release/src/router/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 2007-2010 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
  31 #include <sys/types.h>
  32 #ifdef _EVENT_HAVE_SYS_TIME_H
  33 #include <sys/time.h>
  34 #endif
  35 #ifdef _EVENT_HAVE_SYS_SELECT_H
  36 #include <sys/select.h>
  37 #endif
  38 #include <sys/queue.h>
  39 #include <signal.h>
  40 #include <stdio.h>
  41 #include <stdlib.h>
  42 #include <string.h>
  43 #include <unistd.h>
  44 #include <errno.h>
  45
  46 #include "event-internal.h"
  47 #include "evsignal-internal.h"
  48 #include "event2/thread.h"
  49 #include "evthread-internal.h"
  50 #include "log-internal.h"
  51 #include "evmap-internal.h"
  52
  53 #ifndef howmany
  54 #define howmany(x, y)   (((x)+((y)-1))/(y))
  55 #endif
  56
  57 #ifndef _EVENT_HAVE_FD_MASK
  58 /* This type is mandatory, but Android doesn't define it. */
  59 #undef NFDBITS
  60 #define NFDBITS (sizeof(long)*8)
  61 typedef unsigned long fd_mask;
  62 #endif
  63
  64 struct selectop {
  65         int event_fds;          /* Highest fd in fd set */
  66         int event_fdsz;
  67         int resize_out_sets;
  68         fd_set *event_readset_in;
  69         fd_set *event_writeset_in;
  70         fd_set *event_readset_out;
  71         fd_set *event_writeset_out;
  72 };
  73
  74 static void *select_init(struct event_base *);
  75 static int select_add(struct event_base *, int, short old, short events, void*);
  76 static int select_del(struct event_base *, int, short old, short events, void*);
  77 static int select_dispatch(struct event_base *, struct timeval *);
  78 static void select_dealloc(struct event_base *);
  79
  80 const struct eventop selectops = {
  81         "select",
  82         select_init,
  83         select_add,
  84         select_del,
  85         select_dispatch,
  86         select_dealloc,
  87         0, /* doesn't need reinit. */
  88         EV_FEATURE_FDS,
  89         0,
  90 };
  91
  92 static int select_resize(struct selectop *sop, int fdsz);
  93
  94 static void *
  95 select_init(struct event_base *base)
  96 {
  97         struct selectop *sop;
  98
  99         if (!(sop = mm_calloc(1, sizeof(struct selectop))))
 100                 return (NULL);
 101
 102         select_resize(sop, howmany(32 + 1, NFDBITS)*sizeof(fd_mask));
 103
 104         evsig_init(base);
 105
 106         return (sop);
 107 }
 108
 109 #ifdef CHECK_INVARIANTS
 110 static void
 111 check_selectop(struct selectop *sop)
 112 {
 113         /* nothing to be done here */
 114 }
 115 #else
 116 #define check_selectop(sop) do { (void) sop; } while (0)
 117 #endif
 118
 119 static int
 120 select_dispatch(struct event_base *base, struct timeval *tv)
 121 {
 122         int res=0, i, j, nfds;
 123         struct selectop *sop = base->evbase;
 124
 125         check_selectop(sop);
 126         if (sop->resize_out_sets) {
 127                 fd_set *readset_out=NULL, *writeset_out=NULL;
 128                 size_t sz = sop->event_fdsz;
 129                 if (!(readset_out = mm_realloc(sop->event_readset_out, sz)))
 130                         return (-1);
 131                 if (!(writeset_out = mm_realloc(sop->event_writeset_out, sz))) {
 132                         mm_free(readset_out);
 133                         return (-1);
 134                 }
 135                 sop->event_readset_out = readset_out;
 136                 sop->event_writeset_out = writeset_out;
 137                 sop->resize_out_sets = 0;
 138         }
 139
 140         memcpy(sop->event_readset_out, sop->event_readset_in,
 141                sop->event_fdsz);
 142         memcpy(sop->event_writeset_out, sop->event_writeset_in,
 143                sop->event_fdsz);
 144
 145         nfds = sop->event_fds+1;
 146
 147         EVBASE_RELEASE_LOCK(base, th_base_lock);
 148
 149         res = select(nfds, sop->event_readset_out,
 150             sop->event_writeset_out, NULL, tv);
 151
 152         EVBASE_ACQUIRE_LOCK(base, th_base_lock);
 153
 154         check_selectop(sop);
 155
 156         if (res == -1) {
 157                 if (errno != EINTR) {
 158                         event_warn("select");
 159                         return (-1);
 160                 }
 161
 162                 return (0);
 163         }
 164
 165         event_debug(("%s: select reports %d", __func__, res));
 166
 167         check_selectop(sop);
 168         i = random() % (nfds+1);
 169         for (j = 0; j <= nfds; ++j) {
 170                 if (++i >= nfds+1)
 171                         i = 0;
 172                 res = 0;
 173                 if (FD_ISSET(i, sop->event_readset_out))
 174                         res |= EV_READ;
 175                 if (FD_ISSET(i, sop->event_writeset_out))
 176                         res |= EV_WRITE;
 177
 178                 if (res == 0)
 179                         continue;
 180
 181                 evmap_io_active(base, i, res);
 182         }
 183         check_selectop(sop);
 184
 185         return (0);
 186 }
 187
 188
 189 static int
 190 select_resize(struct selectop *sop, int fdsz)
 191 {
 192         fd_set *readset_in = NULL;
 193         fd_set *writeset_in = NULL;
 194
 195         if (sop->event_readset_in)
 196                 check_selectop(sop);
 197
 198         if ((readset_in = mm_realloc(sop->event_readset_in, fdsz)) == NULL)
 199                 goto error;
 200         sop->event_readset_in = readset_in;
 201         if ((writeset_in = mm_realloc(sop->event_writeset_in, fdsz)) == NULL)
 202                 goto error;
 203         sop->event_writeset_in = writeset_in;
 204         sop->resize_out_sets = 1;
 205
 206         memset((char *)sop->event_readset_in + sop->event_fdsz, 0,
 207             fdsz - sop->event_fdsz);
 208         memset((char *)sop->event_writeset_in + sop->event_fdsz, 0,
 209             fdsz - sop->event_fdsz);
 210
 211         sop->event_fdsz = fdsz;
 212         check_selectop(sop);
 213
 214         return (0);
 215
 216  error:
 217         event_warn("malloc");
 218         return (-1);
 219 }
 220
 221
 222 static int
 223 select_add(struct event_base *base, int fd, short old, short events, void *p)
 224 {
 225         struct selectop *sop = base->evbase;
 226         (void) p;
 227
 228         EVUTIL_ASSERT((events & EV_SIGNAL) == 0);
 229         check_selectop(sop);
 230         /*
 231          * Keep track of the highest fd, so that we can calculate the size
 232          * of the fd_sets for select(2)
 233          */
 234         if (sop->event_fds < fd) {
 235                 int fdsz = sop->event_fdsz;
 236
 237                 if (fdsz < (int)sizeof(fd_mask))
 238                         fdsz = (int)sizeof(fd_mask);
 239
 240                 /* In theory we should worry about overflow here.  In
 241                  * reality, though, the highest fd on a unixy system will
 242                  * not overflow here. XXXX */
 243                 while (fdsz <
 244                     (int) (howmany(fd + 1, NFDBITS) * sizeof(fd_mask)))
 245                         fdsz *= 2;
 246
 247                 if (fdsz != sop->event_fdsz) {
 248                         if (select_resize(sop, fdsz)) {
 249                                 check_selectop(sop);
 250                                 return (-1);
 251                         }
 252                 }
 253
 254                 sop->event_fds = fd;
 255         }
 256
 257         if (events & EV_READ)
 258                 FD_SET(fd, sop->event_readset_in);
 259         if (events & EV_WRITE)
 260                 FD_SET(fd, sop->event_writeset_in);
 261         check_selectop(sop);
 262
 263         return (0);
 264 }
 265
 266 /*
 267  * Nothing to be done here.
 268  */
 269
 270 static int
 271 select_del(struct event_base *base, int fd, short old, short events, void *p)
 272 {
 273         struct selectop *sop = base->evbase;
 274         (void)p;
 275
 276         EVUTIL_ASSERT((events & EV_SIGNAL) == 0);
 277         check_selectop(sop);
 278
 279         if (sop->event_fds < fd) {
 280                 check_selectop(sop);
 281                 return (0);
 282         }
 283
 284         if (events & EV_READ)
 285                 FD_CLR(fd, sop->event_readset_in);
 286
 287         if (events & EV_WRITE)
 288                 FD_CLR(fd, sop->event_writeset_in);
 289
 290         check_selectop(sop);
 291         return (0);
 292 }
 293
 294 static void
 295 select_dealloc(struct event_base *base)
 296 {
 297         struct selectop *sop = base->evbase;
 298
 299         evsig_dealloc(base);
 300         if (sop->event_readset_in)
 301                 mm_free(sop->event_readset_in);
 302         if (sop->event_writeset_in)
 303                 mm_free(sop->event_writeset_in);
 304         if (sop->event_readset_out)
 305                 mm_free(sop->event_readset_out);
 306         if (sop->event_writeset_out)
 307                 mm_free(sop->event_writeset_out);
 308
 309         memset(sop, 0, sizeof(struct selectop));
 310         mm_free(sop);
 311 }