lib/libevent/poll.c

   1 /*      $NetBSD: poll.c,v 1.7 2008/05/16 20:24:58 peter Exp $   */
   2 /*      $OpenBSD: poll.c,v 1.2 2002/06/25 15:50:15 mickey Exp $ */
   3
   4 /*
   5  * Copyright 2000-2003 Niels Provos <provos@citi.umich.edu>
   6  * All rights reserved.
   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. All advertising materials mentioning features or use of this software
  17  *    must display the following acknowledgement:
  18  *      This product includes software developed by Niels Provos.
  19  * 4. The name of the author may not be used to endorse or promote products
  20  *    derived from this software without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  23  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  24  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  25  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  26  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  27  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  28  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  29  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  30  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  31  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  32  */
  33 #include "config.h"
  34
  35 #include <sys/types.h>
  36 #ifdef HAVE_SYS_TIME_H
  37 #include <sys/time.h>
  38 #else
  39 #include <sys/_time.h>
  40 #endif
  41 #include <sys/queue.h>
  42 #include <poll.h>
  43 #include <signal.h>
  44 #include <stdio.h>
  45 #include <stdlib.h>
  46 #include <string.h>
  47 #include <unistd.h>
  48 #include <errno.h>
  49 #ifdef CHECK_INVARIANTS
  50 #include <assert.h>
  51 #endif
  52
  53 #include "event.h"
  54 #include "event-internal.h"
  55 #include "evsignal.h"
  56 #include "log.h"
  57
  58 struct pollop {
  59         int event_count;                /* Highest number alloc */
  60         int nfds;                       /* Size of event_* */
  61         int fd_count;                   /* Size of idxplus1_by_fd */
  62         struct pollfd *event_set;
  63         struct event **event_r_back;
  64         struct event **event_w_back;
  65         int *idxplus1_by_fd; /* Index into event_set by fd; we add 1 so
  66                               * that 0 (which is easy to memset) can mean
  67                               * "no entry." */
  68 };
  69
  70 static void *poll_init  (struct event_base *);
  71 static int poll_add             (void *, struct event *);
  72 static int poll_del             (void *, struct event *);
  73 static int poll_dispatch        (struct event_base *, void *, struct timeval *);
  74 static void poll_dealloc        (struct event_base *, void *);
  75
  76 const struct eventop pollops = {
  77         "poll",
  78         poll_init,
  79         poll_add,
  80         poll_del,
  81         poll_dispatch,
  82         poll_dealloc,
  83     0
  84 };
  85
  86 static void *
  87 poll_init(struct event_base *base)
  88 {
  89         struct pollop *pollop;
  90
  91         /* Disable poll when this environment variable is set */
  92         if (getenv("EVENT_NOPOLL"))
  93                 return (NULL);
  94
  95         if (!(pollop = calloc(1, sizeof(struct pollop))))
  96                 return (NULL);
  97
  98         evsignal_init(base);
  99
 100         return (pollop);
 101 }
 102
 103 #ifdef CHECK_INVARIANTS
 104 static void
 105 poll_check_ok(struct pollop *pop)
 106 {
 107         int i, idx;
 108         struct event *ev;
 109
 110         for (i = 0; i < pop->fd_count; ++i) {
 111                 idx = pop->idxplus1_by_fd[i]-1;
 112                 if (idx < 0)
 113                         continue;
 114                 assert(pop->event_set[idx].fd == i);
 115                 if (pop->event_set[idx].events & POLLIN) {
 116                         ev = pop->event_r_back[idx];
 117                         assert(ev);
 118                         assert(ev->ev_events & EV_READ);
 119                         assert(ev->ev_fd == i);
 120                 }
 121                 if (pop->event_set[idx].events & POLLOUT) {
 122                         ev = pop->event_w_back[idx];
 123                         assert(ev);
 124                         assert(ev->ev_events & EV_WRITE);
 125                         assert(ev->ev_fd == i);
 126                 }
 127         }
 128         for (i = 0; i < pop->nfds; ++i) {
 129                 struct pollfd *pfd = &pop->event_set[i];
 130                 assert(pop->idxplus1_by_fd[pfd->fd] == i+1);
 131         }
 132 }
 133 #else
 134 #define poll_check_ok(pop)
 135 #endif
 136
 137 static int
 138 poll_dispatch(struct event_base *base, void *arg, struct timeval *tv)
 139 {
 140         int res, i, msec = -1, nfds;
 141         struct pollop *pop = arg;
 142
 143         poll_check_ok(pop);
 144
 145         if (tv != NULL)
 146                 msec = tv->tv_sec * 1000 + (tv->tv_usec + 999) / 1000;
 147
 148         nfds = pop->nfds;
 149         res = poll(pop->event_set, nfds, msec);
 150
 151         if (res == -1) {
 152                 if (errno != EINTR) {
 153                         event_warn("poll");
 154                         return (-1);
 155                 }
 156
 157                 evsignal_process(base);
 158                 return (0);
 159         } else if (base->sig.evsignal_caught) {
 160                 evsignal_process(base);
 161         }
 162
 163         event_debug(("%s: poll reports %d", __func__, res));
 164
 165         if (res == 0)
 166                 return (0);
 167
 168         for (i = 0; i < nfds; i++) {
 169                 int what = pop->event_set[i].revents;
 170                 struct event *r_ev = NULL, *w_ev = NULL;
 171                 if (!what)
 172                         continue;
 173
 174                 res = 0;
 175
 176                 /* If the file gets closed notify */
 177                 if (what & (POLLHUP|POLLERR))
 178                         what |= POLLIN|POLLOUT;
 179                 if (what & POLLIN) {
 180                         res |= EV_READ;
 181                         r_ev = pop->event_r_back[i];
 182                 }
 183                 if (what & POLLOUT) {
 184                         res |= EV_WRITE;
 185                         w_ev = pop->event_w_back[i];
 186                 }
 187                 if (res == 0)
 188                         continue;
 189
 190                 if (r_ev && (res & r_ev->ev_events)) {
 191                         event_active(r_ev, res & r_ev->ev_events, 1);
 192                 }
 193                 if (w_ev && w_ev != r_ev && (res & w_ev->ev_events)) {
 194                         event_active(w_ev, res & w_ev->ev_events, 1);
 195                 }
 196         }
 197
 198         return (0);
 199 }
 200
 201 static int
 202 poll_add(void *arg, struct event *ev)
 203 {
 204         struct pollop *pop = arg;
 205         struct pollfd *pfd = NULL;
 206         int i;
 207
 208         if (ev->ev_events & EV_SIGNAL)
 209                 return (evsignal_add(ev));
 210         if (!(ev->ev_events & (EV_READ|EV_WRITE)))
 211                 return (0);
 212
 213         poll_check_ok(pop);
 214         if (pop->nfds + 1 >= pop->event_count) {
 215                 struct pollfd *tmp_event_set;
 216                 struct event **tmp_event_r_back;
 217                 struct event **tmp_event_w_back;
 218                 int tmp_event_count;
 219
 220                 if (pop->event_count < 32)
 221                         tmp_event_count = 32;
 222                 else
 223                         tmp_event_count = pop->event_count * 2;
 224
 225                 /* We need more file descriptors */
 226                 tmp_event_set = realloc(pop->event_set,
 227                                  tmp_event_count * sizeof(struct pollfd));
 228                 if (tmp_event_set == NULL) {
 229                         event_warn("realloc");
 230                         return (-1);
 231                 }
 232                 pop->event_set = tmp_event_set;
 233
 234                 tmp_event_r_back = realloc(pop->event_r_back,
 235                             tmp_event_count * sizeof(struct event *));
 236                 if (tmp_event_r_back == NULL) {
 237                         /* event_set overallocated; that's okay. */
 238                         event_warn("realloc");
 239                         return (-1);
 240                 }
 241                 pop->event_r_back = tmp_event_r_back;
 242
 243                 tmp_event_w_back = realloc(pop->event_w_back,
 244                             tmp_event_count * sizeof(struct event *));
 245                 if (tmp_event_w_back == NULL) {
 246                         /* event_set and event_r_back overallocated; that's
 247                          * okay. */
 248                         event_warn("realloc");
 249                         return (-1);
 250                 }
 251                 pop->event_w_back = tmp_event_w_back;
 252
 253                 pop->event_count = tmp_event_count;
 254         }
 255         if (ev->ev_fd >= pop->fd_count) {
 256                 int *tmp_idxplus1_by_fd;
 257                 int new_count;
 258                 if (pop->fd_count < 32)
 259                         new_count = 32;
 260                 else
 261                         new_count = pop->fd_count * 2;
 262                 while (new_count <= ev->ev_fd)
 263                         new_count *= 2;
 264                 tmp_idxplus1_by_fd =
 265                         realloc(pop->idxplus1_by_fd, new_count * sizeof(int));
 266                 if (tmp_idxplus1_by_fd == NULL) {
 267                         event_warn("realloc");
 268                         return (-1);
 269                 }
 270                 pop->idxplus1_by_fd = tmp_idxplus1_by_fd;
 271                 memset(pop->idxplus1_by_fd + pop->fd_count,
 272                        0, sizeof(int)*(new_count - pop->fd_count));
 273                 pop->fd_count = new_count;
 274         }
 275
 276         i = pop->idxplus1_by_fd[ev->ev_fd] - 1;
 277         if (i >= 0) {
 278                 pfd = &pop->event_set[i];
 279         } else {
 280                 i = pop->nfds++;
 281                 pfd = &pop->event_set[i];
 282                 pfd->events = 0;
 283                 pfd->fd = ev->ev_fd;
 284                 pop->event_w_back[i] = pop->event_r_back[i] = NULL;
 285                 pop->idxplus1_by_fd[ev->ev_fd] = i + 1;
 286         }
 287
 288         pfd->revents = 0;
 289         if (ev->ev_events & EV_WRITE) {
 290                 pfd->events |= POLLOUT;
 291                 pop->event_w_back[i] = ev;
 292         }
 293         if (ev->ev_events & EV_READ) {
 294                 pfd->events |= POLLIN;
 295                 pop->event_r_back[i] = ev;
 296         }
 297         poll_check_ok(pop);
 298
 299         return (0);
 300 }
 301
 302 /*
 303  * Nothing to be done here.
 304  */
 305
 306 static int
 307 poll_del(void *arg, struct event *ev)
 308 {
 309         struct pollop *pop = arg;
 310         struct pollfd *pfd = NULL;
 311         int i;
 312
 313         if (ev->ev_events & EV_SIGNAL)
 314                 return (evsignal_del(ev));
 315
 316         if (!(ev->ev_events & (EV_READ|EV_WRITE)))
 317                 return (0);
 318
 319         poll_check_ok(pop);
 320         i = pop->idxplus1_by_fd[ev->ev_fd] - 1;
 321         if (i < 0)
 322                 return (-1);
 323
 324         /* Do we still want to read or write? */
 325         pfd = &pop->event_set[i];
 326         if (ev->ev_events & EV_READ) {
 327                 pfd->events &= ~POLLIN;
 328                 pop->event_r_back[i] = NULL;
 329         }
 330         if (ev->ev_events & EV_WRITE) {
 331                 pfd->events &= ~POLLOUT;
 332                 pop->event_w_back[i] = NULL;
 333         }
 334         poll_check_ok(pop);
 335         if (pfd->events)
 336                 /* Another event cares about that fd. */
 337                 return (0);
 338
 339         /* Okay, so we aren't interested in that fd anymore. */
 340         pop->idxplus1_by_fd[ev->ev_fd] = 0;
 341
 342         --pop->nfds;
 343         if (i != pop->nfds) {
 344                 /*
 345                  * Shift the last pollfd down into the now-unoccupied
 346                  * position.
 347                  */
 348                 memcpy(&pop->event_set[i], &pop->event_set[pop->nfds],
 349                        sizeof(struct pollfd));
 350                 pop->event_r_back[i] = pop->event_r_back[pop->nfds];
 351                 pop->event_w_back[i] = pop->event_w_back[pop->nfds];
 352                 pop->idxplus1_by_fd[pop->event_set[i].fd] = i + 1;
 353         }
 354
 355         poll_check_ok(pop);
 356         return (0);
 357 }
 358
 359 static void
 360 poll_dealloc(struct event_base *base, void *arg)
 361 {
 362         struct pollop *pop = arg;
 363
 364         evsignal_dealloc(base);
 365         if (pop->event_set)
 366                 free(pop->event_set);
 367         if (pop->event_r_back)
 368                 free(pop->event_r_back);
 369         if (pop->event_w_back)
 370                 free(pop->event_w_back);
 371         if (pop->idxplus1_by_fd)
 372                 free(pop->idxplus1_by_fd);
 373
 374         memset(pop, 0, sizeof(struct pollop));
 375         free(pop);
 376 }