src/libsystemd-bus/sd-event.c

   1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
   2
   3 /***
   4   This file is part of systemd.
   5
   6   Copyright 2013 Lennart Poettering
   7
   8   systemd is free software; you can redistribute it and/or modify it
   9   under the terms of the GNU Lesser General Public License as published by
  10   the Free Software Foundation; either version 2.1 of the License, or
  11   (at your option) any later version.
  12
  13   systemd is distributed in the hope that it will be useful, but
  14   WITHOUT ANY WARRANTY; without even the implied warranty of
  15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16   Lesser General Public License for more details.
  17
  18   You should have received a copy of the GNU Lesser General Public License
  19   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  20 ***/
  21
  22 #include <sys/epoll.h>
  23 #include <sys/timerfd.h>
  24 #include <sys/wait.h>
  25
  26 #include "sd-id128.h"
  27 #include "sd-daemon.h"
  28 #include "macro.h"
  29 #include "prioq.h"
  30 #include "hashmap.h"
  31 #include "util.h"
  32 #include "time-util.h"
  33 #include "missing.h"
  34
  35 #include "sd-event.h"
  36
  37 #define EPOLL_QUEUE_MAX 512U
  38 #define DEFAULT_ACCURACY_USEC (250 * USEC_PER_MSEC)
  39
  40 typedef enum EventSourceType {
  41         SOURCE_IO,
  42         SOURCE_MONOTONIC,
  43         SOURCE_REALTIME,
  44         SOURCE_SIGNAL,
  45         SOURCE_CHILD,
  46         SOURCE_DEFER,
  47         SOURCE_EXIT,
  48         SOURCE_WATCHDOG
  49 } EventSourceType;
  50
  51 struct sd_event_source {
  52         unsigned n_ref;
  53
  54         sd_event *event;
  55         void *userdata;
  56         sd_event_handler_t prepare;
  57
  58         EventSourceType type:4;
  59         int enabled:3;
  60         bool pending:1;
  61         bool dispatching:1;
  62
  63         int priority;
  64         unsigned pending_index;
  65         unsigned prepare_index;
  66         unsigned pending_iteration;
  67         unsigned prepare_iteration;
  68
  69         union {
  70                 struct {
  71                         sd_event_io_handler_t callback;
  72                         int fd;
  73                         uint32_t events;
  74                         uint32_t revents;
  75                         bool registered:1;
  76                 } io;
  77                 struct {
  78                         sd_event_time_handler_t callback;
  79                         usec_t next, accuracy;
  80                         unsigned earliest_index;
  81                         unsigned latest_index;
  82                 } time;
  83                 struct {
  84                         sd_event_signal_handler_t callback;
  85                         struct signalfd_siginfo siginfo;
  86                         int sig;
  87                 } signal;
  88                 struct {
  89                         sd_event_child_handler_t callback;
  90                         siginfo_t siginfo;
  91                         pid_t pid;
  92                         int options;
  93                 } child;
  94                 struct {
  95                         sd_event_handler_t callback;
  96                 } defer;
  97                 struct {
  98                         sd_event_handler_t callback;
  99                         unsigned prioq_index;
 100                 } exit;
 101         };
 102 };
 103
 104 struct sd_event {
 105         unsigned n_ref;
 106
 107         int epoll_fd;
 108         int signal_fd;
 109         int realtime_fd;
 110         int monotonic_fd;
 111         int watchdog_fd;
 112
 113         Prioq *pending;
 114         Prioq *prepare;
 115
 116         /* For both clocks we maintain two priority queues each, one
 117          * ordered for the earliest times the events may be
 118          * dispatched, and one ordered by the latest times they must
 119          * have been dispatched. The range between the top entries in
 120          * the two prioqs is the time window we can freely schedule
 121          * wakeups in */
 122         Prioq *monotonic_earliest;
 123         Prioq *monotonic_latest;
 124         Prioq *realtime_earliest;
 125         Prioq *realtime_latest;
 126
 127         usec_t realtime_next, monotonic_next;
 128         usec_t perturb;
 129
 130         sigset_t sigset;
 131         sd_event_source **signal_sources;
 132
 133         Hashmap *child_sources;
 134         unsigned n_enabled_child_sources;
 135
 136         Prioq *exit;
 137
 138         pid_t original_pid;
 139
 140         unsigned iteration;
 141         dual_timestamp timestamp;
 142         int state;
 143
 144         bool exit_requested:1;
 145         bool need_process_child:1;
 146         bool watchdog:1;
 147
 148         int exit_code;
 149
 150         pid_t tid;
 151         sd_event **default_event_ptr;
 152
 153         usec_t watchdog_last, watchdog_period;
 154
 155         unsigned n_sources;
 156 };
 157
 158 static int pending_prioq_compare(const void *a, const void *b) {
 159         const sd_event_source *x = a, *y = b;
 160
 161         assert(x->pending);
 162         assert(y->pending);
 163
 164         /* Enabled ones first */
 165         if (x->enabled != SD_EVENT_OFF && y->enabled == SD_EVENT_OFF)
 166                 return -1;
 167         if (x->enabled == SD_EVENT_OFF && y->enabled != SD_EVENT_OFF)
 168                 return 1;
 169
 170         /* Lower priority values first */
 171         if (x->priority < y->priority)
 172                 return -1;
 173         if (x->priority > y->priority)
 174                 return 1;
 175
 176         /* Older entries first */
 177         if (x->pending_iteration < y->pending_iteration)
 178                 return -1;
 179         if (x->pending_iteration > y->pending_iteration)
 180                 return 1;
 181
 182         /* Stability for the rest */
 183         if (x < y)
 184                 return -1;
 185         if (x > y)
 186                 return 1;
 187
 188         return 0;
 189 }
 190
 191 static int prepare_prioq_compare(const void *a, const void *b) {
 192         const sd_event_source *x = a, *y = b;
 193
 194         assert(x->prepare);
 195         assert(y->prepare);
 196
 197         /* Move most recently prepared ones last, so that we can stop
 198          * preparing as soon as we hit one that has already been
 199          * prepared in the current iteration */
 200         if (x->prepare_iteration < y->prepare_iteration)
 201                 return -1;
 202         if (x->prepare_iteration > y->prepare_iteration)
 203                 return 1;
 204
 205         /* Enabled ones first */
 206         if (x->enabled != SD_EVENT_OFF && y->enabled == SD_EVENT_OFF)
 207                 return -1;
 208         if (x->enabled == SD_EVENT_OFF && y->enabled != SD_EVENT_OFF)
 209                 return 1;
 210
 211         /* Lower priority values first */
 212         if (x->priority < y->priority)
 213                 return -1;
 214         if (x->priority > y->priority)
 215                 return 1;
 216
 217         /* Stability for the rest */
 218         if (x < y)
 219                 return -1;
 220         if (x > y)
 221                 return 1;
 222
 223         return 0;
 224 }
 225
 226 static int earliest_time_prioq_compare(const void *a, const void *b) {
 227         const sd_event_source *x = a, *y = b;
 228
 229         assert(x->type == SOURCE_MONOTONIC || x->type == SOURCE_REALTIME);
 230         assert(y->type == SOURCE_MONOTONIC || y->type == SOURCE_REALTIME);
 231
 232         /* Enabled ones first */
 233         if (x->enabled != SD_EVENT_OFF && y->enabled == SD_EVENT_OFF)
 234                 return -1;
 235         if (x->enabled == SD_EVENT_OFF && y->enabled != SD_EVENT_OFF)
 236                 return 1;
 237
 238         /* Move the pending ones to the end */
 239         if (!x->pending && y->pending)
 240                 return -1;
 241         if (x->pending && !y->pending)
 242                 return 1;
 243
 244         /* Order by time */
 245         if (x->time.next < y->time.next)
 246                 return -1;
 247         if (x->time.next > y->time.next)
 248                 return 1;
 249
 250         /* Stability for the rest */
 251         if (x < y)
 252                 return -1;
 253         if (x > y)
 254                 return 1;
 255
 256         return 0;
 257 }
 258
 259 static int latest_time_prioq_compare(const void *a, const void *b) {
 260         const sd_event_source *x = a, *y = b;
 261
 262         assert((x->type == SOURCE_MONOTONIC && y->type == SOURCE_MONOTONIC) ||
 263                (x->type == SOURCE_REALTIME && y->type == SOURCE_REALTIME));
 264
 265         /* Enabled ones first */
 266         if (x->enabled != SD_EVENT_OFF && y->enabled == SD_EVENT_OFF)
 267                 return -1;
 268         if (x->enabled == SD_EVENT_OFF && y->enabled != SD_EVENT_OFF)
 269                 return 1;
 270
 271         /* Move the pending ones to the end */
 272         if (!x->pending && y->pending)
 273                 return -1;
 274         if (x->pending && !y->pending)
 275                 return 1;
 276
 277         /* Order by time */
 278         if (x->time.next + x->time.accuracy < y->time.next + y->time.accuracy)
 279                 return -1;
 280         if (x->time.next + x->time.accuracy > y->time.next + y->time.accuracy)
 281                 return 1;
 282
 283         /* Stability for the rest */
 284         if (x < y)
 285                 return -1;
 286         if (x > y)
 287                 return 1;
 288
 289         return 0;
 290 }
 291
 292 static int exit_prioq_compare(const void *a, const void *b) {
 293         const sd_event_source *x = a, *y = b;
 294
 295         assert(x->type == SOURCE_EXIT);
 296         assert(y->type == SOURCE_EXIT);
 297
 298         /* Enabled ones first */
 299         if (x->enabled != SD_EVENT_OFF && y->enabled == SD_EVENT_OFF)
 300                 return -1;
 301         if (x->enabled == SD_EVENT_OFF && y->enabled != SD_EVENT_OFF)
 302                 return 1;
 303
 304         /* Lower priority values first */
 305         if (x->priority < y->priority)
 306                 return -1;
 307         if (x->priority > y->priority)
 308                 return 1;
 309
 310         /* Stability for the rest */
 311         if (x < y)
 312                 return -1;
 313         if (x > y)
 314                 return 1;
 315
 316         return 0;
 317 }
 318
 319 static void event_free(sd_event *e) {
 320         assert(e);
 321         assert(e->n_sources == 0);
 322
 323         if (e->default_event_ptr)
 324                 *(e->default_event_ptr) = NULL;
 325
 326         if (e->epoll_fd >= 0)
 327                 close_nointr_nofail(e->epoll_fd);
 328
 329         if (e->signal_fd >= 0)
 330                 close_nointr_nofail(e->signal_fd);
 331
 332         if (e->realtime_fd >= 0)
 333                 close_nointr_nofail(e->realtime_fd);
 334
 335         if (e->monotonic_fd >= 0)
 336                 close_nointr_nofail(e->monotonic_fd);
 337
 338         if (e->watchdog_fd >= 0)
 339                 close_nointr_nofail(e->watchdog_fd);
 340
 341         prioq_free(e->pending);
 342         prioq_free(e->prepare);
 343         prioq_free(e->monotonic_earliest);
 344         prioq_free(e->monotonic_latest);
 345         prioq_free(e->realtime_earliest);
 346         prioq_free(e->realtime_latest);
 347         prioq_free(e->exit);
 348
 349         free(e->signal_sources);
 350
 351         hashmap_free(e->child_sources);
 352         free(e);
 353 }
 354
 355 _public_ int sd_event_new(sd_event** ret) {
 356         sd_event *e;
 357         int r;
 358
 359         assert_return(ret, -EINVAL);
 360
 361         e = new0(sd_event, 1);
 362         if (!e)
 363                 return -ENOMEM;
 364
 365         e->n_ref = 1;
 366         e->signal_fd = e->realtime_fd = e->monotonic_fd = e->watchdog_fd = e->epoll_fd = -1;
 367         e->realtime_next = e->monotonic_next = (usec_t) -1;
 368         e->original_pid = getpid();
 369
 370         assert_se(sigemptyset(&e->sigset) == 0);
 371
 372         e->pending = prioq_new(pending_prioq_compare);
 373         if (!e->pending) {
 374                 r = -ENOMEM;
 375                 goto fail;
 376         }
 377
 378         e->epoll_fd = epoll_create1(EPOLL_CLOEXEC);
 379         if (e->epoll_fd < 0) {
 380                 r = -errno;
 381                 goto fail;
 382         }
 383
 384         *ret = e;
 385         return 0;
 386
 387 fail:
 388         event_free(e);
 389         return r;
 390 }
 391
 392 _public_ sd_event* sd_event_ref(sd_event *e) {
 393         assert_return(e, NULL);
 394
 395         assert(e->n_ref >= 1);
 396         e->n_ref++;
 397
 398         return e;
 399 }
 400
 401 _public_ sd_event* sd_event_unref(sd_event *e) {
 402
 403         if (!e)
 404                 return NULL;
 405
 406         assert(e->n_ref >= 1);
 407         e->n_ref--;
 408
 409         if (e->n_ref <= 0)
 410                 event_free(e);
 411
 412         return NULL;
 413 }
 414
 415 static bool event_pid_changed(sd_event *e) {
 416         assert(e);
 417
 418         /* We don't support people creating am event loop and keeping
 419          * it around over a fork(). Let's complain. */
 420
 421         return e->original_pid != getpid();
 422 }
 423
 424 static int source_io_unregister(sd_event_source *s) {
 425         int r;
 426
 427         assert(s);
 428         assert(s->type == SOURCE_IO);
 429
 430         if (!s->io.registered)
 431                 return 0;
 432
 433         r = epoll_ctl(s->event->epoll_fd, EPOLL_CTL_DEL, s->io.fd, NULL);
 434         if (r < 0)
 435                 return -errno;
 436
 437         s->io.registered = false;
 438         return 0;
 439 }
 440
 441 static int source_io_register(
 442                 sd_event_source *s,
 443                 int enabled,
 444                 uint32_t events) {
 445
 446         struct epoll_event ev = {};
 447         int r;
 448
 449         assert(s);
 450         assert(s->type == SOURCE_IO);
 451         assert(enabled != SD_EVENT_OFF);
 452
 453         ev.events = events;
 454         ev.data.ptr = s;
 455
 456         if (enabled == SD_EVENT_ONESHOT)
 457                 ev.events |= EPOLLONESHOT;
 458
 459         if (s->io.registered)
 460                 r = epoll_ctl(s->event->epoll_fd, EPOLL_CTL_MOD, s->io.fd, &ev);
 461         else
 462                 r = epoll_ctl(s->event->epoll_fd, EPOLL_CTL_ADD, s->io.fd, &ev);
 463
 464         if (r < 0)
 465                 return -errno;
 466
 467         s->io.registered = true;
 468
 469         return 0;
 470 }
 471
 472 static void source_free(sd_event_source *s) {
 473         assert(s);
 474
 475         if (s->event) {
 476                 assert(s->event->n_sources > 0);
 477
 478                 switch (s->type) {
 479
 480                 case SOURCE_IO:
 481                         if (s->io.fd >= 0)
 482                                 source_io_unregister(s);
 483
 484                         break;
 485
 486                 case SOURCE_MONOTONIC:
 487                         prioq_remove(s->event->monotonic_earliest, s, &s->time.earliest_index);
 488                         prioq_remove(s->event->monotonic_latest, s, &s->time.latest_index);
 489                         break;
 490
 491                 case SOURCE_REALTIME:
 492                         prioq_remove(s->event->realtime_earliest, s, &s->time.earliest_index);
 493                         prioq_remove(s->event->realtime_latest, s, &s->time.latest_index);
 494                         break;
 495
 496                 case SOURCE_SIGNAL:
 497                         if (s->signal.sig > 0) {
 498                                 if (s->signal.sig != SIGCHLD || s->event->n_enabled_child_sources == 0)
 499                                         assert_se(sigdelset(&s->event->sigset, s->signal.sig) == 0);
 500
 501                                 if (s->event->signal_sources)
 502                                         s->event->signal_sources[s->signal.sig] = NULL;
 503                         }
 504
 505                         break;
 506
 507                 case SOURCE_CHILD:
 508                         if (s->child.pid > 0) {
 509                                 if (s->enabled != SD_EVENT_OFF) {
 510                                         assert(s->event->n_enabled_child_sources > 0);
 511                                         s->event->n_enabled_child_sources--;
 512                                 }
 513
 514                                 if (!s->event->signal_sources || !s->event->signal_sources[SIGCHLD])
 515                                         assert_se(sigdelset(&s->event->sigset, SIGCHLD) == 0);
 516
 517                                 hashmap_remove(s->event->child_sources, INT_TO_PTR(s->child.pid));
 518                         }
 519
 520                         break;
 521
 522                 case SOURCE_DEFER:
 523                         /* nothing */
 524                         break;
 525
 526                 case SOURCE_EXIT:
 527                         prioq_remove(s->event->exit, s, &s->exit.prioq_index);
 528                         break;
 529
 530                 case SOURCE_WATCHDOG:
 531                         assert_not_reached("Wut? I shouldn't exist.");
 532                 }
 533
 534                 if (s->pending)
 535                         prioq_remove(s->event->pending, s, &s->pending_index);
 536
 537                 if (s->prepare)
 538                         prioq_remove(s->event->prepare, s, &s->prepare_index);
 539
 540                 s->event->n_sources--;
 541                 sd_event_unref(s->event);
 542         }
 543
 544         free(s);
 545 }
 546
 547 static int source_set_pending(sd_event_source *s, bool b) {
 548         int r;
 549
 550         assert(s);
 551         assert(s->type != SOURCE_EXIT);
 552
 553         if (s->pending == b)
 554                 return 0;
 555
 556         s->pending = b;
 557
 558         if (b) {
 559                 s->pending_iteration = s->event->iteration;
 560
 561                 r = prioq_put(s->event->pending, s, &s->pending_index);
 562                 if (r < 0) {
 563                         s->pending = false;
 564                         return r;
 565                 }
 566         } else
 567                 assert_se(prioq_remove(s->event->pending, s, &s->pending_index));
 568
 569         if (s->type == SOURCE_REALTIME) {
 570                 prioq_reshuffle(s->event->realtime_earliest, s, &s->time.earliest_index);
 571                 prioq_reshuffle(s->event->realtime_latest, s, &s->time.latest_index);
 572         } else if (s->type == SOURCE_MONOTONIC) {
 573                 prioq_reshuffle(s->event->monotonic_earliest, s, &s->time.earliest_index);
 574                 prioq_reshuffle(s->event->monotonic_latest, s, &s->time.latest_index);
 575         }
 576
 577         return 0;
 578 }
 579
 580 static sd_event_source *source_new(sd_event *e, EventSourceType type) {
 581         sd_event_source *s;
 582
 583         assert(e);
 584
 585         s = new0(sd_event_source, 1);
 586         if (!s)
 587                 return NULL;
 588
 589         s->n_ref = 1;
 590         s->event = sd_event_ref(e);
 591         s->type = type;
 592         s->pending_index = s->prepare_index = PRIOQ_IDX_NULL;
 593
 594         e->n_sources ++;
 595
 596         return s;
 597 }
 598
 599 _public_ int sd_event_add_io(
 600                 sd_event *e,
 601                 int fd,
 602                 uint32_t events,
 603                 sd_event_io_handler_t callback,
 604                 void *userdata,
 605                 sd_event_source **ret) {
 606
 607         sd_event_source *s;
 608         int r;
 609
 610         assert_return(e, -EINVAL);
 611         assert_return(fd >= 0, -EINVAL);
 612         assert_return(!(events & ~(EPOLLIN|EPOLLOUT|EPOLLRDHUP|EPOLLPRI|EPOLLERR|EPOLLHUP|EPOLLET)), -EINVAL);
 613         assert_return(callback, -EINVAL);
 614         assert_return(ret, -EINVAL);
 615         assert_return(e->state != SD_EVENT_FINISHED, -ESTALE);
 616         assert_return(!event_pid_changed(e), -ECHILD);
 617
 618         s = source_new(e, SOURCE_IO);
 619         if (!s)
 620                 return -ENOMEM;
 621
 622         s->io.fd = fd;
 623         s->io.events = events;
 624         s->io.callback = callback;
 625         s->userdata = userdata;
 626         s->enabled = SD_EVENT_ON;
 627
 628         r = source_io_register(s, s->enabled, events);
 629         if (r < 0) {
 630                 source_free(s);
 631                 return -errno;
 632         }
 633
 634         *ret = s;
 635         return 0;
 636 }
 637
 638 static int event_setup_timer_fd(
 639                 sd_event *e,
 640                 EventSourceType type,
 641                 int *timer_fd,
 642                 clockid_t id) {
 643
 644         struct epoll_event ev = {};
 645         int r, fd;
 646         sd_id128_t bootid;
 647
 648         assert(e);
 649         assert(timer_fd);
 650
 651         if (_likely_(*timer_fd >= 0))
 652                 return 0;
 653
 654         fd = timerfd_create(id, TFD_NONBLOCK|TFD_CLOEXEC);
 655         if (fd < 0)
 656                 return -errno;
 657
 658         ev.events = EPOLLIN;
 659         ev.data.ptr = INT_TO_PTR(type);
 660
 661         r = epoll_ctl(e->epoll_fd, EPOLL_CTL_ADD, fd, &ev);
 662         if (r < 0) {
 663                 close_nointr_nofail(fd);
 664                 return -errno;
 665         }
 666
 667         /* When we sleep for longer, we try to realign the wakeup to
 668            the same time wihtin each minute/second/250ms, so that
 669            events all across the system can be coalesced into a single
 670            CPU wakeup. However, let's take some system-specific
 671            randomness for this value, so that in a network of systems
 672            with synced clocks timer events are distributed a
 673            bit. Here, we calculate a perturbation usec offset from the
 674            boot ID. */
 675
 676         if (sd_id128_get_boot(&bootid) >= 0)
 677                 e->perturb = (bootid.qwords[0] ^ bootid.qwords[1]) % USEC_PER_MINUTE;
 678
 679         *timer_fd = fd;
 680         return 0;
 681 }
 682
 683 static int event_add_time_internal(
 684                 sd_event *e,
 685                 EventSourceType type,
 686                 int *timer_fd,
 687                 clockid_t id,
 688                 Prioq **earliest,
 689                 Prioq **latest,
 690                 uint64_t usec,
 691                 uint64_t accuracy,
 692                 sd_event_time_handler_t callback,
 693                 void *userdata,
 694                 sd_event_source **ret) {
 695
 696         sd_event_source *s;
 697         int r;
 698
 699         assert_return(e, -EINVAL);
 700         assert_return(callback, -EINVAL);
 701         assert_return(ret, -EINVAL);
 702         assert_return(usec != (uint64_t) -1, -EINVAL);
 703         assert_return(accuracy != (uint64_t) -1, -EINVAL);
 704         assert_return(e->state != SD_EVENT_FINISHED, -ESTALE);
 705         assert_return(!event_pid_changed(e), -ECHILD);
 706
 707         assert(timer_fd);
 708         assert(earliest);
 709         assert(latest);
 710
 711         if (!*earliest) {
 712                 *earliest = prioq_new(earliest_time_prioq_compare);
 713                 if (!*earliest)
 714                         return -ENOMEM;
 715         }
 716
 717         if (!*latest) {
 718                 *latest = prioq_new(latest_time_prioq_compare);
 719                 if (!*latest)
 720                         return -ENOMEM;
 721         }
 722
 723         if (*timer_fd < 0) {
 724                 r = event_setup_timer_fd(e, type, timer_fd, id);
 725                 if (r < 0)
 726                         return r;
 727         }
 728
 729         s = source_new(e, type);
 730         if (!s)
 731                 return -ENOMEM;
 732
 733         s->time.next = usec;
 734         s->time.accuracy = accuracy == 0 ? DEFAULT_ACCURACY_USEC : accuracy;
 735         s->time.callback = callback;
 736         s->time.earliest_index = s->time.latest_index = PRIOQ_IDX_NULL;
 737         s->userdata = userdata;
 738         s->enabled = SD_EVENT_ONESHOT;
 739
 740         r = prioq_put(*earliest, s, &s->time.earliest_index);
 741         if (r < 0)
 742                 goto fail;
 743
 744         r = prioq_put(*latest, s, &s->time.latest_index);
 745         if (r < 0)
 746                 goto fail;
 747
 748         *ret = s;
 749         return 0;
 750
 751 fail:
 752         source_free(s);
 753         return r;
 754 }
 755
 756 _public_ int sd_event_add_monotonic(sd_event *e,
 757                                     uint64_t usec,
 758                                     uint64_t accuracy,
 759                                     sd_event_time_handler_t callback,
 760                                     void *userdata,
 761                                     sd_event_source **ret) {
 762
 763         return event_add_time_internal(e, SOURCE_MONOTONIC, &e->monotonic_fd, CLOCK_MONOTONIC, &e->monotonic_earliest, &e->monotonic_latest, usec, accuracy, callback, userdata, ret);
 764 }
 765
 766 _public_ int sd_event_add_realtime(sd_event *e,
 767                                    uint64_t usec,
 768                                    uint64_t accuracy,
 769                                    sd_event_time_handler_t callback,
 770                                    void *userdata,
 771                                    sd_event_source **ret) {
 772
 773         return event_add_time_internal(e, SOURCE_REALTIME, &e->realtime_fd, CLOCK_REALTIME, &e->realtime_earliest, &e->monotonic_latest, usec, accuracy, callback, userdata, ret);
 774 }
 775
 776 static int event_update_signal_fd(sd_event *e) {
 777         struct epoll_event ev = {};
 778         bool add_to_epoll;
 779         int r;
 780
 781         assert(e);
 782
 783         add_to_epoll = e->signal_fd < 0;
 784
 785         r = signalfd(e->signal_fd, &e->sigset, SFD_NONBLOCK|SFD_CLOEXEC);
 786         if (r < 0)
 787                 return -errno;
 788
 789         e->signal_fd = r;
 790
 791         if (!add_to_epoll)
 792                 return 0;
 793
 794         ev.events = EPOLLIN;
 795         ev.data.ptr = INT_TO_PTR(SOURCE_SIGNAL);
 796
 797         r = epoll_ctl(e->epoll_fd, EPOLL_CTL_ADD, e->signal_fd, &ev);
 798         if (r < 0) {
 799                 close_nointr_nofail(e->signal_fd);
 800                 e->signal_fd = -1;
 801
 802                 return -errno;
 803         }
 804
 805         return 0;
 806 }
 807
 808 _public_ int sd_event_add_signal(
 809                 sd_event *e,
 810                 int sig,
 811                 sd_event_signal_handler_t callback,
 812                 void *userdata,
 813                 sd_event_source **ret) {
 814
 815         sd_event_source *s;
 816         int r;
 817
 818         assert_return(e, -EINVAL);
 819         assert_return(sig > 0, -EINVAL);
 820         assert_return(sig < _NSIG, -EINVAL);
 821         assert_return(callback, -EINVAL);
 822         assert_return(ret, -EINVAL);
 823         assert_return(e->state != SD_EVENT_FINISHED, -ESTALE);
 824         assert_return(!event_pid_changed(e), -ECHILD);
 825
 826         if (!e->signal_sources) {
 827                 e->signal_sources = new0(sd_event_source*, _NSIG);
 828                 if (!e->signal_sources)
 829                         return -ENOMEM;
 830         } else if (e->signal_sources[sig])
 831                 return -EBUSY;
 832
 833         s = source_new(e, SOURCE_SIGNAL);
 834         if (!s)
 835                 return -ENOMEM;
 836
 837         s->signal.sig = sig;
 838         s->signal.callback = callback;
 839         s->userdata = userdata;
 840         s->enabled = SD_EVENT_ON;
 841
 842         e->signal_sources[sig] = s;
 843         assert_se(sigaddset(&e->sigset, sig) == 0);
 844
 845         if (sig != SIGCHLD || e->n_enabled_child_sources == 0) {
 846                 r = event_update_signal_fd(e);
 847                 if (r < 0) {
 848                         source_free(s);
 849                         return r;
 850                 }
 851         }
 852
 853         *ret = s;
 854         return 0;
 855 }
 856
 857 _public_ int sd_event_add_child(
 858                 sd_event *e,
 859                 pid_t pid,
 860                 int options,
 861                 sd_event_child_handler_t callback,
 862                 void *userdata,
 863                 sd_event_source **ret) {
 864
 865         sd_event_source *s;
 866         int r;
 867
 868         assert_return(e, -EINVAL);
 869         assert_return(pid > 1, -EINVAL);
 870         assert_return(!(options & ~(WEXITED|WSTOPPED|WCONTINUED)), -EINVAL);
 871         assert_return(options != 0, -EINVAL);
 872         assert_return(callback, -EINVAL);
 873         assert_return(ret, -EINVAL);
 874         assert_return(e->state != SD_EVENT_FINISHED, -ESTALE);
 875         assert_return(!event_pid_changed(e), -ECHILD);
 876
 877         r = hashmap_ensure_allocated(&e->child_sources, trivial_hash_func, trivial_compare_func);
 878         if (r < 0)
 879                 return r;
 880
 881         if (hashmap_contains(e->child_sources, INT_TO_PTR(pid)))
 882                 return -EBUSY;
 883
 884         s = source_new(e, SOURCE_CHILD);
 885         if (!s)
 886                 return -ENOMEM;
 887
 888         s->child.pid = pid;
 889         s->child.options = options;
 890         s->child.callback = callback;
 891         s->userdata = userdata;
 892         s->enabled = SD_EVENT_ONESHOT;
 893
 894         r = hashmap_put(e->child_sources, INT_TO_PTR(pid), s);
 895         if (r < 0) {
 896                 source_free(s);
 897                 return r;
 898         }
 899
 900         e->n_enabled_child_sources ++;
 901
 902         assert_se(sigaddset(&e->sigset, SIGCHLD) == 0);
 903
 904         if (!e->signal_sources || !e->signal_sources[SIGCHLD]) {
 905                 r = event_update_signal_fd(e);
 906                 if (r < 0) {
 907                         source_free(s);
 908                         return -errno;
 909                 }
 910         }
 911
 912         e->need_process_child = true;
 913
 914         *ret = s;
 915         return 0;
 916 }
 917
 918 _public_ int sd_event_add_defer(
 919                 sd_event *e,
 920                 sd_event_handler_t callback,
 921                 void *userdata,
 922                 sd_event_source **ret) {
 923
 924         sd_event_source *s;
 925         int r;
 926
 927         assert_return(e, -EINVAL);
 928         assert_return(callback, -EINVAL);
 929         assert_return(ret, -EINVAL);
 930         assert_return(e->state != SD_EVENT_FINISHED, -ESTALE);
 931         assert_return(!event_pid_changed(e), -ECHILD);
 932
 933         s = source_new(e, SOURCE_DEFER);
 934         if (!s)
 935                 return -ENOMEM;
 936
 937         s->defer.callback = callback;
 938         s->userdata = userdata;
 939         s->enabled = SD_EVENT_ONESHOT;
 940
 941         r = source_set_pending(s, true);
 942         if (r < 0) {
 943                 source_free(s);
 944                 return r;
 945         }
 946
 947         *ret = s;
 948         return 0;
 949 }
 950
 951 _public_ int sd_event_add_exit(
 952                 sd_event *e,
 953                 sd_event_handler_t callback,
 954                 void *userdata,
 955                 sd_event_source **ret) {
 956
 957         sd_event_source *s;
 958         int r;
 959
 960         assert_return(e, -EINVAL);
 961         assert_return(callback, -EINVAL);
 962         assert_return(ret, -EINVAL);
 963         assert_return(e->state != SD_EVENT_FINISHED, -ESTALE);
 964         assert_return(!event_pid_changed(e), -ECHILD);
 965
 966         if (!e->exit) {
 967                 e->exit = prioq_new(exit_prioq_compare);
 968                 if (!e->exit)
 969                         return -ENOMEM;
 970         }
 971
 972         s = source_new(e, SOURCE_EXIT);
 973         if (!s)
 974                 return -ENOMEM;
 975
 976         s->exit.callback = callback;
 977         s->userdata = userdata;
 978         s->exit.prioq_index = PRIOQ_IDX_NULL;
 979         s->enabled = SD_EVENT_ONESHOT;
 980
 981         r = prioq_put(s->event->exit, s, &s->exit.prioq_index);
 982         if (r < 0) {
 983                 source_free(s);
 984                 return r;
 985         }
 986
 987         *ret = s;
 988         return 0;
 989 }
 990
 991 _public_ sd_event_source* sd_event_source_ref(sd_event_source *s) {
 992         assert_return(s, NULL);
 993
 994         assert(s->n_ref >= 1);
 995         s->n_ref++;
 996
 997         return s;
 998 }
 999
1000 _public_ sd_event_source* sd_event_source_unref(sd_event_source *s) {
1001
1002         if (!s)
1003                 return NULL;
1004
1005         assert(s->n_ref >= 1);
1006         s->n_ref--;
1007
1008         if (s->n_ref <= 0) {
1009                 /* Here's a special hack: when we are called from a
1010                  * dispatch handler we won't free the event source
1011                  * immediately, but we will detach the fd from the
1012                  * epoll. This way it is safe for the caller to unref
1013                  * the event source and immediately close the fd, but
1014                  * we still retain a valid event source object after
1015                  * the callback. */
1016
1017                 if (s->dispatching) {
1018                         if (s->type == SOURCE_IO)
1019                                 source_io_unregister(s);
1020                 } else
1021                         source_free(s);
1022         }
1023
1024         return NULL;
1025 }
1026
1027 _public_ sd_event *sd_event_source_get_event(sd_event_source *s) {
1028         assert_return(s, NULL);
1029
1030         return s->event;
1031 }
1032
1033 _public_ int sd_event_source_get_pending(sd_event_source *s) {
1034         assert_return(s, -EINVAL);
1035         assert_return(s->type != SOURCE_EXIT, -EDOM);
1036         assert_return(s->event->state != SD_EVENT_FINISHED, -ESTALE);
1037         assert_return(!event_pid_changed(s->event), -ECHILD);
1038
1039         return s->pending;
1040 }
1041
1042 _public_ int sd_event_source_get_io_fd(sd_event_source *s) {
1043         assert_return(s, -EINVAL);
1044         assert_return(s->type == SOURCE_IO, -EDOM);
1045         assert_return(!event_pid_changed(s->event), -ECHILD);
1046
1047         return s->io.fd;
1048 }
1049
1050 _public_ int sd_event_source_set_io_fd(sd_event_source *s, int fd) {
1051         int r;
1052
1053         assert_return(s, -EINVAL);
1054         assert_return(fd >= 0, -EINVAL);
1055         assert_return(s->type == SOURCE_IO, -EDOM);
1056         assert_return(!event_pid_changed(s->event), -ECHILD);
1057
1058         if (s->io.fd == fd)
1059                 return 0;
1060
1061         if (s->enabled == SD_EVENT_OFF) {
1062                 s->io.fd = fd;
1063                 s->io.registered = false;
1064         } else {
1065                 int saved_fd;
1066
1067                 saved_fd = s->io.fd;
1068                 assert(s->io.registered);
1069
1070                 s->io.fd = fd;
1071                 s->io.registered = false;
1072
1073                 r = source_io_register(s, s->enabled, s->io.events);
1074                 if (r < 0) {
1075                         s->io.fd = saved_fd;
1076                         s->io.registered = true;
1077                         return r;
1078                 }
1079
1080                 epoll_ctl(s->event->epoll_fd, EPOLL_CTL_DEL, saved_fd, NULL);
1081         }
1082
1083         return 0;
1084 }
1085
1086 _public_ int sd_event_source_get_io_events(sd_event_source *s, uint32_t* events) {
1087         assert_return(s, -EINVAL);
1088         assert_return(events, -EINVAL);
1089         assert_return(s->type == SOURCE_IO, -EDOM);
1090         assert_return(!event_pid_changed(s->event), -ECHILD);
1091
1092         *events = s->io.events;
1093         return 0;
1094 }
1095
1096 _public_ int sd_event_source_set_io_events(sd_event_source *s, uint32_t events) {
1097         int r;
1098
1099         assert_return(s, -EINVAL);
1100         assert_return(s->type == SOURCE_IO, -EDOM);
1101         assert_return(!(events & ~(EPOLLIN|EPOLLOUT|EPOLLRDHUP|EPOLLPRI|EPOLLERR|EPOLLHUP|EPOLLET)), -EINVAL);
1102         assert_return(s->event->state != SD_EVENT_FINISHED, -ESTALE);
1103         assert_return(!event_pid_changed(s->event), -ECHILD);
1104
1105         if (s->io.events == events)
1106                 return 0;
1107
1108         if (s->enabled != SD_EVENT_OFF) {
1109                 r = source_io_register(s, s->enabled, events);
1110                 if (r < 0)
1111                         return r;
1112         }
1113
1114         s->io.events = events;
1115         source_set_pending(s, false);
1116
1117         return 0;
1118 }
1119
1120 _public_ int sd_event_source_get_io_revents(sd_event_source *s, uint32_t* revents) {
1121         assert_return(s, -EINVAL);
1122         assert_return(revents, -EINVAL);
1123         assert_return(s->type == SOURCE_IO, -EDOM);
1124         assert_return(s->pending, -ENODATA);
1125         assert_return(!event_pid_changed(s->event), -ECHILD);
1126
1127         *revents = s->io.revents;
1128         return 0;
1129 }
1130
1131 _public_ int sd_event_source_get_signal(sd_event_source *s) {
1132         assert_return(s, -EINVAL);
1133         assert_return(s->type == SOURCE_SIGNAL, -EDOM);
1134         assert_return(!event_pid_changed(s->event), -ECHILD);
1135
1136         return s->signal.sig;
1137 }
1138
1139 _public_ int sd_event_source_get_priority(sd_event_source *s, int *priority) {
1140         assert_return(s, -EINVAL);
1141         assert_return(!event_pid_changed(s->event), -ECHILD);
1142
1143         return s->priority;
1144 }
1145
1146 _public_ int sd_event_source_set_priority(sd_event_source *s, int priority) {
1147         assert_return(s, -EINVAL);
1148         assert_return(s->event->state != SD_EVENT_FINISHED, -ESTALE);
1149         assert_return(!event_pid_changed(s->event), -ECHILD);
1150
1151         if (s->priority == priority)
1152                 return 0;
1153
1154         s->priority = priority;
1155
1156         if (s->pending)
1157                 prioq_reshuffle(s->event->pending, s, &s->pending_index);
1158
1159         if (s->prepare)
1160                 prioq_reshuffle(s->event->prepare, s, &s->prepare_index);
1161
1162         if (s->type == SOURCE_EXIT)
1163                 prioq_reshuffle(s->event->exit, s, &s->exit.prioq_index);
1164
1165         return 0;
1166 }
1167
1168 _public_ int sd_event_source_get_enabled(sd_event_source *s, int *m) {
1169         assert_return(s, -EINVAL);
1170         assert_return(m, -EINVAL);
1171         assert_return(!event_pid_changed(s->event), -ECHILD);
1172
1173         *m = s->enabled;
1174         return 0;
1175 }
1176
1177 _public_ int sd_event_source_set_enabled(sd_event_source *s, int m) {
1178         int r;
1179
1180         assert_return(s, -EINVAL);
1181         assert_return(m == SD_EVENT_OFF || m == SD_EVENT_ON || m == SD_EVENT_ONESHOT, -EINVAL);
1182         assert_return(s->event->state != SD_EVENT_FINISHED, -ESTALE);
1183         assert_return(!event_pid_changed(s->event), -ECHILD);
1184
1185         if (s->enabled == m)
1186                 return 0;
1187
1188         if (m == SD_EVENT_OFF) {
1189
1190                 switch (s->type) {
1191
1192                 case SOURCE_IO:
1193                         r = source_io_unregister(s);
1194                         if (r < 0)
1195                                 return r;
1196
1197                         s->enabled = m;
1198                         break;
1199
1200                 case SOURCE_MONOTONIC:
1201                         s->enabled = m;
1202                         prioq_reshuffle(s->event->monotonic_earliest, s, &s->time.earliest_index);
1203                         prioq_reshuffle(s->event->monotonic_latest, s, &s->time.latest_index);
1204                         break;
1205
1206                 case SOURCE_REALTIME:
1207                         s->enabled = m;
1208                         prioq_reshuffle(s->event->realtime_earliest, s, &s->time.earliest_index);
1209                         prioq_reshuffle(s->event->realtime_latest, s, &s->time.latest_index);
1210                         break;
1211
1212                 case SOURCE_SIGNAL:
1213                         s->enabled = m;
1214                         if (s->signal.sig != SIGCHLD || s->event->n_enabled_child_sources == 0) {
1215                                 assert_se(sigdelset(&s->event->sigset, s->signal.sig) == 0);
1216                                 event_update_signal_fd(s->event);
1217                         }
1218
1219                         break;
1220
1221                 case SOURCE_CHILD:
1222                         s->enabled = m;
1223
1224                         assert(s->event->n_enabled_child_sources > 0);
1225                         s->event->n_enabled_child_sources--;
1226
1227                         if (!s->event->signal_sources || !s->event->signal_sources[SIGCHLD]) {
1228                                 assert_se(sigdelset(&s->event->sigset, SIGCHLD) == 0);
1229                                 event_update_signal_fd(s->event);
1230                         }
1231
1232                         break;
1233
1234                 case SOURCE_EXIT:
1235                         s->enabled = m;
1236                         prioq_reshuffle(s->event->exit, s, &s->exit.prioq_index);
1237                         break;
1238
1239                 case SOURCE_DEFER:
1240                         s->enabled = m;
1241                         break;
1242
1243                 case SOURCE_WATCHDOG:
1244                         assert_not_reached("Wut? I shouldn't exist.");
1245                 }
1246
1247         } else {
1248                 switch (s->type) {
1249
1250                 case SOURCE_IO:
1251                         r = source_io_register(s, m, s->io.events);
1252                         if (r < 0)
1253                                 return r;
1254
1255                         s->enabled = m;
1256                         break;
1257
1258                 case SOURCE_MONOTONIC:
1259                         s->enabled = m;
1260                         prioq_reshuffle(s->event->monotonic_earliest, s, &s->time.earliest_index);
1261                         prioq_reshuffle(s->event->monotonic_latest, s, &s->time.latest_index);
1262                         break;
1263
1264                 case SOURCE_REALTIME:
1265                         s->enabled = m;
1266                         prioq_reshuffle(s->event->realtime_earliest, s, &s->time.earliest_index);
1267                         prioq_reshuffle(s->event->realtime_latest, s, &s->time.latest_index);
1268                         break;
1269
1270                 case SOURCE_SIGNAL:
1271                         s->enabled = m;
1272
1273                         if (s->signal.sig != SIGCHLD || s->event->n_enabled_child_sources == 0)  {
1274                                 assert_se(sigaddset(&s->event->sigset, s->signal.sig) == 0);
1275                                 event_update_signal_fd(s->event);
1276                         }
1277                         break;
1278
1279                 case SOURCE_CHILD:
1280                         s->enabled = m;
1281
1282                         if (s->enabled == SD_EVENT_OFF) {
1283                                 s->event->n_enabled_child_sources++;
1284
1285                                 if (!s->event->signal_sources || !s->event->signal_sources[SIGCHLD]) {
1286                                         assert_se(sigaddset(&s->event->sigset, SIGCHLD) == 0);
1287                                         event_update_signal_fd(s->event);
1288                                 }
1289                         }
1290                         break;
1291
1292                 case SOURCE_EXIT:
1293                         s->enabled = m;
1294                         prioq_reshuffle(s->event->exit, s, &s->exit.prioq_index);
1295                         break;
1296
1297                 case SOURCE_DEFER:
1298                         s->enabled = m;
1299                         break;
1300
1301                 case SOURCE_WATCHDOG:
1302                         assert_not_reached("Wut? I shouldn't exist.");
1303                 }
1304         }
1305
1306         if (s->pending)
1307                 prioq_reshuffle(s->event->pending, s, &s->pending_index);
1308
1309         if (s->prepare)
1310                 prioq_reshuffle(s->event->prepare, s, &s->prepare_index);
1311
1312         return 0;
1313 }
1314
1315 _public_ int sd_event_source_get_time(sd_event_source *s, uint64_t *usec) {
1316         assert_return(s, -EINVAL);
1317         assert_return(usec, -EINVAL);
1318         assert_return(s->type == SOURCE_REALTIME || s->type == SOURCE_MONOTONIC, -EDOM);
1319         assert_return(!event_pid_changed(s->event), -ECHILD);
1320
1321         *usec = s->time.next;
1322         return 0;
1323 }
1324
1325 _public_ int sd_event_source_set_time(sd_event_source *s, uint64_t usec) {
1326         assert_return(s, -EINVAL);
1327         assert_return(usec != (uint64_t) -1, -EINVAL);
1328         assert_return(s->type == SOURCE_REALTIME || s->type == SOURCE_MONOTONIC, -EDOM);
1329         assert_return(s->event->state != SD_EVENT_FINISHED, -ESTALE);
1330         assert_return(!event_pid_changed(s->event), -ECHILD);
1331
1332         s->time.next = usec;
1333
1334         source_set_pending(s, false);
1335
1336         if (s->type == SOURCE_REALTIME) {
1337                 prioq_reshuffle(s->event->realtime_earliest, s, &s->time.earliest_index);
1338                 prioq_reshuffle(s->event->realtime_latest, s, &s->time.latest_index);
1339         } else {
1340                 prioq_reshuffle(s->event->monotonic_earliest, s, &s->time.earliest_index);
1341                 prioq_reshuffle(s->event->monotonic_latest, s, &s->time.latest_index);
1342         }
1343
1344         return 0;
1345 }
1346
1347 _public_ int sd_event_source_get_time_accuracy(sd_event_source *s, uint64_t *usec) {
1348         assert_return(s, -EINVAL);
1349         assert_return(usec, -EINVAL);
1350         assert_return(s->type == SOURCE_REALTIME || s->type == SOURCE_MONOTONIC, -EDOM);
1351         assert_return(!event_pid_changed(s->event), -ECHILD);
1352
1353         *usec = s->time.accuracy;
1354         return 0;
1355 }
1356
1357 _public_ int sd_event_source_set_time_accuracy(sd_event_source *s, uint64_t usec) {
1358         assert_return(s, -EINVAL);
1359         assert_return(usec != (uint64_t) -1, -EINVAL);
1360         assert_return(s->type == SOURCE_REALTIME || s->type == SOURCE_MONOTONIC, -EDOM);
1361         assert_return(s->event->state != SD_EVENT_FINISHED, -ESTALE);
1362         assert_return(!event_pid_changed(s->event), -ECHILD);
1363
1364         if (usec == 0)
1365                 usec = DEFAULT_ACCURACY_USEC;
1366
1367         s->time.accuracy = usec;
1368
1369         source_set_pending(s, false);
1370
1371         if (s->type == SOURCE_REALTIME)
1372                 prioq_reshuffle(s->event->realtime_latest, s, &s->time.latest_index);
1373         else
1374                 prioq_reshuffle(s->event->monotonic_latest, s, &s->time.latest_index);
1375
1376         return 0;
1377 }
1378
1379 _public_ int sd_event_source_get_child_pid(sd_event_source *s, pid_t *pid) {
1380         assert_return(s, -EINVAL);
1381         assert_return(pid, -EINVAL);
1382         assert_return(s->type == SOURCE_CHILD, -EDOM);
1383         assert_return(!event_pid_changed(s->event), -ECHILD);
1384
1385         *pid = s->child.pid;
1386         return 0;
1387 }
1388
1389 _public_ int sd_event_source_set_prepare(sd_event_source *s, sd_event_handler_t callback) {
1390         int r;
1391
1392         assert_return(s, -EINVAL);
1393         assert_return(s->type != SOURCE_EXIT, -EDOM);
1394         assert_return(s->event->state != SD_EVENT_FINISHED, -ESTALE);
1395         assert_return(!event_pid_changed(s->event), -ECHILD);
1396
1397         if (s->prepare == callback)
1398                 return 0;
1399
1400         if (callback && s->prepare) {
1401                 s->prepare = callback;
1402                 return 0;
1403         }
1404
1405         r = prioq_ensure_allocated(&s->event->prepare, prepare_prioq_compare);
1406         if (r < 0)
1407                 return r;
1408
1409         s->prepare = callback;
1410
1411         if (callback) {
1412                 r = prioq_put(s->event->prepare, s, &s->prepare_index);
1413                 if (r < 0)
1414                         return r;
1415         } else
1416                 prioq_remove(s->event->prepare, s, &s->prepare_index);
1417
1418         return 0;
1419 }
1420
1421 _public_ void* sd_event_source_get_userdata(sd_event_source *s) {
1422         assert_return(s, NULL);
1423
1424         return s->userdata;
1425 }
1426
1427 _public_ void *sd_event_source_set_userdata(sd_event_source *s, void *userdata) {
1428         void *ret;
1429
1430         assert_return(s, NULL);
1431
1432         ret = s->userdata;
1433         s->userdata = userdata;
1434
1435         return ret;
1436 }
1437
1438 static usec_t sleep_between(sd_event *e, usec_t a, usec_t b) {
1439         usec_t c;
1440         assert(e);
1441         assert(a <= b);
1442
1443         if (a <= 0)
1444                 return 0;
1445
1446         if (b <= a + 1)
1447                 return a;
1448
1449         /*
1450           Find a good time to wake up again between times a and b. We
1451           have two goals here:
1452
1453           a) We want to wake up as seldom as possible, hence prefer
1454              later times over earlier times.
1455
1456           b) But if we have to wake up, then let's make sure to
1457              dispatch as much as possible on the entire system.
1458
1459           We implement this by waking up everywhere at the same time
1460           within any given minute if we can, synchronised via the
1461           perturbation value determined from the boot ID. If we can't,
1462           then we try to find the same spot in every 10s, then 1s and
1463           then 250ms step. Otherwise, we pick the last possible time
1464           to wake up.
1465         */
1466
1467         c = (b / USEC_PER_MINUTE) * USEC_PER_MINUTE + e->perturb;
1468         if (c >= b) {
1469                 if (_unlikely_(c < USEC_PER_MINUTE))
1470                         return b;
1471
1472                 c -= USEC_PER_MINUTE;
1473         }
1474
1475         if (c >= a)
1476                 return c;
1477
1478         c = (b / (USEC_PER_SEC*10)) * (USEC_PER_SEC*10) + (e->perturb % (USEC_PER_SEC*10));
1479         if (c >= b) {
1480                 if (_unlikely_(c < USEC_PER_SEC*10))
1481                         return b;
1482
1483                 c -= USEC_PER_SEC*10;
1484         }
1485
1486         if (c >= a)
1487                 return c;
1488
1489         c = (b / USEC_PER_SEC) * USEC_PER_SEC + (e->perturb % USEC_PER_SEC);
1490         if (c >= b) {
1491                 if (_unlikely_(c < USEC_PER_SEC))
1492                         return b;
1493
1494                 c -= USEC_PER_SEC;
1495         }
1496
1497         if (c >= a)
1498                 return c;
1499
1500         c = (b / (USEC_PER_MSEC*250)) * (USEC_PER_MSEC*250) + (e->perturb % (USEC_PER_MSEC*250));
1501         if (c >= b) {
1502                 if (_unlikely_(c < USEC_PER_MSEC*250))
1503                         return b;
1504
1505                 c -= USEC_PER_MSEC*250;
1506         }
1507
1508         if (c >= a)
1509                 return c;
1510
1511         return b;
1512 }
1513
1514 static int event_arm_timer(
1515                 sd_event *e,
1516                 int timer_fd,
1517                 Prioq *earliest,
1518                 Prioq *latest,
1519                 usec_t *next) {
1520
1521         struct itimerspec its = {};
1522         sd_event_source *a, *b;
1523         usec_t t;
1524         int r;
1525
1526         assert(e);
1527         assert(next);
1528
1529         a = prioq_peek(earliest);
1530         if (!a || a->enabled == SD_EVENT_OFF) {
1531
1532                 if (timer_fd < 0)
1533                         return 0;
1534
1535                 if (*next == (usec_t) -1)
1536                         return 0;
1537
1538                 /* disarm */
1539                 r = timerfd_settime(timer_fd, TFD_TIMER_ABSTIME, &its, NULL);
1540                 if (r < 0)
1541                         return r;
1542
1543                 *next = (usec_t) -1;
1544
1545                 return 0;
1546         }
1547
1548         b = prioq_peek(latest);
1549         assert_se(b && b->enabled != SD_EVENT_OFF);
1550
1551         t = sleep_between(e, a->time.next, b->time.next + b->time.accuracy);
1552         if (*next == t)
1553                 return 0;
1554
1555         assert_se(timer_fd >= 0);
1556
1557         if (t == 0) {
1558                 /* We don' want to disarm here, just mean some time looooong ago. */
1559                 its.it_value.tv_sec = 0;
1560                 its.it_value.tv_nsec = 1;
1561         } else
1562                 timespec_store(&its.it_value, t);
1563
1564         r = timerfd_settime(timer_fd, TFD_TIMER_ABSTIME, &its, NULL);
1565         if (r < 0)
1566                 return -errno;
1567
1568         *next = t;
1569         return 0;
1570 }
1571
1572 static int process_io(sd_event *e, sd_event_source *s, uint32_t revents) {
1573         assert(e);
1574         assert(s);
1575         assert(s->type == SOURCE_IO);
1576
1577         /* If the event source was already pending, we just OR in the
1578          * new revents, otherwise we reset the value. The ORing is
1579          * necessary to handle EPOLLONESHOT events properly where
1580          * readability might happen independently of writability, and
1581          * we need to keep track of both */
1582
1583         if (s->pending)
1584                 s->io.revents |= revents;
1585         else
1586                 s->io.revents = revents;
1587
1588         return source_set_pending(s, true);
1589 }
1590
1591 static int flush_timer(sd_event *e, int fd, uint32_t events, usec_t *next) {
1592         uint64_t x;
1593         ssize_t ss;
1594
1595         assert(e);
1596         assert(fd >= 0);
1597
1598         assert_return(events == EPOLLIN, -EIO);
1599
1600         ss = read(fd, &x, sizeof(x));
1601         if (ss < 0) {
1602                 if (errno == EAGAIN || errno == EINTR)
1603                         return 0;
1604
1605                 return -errno;
1606         }
1607
1608         if (_unlikely_(ss != sizeof(x)))
1609                 return -EIO;
1610
1611         if (next)
1612                 *next = (usec_t) -1;
1613
1614         return 0;
1615 }
1616
1617 static int process_timer(
1618                 sd_event *e,
1619                 usec_t n,
1620                 Prioq *earliest,
1621                 Prioq *latest) {
1622
1623         sd_event_source *s;
1624         int r;
1625
1626         assert(e);
1627
1628         for (;;) {
1629                 s = prioq_peek(earliest);
1630                 if (!s ||
1631                     s->time.next > n ||
1632                     s->enabled == SD_EVENT_OFF ||
1633                     s->pending)
1634                         break;
1635
1636                 r = source_set_pending(s, true);
1637                 if (r < 0)
1638                         return r;
1639
1640                 prioq_reshuffle(earliest, s, &s->time.earliest_index);
1641                 prioq_reshuffle(latest, s, &s->time.latest_index);
1642         }
1643
1644         return 0;
1645 }
1646
1647 static int process_child(sd_event *e) {
1648         sd_event_source *s;
1649         Iterator i;
1650         int r;
1651
1652         assert(e);
1653
1654         e->need_process_child = false;
1655
1656         /*
1657            So, this is ugly. We iteratively invoke waitid() with P_PID
1658            + WNOHANG for each PID we wait for, instead of using
1659            P_ALL. This is because we only want to get child
1660            information of very specific child processes, and not all
1661            of them. We might not have processed the SIGCHLD even of a
1662            previous invocation and we don't want to maintain a
1663            unbounded *per-child* event queue, hence we really don't
1664            want anything flushed out of the kernel's queue that we
1665            don't care about. Since this is O(n) this means that if you
1666            have a lot of processes you probably want to handle SIGCHLD
1667            yourself.
1668
1669            We do not reap the children here (by using WNOWAIT), this
1670            is only done after the event source is dispatched so that
1671            the callback still sees the process as a zombie.
1672         */
1673
1674         HASHMAP_FOREACH(s, e->child_sources, i) {
1675                 assert(s->type == SOURCE_CHILD);
1676
1677                 if (s->pending)
1678                         continue;
1679
1680                 if (s->enabled == SD_EVENT_OFF)
1681                         continue;
1682
1683                 zero(s->child.siginfo);
1684                 r = waitid(P_PID, s->child.pid, &s->child.siginfo,
1685                            WNOHANG | (s->child.options & WEXITED ? WNOWAIT : 0) | s->child.options);
1686                 if (r < 0)
1687                         return -errno;
1688
1689                 if (s->child.siginfo.si_pid != 0) {
1690                         bool zombie =
1691                                 s->child.siginfo.si_code == CLD_EXITED ||
1692                                 s->child.siginfo.si_code == CLD_KILLED ||
1693                                 s->child.siginfo.si_code == CLD_DUMPED;
1694
1695                         if (!zombie && (s->child.options & WEXITED)) {
1696                                 /* If the child isn't dead then let's
1697                                  * immediately remove the state change
1698                                  * from the queue, since there's no
1699                                  * benefit in leaving it queued */
1700
1701                                 assert(s->child.options & (WSTOPPED|WCONTINUED));
1702                                 waitid(P_PID, s->child.pid, &s->child.siginfo, WNOHANG|(s->child.options & (WSTOPPED|WCONTINUED)));
1703                         }
1704
1705                         r = source_set_pending(s, true);
1706                         if (r < 0)
1707                                 return r;
1708                 }
1709         }
1710
1711         return 0;
1712 }
1713
1714 static int process_signal(sd_event *e, uint32_t events) {
1715         bool read_one = false;
1716         int r;
1717
1718         assert(e);
1719         assert(e->signal_sources);
1720
1721         assert_return(events == EPOLLIN, -EIO);
1722
1723         for (;;) {
1724                 struct signalfd_siginfo si;
1725                 ssize_t ss;
1726                 sd_event_source *s;
1727
1728                 ss = read(e->signal_fd, &si, sizeof(si));
1729                 if (ss < 0) {
1730                         if (errno == EAGAIN || errno == EINTR)
1731                                 return read_one;
1732
1733                         return -errno;
1734                 }
1735
1736                 if (_unlikely_(ss != sizeof(si)))
1737                         return -EIO;
1738
1739                 read_one = true;
1740
1741                 s = e->signal_sources[si.ssi_signo];
1742                 if (si.ssi_signo == SIGCHLD) {
1743                         r = process_child(e);
1744                         if (r < 0)
1745                                 return r;
1746                         if (r > 0 || !s)
1747                                 continue;
1748                 } else
1749                         if (!s)
1750                                 return -EIO;
1751
1752                 s->signal.siginfo = si;
1753                 r = source_set_pending(s, true);
1754                 if (r < 0)
1755                         return r;
1756         }
1757
1758         return 0;
1759 }
1760
1761 static int source_dispatch(sd_event_source *s) {
1762         int r = 0;
1763
1764         assert(s);
1765         assert(s->pending || s->type == SOURCE_EXIT);
1766
1767         if (s->type != SOURCE_DEFER && s->type != SOURCE_EXIT) {
1768                 r = source_set_pending(s, false);
1769                 if (r < 0)
1770                         return r;
1771         }
1772
1773         if (s->enabled == SD_EVENT_ONESHOT) {
1774                 r = sd_event_source_set_enabled(s, SD_EVENT_OFF);
1775                 if (r < 0)
1776                         return r;
1777         }
1778
1779         s->dispatching = true;
1780
1781         switch (s->type) {
1782
1783         case SOURCE_IO:
1784                 r = s->io.callback(s, s->io.fd, s->io.revents, s->userdata);
1785                 break;
1786
1787         case SOURCE_MONOTONIC:
1788                 r = s->time.callback(s, s->time.next, s->userdata);
1789                 break;
1790
1791         case SOURCE_REALTIME:
1792                 r = s->time.callback(s, s->time.next, s->userdata);
1793                 break;
1794
1795         case SOURCE_SIGNAL:
1796                 r = s->signal.callback(s, &s->signal.siginfo, s->userdata);
1797                 break;
1798
1799         case SOURCE_CHILD: {
1800                 bool zombie;
1801
1802                 zombie = s->child.siginfo.si_code == CLD_EXITED ||
1803                          s->child.siginfo.si_code == CLD_KILLED ||
1804                          s->child.siginfo.si_code == CLD_DUMPED;
1805
1806                 r = s->child.callback(s, &s->child.siginfo, s->userdata);
1807
1808                 /* Now, reap the PID for good. */
1809                 if (zombie)
1810                         waitid(P_PID, s->child.pid, &s->child.siginfo, WNOHANG|WEXITED);
1811
1812                 break;
1813         }
1814
1815         case SOURCE_DEFER:
1816                 r = s->defer.callback(s, s->userdata);
1817                 break;
1818
1819         case SOURCE_EXIT:
1820                 r = s->exit.callback(s, s->userdata);
1821                 break;
1822
1823         case SOURCE_WATCHDOG:
1824                 assert_not_reached("Wut? I shouldn't exist.");
1825         }
1826
1827         s->dispatching = false;
1828
1829         if (r < 0)
1830                 log_debug("Event source %p returned error, disabling: %s", s, strerror(-r));
1831
1832         if (s->n_ref == 0)
1833                 source_free(s);
1834         else if (r < 0)
1835                 sd_event_source_set_enabled(s, SD_EVENT_OFF);
1836
1837         return 1;
1838 }
1839
1840 static int event_prepare(sd_event *e) {
1841         int r;
1842
1843         assert(e);
1844
1845         for (;;) {
1846                 sd_event_source *s;
1847
1848                 s = prioq_peek(e->prepare);
1849                 if (!s || s->prepare_iteration == e->iteration || s->enabled == SD_EVENT_OFF)
1850                         break;
1851
1852                 s->prepare_iteration = e->iteration;
1853                 r = prioq_reshuffle(e->prepare, s, &s->prepare_index);
1854                 if (r < 0)
1855                         return r;
1856
1857                 assert(s->prepare);
1858
1859                 s->dispatching = true;
1860                 r = s->prepare(s, s->userdata);
1861                 s->dispatching = false;
1862
1863                 if (r < 0)
1864                         log_debug("Prepare callback of event source %p returned error, disabling: %s", s, strerror(-r));
1865
1866                 if (s->n_ref == 0)
1867                         source_free(s);
1868                 else if (r < 0)
1869                         sd_event_source_set_enabled(s, SD_EVENT_OFF);
1870         }
1871
1872         return 0;
1873 }
1874
1875 static int dispatch_exit(sd_event *e) {
1876         sd_event_source *p;
1877         int r;
1878
1879         assert(e);
1880
1881         p = prioq_peek(e->exit);
1882         if (!p || p->enabled == SD_EVENT_OFF) {
1883                 e->state = SD_EVENT_FINISHED;
1884                 return 0;
1885         }
1886
1887         sd_event_ref(e);
1888         e->iteration++;
1889         e->state = SD_EVENT_EXITING;
1890
1891         r = source_dispatch(p);
1892
1893         e->state = SD_EVENT_PASSIVE;
1894         sd_event_unref(e);
1895
1896         return r;
1897 }
1898
1899 static sd_event_source* event_next_pending(sd_event *e) {
1900         sd_event_source *p;
1901
1902         assert(e);
1903
1904         p = prioq_peek(e->pending);
1905         if (!p)
1906                 return NULL;
1907
1908         if (p->enabled == SD_EVENT_OFF)
1909                 return NULL;
1910
1911         return p;
1912 }
1913
1914 static int arm_watchdog(sd_event *e) {
1915         struct itimerspec its = {};
1916         usec_t t;
1917         int r;
1918
1919         assert(e);
1920         assert(e->watchdog_fd >= 0);
1921
1922         t = sleep_between(e,
1923                           e->watchdog_last + (e->watchdog_period / 2),
1924                           e->watchdog_last + (e->watchdog_period * 3 / 4));
1925
1926         timespec_store(&its.it_value, t);
1927
1928         r = timerfd_settime(e->watchdog_fd, TFD_TIMER_ABSTIME, &its, NULL);
1929         if (r < 0)
1930                 return -errno;
1931
1932         return 0;
1933 }
1934
1935 static int process_watchdog(sd_event *e) {
1936         assert(e);
1937
1938         if (!e->watchdog)
1939                 return 0;
1940
1941         /* Don't notify watchdog too often */
1942         if (e->watchdog_last + e->watchdog_period / 4 > e->timestamp.monotonic)
1943                 return 0;
1944
1945         sd_notify(false, "WATCHDOG=1");
1946         e->watchdog_last = e->timestamp.monotonic;
1947
1948         return arm_watchdog(e);
1949 }
1950
1951 _public_ int sd_event_run(sd_event *e, uint64_t timeout) {
1952         struct epoll_event *ev_queue;
1953         unsigned ev_queue_max;
1954         sd_event_source *p;
1955         int r, i, m;
1956
1957         assert_return(e, -EINVAL);
1958         assert_return(!event_pid_changed(e), -ECHILD);
1959         assert_return(e->state != SD_EVENT_FINISHED, -ESTALE);
1960         assert_return(e->state == SD_EVENT_PASSIVE, -EBUSY);
1961
1962         if (e->exit_requested)
1963                 return dispatch_exit(e);
1964
1965         sd_event_ref(e);
1966         e->iteration++;
1967         e->state = SD_EVENT_RUNNING;
1968
1969         r = event_prepare(e);
1970         if (r < 0)
1971                 goto finish;
1972
1973         r = event_arm_timer(e, e->monotonic_fd, e->monotonic_earliest, e->monotonic_latest, &e->monotonic_next);
1974         if (r < 0)
1975                 goto finish;
1976
1977         r = event_arm_timer(e, e->realtime_fd, e->realtime_earliest, e->realtime_latest, &e->realtime_next);
1978         if (r < 0)
1979                 goto finish;
1980
1981         if (event_next_pending(e) || e->need_process_child)
1982                 timeout = 0;
1983         ev_queue_max = CLAMP(e->n_sources, 1U, EPOLL_QUEUE_MAX);
1984         ev_queue = newa(struct epoll_event, ev_queue_max);
1985
1986         m = epoll_wait(e->epoll_fd, ev_queue, ev_queue_max,
1987                        timeout == (uint64_t) -1 ? -1 : (int) ((timeout + USEC_PER_MSEC - 1) / USEC_PER_MSEC));
1988         if (m < 0) {
1989                 r = errno == EAGAIN || errno == EINTR ? 0 : -errno;
1990                 goto finish;
1991         }
1992
1993         dual_timestamp_get(&e->timestamp);
1994
1995         for (i = 0; i < m; i++) {
1996
1997                 if (ev_queue[i].data.ptr == INT_TO_PTR(SOURCE_MONOTONIC))
1998                         r = flush_timer(e, e->monotonic_fd, ev_queue[i].events, &e->monotonic_next);
1999                 else if (ev_queue[i].data.ptr == INT_TO_PTR(SOURCE_REALTIME))
2000                         r = flush_timer(e, e->realtime_fd, ev_queue[i].events, &e->realtime_next);
2001                 else if (ev_queue[i].data.ptr == INT_TO_PTR(SOURCE_SIGNAL))
2002                         r = process_signal(e, ev_queue[i].events);
2003                 else if (ev_queue[i].data.ptr == INT_TO_PTR(SOURCE_WATCHDOG))
2004                         r = flush_timer(e, e->watchdog_fd, ev_queue[i].events, NULL);
2005                 else
2006                         r = process_io(e, ev_queue[i].data.ptr, ev_queue[i].events);
2007
2008                 if (r < 0)
2009                         goto finish;
2010         }
2011
2012         r = process_watchdog(e);
2013         if (r < 0)
2014                 goto finish;
2015
2016         r = process_timer(e, e->timestamp.monotonic, e->monotonic_earliest, e->monotonic_latest);
2017         if (r < 0)
2018                 goto finish;
2019
2020         r = process_timer(e, e->timestamp.realtime, e->realtime_earliest, e->realtime_latest);
2021         if (r < 0)
2022                 goto finish;
2023
2024         if (e->need_process_child) {
2025                 r = process_child(e);
2026                 if (r < 0)
2027                         goto finish;
2028         }
2029
2030         p = event_next_pending(e);
2031         if (!p) {
2032                 r = 0;
2033                 goto finish;
2034         }
2035
2036         r = source_dispatch(p);
2037
2038 finish:
2039         e->state = SD_EVENT_PASSIVE;
2040         sd_event_unref(e);
2041
2042         return r;
2043 }
2044
2045 _public_ int sd_event_loop(sd_event *e) {
2046         int r;
2047
2048         assert_return(e, -EINVAL);
2049         assert_return(!event_pid_changed(e), -ECHILD);
2050         assert_return(e->state == SD_EVENT_PASSIVE, -EBUSY);
2051
2052         sd_event_ref(e);
2053
2054         while (e->state != SD_EVENT_FINISHED) {
2055                 r = sd_event_run(e, (uint64_t) -1);
2056                 if (r < 0)
2057                         goto finish;
2058         }
2059
2060         r = e->exit_code;
2061
2062 finish:
2063         sd_event_unref(e);
2064         return r;
2065 }
2066
2067 _public_ int sd_event_get_state(sd_event *e) {
2068         assert_return(e, -EINVAL);
2069         assert_return(!event_pid_changed(e), -ECHILD);
2070
2071         return e->state;
2072 }
2073
2074 _public_ int sd_event_get_exit_code(sd_event *e, int *code) {
2075         assert_return(e, -EINVAL);
2076         assert_return(code, -EINVAL);
2077         assert_return(!event_pid_changed(e), -ECHILD);
2078
2079         if (!e->exit_requested)
2080                 return -ENODATA;
2081
2082         *code = e->exit_code;
2083         return 0;
2084 }
2085
2086 _public_ int sd_event_exit(sd_event *e, int code) {
2087         assert_return(e, -EINVAL);
2088         assert_return(e->state != SD_EVENT_FINISHED, -ESTALE);
2089         assert_return(!event_pid_changed(e), -ECHILD);
2090
2091         e->exit_requested = true;
2092         e->exit_code = code;
2093
2094         return 0;
2095 }
2096
2097 _public_ int sd_event_get_now_realtime(sd_event *e, uint64_t *usec) {
2098         assert_return(e, -EINVAL);
2099         assert_return(usec, -EINVAL);
2100         assert_return(dual_timestamp_is_set(&e->timestamp), -ENODATA);
2101         assert_return(!event_pid_changed(e), -ECHILD);
2102
2103         *usec = e->timestamp.realtime;
2104         return 0;
2105 }
2106
2107 _public_ int sd_event_get_now_monotonic(sd_event *e, uint64_t *usec) {
2108         assert_return(e, -EINVAL);
2109         assert_return(usec, -EINVAL);
2110         assert_return(dual_timestamp_is_set(&e->timestamp), -ENODATA);
2111         assert_return(!event_pid_changed(e), -ECHILD);
2112
2113         *usec = e->timestamp.monotonic;
2114         return 0;
2115 }
2116
2117 _public_ int sd_event_default(sd_event **ret) {
2118
2119         static thread_local sd_event *default_event = NULL;
2120         sd_event *e;
2121         int r;
2122
2123         if (!ret)
2124                 return !!default_event;
2125
2126         if (default_event) {
2127                 *ret = sd_event_ref(default_event);
2128                 return 0;
2129         }
2130
2131         r = sd_event_new(&e);
2132         if (r < 0)
2133                 return r;
2134
2135         e->default_event_ptr = &default_event;
2136         e->tid = gettid();
2137         default_event = e;
2138
2139         *ret = e;
2140         return 1;
2141 }
2142
2143 _public_ int sd_event_get_tid(sd_event *e, pid_t *tid) {
2144         assert_return(e, -EINVAL);
2145         assert_return(tid, -EINVAL);
2146         assert_return(!event_pid_changed(e), -ECHILD);
2147
2148         if (e->tid != 0) {
2149                 *tid = e->tid;
2150                 return 0;
2151         }
2152
2153         return -ENXIO;
2154 }
2155
2156 _public_ int sd_event_set_watchdog(sd_event *e, int b) {
2157         int r;
2158
2159         assert_return(e, -EINVAL);
2160         assert_return(!event_pid_changed(e), -ECHILD);
2161
2162         if (e->watchdog == !!b)
2163                 return e->watchdog;
2164
2165         if (b) {
2166                 struct epoll_event ev = {};
2167                 const char *env;
2168
2169                 env = getenv("WATCHDOG_USEC");
2170                 if (!env)
2171                         return false;
2172
2173                 r = safe_atou64(env, &e->watchdog_period);
2174                 if (r < 0)
2175                         return r;
2176                 if (e->watchdog_period <= 0)
2177                         return -EIO;
2178
2179                 /* Issue first ping immediately */
2180                 sd_notify(false, "WATCHDOG=1");
2181                 e->watchdog_last = now(CLOCK_MONOTONIC);
2182
2183                 e->watchdog_fd = timerfd_create(CLOCK_MONOTONIC, TFD_NONBLOCK|TFD_CLOEXEC);
2184                 if (e->watchdog_fd < 0)
2185                         return -errno;
2186
2187                 r = arm_watchdog(e);
2188                 if (r < 0)
2189                         goto fail;
2190
2191                 ev.events = EPOLLIN;
2192                 ev.data.ptr = INT_TO_PTR(SOURCE_WATCHDOG);
2193
2194                 r = epoll_ctl(e->epoll_fd, EPOLL_CTL_ADD, e->watchdog_fd, &ev);
2195                 if (r < 0) {
2196                         r = -errno;
2197                         goto fail;
2198                 }
2199
2200         } else {
2201                 if (e->watchdog_fd >= 0) {
2202                         epoll_ctl(e->epoll_fd, EPOLL_CTL_DEL, e->watchdog_fd, NULL);
2203                         close_nointr_nofail(e->watchdog_fd);
2204                         e->watchdog_fd = -1;
2205                 }
2206         }
2207
2208         e->watchdog = !!b;
2209         return e->watchdog;
2210
2211 fail:
2212         close_nointr_nofail(e->watchdog_fd);
2213         e->watchdog_fd = -1;
2214         return r;
2215 }
2216
2217 _public_ int sd_event_get_watchdog(sd_event *e) {
2218         assert_return(e, -EINVAL);
2219         assert_return(!event_pid_changed(e), -ECHILD);
2220
2221         return e->watchdog;
2222 }