src/core/timer.c

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