contrib/ntp/sntp/libevent/select.c

   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 */