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