release/src/router/dnscrypt/src/libevent/devpoll.c

   1 /*
   2  * Copyright 2000-2009 Niels Provos <provos@citi.umich.edu>
   3  * Copyright 2009-2012 Niels Provos and Nick Mathewson
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. The name of the author may not be used to endorse or promote products
  14  *    derived from this software without specific prior written permission.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  17  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  18  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  19  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  20  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  21  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  22  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  23  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  24  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  25  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  26  */
  27 #include "event2/event-config.h"
  28
  29 #include <sys/types.h>
  30 #include <sys/resource.h>
  31 #ifdef _EVENT_HAVE_SYS_TIME_H
  32 #include <sys/time.h>
  33 #endif
  34 #include <sys/queue.h>
  35 #include <sys/devpoll.h>
  36 #include <signal.h>
  37 #include <stdio.h>
  38 #include <stdlib.h>
  39 #include <string.h>
  40 #include <unistd.h>
  41 #include <fcntl.h>
  42 #include <errno.h>
  43
  44 #include "event2/event.h"
  45 #include "event2/event_struct.h"
  46 #include "event2/thread.h"
  47 #include "event-internal.h"
  48 #include "evsignal-internal.h"
  49 #include "log-internal.h"
  50 #include "evmap-internal.h"
  51 #include "evthread-internal.h"
  52
  53 struct devpollop {
  54         struct pollfd *events;
  55         int nevents;
  56         int dpfd;
  57         struct pollfd *changes;
  58         int nchanges;
  59 };
  60
  61 static void *devpoll_init(struct event_base *);
  62 static int devpoll_add(struct event_base *, int fd, short old, short events, void *);
  63 static int devpoll_del(struct event_base *, int fd, short old, short events, void *);
  64 static int devpoll_dispatch(struct event_base *, struct timeval *);
  65 static void devpoll_dealloc(struct event_base *);
  66
  67 const struct eventop devpollops = {
  68         "devpoll",
  69         devpoll_init,
  70         devpoll_add,
  71         devpoll_del,
  72         devpoll_dispatch,
  73         devpoll_dealloc,
  74         1, /* need reinit */
  75         EV_FEATURE_FDS|EV_FEATURE_O1,
  76         0
  77 };
  78
  79 #define NEVENT  32000
  80
  81 static int
  82 devpoll_commit(struct devpollop *devpollop)
  83 {
  84         /*
  85          * Due to a bug in Solaris, we have to use pwrite with an offset of 0.
  86          * Write is limited to 2GB of data, until it will fail.
  87          */
  88         if (pwrite(devpollop->dpfd, devpollop->changes,
  89                 sizeof(struct pollfd) * devpollop->nchanges, 0) == -1)
  90                 return (-1);
  91
  92         devpollop->nchanges = 0;
  93         return (0);
  94 }
  95
  96 static int
  97 devpoll_queue(struct devpollop *devpollop, int fd, int events) {
  98         struct pollfd *pfd;
  99
 100         if (devpollop->nchanges >= devpollop->nevents) {
 101                 /*
 102                  * Change buffer is full, must commit it to /dev/poll before
 103                  * adding more
 104                  */
 105                 if (devpoll_commit(devpollop) != 0)
 106                         return (-1);
 107         }
 108
 109         pfd = &devpollop->changes[devpollop->nchanges++];
 110         pfd->fd = fd;
 111         pfd->events = events;
 112         pfd->revents = 0;
 113
 114         return (0);
 115 }
 116
 117 static void *
 118 devpoll_init(struct event_base *base)
 119 {
 120         int dpfd, nfiles = NEVENT;
 121         struct rlimit rl;
 122         struct devpollop *devpollop;
 123
 124         if (!(devpollop = mm_calloc(1, sizeof(struct devpollop))))
 125                 return (NULL);
 126
 127         if (getrlimit(RLIMIT_NOFILE, &rl) == 0 &&
 128             rl.rlim_cur != RLIM_INFINITY)
 129                 nfiles = rl.rlim_cur;
 130
 131         /* Initialize the kernel queue */
 132         if ((dpfd = evutil_open_closeonexec("/dev/poll", O_RDWR, 0)) == -1) {
 133                 event_warn("open: /dev/poll");
 134                 mm_free(devpollop);
 135                 return (NULL);
 136         }
 137
 138         devpollop->dpfd = dpfd;
 139
 140         /* Initialize fields */
 141         /* FIXME: allocating 'nfiles' worth of space here can be
 142          * expensive and unnecessary.  See how epoll.c does it instead. */
 143         devpollop->events = mm_calloc(nfiles, sizeof(struct pollfd));
 144         if (devpollop->events == NULL) {
 145                 mm_free(devpollop);
 146                 close(dpfd);
 147                 return (NULL);
 148         }
 149         devpollop->nevents = nfiles;
 150
 151         devpollop->changes = mm_calloc(nfiles, sizeof(struct pollfd));
 152         if (devpollop->changes == NULL) {
 153                 mm_free(devpollop->events);
 154                 mm_free(devpollop);
 155                 close(dpfd);
 156                 return (NULL);
 157         }
 158
 159         evsig_init(base);
 160
 161         return (devpollop);
 162 }
 163
 164 static int
 165 devpoll_dispatch(struct event_base *base, struct timeval *tv)
 166 {
 167         struct devpollop *devpollop = base->evbase;
 168         struct pollfd *events = devpollop->events;
 169         struct dvpoll dvp;
 170         int i, res, timeout = -1;
 171
 172         if (devpollop->nchanges)
 173                 devpoll_commit(devpollop);
 174
 175         if (tv != NULL)
 176                 timeout = tv->tv_sec * 1000 + (tv->tv_usec + 999) / 1000;
 177
 178         dvp.dp_fds = devpollop->events;
 179         dvp.dp_nfds = devpollop->nevents;
 180         dvp.dp_timeout = timeout;
 181
 182         EVBASE_RELEASE_LOCK(base, th_base_lock);
 183
 184         res = ioctl(devpollop->dpfd, DP_POLL, &dvp);
 185
 186         EVBASE_ACQUIRE_LOCK(base, th_base_lock);
 187
 188         if (res == -1) {
 189                 if (errno != EINTR) {
 190                         event_warn("ioctl: DP_POLL");
 191                         return (-1);
 192                 }
 193
 194                 return (0);
 195         }
 196
 197         event_debug(("%s: devpoll_wait reports %d", __func__, res));
 198
 199         for (i = 0; i < res; i++) {
 200                 int which = 0;
 201                 int what = events[i].revents;
 202
 203                 if (what & POLLHUP)
 204                         what |= POLLIN | POLLOUT;
 205                 else if (what & POLLERR)
 206                         what |= POLLIN | POLLOUT;
 207
 208                 if (what & POLLIN)
 209                         which |= EV_READ;
 210                 if (what & POLLOUT)
 211                         which |= EV_WRITE;
 212
 213                 if (!which)
 214                         continue;
 215
 216                 /* XXX(niels): not sure if this works for devpoll */
 217                 evmap_io_active(base, events[i].fd, which);
 218         }
 219
 220         return (0);
 221 }
 222
 223
 224 static int
 225 devpoll_add(struct event_base *base, int fd, short old, short events, void *p)
 226 {
 227         struct devpollop *devpollop = base->evbase;
 228         int res;
 229         (void)p;
 230
 231         /*
 232          * It's not necessary to OR the existing read/write events that we
 233          * are currently interested in with the new event we are adding.
 234          * The /dev/poll driver ORs any new events with the existing events
 235          * that it has cached for the fd.
 236          */
 237
 238         res = 0;
 239         if (events & EV_READ)
 240                 res |= POLLIN;
 241         if (events & EV_WRITE)
 242                 res |= POLLOUT;
 243
 244         if (devpoll_queue(devpollop, fd, res) != 0)
 245                 return (-1);
 246
 247         return (0);
 248 }
 249
 250 static int
 251 devpoll_del(struct event_base *base, int fd, short old, short events, void *p)
 252 {
 253         struct devpollop *devpollop = base->evbase;
 254         int res;
 255         (void)p;
 256
 257         res = 0;
 258         if (events & EV_READ)
 259                 res |= POLLIN;
 260         if (events & EV_WRITE)
 261                 res |= POLLOUT;
 262
 263         /*
 264          * The only way to remove an fd from the /dev/poll monitored set is
 265          * to use POLLREMOVE by itself.  This removes ALL events for the fd
 266          * provided so if we care about two events and are only removing one
 267          * we must re-add the other event after POLLREMOVE.
 268          */
 269
 270         if (devpoll_queue(devpollop, fd, POLLREMOVE) != 0)
 271                 return (-1);
 272
 273         if ((res & (POLLIN|POLLOUT)) != (POLLIN|POLLOUT)) {
 274                 /*
 275                  * We're not deleting all events, so we must resubmit the
 276                  * event that we are still interested in if one exists.
 277                  */
 278
 279                 if ((res & POLLIN) && (old & EV_WRITE)) {
 280                         /* Deleting read, still care about write */
 281                         devpoll_queue(devpollop, fd, POLLOUT);
 282                 } else if ((res & POLLOUT) && (old & EV_READ)) {
 283                         /* Deleting write, still care about read */
 284                         devpoll_queue(devpollop, fd, POLLIN);
 285                 }
 286         }
 287
 288         return (0);
 289 }
 290
 291 static void
 292 devpoll_dealloc(struct event_base *base)
 293 {
 294         struct devpollop *devpollop = base->evbase;
 295
 296         evsig_dealloc(base);
 297         if (devpollop->events)
 298                 mm_free(devpollop->events);
 299         if (devpollop->changes)
 300                 mm_free(devpollop->changes);
 301         if (devpollop->dpfd >= 0)
 302                 close(devpollop->dpfd);
 303
 304         memset(devpollop, 0, sizeof(struct devpollop));
 305         mm_free(devpollop);
 306 }