libevent/kqueue.c

   1 /*      $OpenBSD: kqueue.c,v 1.5 2002/07/10 14:41:31 art 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
  31 #define _GNU_SOURCE
  32
  33 #include <sys/types.h>
  34 #ifdef _EVENT_HAVE_SYS_TIME_H
  35 #include <sys/time.h>
  36 #endif
  37 #include <sys/queue.h>
  38 #include <sys/event.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 #ifdef _EVENT_HAVE_INTTYPES_H
  46 #include <inttypes.h>
  47 #endif
  48
  49 /* Some platforms apparently define the udata field of struct kevent as
  50  * intptr_t, whereas others define it as void*.  There doesn't seem to be an
  51  * easy way to tell them apart via autoconf, so we need to use OS macros. */
  52 #if defined(_EVENT_HAVE_INTTYPES_H) && !defined(__OpenBSD__) && !defined(__FreeBSD__) && !defined(__darwin__) && !defined(__APPLE__)
  53 #define PTR_TO_UDATA(x) ((intptr_t)(x))
  54 #define INT_TO_UDATA(x) ((intptr_t)(x))
  55 #else
  56 #define PTR_TO_UDATA(x) (x)
  57 #define INT_TO_UDATA(x) ((void*)(x))
  58 #endif
  59
  60 #include "event-internal.h"
  61 #include "log-internal.h"
  62 #include "evmap-internal.h"
  63 #include "event2/thread.h"
  64 #include "evthread-internal.h"
  65 #include "changelist-internal.h"
  66
  67 #define NEVENT          64
  68
  69 struct kqop {
  70         struct kevent *changes;
  71         int changes_size;
  72
  73         struct kevent *events;
  74         int events_size;
  75         int kq;
  76         pid_t pid;
  77 };
  78
  79 static void kqop_free(struct kqop *kqop);
  80
  81 static void *kq_init(struct event_base *);
  82 static int kq_sig_add(struct event_base *, int, short, short, void *);
  83 static int kq_sig_del(struct event_base *, int, short, short, void *);
  84 static int kq_dispatch(struct event_base *, struct timeval *);
  85 static void kq_dealloc(struct event_base *);
  86
  87 const struct eventop kqops = {
  88         "kqueue",
  89         kq_init,
  90         event_changelist_add,
  91         event_changelist_del,
  92         kq_dispatch,
  93         kq_dealloc,
  94         1 /* need reinit */,
  95     EV_FEATURE_ET|EV_FEATURE_O1|EV_FEATURE_FDS,
  96         EVENT_CHANGELIST_FDINFO_SIZE
  97 };
  98
  99 static const struct eventop kqsigops = {
 100         "kqueue_signal",
 101         NULL,
 102         kq_sig_add,
 103         kq_sig_del,
 104         NULL,
 105         NULL,
 106         1 /* need reinit */,
 107         0,
 108         0
 109 };
 110
 111 static void *
 112 kq_init(struct event_base *base)
 113 {
 114         int kq = -1;
 115         struct kqop *kqueueop = NULL;
 116
 117         if (!(kqueueop = mm_calloc(1, sizeof(struct kqop))))
 118                 return (NULL);
 119
 120 /* Initialize the kernel queue */
 121
 122         if ((kq = kqueue()) == -1) {
 123                 event_warn("kqueue");
 124                 goto err;
 125         }
 126
 127         kqueueop->kq = kq;
 128
 129         kqueueop->pid = getpid();
 130
 131         /* Initialize fields */
 132         kqueueop->changes = mm_calloc(NEVENT, sizeof(struct kevent));
 133         if (kqueueop->changes == NULL)
 134                 goto err;
 135         kqueueop->events = mm_calloc(NEVENT, sizeof(struct kevent));
 136         if (kqueueop->events == NULL)
 137                 goto err;
 138         kqueueop->events_size = kqueueop->changes_size = NEVENT;
 139
 140         /* Check for Mac OS X kqueue bug. */
 141         memset(&kqueueop->changes[0], 0, sizeof kqueueop->changes[0]);
 142         kqueueop->changes[0].ident = -1;
 143         kqueueop->changes[0].filter = EVFILT_READ;
 144         kqueueop->changes[0].flags = EV_ADD;
 145         /*
 146          * If kqueue works, then kevent will succeed, and it will
 147          * stick an error in events[0].  If kqueue is broken, then
 148          * kevent will fail.
 149          */
 150         if (kevent(kq,
 151                 kqueueop->changes, 1, kqueueop->events, NEVENT, NULL) != 1 ||
 152             (int)kqueueop->events[0].ident != -1 ||
 153             kqueueop->events[0].flags != EV_ERROR) {
 154                 event_warn("%s: detected broken kqueue; not using.", __func__);
 155                 goto err;
 156         }
 157
 158         base->evsigsel = &kqsigops;
 159
 160         return (kqueueop);
 161 err:
 162         if (kqueueop)
 163                 kqop_free(kqueueop);
 164
 165         return (NULL);
 166 }
 167
 168 static void
 169 kq_sighandler(int sig)
 170 {
 171         /* Do nothing here */
 172 }
 173
 174 #define ADD_UDATA 0x30303
 175
 176 static void
 177 kq_setup_kevent(struct kevent *out, evutil_socket_t fd, int filter, short change)
 178 {
 179         memset(out, 0, sizeof(struct kevent));
 180         out->ident = fd;
 181         out->filter = filter;
 182
 183         if (change & EV_CHANGE_ADD) {
 184                 out->flags = EV_ADD;
 185                 /* We set a magic number here so that we can tell 'add'
 186                  * errors from 'del' errors. */
 187                 out->udata = INT_TO_UDATA(ADD_UDATA);
 188                 if (change & EV_ET)
 189                         out->flags |= EV_CLEAR;
 190 #ifdef NOTE_EOF
 191                 /* Make it behave like select() and poll() */
 192                 if (filter == EVFILT_READ)
 193                         out->fflags = NOTE_EOF;
 194 #endif
 195         } else {
 196                 EVUTIL_ASSERT(change & EV_CHANGE_DEL);
 197                 out->flags = EV_DELETE;
 198         }
 199 }
 200
 201 static int
 202 kq_build_changes_list(const struct event_changelist *changelist,
 203     struct kqop *kqop)
 204 {
 205         int i;
 206         int n_changes = 0;
 207
 208         for (i = 0; i < changelist->n_changes; ++i) {
 209                 struct event_change *in_ch = &changelist->changes[i];
 210                 struct kevent *out_ch;
 211                 if (n_changes >= kqop->changes_size - 1) {
 212                         int newsize = kqop->changes_size * 2;
 213                         struct kevent *newchanges;
 214
 215                         newchanges = mm_realloc(kqop->changes,
 216                             newsize * sizeof(struct kevent));
 217                         if (newchanges == NULL) {
 218                                 event_warn("%s: realloc", __func__);
 219                                 return (-1);
 220                         }
 221                         kqop->changes = newchanges;
 222                         kqop->changes_size = newsize;
 223                 }
 224                 if (in_ch->read_change) {
 225                         out_ch = &kqop->changes[n_changes++];
 226                         kq_setup_kevent(out_ch, in_ch->fd, EVFILT_READ,
 227                             in_ch->read_change);
 228                 }
 229                 if (in_ch->write_change) {
 230                         out_ch = &kqop->changes[n_changes++];
 231                         kq_setup_kevent(out_ch, in_ch->fd, EVFILT_WRITE,
 232                             in_ch->write_change);
 233                 }
 234         }
 235         return n_changes;
 236 }
 237
 238 static int
 239 kq_grow_events(struct kqop *kqop, size_t new_size)
 240 {
 241         struct kevent *newresult;
 242
 243         newresult = mm_realloc(kqop->events,
 244             new_size * sizeof(struct kevent));
 245
 246         if (newresult) {
 247                 kqop->events = newresult;
 248                 kqop->events_size = new_size;
 249                 return 0;
 250         } else {
 251                 return -1;
 252         }
 253 }
 254
 255 static int
 256 kq_dispatch(struct event_base *base, struct timeval *tv)
 257 {
 258         struct kqop *kqop = base->evbase;
 259         struct kevent *events = kqop->events;
 260         struct kevent *changes;
 261         struct timespec ts, *ts_p = NULL;
 262         int i, n_changes, res;
 263
 264         if (tv != NULL) {
 265                 TIMEVAL_TO_TIMESPEC(tv, &ts);
 266                 ts_p = &ts;
 267         }
 268
 269         /* Build "changes" from "base->changes" */
 270         EVUTIL_ASSERT(kqop->changes);
 271         n_changes = kq_build_changes_list(&base->changelist, kqop);
 272         if (n_changes < 0)
 273                 return -1;
 274
 275         event_changelist_remove_all(&base->changelist, base);
 276
 277         /* steal the changes array in case some broken code tries to call
 278          * dispatch twice at once. */
 279         changes = kqop->changes;
 280         kqop->changes = NULL;
 281
 282         /* Make sure that 'events' is at least as long as the list of changes:
 283          * otherwise errors in the changes can get reported as a -1 return
 284          * value from kevent() rather than as EV_ERROR events in the events
 285          * array.
 286          *
 287          * (We could instead handle -1 return values from kevent() by
 288          * retrying with a smaller changes array or a larger events array,
 289          * but this approach seems less risky for now.)
 290          */
 291         if (kqop->events_size < n_changes) {
 292                 int new_size = kqop->events_size;
 293                 do {
 294                         new_size *= 2;
 295                 } while (new_size < n_changes);
 296
 297                 kq_grow_events(kqop, new_size);
 298                 events = kqop->events;
 299         }
 300
 301         EVBASE_RELEASE_LOCK(base, th_base_lock);
 302
 303         res = kevent(kqop->kq, changes, n_changes,
 304             events, kqop->events_size, ts_p);
 305
 306         EVBASE_ACQUIRE_LOCK(base, th_base_lock);
 307
 308         EVUTIL_ASSERT(kqop->changes == NULL);
 309         kqop->changes = changes;
 310
 311         if (res == -1) {
 312                 if (errno != EINTR) {
 313                         event_warn("kevent");
 314                         return (-1);
 315                 }
 316
 317                 return (0);
 318         }
 319
 320         event_debug(("%s: kevent reports %d", __func__, res));
 321
 322         for (i = 0; i < res; i++) {
 323                 int which = 0;
 324
 325                 if (events[i].flags & EV_ERROR) {
 326                         switch (events[i].data) {
 327
 328                         /* Can occur on delete if we are not currently
 329                          * watching any events on this fd.  That can
 330                          * happen when the fd was closed and another
 331                          * file was opened with that fd. */
 332                         case ENOENT:
 333                         /* Can occur for reasons not fully understood
 334                          * on FreeBSD. */
 335                         case EINVAL:
 336                                 continue;
 337
 338                         /* Can occur on a delete if the fd is closed. */
 339                         case EBADF:
 340                                 /* XXXX On NetBSD, we can also get EBADF if we
 341                                  * try to add the write side of a pipe, but
 342                                  * the read side has already been closed.
 343                                  * Other BSDs call this situation 'EPIPE'. It
 344                                  * would be good if we had a way to report
 345                                  * this situation. */
 346                                 continue;
 347                         /* These two can occur on an add if the fd was one side
 348                          * of a pipe, and the other side was closed. */
 349                         case EPERM:
 350                         case EPIPE:
 351                                 /* Report read events, if we're listening for
 352                                  * them, so that the user can learn about any
 353                                  * add errors.  (If the operation was a
 354                                  * delete, then udata should be cleared.) */
 355                                 if (events[i].udata) {
 356                                         /* The operation was an add:
 357                                          * report the error as a read. */
 358                                         which |= EV_READ;
 359                                         break;
 360                                 } else {
 361                                         /* The operation was a del:
 362                                          * report nothing. */
 363                                         continue;
 364                                 }
 365
 366                         /* Other errors shouldn't occur. */
 367                         default:
 368                                 errno = events[i].data;
 369                                 return (-1);
 370                         }
 371                 } else if (events[i].filter == EVFILT_READ) {
 372                         which |= EV_READ;
 373                 } else if (events[i].filter == EVFILT_WRITE) {
 374                         which |= EV_WRITE;
 375                 } else if (events[i].filter == EVFILT_SIGNAL) {
 376                         which |= EV_SIGNAL;
 377                 }
 378
 379                 if (!which)
 380                         continue;
 381
 382                 if (events[i].filter == EVFILT_SIGNAL) {
 383                         evmap_signal_active(base, events[i].ident, 1);
 384                 } else {
 385                         evmap_io_active(base, events[i].ident, which | EV_ET);
 386                 }
 387         }
 388
 389         if (res == kqop->events_size) {
 390                 /* We used all the events space that we have. Maybe we should
 391                    make it bigger. */
 392                 kq_grow_events(kqop, kqop->events_size * 2);
 393         }
 394
 395         return (0);
 396 }
 397
 398 static void
 399 kqop_free(struct kqop *kqop)
 400 {
 401         if (kqop->changes)
 402                 mm_free(kqop->changes);
 403         if (kqop->events)
 404                 mm_free(kqop->events);
 405         if (kqop->kq >= 0 && kqop->pid == getpid())
 406                 close(kqop->kq);
 407         memset(kqop, 0, sizeof(struct kqop));
 408         mm_free(kqop);
 409 }
 410
 411 static void
 412 kq_dealloc(struct event_base *base)
 413 {
 414         struct kqop *kqop = base->evbase;
 415         evsig_dealloc(base);
 416         kqop_free(kqop);
 417 }
 418
 419 /* signal handling */
 420 static int
 421 kq_sig_add(struct event_base *base, int nsignal, short old, short events, void *p)
 422 {
 423         struct kqop *kqop = base->evbase;
 424         struct kevent kev;
 425         struct timespec timeout = { 0, 0 };
 426         (void)p;
 427
 428         EVUTIL_ASSERT(nsignal >= 0 && nsignal < NSIG);
 429
 430         memset(&kev, 0, sizeof(kev));
 431         kev.ident = nsignal;
 432         kev.filter = EVFILT_SIGNAL;
 433         kev.flags = EV_ADD;
 434
 435         /* Be ready for the signal if it is sent any
 436          * time between now and the next call to
 437          * kq_dispatch. */
 438         if (kevent(kqop->kq, &kev, 1, NULL, 0, &timeout) == -1)
 439                 return (-1);
 440
 441         /* XXXX The manpage suggest we could use SIG_IGN instead of a
 442          * do-nothing handler */
 443         if (_evsig_set_handler(base, nsignal, kq_sighandler) == -1)
 444                 return (-1);
 445
 446         return (0);
 447 }
 448
 449 static int
 450 kq_sig_del(struct event_base *base, int nsignal, short old, short events, void *p)
 451 {
 452         struct kqop *kqop = base->evbase;
 453         struct kevent kev;
 454
 455         struct timespec timeout = { 0, 0 };
 456         (void)p;
 457
 458         EVUTIL_ASSERT(nsignal >= 0 && nsignal < NSIG);
 459
 460         memset(&kev, 0, sizeof(kev));
 461         kev.ident = nsignal;
 462         kev.filter = EVFILT_SIGNAL;
 463         kev.flags = EV_DELETE;
 464
 465         /* Because we insert signal events
 466          * immediately, we need to delete them
 467          * immediately, too */
 468         if (kevent(kqop->kq, &kev, 1, NULL, 0, &timeout) == -1)
 469                 return (-1);
 470
 471         if (_evsig_restore_handler(base, nsignal) == -1)
 472                 return (-1);
 473
 474         return (0);
 475 }