src/core/timer.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2
   3 #include <sys/stat.h>
   4 #include <sys/types.h>
   5 #include <unistd.h>
   6
   7 #include <errno.h>
   8
   9 #include "alloc-util.h"
  10 #include "bus-error.h"
  11 #include "bus-util.h"
  12 #include "dbus-timer.h"
  13 #include "dbus-unit.h"
  14 #include "fs-util.h"
  15 #include "parse-util.h"
  16 #include "random-util.h"
  17 #include "serialize.h"
  18 #include "special.h"
  19 #include "string-table.h"
  20 #include "string-util.h"
  21 #include "timer.h"
  22 #include "unit-name.h"
  23 #include "unit.h"
  24 #include "user-util.h"
  25 #include "virt.h"
  26
  27 static const UnitActiveState state_translation_table[_TIMER_STATE_MAX] = {
  28         [TIMER_DEAD] = UNIT_INACTIVE,
  29         [TIMER_WAITING] = UNIT_ACTIVE,
  30         [TIMER_RUNNING] = UNIT_ACTIVE,
  31         [TIMER_ELAPSED] = UNIT_ACTIVE,
  32         [TIMER_FAILED] = UNIT_FAILED
  33 };
  34
  35 static int timer_dispatch(sd_event_source *s, uint64_t usec, void *userdata);
  36
  37 static void timer_init(Unit *u) {
  38         Timer *t = TIMER(u);
  39
  40         assert(u);
  41         assert(u->load_state == UNIT_STUB);
  42
  43         t->next_elapse_monotonic_or_boottime = USEC_INFINITY;
  44         t->next_elapse_realtime = USEC_INFINITY;
  45         t->accuracy_usec = u->manager->default_timer_accuracy_usec;
  46         t->remain_after_elapse = true;
  47 }
  48
  49 void timer_free_values(Timer *t) {
  50         TimerValue *v;
  51
  52         assert(t);
  53
  54         while ((v = t->values)) {
  55                 LIST_REMOVE(value, t->values, v);
  56                 calendar_spec_free(v->calendar_spec);
  57                 free(v);
  58         }
  59 }
  60
  61 static void timer_done(Unit *u) {
  62         Timer *t = TIMER(u);
  63
  64         assert(t);
  65
  66         timer_free_values(t);
  67
  68         t->monotonic_event_source = sd_event_source_unref(t->monotonic_event_source);
  69         t->realtime_event_source = sd_event_source_unref(t->realtime_event_source);
  70
  71         free(t->stamp_path);
  72 }
  73
  74 static int timer_verify(Timer *t) {
  75         assert(t);
  76
  77         if (UNIT(t)->load_state != UNIT_LOADED)
  78                 return 0;
  79
  80         if (!t->values) {
  81                 log_unit_error(UNIT(t), "Timer unit lacks value setting. Refusing.");
  82                 return -ENOEXEC;
  83         }
  84
  85         return 0;
  86 }
  87
  88 static int timer_add_default_dependencies(Timer *t) {
  89         int r;
  90         TimerValue *v;
  91
  92         assert(t);
  93
  94         if (!UNIT(t)->default_dependencies)
  95                 return 0;
  96
  97         r = unit_add_dependency_by_name(UNIT(t), UNIT_BEFORE, SPECIAL_TIMERS_TARGET, true, UNIT_DEPENDENCY_DEFAULT);
  98         if (r < 0)
  99                 return r;
 100
 101         if (MANAGER_IS_SYSTEM(UNIT(t)->manager)) {
 102                 r = unit_add_two_dependencies_by_name(UNIT(t), UNIT_AFTER, UNIT_REQUIRES, SPECIAL_SYSINIT_TARGET, true, UNIT_DEPENDENCY_DEFAULT);
 103                 if (r < 0)
 104                         return r;
 105
 106                 LIST_FOREACH(value, v, t->values) {
 107                         if (v->base == TIMER_CALENDAR) {
 108                                 r = unit_add_dependency_by_name(UNIT(t), UNIT_AFTER, SPECIAL_TIME_SYNC_TARGET, true, UNIT_DEPENDENCY_DEFAULT);
 109                                 if (r < 0)
 110                                         return r;
 111                                 break;
 112                         }
 113                 }
 114         }
 115
 116         return unit_add_two_dependencies_by_name(UNIT(t), UNIT_BEFORE, UNIT_CONFLICTS, SPECIAL_SHUTDOWN_TARGET, true, UNIT_DEPENDENCY_DEFAULT);
 117 }
 118
 119 static int timer_add_trigger_dependencies(Timer *t) {
 120         Unit *x;
 121         int r;
 122
 123         assert(t);
 124
 125         if (!hashmap_isempty(UNIT(t)->dependencies[UNIT_TRIGGERS]))
 126                 return 0;
 127
 128         r = unit_load_related_unit(UNIT(t), ".service", &x);
 129         if (r < 0)
 130                 return r;
 131
 132         return unit_add_two_dependencies(UNIT(t), UNIT_BEFORE, UNIT_TRIGGERS, x, true, UNIT_DEPENDENCY_IMPLICIT);
 133 }
 134
 135 static int timer_setup_persistent(Timer *t) {
 136         int r;
 137
 138         assert(t);
 139
 140         if (!t->persistent)
 141                 return 0;
 142
 143         if (MANAGER_IS_SYSTEM(UNIT(t)->manager)) {
 144
 145                 r = unit_require_mounts_for(UNIT(t), "/var/lib/systemd/timers", UNIT_DEPENDENCY_FILE);
 146                 if (r < 0)
 147                         return r;
 148
 149                 t->stamp_path = strappend("/var/lib/systemd/timers/stamp-", UNIT(t)->id);
 150         } else {
 151                 const char *e;
 152
 153                 e = getenv("XDG_DATA_HOME");
 154                 if (e)
 155                         t->stamp_path = strjoin(e, "/systemd/timers/stamp-", UNIT(t)->id);
 156                 else {
 157
 158                         _cleanup_free_ char *h = NULL;
 159
 160                         r = get_home_dir(&h);
 161                         if (r < 0)
 162                                 return log_unit_error_errno(UNIT(t), r, "Failed to determine home directory: %m");
 163
 164                         t->stamp_path = strjoin(h, "/.local/share/systemd/timers/stamp-", UNIT(t)->id);
 165                 }
 166         }
 167
 168         if (!t->stamp_path)
 169                 return log_oom();
 170
 171         return 0;
 172 }
 173
 174 static int timer_load(Unit *u) {
 175         Timer *t = TIMER(u);
 176         int r;
 177
 178         assert(u);
 179         assert(u->load_state == UNIT_STUB);
 180
 181         r = unit_load_fragment_and_dropin(u);
 182         if (r < 0)
 183                 return r;
 184
 185         if (u->load_state == UNIT_LOADED) {
 186
 187                 r = timer_add_trigger_dependencies(t);
 188                 if (r < 0)
 189                         return r;
 190
 191                 r = timer_setup_persistent(t);
 192                 if (r < 0)
 193                         return r;
 194
 195                 r = timer_add_default_dependencies(t);
 196                 if (r < 0)
 197                         return r;
 198         }
 199
 200         return timer_verify(t);
 201 }
 202
 203 static void timer_dump(Unit *u, FILE *f, const char *prefix) {
 204         char buf[FORMAT_TIMESPAN_MAX];
 205         Timer *t = TIMER(u);
 206         Unit *trigger;
 207         TimerValue *v;
 208
 209         trigger = UNIT_TRIGGER(u);
 210
 211         fprintf(f,
 212                 "%sTimer State: %s\n"
 213                 "%sResult: %s\n"
 214                 "%sUnit: %s\n"
 215                 "%sPersistent: %s\n"
 216                 "%sWakeSystem: %s\n"
 217                 "%sAccuracy: %s\n"
 218                 "%sRemainAfterElapse: %s\n",
 219                 prefix, timer_state_to_string(t->state),
 220                 prefix, timer_result_to_string(t->result),
 221                 prefix, trigger ? trigger->id : "n/a",
 222                 prefix, yes_no(t->persistent),
 223                 prefix, yes_no(t->wake_system),
 224                 prefix, format_timespan(buf, sizeof(buf), t->accuracy_usec, 1),
 225                 prefix, yes_no(t->remain_after_elapse));
 226
 227         LIST_FOREACH(value, v, t->values) {
 228
 229                 if (v->base == TIMER_CALENDAR) {
 230                         _cleanup_free_ char *p = NULL;
 231
 232                         (void) calendar_spec_to_string(v->calendar_spec, &p);
 233
 234                         fprintf(f,
 235                                 "%s%s: %s\n",
 236                                 prefix,
 237                                 timer_base_to_string(v->base),
 238                                 strna(p));
 239                 } else  {
 240                         char timespan1[FORMAT_TIMESPAN_MAX];
 241
 242                         fprintf(f,
 243                                 "%s%s: %s\n",
 244                                 prefix,
 245                                 timer_base_to_string(v->base),
 246                                 format_timespan(timespan1, sizeof(timespan1), v->value, 0));
 247                 }
 248         }
 249 }
 250
 251 static void timer_set_state(Timer *t, TimerState state) {
 252         TimerState old_state;
 253         assert(t);
 254
 255         if (t->state != state)
 256                 bus_unit_send_pending_change_signal(UNIT(t), false);
 257
 258         old_state = t->state;
 259         t->state = state;
 260
 261         if (state != TIMER_WAITING) {
 262                 t->monotonic_event_source = sd_event_source_unref(t->monotonic_event_source);
 263                 t->realtime_event_source = sd_event_source_unref(t->realtime_event_source);
 264                 t->next_elapse_monotonic_or_boottime = USEC_INFINITY;
 265                 t->next_elapse_realtime = USEC_INFINITY;
 266         }
 267
 268         if (state != old_state)
 269                 log_unit_debug(UNIT(t), "Changed %s -> %s", timer_state_to_string(old_state), timer_state_to_string(state));
 270
 271         unit_notify(UNIT(t), state_translation_table[old_state], state_translation_table[state], 0);
 272 }
 273
 274 static void timer_enter_waiting(Timer *t, bool time_change);
 275
 276 static int timer_coldplug(Unit *u) {
 277         Timer *t = TIMER(u);
 278
 279         assert(t);
 280         assert(t->state == TIMER_DEAD);
 281
 282         if (t->deserialized_state == t->state)
 283                 return 0;
 284
 285         if (t->deserialized_state == TIMER_WAITING)
 286                 timer_enter_waiting(t, false);
 287         else
 288                 timer_set_state(t, t->deserialized_state);
 289
 290         return 0;
 291 }
 292
 293 static void timer_enter_dead(Timer *t, TimerResult f) {
 294         assert(t);
 295
 296         if (t->result == TIMER_SUCCESS)
 297                 t->result = f;
 298
 299         unit_log_result(UNIT(t), t->result == TIMER_SUCCESS, timer_result_to_string(t->result));
 300         timer_set_state(t, t->result != TIMER_SUCCESS ? TIMER_FAILED : TIMER_DEAD);
 301 }
 302
 303 static void timer_enter_elapsed(Timer *t, bool leave_around) {
 304         assert(t);
 305
 306         /* If a unit is marked with RemainAfterElapse=yes we leave it
 307          * around even after it elapsed once, so that starting it
 308          * later again does not necessarily mean immediate
 309          * retriggering. We unconditionally leave units with
 310          * TIMER_UNIT_ACTIVE or TIMER_UNIT_INACTIVE triggers around,
 311          * since they might be restarted automatically at any time
 312          * later on. */
 313
 314         if (t->remain_after_elapse || leave_around)
 315                 timer_set_state(t, TIMER_ELAPSED);
 316         else
 317                 timer_enter_dead(t, TIMER_SUCCESS);
 318 }
 319
 320 static void add_random(Timer *t, usec_t *v) {
 321         char s[FORMAT_TIMESPAN_MAX];
 322         usec_t add;
 323
 324         assert(t);
 325         assert(v);
 326
 327         if (t->random_usec == 0)
 328                 return;
 329         if (*v == USEC_INFINITY)
 330                 return;
 331
 332         add = random_u64() % t->random_usec;
 333
 334         if (*v + add < *v) /* overflow */
 335                 *v = (usec_t) -2; /* Highest possible value, that is not USEC_INFINITY */
 336         else
 337                 *v += add;
 338
 339         log_unit_debug(UNIT(t), "Adding %s random time.", format_timespan(s, sizeof(s), add, 0));
 340 }
 341
 342 static void timer_enter_waiting(Timer *t, bool time_change) {
 343         bool found_monotonic = false, found_realtime = false;
 344         bool leave_around = false;
 345         triple_timestamp ts;
 346         TimerValue *v;
 347         Unit *trigger;
 348         int r;
 349
 350         assert(t);
 351
 352         trigger = UNIT_TRIGGER(UNIT(t));
 353         if (!trigger) {
 354                 log_unit_error(UNIT(t), "Unit to trigger vanished.");
 355                 timer_enter_dead(t, TIMER_FAILURE_RESOURCES);
 356                 return;
 357         }
 358
 359         triple_timestamp_get(&ts);
 360         t->next_elapse_monotonic_or_boottime = t->next_elapse_realtime = 0;
 361
 362         LIST_FOREACH(value, v, t->values) {
 363                 if (v->disabled)
 364                         continue;
 365
 366                 if (v->base == TIMER_CALENDAR) {
 367                         usec_t b;
 368
 369                         /* If we know the last time this was
 370                          * triggered, schedule the job based relative
 371                          * to that. If we don't, just start from
 372                          * the activation time. */
 373
 374                         if (t->last_trigger.realtime > 0)
 375                                 b = t->last_trigger.realtime;
 376                         else {
 377                                 if (state_translation_table[t->state] == UNIT_ACTIVE)
 378                                         b = UNIT(t)->inactive_exit_timestamp.realtime;
 379                                 else
 380                                         b = ts.realtime;
 381                         }
 382
 383                         r = calendar_spec_next_usec(v->calendar_spec, b, &v->next_elapse);
 384                         if (r < 0)
 385                                 continue;
 386
 387                         /* To make the delay due to RandomizedDelaySec= work even at boot,
 388                          * if the scheduled time has already passed, set the time when systemd
 389                          * first started as the scheduled time.
 390                          * Also, we don't have to check t->persistent since the logic implicitly express true. */
 391                         if (v->next_elapse < UNIT(t)->manager->timestamps[MANAGER_TIMESTAMP_USERSPACE].realtime)
 392                                 v->next_elapse = UNIT(t)->manager->timestamps[MANAGER_TIMESTAMP_USERSPACE].realtime;
 393
 394                         if (!found_realtime)
 395                                 t->next_elapse_realtime = v->next_elapse;
 396                         else
 397                                 t->next_elapse_realtime = MIN(t->next_elapse_realtime, v->next_elapse);
 398
 399                         found_realtime = true;
 400
 401                 } else {
 402                         usec_t base;
 403
 404                         switch (v->base) {
 405
 406                         case TIMER_ACTIVE:
 407                                 if (state_translation_table[t->state] == UNIT_ACTIVE)
 408                                         base = UNIT(t)->inactive_exit_timestamp.monotonic;
 409                                 else
 410                                         base = ts.monotonic;
 411                                 break;
 412
 413                         case TIMER_BOOT:
 414                                 if (detect_container() <= 0) {
 415                                         /* CLOCK_MONOTONIC equals the uptime on Linux */
 416                                         base = 0;
 417                                         break;
 418                                 }
 419                                 /* In a container we don't want to include the time the host
 420                                  * was already up when the container started, so count from
 421                                  * our own startup. */
 422                                 _fallthrough_;
 423                         case TIMER_STARTUP:
 424                                 base = UNIT(t)->manager->timestamps[MANAGER_TIMESTAMP_USERSPACE].monotonic;
 425                                 break;
 426
 427                         case TIMER_UNIT_ACTIVE:
 428                                 leave_around = true;
 429                                 base = trigger->inactive_exit_timestamp.monotonic;
 430
 431                                 if (base <= 0)
 432                                         base = t->last_trigger.monotonic;
 433
 434                                 if (base <= 0)
 435                                         continue;
 436                                 base = MAX(base, t->last_trigger.monotonic);
 437
 438                                 break;
 439
 440                         case TIMER_UNIT_INACTIVE:
 441                                 leave_around = true;
 442                                 base = trigger->inactive_enter_timestamp.monotonic;
 443
 444                                 if (base <= 0)
 445                                         base = t->last_trigger.monotonic;
 446
 447                                 if (base <= 0)
 448                                         continue;
 449                                 base = MAX(base, t->last_trigger.monotonic);
 450
 451                                 break;
 452
 453                         default:
 454                                 assert_not_reached("Unknown timer base");
 455                         }
 456
 457                         v->next_elapse = usec_add(usec_shift_clock(base, CLOCK_MONOTONIC, TIMER_MONOTONIC_CLOCK(t)), v->value);
 458
 459                         if (dual_timestamp_is_set(&t->last_trigger) &&
 460                             !time_change &&
 461                             v->next_elapse < triple_timestamp_by_clock(&ts, TIMER_MONOTONIC_CLOCK(t)) &&
 462                             IN_SET(v->base, TIMER_ACTIVE, TIMER_BOOT, TIMER_STARTUP)) {
 463                                 /* This is a one time trigger, disable it now */
 464                                 v->disabled = true;
 465                                 continue;
 466                         }
 467
 468                         if (!found_monotonic)
 469                                 t->next_elapse_monotonic_or_boottime = v->next_elapse;
 470                         else
 471                                 t->next_elapse_monotonic_or_boottime = MIN(t->next_elapse_monotonic_or_boottime, v->next_elapse);
 472
 473                         found_monotonic = true;
 474                 }
 475         }
 476
 477         if (!found_monotonic && !found_realtime) {
 478                 log_unit_debug(UNIT(t), "Timer is elapsed.");
 479                 timer_enter_elapsed(t, leave_around);
 480                 return;
 481         }
 482
 483         if (found_monotonic) {
 484                 char buf[FORMAT_TIMESPAN_MAX];
 485                 usec_t left;
 486
 487                 add_random(t, &t->next_elapse_monotonic_or_boottime);
 488
 489                 left = usec_sub_unsigned(t->next_elapse_monotonic_or_boottime, triple_timestamp_by_clock(&ts, TIMER_MONOTONIC_CLOCK(t)));
 490                 log_unit_debug(UNIT(t), "Monotonic timer elapses in %s.", format_timespan(buf, sizeof(buf), left, 0));
 491
 492                 if (t->monotonic_event_source) {
 493                         r = sd_event_source_set_time(t->monotonic_event_source, t->next_elapse_monotonic_or_boottime);
 494                         if (r < 0)
 495                                 goto fail;
 496
 497                         r = sd_event_source_set_enabled(t->monotonic_event_source, SD_EVENT_ONESHOT);
 498                         if (r < 0)
 499                                 goto fail;
 500                 } else {
 501
 502                         r = sd_event_add_time(
 503                                         UNIT(t)->manager->event,
 504                                         &t->monotonic_event_source,
 505                                         t->wake_system ? CLOCK_BOOTTIME_ALARM : CLOCK_MONOTONIC,
 506                                         t->next_elapse_monotonic_or_boottime, t->accuracy_usec,
 507                                         timer_dispatch, t);
 508                         if (r < 0)
 509                                 goto fail;
 510
 511                         (void) sd_event_source_set_description(t->monotonic_event_source, "timer-monotonic");
 512                 }
 513
 514         } else if (t->monotonic_event_source) {
 515
 516                 r = sd_event_source_set_enabled(t->monotonic_event_source, SD_EVENT_OFF);
 517                 if (r < 0)
 518                         goto fail;
 519         }
 520
 521         if (found_realtime) {
 522                 char buf[FORMAT_TIMESTAMP_MAX];
 523
 524                 add_random(t, &t->next_elapse_realtime);
 525
 526                 log_unit_debug(UNIT(t), "Realtime timer elapses at %s.", format_timestamp(buf, sizeof(buf), t->next_elapse_realtime));
 527
 528                 if (t->realtime_event_source) {
 529                         r = sd_event_source_set_time(t->realtime_event_source, t->next_elapse_realtime);
 530                         if (r < 0)
 531                                 goto fail;
 532
 533                         r = sd_event_source_set_enabled(t->realtime_event_source, SD_EVENT_ONESHOT);
 534                         if (r < 0)
 535                                 goto fail;
 536                 } else {
 537                         r = sd_event_add_time(
 538                                         UNIT(t)->manager->event,
 539                                         &t->realtime_event_source,
 540                                         t->wake_system ? CLOCK_REALTIME_ALARM : CLOCK_REALTIME,
 541                                         t->next_elapse_realtime, t->accuracy_usec,
 542                                         timer_dispatch, t);
 543                         if (r < 0)
 544                                 goto fail;
 545
 546                         (void) sd_event_source_set_description(t->realtime_event_source, "timer-realtime");
 547                 }
 548
 549         } else if (t->realtime_event_source) {
 550
 551                 r = sd_event_source_set_enabled(t->realtime_event_source, SD_EVENT_OFF);
 552                 if (r < 0)
 553                         goto fail;
 554         }
 555
 556         timer_set_state(t, TIMER_WAITING);
 557         return;
 558
 559 fail:
 560         log_unit_warning_errno(UNIT(t), r, "Failed to enter waiting state: %m");
 561         timer_enter_dead(t, TIMER_FAILURE_RESOURCES);
 562 }
 563
 564 static void timer_enter_running(Timer *t) {
 565         _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
 566         Unit *trigger;
 567         int r;
 568
 569         assert(t);
 570
 571         /* Don't start job if we are supposed to go down */
 572         if (unit_stop_pending(UNIT(t)))
 573                 return;
 574
 575         trigger = UNIT_TRIGGER(UNIT(t));
 576         if (!trigger) {
 577                 log_unit_error(UNIT(t), "Unit to trigger vanished.");
 578                 timer_enter_dead(t, TIMER_FAILURE_RESOURCES);
 579                 return;
 580         }
 581
 582         r = manager_add_job(UNIT(t)->manager, JOB_START, trigger, JOB_REPLACE, NULL, &error, NULL);
 583         if (r < 0)
 584                 goto fail;
 585
 586         dual_timestamp_get(&t->last_trigger);
 587
 588         if (t->stamp_path)
 589                 touch_file(t->stamp_path, true, t->last_trigger.realtime, UID_INVALID, GID_INVALID, MODE_INVALID);
 590
 591         timer_set_state(t, TIMER_RUNNING);
 592         return;
 593
 594 fail:
 595         log_unit_warning(UNIT(t), "Failed to queue unit startup job: %s", bus_error_message(&error, r));
 596         timer_enter_dead(t, TIMER_FAILURE_RESOURCES);
 597 }
 598
 599 static int timer_start(Unit *u) {
 600         Timer *t = TIMER(u);
 601         TimerValue *v;
 602         int r;
 603
 604         assert(t);
 605         assert(IN_SET(t->state, TIMER_DEAD, TIMER_FAILED));
 606
 607         r = unit_test_trigger_loaded(u);
 608         if (r < 0)
 609                 return r;
 610
 611         r = unit_test_start_limit(u);
 612         if (r < 0) {
 613                 timer_enter_dead(t, TIMER_FAILURE_START_LIMIT_HIT);
 614                 return r;
 615         }
 616
 617         r = unit_acquire_invocation_id(u);
 618         if (r < 0)
 619                 return r;
 620
 621         t->last_trigger = DUAL_TIMESTAMP_NULL;
 622
 623         /* Reenable all timers that depend on unit activation time */
 624         LIST_FOREACH(value, v, t->values)
 625                 if (v->base == TIMER_ACTIVE)
 626                         v->disabled = false;
 627
 628         if (t->stamp_path) {
 629                 struct stat st;
 630
 631                 if (stat(t->stamp_path, &st) >= 0) {
 632                         usec_t ft;
 633
 634                         /* Load the file timestamp, but only if it is actually in the past. If it is in the future,
 635                          * something is wrong with the system clock. */
 636
 637                         ft = timespec_load(&st.st_mtim);
 638                         if (ft < now(CLOCK_REALTIME))
 639                                 t->last_trigger.realtime = ft;
 640                         else {
 641                                 char z[FORMAT_TIMESTAMP_MAX];
 642
 643                                 log_unit_warning(u, "Not using persistent file timestamp %s as it is in the future.",
 644                                                  format_timestamp(z, sizeof(z), ft));
 645                         }
 646
 647                 } else if (errno == ENOENT)
 648                         /* The timer has never run before,
 649                          * make sure a stamp file exists.
 650                          */
 651                         (void) touch_file(t->stamp_path, true, USEC_INFINITY, UID_INVALID, GID_INVALID, MODE_INVALID);
 652         }
 653
 654         t->result = TIMER_SUCCESS;
 655         timer_enter_waiting(t, false);
 656         return 1;
 657 }
 658
 659 static int timer_stop(Unit *u) {
 660         Timer *t = TIMER(u);
 661
 662         assert(t);
 663         assert(IN_SET(t->state, TIMER_WAITING, TIMER_RUNNING, TIMER_ELAPSED));
 664
 665         timer_enter_dead(t, TIMER_SUCCESS);
 666         return 1;
 667 }
 668
 669 static int timer_serialize(Unit *u, FILE *f, FDSet *fds) {
 670         Timer *t = TIMER(u);
 671
 672         assert(u);
 673         assert(f);
 674         assert(fds);
 675
 676         (void) serialize_item(f, "state", timer_state_to_string(t->state));
 677         (void) serialize_item(f, "result", timer_result_to_string(t->result));
 678
 679         if (t->last_trigger.realtime > 0)
 680                 (void) serialize_usec(f, "last-trigger-realtime", t->last_trigger.realtime);
 681
 682         if (t->last_trigger.monotonic > 0)
 683                 (void) serialize_usec(f, "last-trigger-monotonic", t->last_trigger.monotonic);
 684
 685         return 0;
 686 }
 687
 688 static int timer_deserialize_item(Unit *u, const char *key, const char *value, FDSet *fds) {
 689         Timer *t = TIMER(u);
 690
 691         assert(u);
 692         assert(key);
 693         assert(value);
 694         assert(fds);
 695
 696         if (streq(key, "state")) {
 697                 TimerState state;
 698
 699                 state = timer_state_from_string(value);
 700                 if (state < 0)
 701                         log_unit_debug(u, "Failed to parse state value: %s", value);
 702                 else
 703                         t->deserialized_state = state;
 704
 705         } else if (streq(key, "result")) {
 706                 TimerResult f;
 707
 708                 f = timer_result_from_string(value);
 709                 if (f < 0)
 710                         log_unit_debug(u, "Failed to parse result value: %s", value);
 711                 else if (f != TIMER_SUCCESS)
 712                         t->result = f;
 713
 714         } else if (streq(key, "last-trigger-realtime"))
 715                 (void) deserialize_usec(value, &t->last_trigger.realtime);
 716         else if (streq(key, "last-trigger-monotonic"))
 717                 (void) deserialize_usec(value, &t->last_trigger.monotonic);
 718         else
 719                 log_unit_debug(u, "Unknown serialization key: %s", key);
 720
 721         return 0;
 722 }
 723
 724 _pure_ static UnitActiveState timer_active_state(Unit *u) {
 725         assert(u);
 726
 727         return state_translation_table[TIMER(u)->state];
 728 }
 729
 730 _pure_ static const char *timer_sub_state_to_string(Unit *u) {
 731         assert(u);
 732
 733         return timer_state_to_string(TIMER(u)->state);
 734 }
 735
 736 static int timer_dispatch(sd_event_source *s, uint64_t usec, void *userdata) {
 737         Timer *t = TIMER(userdata);
 738
 739         assert(t);
 740
 741         if (t->state != TIMER_WAITING)
 742                 return 0;
 743
 744         log_unit_debug(UNIT(t), "Timer elapsed.");
 745         timer_enter_running(t);
 746         return 0;
 747 }
 748
 749 static void timer_trigger_notify(Unit *u, Unit *other) {
 750         Timer *t = TIMER(u);
 751         TimerValue *v;
 752
 753         assert(u);
 754         assert(other);
 755
 756         if (other->load_state != UNIT_LOADED)
 757                 return;
 758
 759         /* Reenable all timers that depend on unit state */
 760         LIST_FOREACH(value, v, t->values)
 761                 if (IN_SET(v->base, TIMER_UNIT_ACTIVE, TIMER_UNIT_INACTIVE))
 762                         v->disabled = false;
 763
 764         switch (t->state) {
 765
 766         case TIMER_WAITING:
 767         case TIMER_ELAPSED:
 768
 769                 /* Recalculate sleep time */
 770                 timer_enter_waiting(t, false);
 771                 break;
 772
 773         case TIMER_RUNNING:
 774
 775                 if (UNIT_IS_INACTIVE_OR_FAILED(unit_active_state(other))) {
 776                         log_unit_debug(UNIT(t), "Got notified about unit deactivation.");
 777                         timer_enter_waiting(t, false);
 778                 }
 779                 break;
 780
 781         case TIMER_DEAD:
 782         case TIMER_FAILED:
 783                 break;
 784
 785         default:
 786                 assert_not_reached("Unknown timer state");
 787         }
 788 }
 789
 790 static void timer_reset_failed(Unit *u) {
 791         Timer *t = TIMER(u);
 792
 793         assert(t);
 794
 795         if (t->state == TIMER_FAILED)
 796                 timer_set_state(t, TIMER_DEAD);
 797
 798         t->result = TIMER_SUCCESS;
 799 }
 800
 801 static void timer_time_change(Unit *u) {
 802         Timer *t = TIMER(u);
 803         usec_t ts;
 804
 805         assert(u);
 806
 807         if (t->state != TIMER_WAITING)
 808                 return;
 809
 810         /* If we appear to have triggered in the future, the system clock must
 811          * have been set backwards.  So let's rewind our own clock and allow
 812          * the future trigger(s) to happen again :).  Exactly the same as when
 813          * you start a timer unit with Persistent=yes. */
 814         ts = now(CLOCK_REALTIME);
 815         if (t->last_trigger.realtime > ts)
 816                 t->last_trigger.realtime = ts;
 817
 818         log_unit_debug(u, "Time change, recalculating next elapse.");
 819         timer_enter_waiting(t, true);
 820 }
 821
 822 static void timer_timezone_change(Unit *u) {
 823         Timer *t = TIMER(u);
 824
 825         assert(u);
 826
 827         if (t->state != TIMER_WAITING)
 828                 return;
 829
 830         log_unit_debug(u, "Timezone change, recalculating next elapse.");
 831         timer_enter_waiting(t, false);
 832 }
 833
 834 static const char* const timer_base_table[_TIMER_BASE_MAX] = {
 835         [TIMER_ACTIVE] = "OnActiveSec",
 836         [TIMER_BOOT] = "OnBootSec",
 837         [TIMER_STARTUP] = "OnStartupSec",
 838         [TIMER_UNIT_ACTIVE] = "OnUnitActiveSec",
 839         [TIMER_UNIT_INACTIVE] = "OnUnitInactiveSec",
 840         [TIMER_CALENDAR] = "OnCalendar"
 841 };
 842
 843 DEFINE_STRING_TABLE_LOOKUP(timer_base, TimerBase);
 844
 845 static const char* const timer_result_table[_TIMER_RESULT_MAX] = {
 846         [TIMER_SUCCESS] = "success",
 847         [TIMER_FAILURE_RESOURCES] = "resources",
 848         [TIMER_FAILURE_START_LIMIT_HIT] = "start-limit-hit",
 849 };
 850
 851 DEFINE_STRING_TABLE_LOOKUP(timer_result, TimerResult);
 852
 853 const UnitVTable timer_vtable = {
 854         .object_size = sizeof(Timer),
 855
 856         .sections =
 857                 "Unit\0"
 858                 "Timer\0"
 859                 "Install\0",
 860         .private_section = "Timer",
 861
 862         .init = timer_init,
 863         .done = timer_done,
 864         .load = timer_load,
 865
 866         .coldplug = timer_coldplug,
 867
 868         .dump = timer_dump,
 869
 870         .start = timer_start,
 871         .stop = timer_stop,
 872
 873         .serialize = timer_serialize,
 874         .deserialize_item = timer_deserialize_item,
 875
 876         .active_state = timer_active_state,
 877         .sub_state_to_string = timer_sub_state_to_string,
 878
 879         .trigger_notify = timer_trigger_notify,
 880
 881         .reset_failed = timer_reset_failed,
 882         .time_change = timer_time_change,
 883         .timezone_change = timer_timezone_change,
 884
 885         .bus_vtable = bus_timer_vtable,
 886         .bus_set_property = bus_timer_set_property,
 887
 888         .can_transient = true,
 889 };