src/core/timer.c

   1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
   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         assert(UNIT(t)->load_state == UNIT_LOADED);
  77
  78         if (!t->values && !t->on_clock_change && !t->on_timezone_change)
  79                 return log_unit_error_errno(UNIT(t), SYNTHETIC_ERRNO(ENOEXEC), "Timer unit lacks value setting. Refusing.");
  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         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 = strjoin("/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 uint64_t timer_get_fixed_delay_hash(Timer *t) {
 170         static const uint8_t hash_key[] = {
 171                 0x51, 0x0a, 0xdb, 0x76, 0x29, 0x51, 0x42, 0xc2,
 172                 0x80, 0x35, 0xea, 0xe6, 0x8e, 0x3a, 0x37, 0xbd
 173         };
 174
 175         struct siphash state;
 176         sd_id128_t machine_id;
 177         uid_t uid;
 178         int r;
 179
 180         assert(t);
 181
 182         uid = getuid();
 183         r = sd_id128_get_machine(&machine_id);
 184         if (r < 0) {
 185                 log_unit_debug_errno(UNIT(t), r,
 186                                      "Failed to get machine ID for the fixed delay calculation, proceeding with 0: %m");
 187                 machine_id = SD_ID128_NULL;
 188         }
 189
 190         siphash24_init(&state, hash_key);
 191         siphash24_compress(&machine_id, sizeof(sd_id128_t), &state);
 192         siphash24_compress_boolean(MANAGER_IS_SYSTEM(UNIT(t)->manager), &state);
 193         siphash24_compress(&uid, sizeof(uid_t), &state);
 194         siphash24_compress_string(UNIT(t)->id, &state);
 195
 196         return siphash24_finalize(&state);
 197 }
 198
 199 static int timer_load(Unit *u) {
 200         Timer *t = TIMER(u);
 201         int r;
 202
 203         assert(u);
 204         assert(u->load_state == UNIT_STUB);
 205
 206         r = unit_load_fragment_and_dropin(u, true);
 207         if (r < 0)
 208                 return r;
 209
 210         if (u->load_state != UNIT_LOADED)
 211                 return 0;
 212
 213         /* This is a new unit? Then let's add in some extras */
 214         r = timer_add_trigger_dependencies(t);
 215         if (r < 0)
 216                 return r;
 217
 218         r = timer_setup_persistent(t);
 219         if (r < 0)
 220                 return r;
 221
 222         r = timer_add_default_dependencies(t);
 223         if (r < 0)
 224                 return r;
 225
 226         return timer_verify(t);
 227 }
 228
 229 static void timer_dump(Unit *u, FILE *f, const char *prefix) {
 230         char buf[FORMAT_TIMESPAN_MAX];
 231         Timer *t = TIMER(u);
 232         Unit *trigger;
 233         TimerValue *v;
 234
 235         trigger = UNIT_TRIGGER(u);
 236
 237         fprintf(f,
 238                 "%sTimer State: %s\n"
 239                 "%sResult: %s\n"
 240                 "%sUnit: %s\n"
 241                 "%sPersistent: %s\n"
 242                 "%sWakeSystem: %s\n"
 243                 "%sAccuracy: %s\n"
 244                 "%sRemainAfterElapse: %s\n"
 245                 "%sFixedRandomDelay: %s\n"
 246                 "%sOnClockChange: %s\n"
 247                 "%sOnTimeZoneChange: %s\n",
 248                 prefix, timer_state_to_string(t->state),
 249                 prefix, timer_result_to_string(t->result),
 250                 prefix, trigger ? trigger->id : "n/a",
 251                 prefix, yes_no(t->persistent),
 252                 prefix, yes_no(t->wake_system),
 253                 prefix, format_timespan(buf, sizeof(buf), t->accuracy_usec, 1),
 254                 prefix, yes_no(t->remain_after_elapse),
 255                 prefix, yes_no(t->fixed_random_delay),
 256                 prefix, yes_no(t->on_clock_change),
 257                 prefix, yes_no(t->on_timezone_change));
 258
 259         LIST_FOREACH(value, v, t->values)
 260                 if (v->base == TIMER_CALENDAR) {
 261                         _cleanup_free_ char *p = NULL;
 262
 263                         (void) calendar_spec_to_string(v->calendar_spec, &p);
 264
 265                         fprintf(f,
 266                                 "%s%s: %s\n",
 267                                 prefix,
 268                                 timer_base_to_string(v->base),
 269                                 strna(p));
 270                 } else  {
 271                         char timespan1[FORMAT_TIMESPAN_MAX];
 272
 273                         fprintf(f,
 274                                 "%s%s: %s\n",
 275                                 prefix,
 276                                 timer_base_to_string(v->base),
 277                                 format_timespan(timespan1, sizeof(timespan1), v->value, 0));
 278                 }
 279 }
 280
 281 static void timer_set_state(Timer *t, TimerState state) {
 282         TimerState old_state;
 283         assert(t);
 284
 285         if (t->state != state)
 286                 bus_unit_send_pending_change_signal(UNIT(t), false);
 287
 288         old_state = t->state;
 289         t->state = state;
 290
 291         if (state != TIMER_WAITING) {
 292                 t->monotonic_event_source = sd_event_source_unref(t->monotonic_event_source);
 293                 t->realtime_event_source = sd_event_source_unref(t->realtime_event_source);
 294                 t->next_elapse_monotonic_or_boottime = USEC_INFINITY;
 295                 t->next_elapse_realtime = USEC_INFINITY;
 296         }
 297
 298         if (state != old_state)
 299                 log_unit_debug(UNIT(t), "Changed %s -> %s", timer_state_to_string(old_state), timer_state_to_string(state));
 300
 301         unit_notify(UNIT(t), state_translation_table[old_state], state_translation_table[state], 0);
 302 }
 303
 304 static void timer_enter_waiting(Timer *t, bool time_change);
 305
 306 static int timer_coldplug(Unit *u) {
 307         Timer *t = TIMER(u);
 308
 309         assert(t);
 310         assert(t->state == TIMER_DEAD);
 311
 312         if (t->deserialized_state == t->state)
 313                 return 0;
 314
 315         if (t->deserialized_state == TIMER_WAITING)
 316                 timer_enter_waiting(t, false);
 317         else
 318                 timer_set_state(t, t->deserialized_state);
 319
 320         return 0;
 321 }
 322
 323 static void timer_enter_dead(Timer *t, TimerResult f) {
 324         assert(t);
 325
 326         if (t->result == TIMER_SUCCESS)
 327                 t->result = f;
 328
 329         unit_log_result(UNIT(t), t->result == TIMER_SUCCESS, timer_result_to_string(t->result));
 330         timer_set_state(t, t->result != TIMER_SUCCESS ? TIMER_FAILED : TIMER_DEAD);
 331 }
 332
 333 static void timer_enter_elapsed(Timer *t, bool leave_around) {
 334         assert(t);
 335
 336         /* If a unit is marked with RemainAfterElapse=yes we leave it
 337          * around even after it elapsed once, so that starting it
 338          * later again does not necessarily mean immediate
 339          * retriggering. We unconditionally leave units with
 340          * TIMER_UNIT_ACTIVE or TIMER_UNIT_INACTIVE triggers around,
 341          * since they might be restarted automatically at any time
 342          * later on. */
 343
 344         if (t->remain_after_elapse || leave_around)
 345                 timer_set_state(t, TIMER_ELAPSED);
 346         else
 347                 timer_enter_dead(t, TIMER_SUCCESS);
 348 }
 349
 350 static void add_random(Timer *t, usec_t *v) {
 351         char s[FORMAT_TIMESPAN_MAX];
 352         usec_t add;
 353
 354         assert(t);
 355         assert(v);
 356
 357         if (t->random_usec == 0)
 358                 return;
 359         if (*v == USEC_INFINITY)
 360                 return;
 361
 362         add = (t->fixed_random_delay ? timer_get_fixed_delay_hash(t) : random_u64()) % t->random_usec;
 363
 364         if (*v + add < *v) /* overflow */
 365                 *v = (usec_t) -2; /* Highest possible value, that is not USEC_INFINITY */
 366         else
 367                 *v += add;
 368
 369         log_unit_debug(UNIT(t), "Adding %s random time.", format_timespan(s, sizeof(s), add, 0));
 370 }
 371
 372 static void timer_enter_waiting(Timer *t, bool time_change) {
 373         bool found_monotonic = false, found_realtime = false;
 374         bool leave_around = false;
 375         triple_timestamp ts;
 376         TimerValue *v;
 377         Unit *trigger;
 378         int r;
 379
 380         assert(t);
 381
 382         trigger = UNIT_TRIGGER(UNIT(t));
 383         if (!trigger) {
 384                 log_unit_error(UNIT(t), "Unit to trigger vanished.");
 385                 timer_enter_dead(t, TIMER_FAILURE_RESOURCES);
 386                 return;
 387         }
 388
 389         triple_timestamp_get(&ts);
 390         t->next_elapse_monotonic_or_boottime = t->next_elapse_realtime = 0;
 391
 392         LIST_FOREACH(value, v, t->values) {
 393                 if (v->disabled)
 394                         continue;
 395
 396                 if (v->base == TIMER_CALENDAR) {
 397                         usec_t b, rebased;
 398
 399                         /* If we know the last time this was
 400                          * triggered, schedule the job based relative
 401                          * to that. If we don't, just start from
 402                          * the activation time. */
 403
 404                         if (t->last_trigger.realtime > 0)
 405                                 b = t->last_trigger.realtime;
 406                         else {
 407                                 if (state_translation_table[t->state] == UNIT_ACTIVE)
 408                                         b = UNIT(t)->inactive_exit_timestamp.realtime;
 409                                 else
 410                                         b = ts.realtime;
 411                         }
 412
 413                         r = calendar_spec_next_usec(v->calendar_spec, b, &v->next_elapse);
 414                         if (r < 0)
 415                                 continue;
 416
 417                         /* To make the delay due to RandomizedDelaySec= work even at boot, if the scheduled
 418                          * time has already passed, set the time when systemd first started as the scheduled
 419                          * time. Note that we base this on the monotonic timestamp of the boot, not the
 420                          * realtime one, since the wallclock might have been off during boot. */
 421                         rebased = map_clock_usec(UNIT(t)->manager->timestamps[MANAGER_TIMESTAMP_USERSPACE].monotonic,
 422                                                  CLOCK_MONOTONIC, CLOCK_REALTIME);
 423                         if (v->next_elapse < rebased)
 424                                 v->next_elapse = rebased;
 425
 426                         if (!found_realtime)
 427                                 t->next_elapse_realtime = v->next_elapse;
 428                         else
 429                                 t->next_elapse_realtime = MIN(t->next_elapse_realtime, v->next_elapse);
 430
 431                         found_realtime = true;
 432
 433                 } else {
 434                         usec_t base;
 435
 436                         switch (v->base) {
 437
 438                         case TIMER_ACTIVE:
 439                                 if (state_translation_table[t->state] == UNIT_ACTIVE)
 440                                         base = UNIT(t)->inactive_exit_timestamp.monotonic;
 441                                 else
 442                                         base = ts.monotonic;
 443                                 break;
 444
 445                         case TIMER_BOOT:
 446                                 if (detect_container() <= 0) {
 447                                         /* CLOCK_MONOTONIC equals the uptime on Linux */
 448                                         base = 0;
 449                                         break;
 450                                 }
 451                                 /* In a container we don't want to include the time the host
 452                                  * was already up when the container started, so count from
 453                                  * our own startup. */
 454                                 _fallthrough_;
 455                         case TIMER_STARTUP:
 456                                 base = UNIT(t)->manager->timestamps[MANAGER_TIMESTAMP_USERSPACE].monotonic;
 457                                 break;
 458
 459                         case TIMER_UNIT_ACTIVE:
 460                                 leave_around = true;
 461                                 base = MAX(trigger->inactive_exit_timestamp.monotonic, t->last_trigger.monotonic);
 462                                 if (base <= 0)
 463                                         continue;
 464                                 break;
 465
 466                         case TIMER_UNIT_INACTIVE:
 467                                 leave_around = true;
 468                                 base = MAX(trigger->inactive_enter_timestamp.monotonic, t->last_trigger.monotonic);
 469                                 if (base <= 0)
 470                                         continue;
 471                                 break;
 472
 473                         default:
 474                                 assert_not_reached("Unknown timer base");
 475                         }
 476
 477                         v->next_elapse = usec_add(usec_shift_clock(base, CLOCK_MONOTONIC, TIMER_MONOTONIC_CLOCK(t)), v->value);
 478
 479                         if (dual_timestamp_is_set(&t->last_trigger) &&
 480                             !time_change &&
 481                             v->next_elapse < triple_timestamp_by_clock(&ts, TIMER_MONOTONIC_CLOCK(t)) &&
 482                             IN_SET(v->base, TIMER_ACTIVE, TIMER_BOOT, TIMER_STARTUP)) {
 483                                 /* This is a one time trigger, disable it now */
 484                                 v->disabled = true;
 485                                 continue;
 486                         }
 487
 488                         if (!found_monotonic)
 489                                 t->next_elapse_monotonic_or_boottime = v->next_elapse;
 490                         else
 491                                 t->next_elapse_monotonic_or_boottime = MIN(t->next_elapse_monotonic_or_boottime, v->next_elapse);
 492
 493                         found_monotonic = true;
 494                 }
 495         }
 496
 497         if (!found_monotonic && !found_realtime && !t->on_timezone_change && !t->on_clock_change) {
 498                 log_unit_debug(UNIT(t), "Timer is elapsed.");
 499                 timer_enter_elapsed(t, leave_around);
 500                 return;
 501         }
 502
 503         if (found_monotonic) {
 504                 char buf[FORMAT_TIMESPAN_MAX];
 505                 usec_t left;
 506
 507                 add_random(t, &t->next_elapse_monotonic_or_boottime);
 508
 509                 left = usec_sub_unsigned(t->next_elapse_monotonic_or_boottime, triple_timestamp_by_clock(&ts, TIMER_MONOTONIC_CLOCK(t)));
 510                 log_unit_debug(UNIT(t), "Monotonic timer elapses in %s.", format_timespan(buf, sizeof(buf), left, 0));
 511
 512                 if (t->monotonic_event_source) {
 513                         r = sd_event_source_set_time(t->monotonic_event_source, t->next_elapse_monotonic_or_boottime);
 514                         if (r < 0)
 515                                 goto fail;
 516
 517                         r = sd_event_source_set_enabled(t->monotonic_event_source, SD_EVENT_ONESHOT);
 518                         if (r < 0)
 519                                 goto fail;
 520                 } else {
 521
 522                         r = sd_event_add_time(
 523                                         UNIT(t)->manager->event,
 524                                         &t->monotonic_event_source,
 525                                         t->wake_system ? CLOCK_BOOTTIME_ALARM : CLOCK_MONOTONIC,
 526                                         t->next_elapse_monotonic_or_boottime, t->accuracy_usec,
 527                                         timer_dispatch, t);
 528                         if (r < 0)
 529                                 goto fail;
 530
 531                         (void) sd_event_source_set_description(t->monotonic_event_source, "timer-monotonic");
 532                 }
 533
 534         } else if (t->monotonic_event_source) {
 535
 536                 r = sd_event_source_set_enabled(t->monotonic_event_source, SD_EVENT_OFF);
 537                 if (r < 0)
 538                         goto fail;
 539         }
 540
 541         if (found_realtime) {
 542                 char buf[FORMAT_TIMESTAMP_MAX];
 543
 544                 add_random(t, &t->next_elapse_realtime);
 545
 546                 log_unit_debug(UNIT(t), "Realtime timer elapses at %s.", format_timestamp(buf, sizeof(buf), t->next_elapse_realtime));
 547
 548                 if (t->realtime_event_source) {
 549                         r = sd_event_source_set_time(t->realtime_event_source, t->next_elapse_realtime);
 550                         if (r < 0)
 551                                 goto fail;
 552
 553                         r = sd_event_source_set_enabled(t->realtime_event_source, SD_EVENT_ONESHOT);
 554                         if (r < 0)
 555                                 goto fail;
 556                 } else {
 557                         r = sd_event_add_time(
 558                                         UNIT(t)->manager->event,
 559                                         &t->realtime_event_source,
 560                                         t->wake_system ? CLOCK_REALTIME_ALARM : CLOCK_REALTIME,
 561                                         t->next_elapse_realtime, t->accuracy_usec,
 562                                         timer_dispatch, t);
 563                         if (r < 0)
 564                                 goto fail;
 565
 566                         (void) sd_event_source_set_description(t->realtime_event_source, "timer-realtime");
 567                 }
 568
 569         } else if (t->realtime_event_source) {
 570
 571                 r = sd_event_source_set_enabled(t->realtime_event_source, SD_EVENT_OFF);
 572                 if (r < 0)
 573                         goto fail;
 574         }
 575
 576         timer_set_state(t, TIMER_WAITING);
 577         return;
 578
 579 fail:
 580         log_unit_warning_errno(UNIT(t), r, "Failed to enter waiting state: %m");
 581         timer_enter_dead(t, TIMER_FAILURE_RESOURCES);
 582 }
 583
 584 static void timer_enter_running(Timer *t) {
 585         _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
 586         Unit *trigger;
 587         int r;
 588
 589         assert(t);
 590
 591         /* Don't start job if we are supposed to go down */
 592         if (unit_stop_pending(UNIT(t)))
 593                 return;
 594
 595         trigger = UNIT_TRIGGER(UNIT(t));
 596         if (!trigger) {
 597                 log_unit_error(UNIT(t), "Unit to trigger vanished.");
 598                 timer_enter_dead(t, TIMER_FAILURE_RESOURCES);
 599                 return;
 600         }
 601
 602         r = manager_add_job(UNIT(t)->manager, JOB_START, trigger, JOB_REPLACE, NULL, &error, NULL);
 603         if (r < 0)
 604                 goto fail;
 605
 606         dual_timestamp_get(&t->last_trigger);
 607
 608         if (t->stamp_path)
 609                 touch_file(t->stamp_path, true, t->last_trigger.realtime, UID_INVALID, GID_INVALID, MODE_INVALID);
 610
 611         timer_set_state(t, TIMER_RUNNING);
 612         return;
 613
 614 fail:
 615         log_unit_warning(UNIT(t), "Failed to queue unit startup job: %s", bus_error_message(&error, r));
 616         timer_enter_dead(t, TIMER_FAILURE_RESOURCES);
 617 }
 618
 619 static int timer_start(Unit *u) {
 620         Timer *t = TIMER(u);
 621         TimerValue *v;
 622         int r;
 623
 624         assert(t);
 625         assert(IN_SET(t->state, TIMER_DEAD, TIMER_FAILED));
 626
 627         r = unit_test_trigger_loaded(u);
 628         if (r < 0)
 629                 return r;
 630
 631         r = unit_test_start_limit(u);
 632         if (r < 0) {
 633                 timer_enter_dead(t, TIMER_FAILURE_START_LIMIT_HIT);
 634                 return r;
 635         }
 636
 637         r = unit_acquire_invocation_id(u);
 638         if (r < 0)
 639                 return r;
 640
 641         t->last_trigger = DUAL_TIMESTAMP_NULL;
 642
 643         /* Reenable all timers that depend on unit activation time */
 644         LIST_FOREACH(value, v, t->values)
 645                 if (v->base == TIMER_ACTIVE)
 646                         v->disabled = false;
 647
 648         if (t->stamp_path) {
 649                 struct stat st;
 650
 651                 if (stat(t->stamp_path, &st) >= 0) {
 652                         usec_t ft;
 653
 654                         /* Load the file timestamp, but only if it is actually in the past. If it is in the future,
 655                          * something is wrong with the system clock. */
 656
 657                         ft = timespec_load(&st.st_mtim);
 658                         if (ft < now(CLOCK_REALTIME))
 659                                 t->last_trigger.realtime = ft;
 660                         else {
 661                                 char z[FORMAT_TIMESTAMP_MAX];
 662
 663                                 log_unit_warning(u, "Not using persistent file timestamp %s as it is in the future.",
 664                                                  format_timestamp(z, sizeof(z), ft));
 665                         }
 666
 667                 } else if (errno == ENOENT)
 668                         /* The timer has never run before, make sure a stamp file exists. */
 669                         (void) touch_file(t->stamp_path, true, USEC_INFINITY, UID_INVALID, GID_INVALID, MODE_INVALID);
 670         }
 671
 672         t->result = TIMER_SUCCESS;
 673         timer_enter_waiting(t, false);
 674         return 1;
 675 }
 676
 677 static int timer_stop(Unit *u) {
 678         Timer *t = TIMER(u);
 679
 680         assert(t);
 681         assert(IN_SET(t->state, TIMER_WAITING, TIMER_RUNNING, TIMER_ELAPSED));
 682
 683         timer_enter_dead(t, TIMER_SUCCESS);
 684         return 1;
 685 }
 686
 687 static int timer_serialize(Unit *u, FILE *f, FDSet *fds) {
 688         Timer *t = TIMER(u);
 689
 690         assert(u);
 691         assert(f);
 692         assert(fds);
 693
 694         (void) serialize_item(f, "state", timer_state_to_string(t->state));
 695         (void) serialize_item(f, "result", timer_result_to_string(t->result));
 696
 697         if (t->last_trigger.realtime > 0)
 698                 (void) serialize_usec(f, "last-trigger-realtime", t->last_trigger.realtime);
 699
 700         if (t->last_trigger.monotonic > 0)
 701                 (void) serialize_usec(f, "last-trigger-monotonic", t->last_trigger.monotonic);
 702
 703         return 0;
 704 }
 705
 706 static int timer_deserialize_item(Unit *u, const char *key, const char *value, FDSet *fds) {
 707         Timer *t = TIMER(u);
 708
 709         assert(u);
 710         assert(key);
 711         assert(value);
 712         assert(fds);
 713
 714         if (streq(key, "state")) {
 715                 TimerState state;
 716
 717                 state = timer_state_from_string(value);
 718                 if (state < 0)
 719                         log_unit_debug(u, "Failed to parse state value: %s", value);
 720                 else
 721                         t->deserialized_state = state;
 722
 723         } else if (streq(key, "result")) {
 724                 TimerResult f;
 725
 726                 f = timer_result_from_string(value);
 727                 if (f < 0)
 728                         log_unit_debug(u, "Failed to parse result value: %s", value);
 729                 else if (f != TIMER_SUCCESS)
 730                         t->result = f;
 731
 732         } else if (streq(key, "last-trigger-realtime"))
 733                 (void) deserialize_usec(value, &t->last_trigger.realtime);
 734         else if (streq(key, "last-trigger-monotonic"))
 735                 (void) deserialize_usec(value, &t->last_trigger.monotonic);
 736         else
 737                 log_unit_debug(u, "Unknown serialization key: %s", key);
 738
 739         return 0;
 740 }
 741
 742 _pure_ static UnitActiveState timer_active_state(Unit *u) {
 743         assert(u);
 744
 745         return state_translation_table[TIMER(u)->state];
 746 }
 747
 748 _pure_ static const char *timer_sub_state_to_string(Unit *u) {
 749         assert(u);
 750
 751         return timer_state_to_string(TIMER(u)->state);
 752 }
 753
 754 static int timer_dispatch(sd_event_source *s, uint64_t usec, void *userdata) {
 755         Timer *t = TIMER(userdata);
 756
 757         assert(t);
 758
 759         if (t->state != TIMER_WAITING)
 760                 return 0;
 761
 762         log_unit_debug(UNIT(t), "Timer elapsed.");
 763         timer_enter_running(t);
 764         return 0;
 765 }
 766
 767 static void timer_trigger_notify(Unit *u, Unit *other) {
 768         Timer *t = TIMER(u);
 769         TimerValue *v;
 770
 771         assert(u);
 772         assert(other);
 773
 774         /* Filter out invocations with bogus state */
 775         assert(UNIT_IS_LOAD_COMPLETE(other->load_state));
 776
 777         /* Reenable all timers that depend on unit state */
 778         LIST_FOREACH(value, v, t->values)
 779                 if (IN_SET(v->base, TIMER_UNIT_ACTIVE, TIMER_UNIT_INACTIVE))
 780                         v->disabled = false;
 781
 782         switch (t->state) {
 783
 784         case TIMER_WAITING:
 785         case TIMER_ELAPSED:
 786
 787                 /* Recalculate sleep time */
 788                 timer_enter_waiting(t, false);
 789                 break;
 790
 791         case TIMER_RUNNING:
 792
 793                 if (UNIT_IS_INACTIVE_OR_FAILED(unit_active_state(other))) {
 794                         log_unit_debug(UNIT(t), "Got notified about unit deactivation.");
 795                         timer_enter_waiting(t, false);
 796                 }
 797                 break;
 798
 799         case TIMER_DEAD:
 800         case TIMER_FAILED:
 801                 break;
 802
 803         default:
 804                 assert_not_reached("Unknown timer state");
 805         }
 806 }
 807
 808 static void timer_reset_failed(Unit *u) {
 809         Timer *t = TIMER(u);
 810
 811         assert(t);
 812
 813         if (t->state == TIMER_FAILED)
 814                 timer_set_state(t, TIMER_DEAD);
 815
 816         t->result = TIMER_SUCCESS;
 817 }
 818
 819 static void timer_time_change(Unit *u) {
 820         Timer *t = TIMER(u);
 821         usec_t ts;
 822
 823         assert(u);
 824
 825         if (t->state != TIMER_WAITING)
 826                 return;
 827
 828         /* If we appear to have triggered in the future, the system clock must
 829          * have been set backwards.  So let's rewind our own clock and allow
 830          * the future trigger(s) to happen again :).  Exactly the same as when
 831          * you start a timer unit with Persistent=yes. */
 832         ts = now(CLOCK_REALTIME);
 833         if (t->last_trigger.realtime > ts)
 834                 t->last_trigger.realtime = ts;
 835
 836         if (t->on_clock_change) {
 837                 log_unit_debug(u, "Time change, triggering activation.");
 838                 timer_enter_running(t);
 839         } else {
 840                 log_unit_debug(u, "Time change, recalculating next elapse.");
 841                 timer_enter_waiting(t, true);
 842         }
 843 }
 844
 845 static void timer_timezone_change(Unit *u) {
 846         Timer *t = TIMER(u);
 847
 848         assert(u);
 849
 850         if (t->state != TIMER_WAITING)
 851                 return;
 852
 853         if (t->on_timezone_change) {
 854                 log_unit_debug(u, "Timezone change, triggering activation.");
 855                 timer_enter_running(t);
 856         } else {
 857                 log_unit_debug(u, "Timezone change, recalculating next elapse.");
 858                 timer_enter_waiting(t, false);
 859         }
 860 }
 861
 862 static int timer_clean(Unit *u, ExecCleanMask mask) {
 863         Timer *t = TIMER(u);
 864         int r;
 865
 866         assert(t);
 867         assert(mask != 0);
 868
 869         if (t->state != TIMER_DEAD)
 870                 return -EBUSY;
 871
 872         if (!IN_SET(mask, EXEC_CLEAN_STATE))
 873                 return -EUNATCH;
 874
 875         r = timer_setup_persistent(t);
 876         if (r < 0)
 877                 return r;
 878
 879         if (!t->stamp_path)
 880                 return -EUNATCH;
 881
 882         if (unlink(t->stamp_path) && errno != ENOENT)
 883                 return log_unit_error_errno(u, errno, "Failed to clean stamp file of timer: %m");
 884
 885         return 0;
 886 }
 887
 888 static int timer_can_clean(Unit *u, ExecCleanMask *ret) {
 889         Timer *t = TIMER(u);
 890
 891         assert(t);
 892
 893         *ret = t->persistent ? EXEC_CLEAN_STATE : 0;
 894         return 0;
 895 }
 896
 897 static const char* const timer_base_table[_TIMER_BASE_MAX] = {
 898         [TIMER_ACTIVE] = "OnActiveSec",
 899         [TIMER_BOOT] = "OnBootSec",
 900         [TIMER_STARTUP] = "OnStartupSec",
 901         [TIMER_UNIT_ACTIVE] = "OnUnitActiveSec",
 902         [TIMER_UNIT_INACTIVE] = "OnUnitInactiveSec",
 903         [TIMER_CALENDAR] = "OnCalendar"
 904 };
 905
 906 DEFINE_STRING_TABLE_LOOKUP(timer_base, TimerBase);
 907
 908 static const char* const timer_result_table[_TIMER_RESULT_MAX] = {
 909         [TIMER_SUCCESS] = "success",
 910         [TIMER_FAILURE_RESOURCES] = "resources",
 911         [TIMER_FAILURE_START_LIMIT_HIT] = "start-limit-hit",
 912 };
 913
 914 DEFINE_STRING_TABLE_LOOKUP(timer_result, TimerResult);
 915
 916 const UnitVTable timer_vtable = {
 917         .object_size = sizeof(Timer),
 918
 919         .sections =
 920                 "Unit\0"
 921                 "Timer\0"
 922                 "Install\0",
 923         .private_section = "Timer",
 924
 925         .can_transient = true,
 926         .can_fail = true,
 927         .can_trigger = true,
 928
 929         .init = timer_init,
 930         .done = timer_done,
 931         .load = timer_load,
 932
 933         .coldplug = timer_coldplug,
 934
 935         .dump = timer_dump,
 936
 937         .start = timer_start,
 938         .stop = timer_stop,
 939
 940         .clean = timer_clean,
 941         .can_clean = timer_can_clean,
 942
 943         .serialize = timer_serialize,
 944         .deserialize_item = timer_deserialize_item,
 945
 946         .active_state = timer_active_state,
 947         .sub_state_to_string = timer_sub_state_to_string,
 948
 949         .trigger_notify = timer_trigger_notify,
 950
 951         .reset_failed = timer_reset_failed,
 952         .time_change = timer_time_change,
 953         .timezone_change = timer_timezone_change,
 954
 955         .bus_set_property = bus_timer_set_property,
 956 };