external/bsd/libevent/dist/select.c

   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 *
 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
 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
 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
 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
 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
 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
 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
 331 select_dealloc(struct event_base *base)
 332 {
 333         evsig_dealloc(base);
 334
 335         select_free_selectop(base->evbase);
 336 }