void *select_init(struct event_base *); 91 static int select_add(struct event_base *, int, short old, short events, void*); 92 static int select_del(struct event_base *, int, short old, short events, void*); 93 static int select_dispatch(struct event_base *, struct timeval *); 94 static void select_dealloc(struct event_base *); 95 96 const struct eventop selectops = { 97 "select", 98 select_init, 99 select_add, 100 select_del, 101 select_dispatch, 102 select_dealloc, 103 0, /* doesn't need reinit. */ 104 EV_FEATURE_FDS, 105 0, 106 }; 107 108 static int select_resize(struct selectop *sop, int fdsz); 109 static void select_free_selectop(struct selectop *sop); 110 111 static void * 112 select_init(struct event_base *base) 113 { 114 struct selectop *sop; 115 116 if (!(sop = mm_calloc(1, sizeof(struct selectop)))) 117 return (NULL); 118 119 if (select_resize(sop, SELECT_ALLOC_SIZE(32 + 1))) { 120 select_free_selectop(sop); 121 return (NULL); 122 } 123 124 evsig_init_(base); 125 126 evutil_weakrand_seed_(&base->weakrand_seed, 0); 127 128 return (sop); 129 } 130 131 #ifdef CHECK_INVARIANTS 132 static void 133 check_selectop(struct selectop *sop) 134 { 135 /* nothing to be done here */ 136 } 137 #else 138 #define check_selectop(sop) do { (void) sop; } while (0) 139 #endif 140 141 static int 142 select_dispatch(struct event_base *base, struct timeval *tv) 143 { 144 int res=0, i, j, nfds; 145 struct selectop *sop = base->evbase; 146 147 check_selectop(sop); 148 if (sop->resize_out_sets) { 149 fd_set *readset_out=NULL, *writeset_out=NULL; 150 size_t sz = sop->event_fdsz; 151 if (!(readset_out = mm_realloc(sop->event_readset_out, sz))) 152 return (-1); 153 sop->event_readset_out = readset_out; 154 if (!(writeset_out = mm_realloc(sop->event_writeset_out, sz))) { 155 /* We don't free readset_out here, since it was 156 * already successfully reallocated. The next time 157 * we call select_dispatch, the realloc will be a 158 * no-op. */ 159 return (-1); 160 } 161 sop->event_writeset_out = writeset_out; 162 sop->resize_out_sets = 0; 163 } 164 165 memcpy(sop->event_readset_out, sop->event_readset_in, 166 sop->event_fdsz); 167 memcpy(sop->event_writeset_out, sop->event_writeset_in, 168 sop->event_fdsz); 169 170 nfds = sop->event_fds+1; 171 172 EVBASE_RELEASE_LOCK(base, th_base_lock); 173 174 res = select(nfds, sop->event_readset_out, 175 sop->event_writeset_out, NULL, tv); 176 177 EVBASE_ACQUIRE_LOCK(base, th_base_lock); 178 179 check_selectop(sop); 180 181 if (res == -1) { 182 if (errno != EINTR) { 183 event_warn("select"); 184 return (-1); 185 } 186 187 return (0); 188 } 189 190 event_debug(("%s: select reports %d", __func__, res)); 191 192 check_selectop(sop); 193 i = evutil_weakrand_range_(&base->weakrand_seed, nfds); 194 for (j = 0; j < nfds; ++j) { 195 if (++i >= nfds) 196 i = 0; 197 res = 0; 198 if (FD_ISSET(i, sop->event_readset_out)) 199 res |= EV_READ; 200 if (FD_ISSET(i, sop->event_writeset_out)) 201 res |= EV_WRITE; 202 203 if (res == 0) 204 continue; 205 206 evmap_io_active_(base, i, res); 207 } 208 check_selectop(sop); 209 210 return (0); 211 } 212 213 static int 214 select_resize(struct selectop *sop, int fdsz) 215 { 216 fd_set *readset_in = NULL; 217 fd_set *writeset_in = NULL; 218 219 if (sop->event_readset_in) 220 check_selectop(sop); 221 222 if ((readset_in = mm_realloc(sop->event_readset_in, fdsz)) == NULL) 223 goto error; 224 sop->event_readset_in = readset_in; 225 if ((writeset_in = mm_realloc(sop->event_writeset_in, fdsz)) == NULL) { 226 /* Note that this will leave event_readset_in expanded. 227 * That's okay; we wouldn't want to free it, since that would 228 * change the semantics of select_resize from "expand the 229 * readset_in and writeset_in, or return -1" to "expand the 230 * *set_in members, or trash them and return -1." 231 */ 232 goto error; 233 } 234 sop->event_writeset_in = writeset_in; 235 sop->resize_out_sets = 1; 236 237 memset((char *)sop->event_readset_in + sop->event_fdsz, 0, 238 fdsz - sop->event_fdsz); 239 memset((char *)sop->event_writeset_in + sop->event_fdsz, 0, 240 fdsz - sop->event_fdsz); 241 242 sop->event_fdsz = fdsz; 243 check_selectop(sop); 244 245 return (0); 246 247 error: 248 event_warn("malloc"); 249 return (-1); 250 } 251 252 253 static int 254 select_add(struct event_base *base, int fd, short old, short events, void *p) 255 { 256 struct selectop *sop = base->evbase; 257 (void) p; 258 259 EVUTIL_ASSERT((events & EV_SIGNAL) == 0); 260 check_selectop(sop); 261 /* 262 * Keep track of the highest fd, so that we can calculate the size 263 * of the fd_sets for select(2) 264 */ 265 if (sop->event_fds < fd) { 266 int fdsz = sop->event_fdsz; 267 268 if (fdsz < (int)sizeof(fd_mask)) 269 fdsz = (int)sizeof(fd_mask); 270 271 /* In theory we should worry about overflow here. In 272 * reality, though, the highest fd on a unixy system will 273 * not overflow here. XXXX */ 274 while (fdsz < (int) SELECT_ALLOC_SIZE(fd + 1)) 275 fdsz *= 2; 276 277 if (fdsz != sop->event_fdsz) { 278 if (select_resize(sop, fdsz)) { 279 check_selectop(sop); 280 return (-1); 281 } 282 } 283 284 sop->event_fds = fd; 285 } 286 287 if (events & EV_READ) 288 FD_SET(fd, sop->event_readset_in); 289 if (events & EV_WRITE) 290 FD_SET(fd, sop->event_writeset_in); 291 check_selectop(sop); 292 293 return (0); 294 } 295 296 /* 297 * Nothing to be done here. 298 */ 299 300 static int 301 select_del(struct event_base *base, int fd, short old, short events, void *p) 302 { 303 struct selectop *sop = base->evbase; 304 (void)p; 305 306 EVUTIL_ASSERT((events & EV_SIGNAL) == 0); 307 check_selectop(sop); 308 309 if (sop->event_fds < fd) { 310 check_selectop(sop); 311 return (0); 312 } 313 314 if (events & EV_READ) 315 FD_CLR(fd, sop->event_readset_in); 316 317 if (events & EV_WRITE) 318 FD_CLR(fd, sop->event_writeset_in); 319 320 check_selectop(sop); 321 return (0); 322 } 323 324 static void 325 select_free_selectop(struct selectop *sop) 326 { 327 if (sop->event_readset_in) 328 mm_free(sop->event_readset_in); 329 if (sop->event_writeset_in) 330 mm_free(sop->event_writeset_in); 331 if (sop->event_readset_out) 332 mm_free(sop->event_readset_out); 333 if (sop->event_writeset_out) 334 mm_free(sop->event_writeset_out); 335 336 memset(sop, 0, sizeof(struct selectop)); 337 mm_free(sop); 338 } 339 340 static void 341 select_dealloc(struct event_base *base) 342 { 343 evsig_dealloc_(base); 344 345 select_free_selectop(base->evbase); 346 } 347 348 #endif /* EVENT__HAVE_SELECT */ 349