lib/tevent/tevent_epoll.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3
   4    main select loop and event handling - epoll implementation
   5
   6    Copyright (C) Andrew Tridgell        2003-2005
   7    Copyright (C) Stefan Metzmacher      2005-2013
   8    Copyright (C) Jeremy Allison         2013
   9
  10      ** NOTE! The following LGPL license applies to the tevent
  11      ** library. This does NOT imply that all of Samba is released
  12      ** under the LGPL
  13
  14    This library is free software; you can redistribute it and/or
  15    modify it under the terms of the GNU Lesser General Public
  16    License as published by the Free Software Foundation; either
  17    version 3 of the License, or (at your option) any later version.
  18
  19    This library is distributed in the hope that it will be useful,
  20    but WITHOUT ANY WARRANTY; without even the implied warranty of
  21    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  22    Lesser General Public License for more details.
  23
  24    You should have received a copy of the GNU Lesser General Public
  25    License along with this library; if not, see <http://www.gnu.org/licenses/>.
  26 */
  27
  28 #include "replace.h"
  29 #include "system/filesys.h"
  30 #include "system/select.h"
  31 #include "tevent.h"
  32 #include "tevent_internal.h"
  33 #include "tevent_util.h"
  34
  35 struct epoll_event_context {
  36         /* a pointer back to the generic event_context */
  37         struct tevent_context *ev;
  38
  39         /* when using epoll this is the handle from epoll_create */
  40         int epoll_fd;
  41
  42         pid_t pid;
  43
  44         bool panic_force_replay;
  45         bool *panic_state;
  46         bool (*panic_fallback)(struct tevent_context *ev, bool replay);
  47 };
  48
  49 #define EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT      (1<<0)
  50 #define EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR   (1<<1)
  51 #define EPOLL_ADDITIONAL_FD_FLAG_GOT_ERROR      (1<<2)
  52 #define EPOLL_ADDITIONAL_FD_FLAG_HAS_MPX        (1<<3)
  53
  54 #ifdef TEST_PANIC_FALLBACK
  55
  56 static int epoll_create_panic_fallback(struct epoll_event_context *epoll_ev,
  57                                        int size)
  58 {
  59         if (epoll_ev->panic_fallback == NULL) {
  60                 return epoll_create(size);
  61         }
  62
  63         /* 50% of the time, fail... */
  64         if ((random() % 2) == 0) {
  65                 errno = EINVAL;
  66                 return -1;
  67         }
  68
  69         return epoll_create(size);
  70 }
  71
  72 static int epoll_ctl_panic_fallback(struct epoll_event_context *epoll_ev,
  73                                     int epfd, int op, int fd,
  74                                     struct epoll_event *event)
  75 {
  76         if (epoll_ev->panic_fallback == NULL) {
  77                 return epoll_ctl(epfd, op, fd, event);
  78         }
  79
  80         /* 50% of the time, fail... */
  81         if ((random() % 2) == 0) {
  82                 errno = EINVAL;
  83                 return -1;
  84         }
  85
  86         return epoll_ctl(epfd, op, fd, event);
  87 }
  88
  89 static int epoll_wait_panic_fallback(struct epoll_event_context *epoll_ev,
  90                                      int epfd,
  91                                      struct epoll_event *events,
  92                                      int maxevents,
  93                                      int timeout)
  94 {
  95         if (epoll_ev->panic_fallback == NULL) {
  96                 return epoll_wait(epfd, events, maxevents, timeout);
  97         }
  98
  99         /* 50% of the time, fail... */
 100         if ((random() % 2) == 0) {
 101                 errno = EINVAL;
 102                 return -1;
 103         }
 104
 105         return epoll_wait(epfd, events, maxevents, timeout);
 106 }
 107
 108 #define epoll_create(_size) \
 109         epoll_create_panic_fallback(epoll_ev, _size)
 110 #define epoll_ctl(_epfd, _op, _fd, _event) \
 111         epoll_ctl_panic_fallback(epoll_ev,_epfd, _op, _fd, _event)
 112 #define epoll_wait(_epfd, _events, _maxevents, _timeout) \
 113         epoll_wait_panic_fallback(epoll_ev, _epfd, _events, _maxevents, _timeout)
 114 #endif
 115
 116 /*
 117   called to set the panic fallback function.
 118 */
 119 _PRIVATE_ bool tevent_epoll_set_panic_fallback(struct tevent_context *ev,
 120                                 bool (*panic_fallback)(struct tevent_context *ev,
 121                                                        bool replay))
 122 {
 123         struct epoll_event_context *epoll_ev;
 124
 125         if (ev->additional_data == NULL) {
 126                 return false;
 127         }
 128
 129         epoll_ev = talloc_get_type(ev->additional_data,
 130                                 struct epoll_event_context);
 131         if (epoll_ev == NULL) {
 132                 return false;
 133         }
 134         epoll_ev->panic_fallback = panic_fallback;
 135         return true;
 136 }
 137
 138 /*
 139   called when a epoll call fails
 140 */
 141 static void epoll_panic(struct epoll_event_context *epoll_ev,
 142                         const char *reason, bool replay)
 143 {
 144         struct tevent_context *ev = epoll_ev->ev;
 145         bool (*panic_fallback)(struct tevent_context *ev, bool replay);
 146
 147         panic_fallback = epoll_ev->panic_fallback;
 148
 149         if (epoll_ev->panic_state != NULL) {
 150                 *epoll_ev->panic_state = true;
 151         }
 152
 153         if (epoll_ev->panic_force_replay) {
 154                 replay = true;
 155         }
 156
 157         TALLOC_FREE(ev->additional_data);
 158
 159         if (panic_fallback == NULL) {
 160                 tevent_debug(ev, TEVENT_DEBUG_FATAL,
 161                         "%s (%s) replay[%u] - calling abort()\n",
 162                         reason, strerror(errno), (unsigned)replay);
 163                 abort();
 164         }
 165
 166         tevent_debug(ev, TEVENT_DEBUG_WARNING,
 167                      "%s (%s) replay[%u] - calling panic_fallback\n",
 168                      reason, strerror(errno), (unsigned)replay);
 169
 170         if (!panic_fallback(ev, replay)) {
 171                 /* Fallback failed. */
 172                 tevent_debug(ev, TEVENT_DEBUG_FATAL,
 173                         "%s (%s) replay[%u] - calling abort()\n",
 174                         reason, strerror(errno), (unsigned)replay);
 175                 abort();
 176         }
 177 }
 178
 179 /*
 180   map from TEVENT_FD_* to EPOLLIN/EPOLLOUT
 181 */
 182 static uint32_t epoll_map_flags(uint16_t flags)
 183 {
 184         uint32_t ret = 0;
 185         if (flags & TEVENT_FD_READ) ret |= (EPOLLIN | EPOLLERR | EPOLLHUP);
 186         if (flags & TEVENT_FD_WRITE) ret |= (EPOLLOUT | EPOLLERR | EPOLLHUP);
 187         return ret;
 188 }
 189
 190 /*
 191  free the epoll fd
 192 */
 193 static int epoll_ctx_destructor(struct epoll_event_context *epoll_ev)
 194 {
 195         close(epoll_ev->epoll_fd);
 196         epoll_ev->epoll_fd = -1;
 197         return 0;
 198 }
 199
 200 /*
 201  init the epoll fd
 202 */
 203 static int epoll_init_ctx(struct epoll_event_context *epoll_ev)
 204 {
 205         epoll_ev->epoll_fd = epoll_create(64);
 206         if (epoll_ev->epoll_fd == -1) {
 207                 tevent_debug(epoll_ev->ev, TEVENT_DEBUG_FATAL,
 208                              "Failed to create epoll handle.\n");
 209                 return -1;
 210         }
 211
 212         if (!ev_set_close_on_exec(epoll_ev->epoll_fd)) {
 213                 tevent_debug(epoll_ev->ev, TEVENT_DEBUG_WARNING,
 214                              "Failed to set close-on-exec, file descriptor may be leaked to children.\n");
 215         }
 216
 217         epoll_ev->pid = getpid();
 218         talloc_set_destructor(epoll_ev, epoll_ctx_destructor);
 219
 220         return 0;
 221 }
 222
 223 static void epoll_update_event(struct epoll_event_context *epoll_ev, struct tevent_fd *fde);
 224
 225 /*
 226   reopen the epoll handle when our pid changes
 227   see http://junkcode.samba.org/ftp/unpacked/junkcode/epoll_fork.c for an
 228   demonstration of why this is needed
 229  */
 230 static void epoll_check_reopen(struct epoll_event_context *epoll_ev)
 231 {
 232         struct tevent_fd *fde;
 233         bool *caller_panic_state = epoll_ev->panic_state;
 234         bool panic_triggered = false;
 235
 236         if (epoll_ev->pid == getpid()) {
 237                 return;
 238         }
 239
 240         close(epoll_ev->epoll_fd);
 241         epoll_ev->epoll_fd = epoll_create(64);
 242         if (epoll_ev->epoll_fd == -1) {
 243                 epoll_panic(epoll_ev, "epoll_create() failed", false);
 244                 return;
 245         }
 246
 247         if (!ev_set_close_on_exec(epoll_ev->epoll_fd)) {
 248                 tevent_debug(epoll_ev->ev, TEVENT_DEBUG_WARNING,
 249                              "Failed to set close-on-exec, file descriptor may be leaked to children.\n");
 250         }
 251
 252         epoll_ev->pid = getpid();
 253         epoll_ev->panic_state = &panic_triggered;
 254         for (fde=epoll_ev->ev->fd_events;fde;fde=fde->next) {
 255                 fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT;
 256                 epoll_update_event(epoll_ev, fde);
 257
 258                 if (panic_triggered) {
 259                         if (caller_panic_state != NULL) {
 260                                 *caller_panic_state = true;
 261                         }
 262                         return;
 263                 }
 264         }
 265         epoll_ev->panic_state = NULL;
 266 }
 267
 268 /*
 269  epoll cannot add the same file descriptor twice, once
 270  with read, once with write which is allowed by the
 271  tevent backend. Multiplex the existing fde, flag it
 272  as such so we can search for the correct fde on
 273  event triggering.
 274 */
 275
 276 static int epoll_add_multiplex_fd(struct epoll_event_context *epoll_ev,
 277                                   struct tevent_fd *add_fde)
 278 {
 279         struct epoll_event event;
 280         struct tevent_fd *mpx_fde;
 281         int ret;
 282
 283         /* Find the existing fde that caused the EEXIST error. */
 284         for (mpx_fde = epoll_ev->ev->fd_events; mpx_fde; mpx_fde = mpx_fde->next) {
 285                 if (mpx_fde->fd != add_fde->fd) {
 286                         continue;
 287                 }
 288
 289                 if (mpx_fde == add_fde) {
 290                         continue;
 291                 }
 292
 293                 break;
 294         }
 295         if (mpx_fde == NULL) {
 296                 tevent_debug(epoll_ev->ev, TEVENT_DEBUG_FATAL,
 297                              "can't find multiplex fde for fd[%d]",
 298                              add_fde->fd);
 299                 return -1;
 300         }
 301
 302         if (mpx_fde->additional_flags & EPOLL_ADDITIONAL_FD_FLAG_HAS_MPX) {
 303                 /* Logic error. Can't have more than 2 multiplexed fde's. */
 304                 tevent_debug(epoll_ev->ev, TEVENT_DEBUG_FATAL,
 305                              "multiplex fde for fd[%d] is already multiplexed\n",
 306                              mpx_fde->fd);
 307                 return -1;
 308         }
 309
 310         /*
 311          * The multiplex fde must have the same fd, and also
 312          * already have an epoll event attached.
 313          */
 314         if (!(mpx_fde->additional_flags & EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT)) {
 315                 /* Logic error. Can't have more than 2 multiplexed fde's. */
 316                 tevent_debug(epoll_ev->ev, TEVENT_DEBUG_FATAL,
 317                              "multiplex fde for fd[%d] has no event\n",
 318                              mpx_fde->fd);
 319                 return -1;
 320         }
 321
 322         /* Modify the mpx_fde to add in the new flags. */
 323         ZERO_STRUCT(event);
 324         event.events = epoll_map_flags(mpx_fde->flags);
 325         event.events |= epoll_map_flags(add_fde->flags);
 326         event.data.ptr = mpx_fde;
 327         ret = epoll_ctl(epoll_ev->epoll_fd, EPOLL_CTL_MOD, mpx_fde->fd, &event);
 328         if (ret != 0 && errno == EBADF) {
 329                 tevent_debug(epoll_ev->ev, TEVENT_DEBUG_ERROR,
 330                              "EPOLL_CTL_MOD EBADF for "
 331                              "add_fde[%p] mpx_fde[%p] fd[%d] - disabling\n",
 332                              add_fde, mpx_fde, add_fde->fd);
 333                 DLIST_REMOVE(epoll_ev->ev->fd_events, mpx_fde);
 334                 mpx_fde->event_ctx = NULL;
 335                 DLIST_REMOVE(epoll_ev->ev->fd_events, add_fde);
 336                 add_fde->event_ctx = NULL;
 337                 return 0;
 338         } else if (ret != 0) {
 339                 return ret;
 340         }
 341
 342         /*
 343          * Make each fde->additional_data pointers point at each other
 344          * so we can look them up from each other. They are now paired.
 345          */
 346         mpx_fde->additional_data = (struct tevent_fd *)add_fde;
 347         add_fde->additional_data = (struct tevent_fd *)mpx_fde;
 348
 349         /* Now flag both fde's as being multiplexed. */
 350         mpx_fde->additional_flags |= EPOLL_ADDITIONAL_FD_FLAG_HAS_MPX;
 351         add_fde->additional_flags |= EPOLL_ADDITIONAL_FD_FLAG_HAS_MPX;
 352
 353         /* we need to keep the GOT_ERROR flag */
 354         if (mpx_fde->additional_flags & EPOLL_ADDITIONAL_FD_FLAG_GOT_ERROR) {
 355                 add_fde->additional_flags |= EPOLL_ADDITIONAL_FD_FLAG_GOT_ERROR;
 356         }
 357
 358         return 0;
 359 }
 360
 361 /*
 362  add the epoll event to the given fd_event
 363 */
 364 static void epoll_add_event(struct epoll_event_context *epoll_ev, struct tevent_fd *fde)
 365 {
 366         struct epoll_event event;
 367         int ret;
 368         struct tevent_fd *mpx_fde = NULL;
 369
 370         fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT;
 371         fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR;
 372
 373         if (fde->additional_flags & EPOLL_ADDITIONAL_FD_FLAG_HAS_MPX) {
 374                 /*
 375                  * This is a multiplexed fde, we need to include both
 376                  * flags in the modified event.
 377                  */
 378                 mpx_fde = talloc_get_type_abort(fde->additional_data,
 379                                                 struct tevent_fd);
 380
 381                 mpx_fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT;
 382                 mpx_fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR;
 383         }
 384
 385         ZERO_STRUCT(event);
 386         event.events = epoll_map_flags(fde->flags);
 387         if (mpx_fde != NULL) {
 388                 event.events |= epoll_map_flags(mpx_fde->flags);
 389         }
 390         event.data.ptr = fde;
 391         ret = epoll_ctl(epoll_ev->epoll_fd, EPOLL_CTL_ADD, fde->fd, &event);
 392         if (ret != 0 && errno == EBADF) {
 393                 tevent_debug(epoll_ev->ev, TEVENT_DEBUG_ERROR,
 394                              "EPOLL_CTL_ADD EBADF for "
 395                              "fde[%p] mpx_fde[%p] fd[%d] - disabling\n",
 396                              fde, mpx_fde, fde->fd);
 397                 DLIST_REMOVE(epoll_ev->ev->fd_events, fde);
 398                 fde->event_ctx = NULL;
 399                 if (mpx_fde != NULL) {
 400                         DLIST_REMOVE(epoll_ev->ev->fd_events, mpx_fde);
 401                         mpx_fde->event_ctx = NULL;
 402                 }
 403                 return;
 404         } else if (ret != 0) {
 405                 epoll_panic(epoll_ev, "EPOLL_CTL_ADD failed", false);
 406                 return;
 407         }
 408
 409         fde->additional_flags |= EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT;
 410         /* only if we want to read we want to tell the event handler about errors */
 411         if (fde->flags & TEVENT_FD_READ) {
 412                 fde->additional_flags |= EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR;
 413         }
 414
 415         if (mpx_fde == NULL) {
 416                 return;
 417         }
 418
 419         mpx_fde->additional_flags |= EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT;
 420         /* only if we want to read we want to tell the event handler about errors */
 421         if (mpx_fde->flags & TEVENT_FD_READ) {
 422                 mpx_fde->additional_flags |= EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR;
 423         }
 424 }
 425
 426 /*
 427  delete the epoll event for given fd_event
 428 */
 429 static void epoll_del_event(struct epoll_event_context *epoll_ev, struct tevent_fd *fde)
 430 {
 431         struct epoll_event event;
 432         int ret;
 433         struct tevent_fd *mpx_fde = NULL;
 434
 435         fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT;
 436         fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR;
 437
 438         if (fde->additional_flags & EPOLL_ADDITIONAL_FD_FLAG_HAS_MPX) {
 439                 /*
 440                  * This is a multiplexed fde, we need to modify both events.
 441                  */
 442                 mpx_fde = talloc_get_type_abort(fde->additional_data,
 443                                                 struct tevent_fd);
 444
 445                 mpx_fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT;
 446                 mpx_fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR;
 447         }
 448
 449         ZERO_STRUCT(event);
 450         ret = epoll_ctl(epoll_ev->epoll_fd, EPOLL_CTL_DEL, fde->fd, &event);
 451         if (ret != 0 && errno == ENOENT) {
 452                 /*
 453                  * This can happen after a epoll_check_reopen
 454                  * within epoll_event_fd_destructor.
 455                  */
 456                 tevent_debug(epoll_ev->ev, TEVENT_DEBUG_TRACE,
 457                              "EPOLL_CTL_DEL ignoring ENOENT for fd[%d]\n",
 458                              fde->fd);
 459                 return;
 460         } else if (ret != 0 && errno == EBADF) {
 461                 tevent_debug(epoll_ev->ev, TEVENT_DEBUG_WARNING,
 462                              "EPOLL_CTL_DEL EBADF for "
 463                              "fde[%p] mpx_fde[%p] fd[%d] - disabling\n",
 464                              fde, mpx_fde, fde->fd);
 465                 DLIST_REMOVE(epoll_ev->ev->fd_events, fde);
 466                 fde->event_ctx = NULL;
 467                 if (mpx_fde != NULL) {
 468                         DLIST_REMOVE(epoll_ev->ev->fd_events, mpx_fde);
 469                         mpx_fde->event_ctx = NULL;
 470                 }
 471                 return;
 472         } else if (ret != 0) {
 473                 epoll_panic(epoll_ev, "EPOLL_CTL_DEL failed", false);
 474                 return;
 475         }
 476 }
 477
 478 /*
 479  change the epoll event to the given fd_event
 480 */
 481 static void epoll_mod_event(struct epoll_event_context *epoll_ev, struct tevent_fd *fde)
 482 {
 483         struct epoll_event event;
 484         int ret;
 485
 486         fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT;
 487         fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR;
 488
 489         ZERO_STRUCT(event);
 490         event.events = epoll_map_flags(fde->flags);
 491         event.data.ptr = fde;
 492         ret = epoll_ctl(epoll_ev->epoll_fd, EPOLL_CTL_MOD, fde->fd, &event);
 493         if (ret != 0 && errno == EBADF) {
 494                 tevent_debug(epoll_ev->ev, TEVENT_DEBUG_ERROR,
 495                              "EPOLL_CTL_MOD EBADF for "
 496                              "fde[%p] fd[%d] - disabling\n",
 497                              fde, fde->fd);
 498                 DLIST_REMOVE(epoll_ev->ev->fd_events, fde);
 499                 fde->event_ctx = NULL;
 500                 return;
 501         } else if (ret != 0) {
 502                 epoll_panic(epoll_ev, "EPOLL_CTL_MOD failed", false);
 503                 return;
 504         }
 505
 506         fde->additional_flags |= EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT;
 507         /* only if we want to read we want to tell the event handler about errors */
 508         if (fde->flags & TEVENT_FD_READ) {
 509                 fde->additional_flags |= EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR;
 510         }
 511 }
 512
 513 static void epoll_update_event(struct epoll_event_context *epoll_ev, struct tevent_fd *fde)
 514 {
 515         bool got_error = (fde->additional_flags & EPOLL_ADDITIONAL_FD_FLAG_GOT_ERROR);
 516         bool want_read = (fde->flags & TEVENT_FD_READ);
 517         bool want_write= (fde->flags & TEVENT_FD_WRITE);
 518
 519         /* there's already an event */
 520         if (fde->additional_flags & EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT) {
 521                 if (want_read || (want_write && !got_error)) {
 522                         epoll_mod_event(epoll_ev, fde);
 523                         return;
 524                 }
 525                 /*
 526                  * if we want to match the select behavior, we need to remove the epoll_event
 527                  * when the caller isn't interested in events.
 528                  *
 529                  * this is because epoll reports EPOLLERR and EPOLLHUP, even without asking for them
 530                  */
 531                 epoll_del_event(epoll_ev, fde);
 532                 return;
 533         }
 534
 535         /* there's no epoll_event attached to the fde */
 536         if (want_read || (want_write && !got_error)) {
 537                 epoll_add_event(epoll_ev, fde);
 538                 return;
 539         }
 540 }
 541
 542 /*
 543   event loop handling using epoll
 544 */
 545 static int epoll_event_loop(struct epoll_event_context *epoll_ev, struct timeval *tvalp)
 546 {
 547         int ret, i;
 548 #define MAXEVENTS 1
 549         struct epoll_event events[MAXEVENTS];
 550         int timeout = -1;
 551         int wait_errno;
 552
 553         if (tvalp) {
 554                 /* it's better to trigger timed events a bit later than too early */
 555                 timeout = ((tvalp->tv_usec+999) / 1000) + (tvalp->tv_sec*1000);
 556         }
 557
 558         if (epoll_ev->ev->signal_events &&
 559             tevent_common_check_signal(epoll_ev->ev)) {
 560                 return 0;
 561         }
 562
 563         tevent_trace_point_callback(epoll_ev->ev, TEVENT_TRACE_BEFORE_WAIT);
 564         ret = epoll_wait(epoll_ev->epoll_fd, events, MAXEVENTS, timeout);
 565         wait_errno = errno;
 566         tevent_trace_point_callback(epoll_ev->ev, TEVENT_TRACE_AFTER_WAIT);
 567
 568         if (ret == -1 && wait_errno == EINTR && epoll_ev->ev->signal_events) {
 569                 if (tevent_common_check_signal(epoll_ev->ev)) {
 570                         return 0;
 571                 }
 572         }
 573
 574         if (ret == -1 && wait_errno != EINTR) {
 575                 epoll_panic(epoll_ev, "epoll_wait() failed", true);
 576                 return -1;
 577         }
 578
 579         if (ret == 0 && tvalp) {
 580                 /* we don't care about a possible delay here */
 581                 tevent_common_loop_timer_delay(epoll_ev->ev);
 582                 return 0;
 583         }
 584
 585         for (i=0;i<ret;i++) {
 586                 struct tevent_fd *fde = talloc_get_type(events[i].data.ptr,
 587                                                        struct tevent_fd);
 588                 uint16_t flags = 0;
 589
 590                 if (fde == NULL) {
 591                         epoll_panic(epoll_ev, "epoll_wait() gave bad data", true);
 592                         return -1;
 593                 }
 594                 if (events[i].events & (EPOLLHUP|EPOLLERR)) {
 595                         fde->additional_flags |= EPOLL_ADDITIONAL_FD_FLAG_GOT_ERROR;
 596                         /*
 597                          * if we only wait for TEVENT_FD_WRITE, we should not tell the
 598                          * event handler about it, and remove the epoll_event,
 599                          * as we only report errors when waiting for read events,
 600                          * to match the select() behavior
 601                          */
 602                         if (!(fde->additional_flags & EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR)) {
 603                                 epoll_update_event(epoll_ev, fde);
 604                                 continue;
 605                         }
 606                         flags |= TEVENT_FD_READ;
 607                 }
 608                 if (events[i].events & EPOLLIN) flags |= TEVENT_FD_READ;
 609                 if (events[i].events & EPOLLOUT) flags |= TEVENT_FD_WRITE;
 610                 if (flags) {
 611                         fde->handler(epoll_ev->ev, fde, flags, fde->private_data);
 612                         break;
 613                 }
 614         }
 615
 616         return 0;
 617 }
 618
 619 /*
 620   create a epoll_event_context structure.
 621 */
 622 static int epoll_event_context_init(struct tevent_context *ev)
 623 {
 624         int ret;
 625         struct epoll_event_context *epoll_ev;
 626
 627         /*
 628          * We might be called during tevent_re_initialise()
 629          * which means we need to free our old additional_data.
 630          */
 631         TALLOC_FREE(ev->additional_data);
 632
 633         epoll_ev = talloc_zero(ev, struct epoll_event_context);
 634         if (!epoll_ev) return -1;
 635         epoll_ev->ev = ev;
 636         epoll_ev->epoll_fd = -1;
 637
 638         ret = epoll_init_ctx(epoll_ev);
 639         if (ret != 0) {
 640                 talloc_free(epoll_ev);
 641                 return ret;
 642         }
 643
 644         ev->additional_data = epoll_ev;
 645         return 0;
 646 }
 647
 648 /*
 649   destroy an fd_event
 650 */
 651 static int epoll_event_fd_destructor(struct tevent_fd *fde)
 652 {
 653         struct tevent_context *ev = fde->event_ctx;
 654         struct epoll_event_context *epoll_ev = NULL;
 655         bool panic_triggered = false;
 656         int flags = fde->flags;
 657
 658         if (ev == NULL) {
 659                 return tevent_common_fd_destructor(fde);
 660         }
 661
 662         epoll_ev = talloc_get_type_abort(ev->additional_data,
 663                                          struct epoll_event_context);
 664
 665         /*
 666          * we must remove the event from the list
 667          * otherwise a panic fallback handler may
 668          * reuse invalid memory
 669          */
 670         DLIST_REMOVE(ev->fd_events, fde);
 671
 672         epoll_ev->panic_state = &panic_triggered;
 673         epoll_check_reopen(epoll_ev);
 674         if (panic_triggered) {
 675                 return tevent_common_fd_destructor(fde);
 676         }
 677
 678         fde->flags = 0;
 679         epoll_update_event(epoll_ev, fde);
 680         fde->flags = flags;
 681         if (panic_triggered) {
 682                 return tevent_common_fd_destructor(fde);
 683         }
 684         epoll_ev->panic_state = NULL;
 685
 686         return tevent_common_fd_destructor(fde);
 687 }
 688
 689 /*
 690   add a fd based event
 691   return NULL on failure (memory allocation error)
 692 */
 693 static struct tevent_fd *epoll_event_add_fd(struct tevent_context *ev, TALLOC_CTX *mem_ctx,
 694                                             int fd, uint16_t flags,
 695                                             tevent_fd_handler_t handler,
 696                                             void *private_data,
 697                                             const char *handler_name,
 698                                             const char *location)
 699 {
 700         struct epoll_event_context *epoll_ev = talloc_get_type(ev->additional_data,
 701                                                            struct epoll_event_context);
 702         struct tevent_fd *fde;
 703         bool panic_triggered = false;
 704
 705         fde = tevent_common_add_fd(ev, mem_ctx, fd, flags,
 706                                    handler, private_data,
 707                                    handler_name, location);
 708         if (!fde) return NULL;
 709
 710         talloc_set_destructor(fde, epoll_event_fd_destructor);
 711
 712         epoll_ev->panic_state = &panic_triggered;
 713         epoll_check_reopen(epoll_ev);
 714         if (panic_triggered) {
 715                 return fde;
 716         }
 717         epoll_ev->panic_state = NULL;
 718
 719         epoll_update_event(epoll_ev, fde);
 720
 721         return fde;
 722 }
 723
 724 /*
 725   set the fd event flags
 726 */
 727 static void epoll_event_set_fd_flags(struct tevent_fd *fde, uint16_t flags)
 728 {
 729         struct tevent_context *ev;
 730         struct epoll_event_context *epoll_ev;
 731         bool panic_triggered = false;
 732
 733         if (fde->flags == flags) return;
 734
 735         ev = fde->event_ctx;
 736         epoll_ev = talloc_get_type(ev->additional_data, struct epoll_event_context);
 737
 738         fde->flags = flags;
 739
 740         epoll_ev->panic_state = &panic_triggered;
 741         epoll_check_reopen(epoll_ev);
 742         if (panic_triggered) {
 743                 return;
 744         }
 745         epoll_ev->panic_state = NULL;
 746
 747         epoll_update_event(epoll_ev, fde);
 748 }
 749
 750 /*
 751   do a single event loop using the events defined in ev
 752 */
 753 static int epoll_event_loop_once(struct tevent_context *ev, const char *location)
 754 {
 755         struct epoll_event_context *epoll_ev = talloc_get_type(ev->additional_data,
 756                                                            struct epoll_event_context);
 757         struct timeval tval;
 758         bool panic_triggered = false;
 759
 760         if (ev->signal_events &&
 761             tevent_common_check_signal(ev)) {
 762                 return 0;
 763         }
 764
 765         if (ev->immediate_events &&
 766             tevent_common_loop_immediate(ev)) {
 767                 return 0;
 768         }
 769
 770         tval = tevent_common_loop_timer_delay(ev);
 771         if (tevent_timeval_is_zero(&tval)) {
 772                 return 0;
 773         }
 774
 775         epoll_ev->panic_state = &panic_triggered;
 776         epoll_ev->panic_force_replay = true;
 777         epoll_check_reopen(epoll_ev);
 778         if (panic_triggered) {
 779                 errno = EINVAL;
 780                 return -1;
 781         }
 782         epoll_ev->panic_force_replay = false;
 783         epoll_ev->panic_state = NULL;
 784
 785         return epoll_event_loop(epoll_ev, &tval);
 786 }
 787
 788 static const struct tevent_ops epoll_event_ops = {
 789         .context_init           = epoll_event_context_init,
 790         .add_fd                 = epoll_event_add_fd,
 791         .set_fd_close_fn        = tevent_common_fd_set_close_fn,
 792         .get_fd_flags           = tevent_common_fd_get_flags,
 793         .set_fd_flags           = epoll_event_set_fd_flags,
 794         .add_timer              = tevent_common_add_timer,
 795         .schedule_immediate     = tevent_common_schedule_immediate,
 796         .add_signal             = tevent_common_add_signal,
 797         .loop_once              = epoll_event_loop_once,
 798         .loop_wait              = tevent_common_loop_wait,
 799 };
 800
 801 _PRIVATE_ bool tevent_epoll_init(void)
 802 {
 803         return tevent_register_backend("epoll", &epoll_event_ops);
 804 }