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 #include "evconfig-private.h"
  31
  32 #ifdef EVENT__HAVE_KQUEUE
  33
  34 #include <sys/types.h>
  35 #ifdef EVENT__HAVE_SYS_TIME_H
  36 #include <sys/time.h>
  37 #endif
  38 #include <sys/queue.h>
  39 #include <sys/event.h>
  40 #include <signal.h>
  41 #include <stdio.h>
  42 #include <stdlib.h>
  43 #include <string.h>
  44 #include <unistd.h>
  45 #include <errno.h>
  46 #ifdef EVENT__HAVE_INTTYPES_H
  47 #include <inttypes.h>
  48 #endif
  49
  50 /* Some platforms apparently define the udata field of struct kevent as
  51  * intptr_t, whereas others define it as void*.  There doesn't seem to be an
  52  * easy way to tell them apart via autoconf, so we need to use OS macros. */
  53 #if defined(EVENT__HAVE_INTTYPES_H) && !defined(__OpenBSD__) && !defined(__FreeBSD__) && !defined(__darwin__) && !defined(__APPLE__) && !defined(__CloudABI__)
  54 #define PTR_TO_UDATA(x) ((intptr_t)(x))
  55 #define INT_TO_UDATA(x) ((intptr_t)(x))
  56 #else
  57 #define PTR_TO_UDATA(x) (x)
  58 #define INT_TO_UDATA(x) ((void*)(x))
  59 #endif
  60
  61 #include "event-internal.h"
  62 #include "log-internal.h"
  63 #include "evmap-internal.h"
  64 #include "event2/thread.h"
  65 #include "evthread-internal.h"
  66 #include "changelist-internal.h"
  67
  68 #include "kqueue-internal.h"
  69
  70 #define NEVENT          64
  71
  72 struct kqop {
  73         struct kevent *changes;
  74         int changes_size;
  75
  76         struct kevent *events;
  77         int events_size;
  78         int kq;
  79         int notify_event_added;
  80         pid_t pid;
  81 };
  82
  83 static void kqop_free(struct kqop *kqop);
  84
  85 static void *kq_init(struct event_base *);
  86 static int kq_sig_add(struct event_base *, int, short, short, void *);
  87 static int kq_sig_del(struct event_base *, int, short, short, void *);
  88 static int kq_dispatch(struct event_base *, struct timeval *);
  89 static void kq_dealloc(struct event_base *);
  90
  91 const struct eventop kqops = {
  92         "kqueue",
  93         kq_init,
  94         event_changelist_add_,
  95         event_changelist_del_,
  96         kq_dispatch,
  97         kq_dealloc,
  98         1 /* need reinit */,
  99     EV_FEATURE_ET|EV_FEATURE_O1|EV_FEATURE_FDS,
 100         EVENT_CHANGELIST_FDINFO_SIZE
 101 };
 102
 103 static const struct eventop kqsigops = {
 104         "kqueue_signal",
 105         NULL,
 106         kq_sig_add,
 107         kq_sig_del,
 108         NULL,
 109         NULL,
 110         1 /* need reinit */,
 111         0,
 112         0
 113 };
 114
 115 static void *
 116 kq_init(struct event_base *base)
 117 {
 118         int kq = -1;
 119         struct kqop *kqueueop = NULL;
 120
 121         if (!(kqueueop = mm_calloc(1, sizeof(struct kqop))))
 122                 return (NULL);
 123
 124 /* Initialize the kernel queue */
 125
 126         if ((kq = kqueue()) == -1) {
 127                 event_warn("kqueue");
 128                 goto err;
 129         }
 130
 131         kqueueop->kq = kq;
 132
 133         kqueueop->pid = getpid();
 134
 135         /* Initialize fields */
 136         kqueueop->changes = mm_calloc(NEVENT, sizeof(struct kevent));
 137         if (kqueueop->changes == NULL)
 138                 goto err;
 139         kqueueop->events = mm_calloc(NEVENT, sizeof(struct kevent));
 140         if (kqueueop->events == NULL)
 141                 goto err;
 142         kqueueop->events_size = kqueueop->changes_size = NEVENT;
 143
 144         /* Check for Mac OS X kqueue bug. */
 145         memset(&kqueueop->changes[0], 0, sizeof kqueueop->changes[0]);
 146         kqueueop->changes[0].ident = -1;
 147         kqueueop->changes[0].filter = EVFILT_READ;
 148         kqueueop->changes[0].flags = EV_ADD;
 149         /*
 150          * If kqueue works, then kevent will succeed, and it will
 151          * stick an error in events[0].  If kqueue is broken, then
 152          * kevent will fail.
 153          */
 154         if (kevent(kq,
 155                 kqueueop->changes, 1, kqueueop->events, NEVENT, NULL) != 1 ||
 156             (int)kqueueop->events[0].ident != -1 ||
 157             kqueueop->events[0].flags != EV_ERROR) {
 158                 event_warn("%s: detected broken kqueue; not using.", __func__);
 159                 goto err;
 160         }
 161
 162         base->evsigsel = &kqsigops;
 163
 164         return (kqueueop);
 165 err:
 166         if (kqueueop)
 167                 kqop_free(kqueueop);
 168
 169         return (NULL);
 170 }
 171
 172 #define ADD_UDATA 0x30303
 173
 174 static void
 175 kq_setup_kevent(struct kevent *out, evutil_socket_t fd, int filter, short change)
 176 {
 177         memset(out, 0, sizeof(struct kevent));
 178         out->ident = fd;
 179         out->filter = filter;
 180
 181         if (change & EV_CHANGE_ADD) {
 182                 out->flags = EV_ADD;
 183                 /* We set a magic number here so that we can tell 'add'
 184                  * errors from 'del' errors. */
 185                 out->udata = INT_TO_UDATA(ADD_UDATA);
 186                 if (change & EV_ET)
 187                         out->flags |= EV_CLEAR;
 188 #ifdef NOTE_EOF
 189                 /* Make it behave like select() and poll() */
 190                 if (filter == EVFILT_READ)
 191                         out->fflags = NOTE_EOF;
 192 #endif
 193         } else {
 194                 EVUTIL_ASSERT(change & EV_CHANGE_DEL);
 195                 out->flags = EV_DELETE;
 196         }
 197 }
 198
 199 static int
 200 kq_build_changes_list(const struct event_changelist *changelist,
 201     struct kqop *kqop)
 202 {
 203         int i;
 204         int n_changes = 0;
 205
 206         for (i = 0; i < changelist->n_changes; ++i) {
 207                 struct event_change *in_ch = &changelist->changes[i];
 208                 struct kevent *out_ch;
 209                 if (n_changes >= kqop->changes_size - 1) {
 210                         int newsize = kqop->changes_size * 2;
 211                         struct kevent *newchanges;
 212
 213                         newchanges = mm_realloc(kqop->changes,
 214                             newsize * sizeof(struct kevent));
 215                         if (newchanges == NULL) {
 216                                 event_warn("%s: realloc", __func__);
 217                                 return (-1);
 218                         }
 219                         kqop->changes = newchanges;
 220                         kqop->changes_size = newsize;
 221                 }
 222                 if (in_ch->read_change) {
 223                         out_ch = &kqop->changes[n_changes++];
 224                         kq_setup_kevent(out_ch, in_ch->fd, EVFILT_READ,
 225                             in_ch->read_change);
 226                 }
 227                 if (in_ch->write_change) {
 228                         out_ch = &kqop->changes[n_changes++];
 229                         kq_setup_kevent(out_ch, in_ch->fd, EVFILT_WRITE,
 230                             in_ch->write_change);
 231                 }
 232         }
 233         return n_changes;
 234 }
 235
 236 static int
 237 kq_grow_events(struct kqop *kqop, size_t new_size)
 238 {
 239         struct kevent *newresult;
 240
 241         newresult = mm_realloc(kqop->events,
 242             new_size * sizeof(struct kevent));
 243
 244         if (newresult) {
 245                 kqop->events = newresult;
 246                 kqop->events_size = new_size;
 247                 return 0;
 248         } else {
 249                 return -1;
 250         }
 251 }
 252
 253 static int
 254 kq_dispatch(struct event_base *base, struct timeval *tv)
 255 {
 256         struct kqop *kqop = base->evbase;
 257         struct kevent *events = kqop->events;
 258         struct kevent *changes;
 259         struct timespec ts, *ts_p = NULL;
 260         int i, n_changes, res;
 261
 262         if (tv != NULL) {
 263                 ts.tv_sec = tv->tv_sec;
 264                 ts.tv_nsec = tv->tv_usec * 1000;
 265                 ts_p = &ts;
 266         }
 267
 268         /* Build "changes" from "base->changes" */
 269         EVUTIL_ASSERT(kqop->changes);
 270         n_changes = kq_build_changes_list(&base->changelist, kqop);
 271         if (n_changes < 0)
 272                 return -1;
 273
 274         event_changelist_remove_all_(&base->changelist, base);
 275
 276         /* steal the changes array in case some broken code tries to call
 277          * dispatch twice at once. */
 278         changes = kqop->changes;
 279         kqop->changes = NULL;
 280
 281         /* Make sure that 'events' is at least as long as the list of changes:
 282          * otherwise errors in the changes can get reported as a -1 return
 283          * value from kevent() rather than as EV_ERROR events in the events
 284          * array.
 285          *
 286          * (We could instead handle -1 return values from kevent() by
 287          * retrying with a smaller changes array or a larger events array,
 288          * but this approach seems less risky for now.)
 289          */
 290         if (kqop->events_size < n_changes) {
 291                 int new_size = kqop->events_size;
 292                 do {
 293                         new_size *= 2;
 294                 } while (new_size < n_changes);
 295
 296                 kq_grow_events(kqop, new_size);
 297                 events = kqop->events;
 298         }
 299
 300         EVBASE_RELEASE_LOCK(base, th_base_lock);
 301
 302         res = kevent(kqop->kq, changes, n_changes,
 303             events, kqop->events_size, ts_p);
 304
 305         EVBASE_ACQUIRE_LOCK(base, th_base_lock);
 306
 307         EVUTIL_ASSERT(kqop->changes == NULL);
 308         kqop->changes = changes;
 309
 310         if (res == -1) {
 311                 if (errno != EINTR) {
 312                         event_warn("kevent");
 313                         return (-1);
 314                 }
 315
 316                 return (0);
 317         }
 318
 319         event_debug(("%s: kevent reports %d", __func__, res));
 320
 321         for (i = 0; i < res; i++) {
 322                 int which = 0;
 323
 324                 if (events[i].flags & EV_ERROR) {
 325                         switch (events[i].data) {
 326
 327                         /* Can occur on delete if we are not currently
 328                          * watching any events on this fd.  That can
 329                          * happen when the fd was closed and another
 330                          * file was opened with that fd. */
 331                         case ENOENT:
 332                         /* Can occur for reasons not fully understood
 333                          * on FreeBSD. */
 334                         case EINVAL:
 335                                 continue;
 336 #if defined(__FreeBSD__)
 337                         /*
 338                          * This currently occurs if an FD is closed
 339                          * before the EV_DELETE makes it out via kevent().
 340                          * The FreeBSD capabilities code sees the blank
 341                          * capability set and rejects the request to
 342                          * modify an event.
 343                          *
 344                          * To be strictly correct - when an FD is closed,
 345                          * all the registered events are also removed.
 346                          * Queuing EV_DELETE to a closed FD is wrong.
 347                          * The event(s) should just be deleted from
 348                          * the pending changelist.
 349                          */
 350                         case ENOTCAPABLE:
 351                                 continue;
 352 #endif
 353
 354                         /* Can occur on a delete if the fd is closed. */
 355                         case EBADF:
 356                                 /* XXXX On NetBSD, we can also get EBADF if we
 357                                  * try to add the write side of a pipe, but
 358                                  * the read side has already been closed.
 359                                  * Other BSDs call this situation 'EPIPE'. It
 360                                  * would be good if we had a way to report
 361                                  * this situation. */
 362                                 continue;
 363                         /* These two can occur on an add if the fd was one side
 364                          * of a pipe, and the other side was closed. */
 365                         case EPERM:
 366                         case EPIPE:
 367                                 /* Report read events, if we're listening for
 368                                  * them, so that the user can learn about any
 369                                  * add errors.  (If the operation was a
 370                                  * delete, then udata should be cleared.) */
 371                                 if (events[i].udata) {
 372                                         /* The operation was an add:
 373                                          * report the error as a read. */
 374                                         which |= EV_READ;
 375                                         break;
 376                                 } else {
 377                                         /* The operation was a del:
 378                                          * report nothing. */
 379                                         continue;
 380                                 }
 381
 382                         /* Other errors shouldn't occur. */
 383                         default:
 384                                 errno = events[i].data;
 385                                 return (-1);
 386                         }
 387                 } else if (events[i].filter == EVFILT_READ) {
 388                         which |= EV_READ;
 389                 } else if (events[i].filter == EVFILT_WRITE) {
 390                         which |= EV_WRITE;
 391                 } else if (events[i].filter == EVFILT_SIGNAL) {
 392                         which |= EV_SIGNAL;
 393 #ifdef EVFILT_USER
 394                 } else if (events[i].filter == EVFILT_USER) {
 395                         base->is_notify_pending = 0;
 396 #endif
 397                 }
 398
 399                 if (!which)
 400                         continue;
 401
 402                 if (events[i].filter == EVFILT_SIGNAL) {
 403                         evmap_signal_active_(base, events[i].ident, 1);
 404                 } else {
 405                         evmap_io_active_(base, events[i].ident, which | EV_ET);
 406                 }
 407         }
 408
 409         if (res == kqop->events_size) {
 410                 /* We used all the events space that we have. Maybe we should
 411                    make it bigger. */
 412                 kq_grow_events(kqop, kqop->events_size * 2);
 413         }
 414
 415         return (0);
 416 }
 417
 418 static void
 419 kqop_free(struct kqop *kqop)
 420 {
 421         if (kqop->changes)
 422                 mm_free(kqop->changes);
 423         if (kqop->events)
 424                 mm_free(kqop->events);
 425         if (kqop->kq >= 0 && kqop->pid == getpid())
 426                 close(kqop->kq);
 427         memset(kqop, 0, sizeof(struct kqop));
 428         mm_free(kqop);
 429 }
 430
 431 static void
 432 kq_dealloc(struct event_base *base)
 433 {
 434         struct kqop *kqop = base->evbase;
 435         evsig_dealloc_(base);
 436         kqop_free(kqop);
 437 }
 438
 439 /* signal handling */
 440 static int
 441 kq_sig_add(struct event_base *base, int nsignal, short old, short events, void *p)
 442 {
 443         struct kqop *kqop = base->evbase;
 444         struct kevent kev;
 445         struct timespec timeout = { 0, 0 };
 446         (void)p;
 447
 448         EVUTIL_ASSERT(nsignal >= 0 && nsignal < NSIG);
 449
 450         memset(&kev, 0, sizeof(kev));
 451         kev.ident = nsignal;
 452         kev.filter = EVFILT_SIGNAL;
 453         kev.flags = EV_ADD;
 454
 455         /* Be ready for the signal if it is sent any
 456          * time between now and the next call to
 457          * kq_dispatch. */
 458         if (kevent(kqop->kq, &kev, 1, NULL, 0, &timeout) == -1)
 459                 return (-1);
 460
 461         /* We can set the handler for most signals to SIG_IGN and
 462          * still have them reported to us in the queue.  However,
 463          * if the handler for SIGCHLD is SIG_IGN, the system reaps
 464          * zombie processes for us, and we don't get any notification.
 465          * This appears to be the only signal with this quirk. */
 466         if (evsig_set_handler_(base, nsignal,
 467                                nsignal == SIGCHLD ? SIG_DFL : SIG_IGN) == -1)
 468                 return (-1);
 469
 470         return (0);
 471 }
 472
 473 static int
 474 kq_sig_del(struct event_base *base, int nsignal, short old, short events, void *p)
 475 {
 476         struct kqop *kqop = base->evbase;
 477         struct kevent kev;
 478
 479         struct timespec timeout = { 0, 0 };
 480         (void)p;
 481
 482         EVUTIL_ASSERT(nsignal >= 0 && nsignal < NSIG);
 483
 484         memset(&kev, 0, sizeof(kev));
 485         kev.ident = nsignal;
 486         kev.filter = EVFILT_SIGNAL;
 487         kev.flags = EV_DELETE;
 488
 489         /* Because we insert signal events
 490          * immediately, we need to delete them
 491          * immediately, too */
 492         if (kevent(kqop->kq, &kev, 1, NULL, 0, &timeout) == -1)
 493                 return (-1);
 494
 495         if (evsig_restore_handler_(base, nsignal) == -1)
 496                 return (-1);
 497
 498         return (0);
 499 }
 500
 501
 502 /* OSX 10.6 and FreeBSD 8.1 add support for EVFILT_USER, which we can use
 503  * to wake up the event loop from another thread. */
 504
 505 /* Magic number we use for our filter ID. */
 506 #define NOTIFY_IDENT 42
 507
 508 int
 509 event_kq_add_notify_event_(struct event_base *base)
 510 {
 511         struct kqop *kqop = base->evbase;
 512 #if defined(EVFILT_USER) && defined(NOTE_TRIGGER)
 513         struct kevent kev;
 514         struct timespec timeout = { 0, 0 };
 515 #endif
 516
 517         if (kqop->notify_event_added)
 518                 return 0;
 519
 520 #if defined(EVFILT_USER) && defined(NOTE_TRIGGER)
 521         memset(&kev, 0, sizeof(kev));
 522         kev.ident = NOTIFY_IDENT;
 523         kev.filter = EVFILT_USER;
 524         kev.flags = EV_ADD | EV_CLEAR;
 525
 526         if (kevent(kqop->kq, &kev, 1, NULL, 0, &timeout) == -1) {
 527                 event_warn("kevent: adding EVFILT_USER event");
 528                 return -1;
 529         }
 530
 531         kqop->notify_event_added = 1;
 532
 533         return 0;
 534 #else
 535         return -1;
 536 #endif
 537 }
 538
 539 int
 540 event_kq_notify_base_(struct event_base *base)
 541 {
 542         struct kqop *kqop = base->evbase;
 543 #if defined(EVFILT_USER) && defined(NOTE_TRIGGER)
 544         struct kevent kev;
 545         struct timespec timeout = { 0, 0 };
 546 #endif
 547         if (! kqop->notify_event_added)
 548                 return -1;
 549
 550 #if defined(EVFILT_USER) && defined(NOTE_TRIGGER)
 551         memset(&kev, 0, sizeof(kev));
 552         kev.ident = NOTIFY_IDENT;
 553         kev.filter = EVFILT_USER;
 554         kev.fflags = NOTE_TRIGGER;
 555
 556         if (kevent(kqop->kq, &kev, 1, NULL, 0, &timeout) == -1) {
 557                 event_warn("kevent: triggering EVFILT_USER event");
 558                 return -1;
 559         }
 560
 561         return 0;
 562 #else
 563         return -1;
 564 #endif
 565 }
 566
 567 #endif /* EVENT__HAVE_KQUEUE */