Adding upstream version 252.22.upstream/252.22upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1060 insertions, 0 deletions

diff --git a/src/core/timer.c b/src/core/timer.c
new file mode 100644
index 0000000..60e8fea
--- /dev/null
+++ b/src/core/timer.c
@@ -0,0 +1,1060 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include <errno.h>
+
+#include "alloc-util.h"
+#include "bus-error.h"
+#include "bus-util.h"
+#include "dbus-timer.h"
+#include "dbus-unit.h"
+#include "fs-util.h"
+#include "parse-util.h"
+#include "random-util.h"
+#include "serialize.h"
+#include "special.h"
+#include "string-table.h"
+#include "string-util.h"
+#include "timer.h"
+#include "unit-name.h"
+#include "unit.h"
+#include "user-util.h"
+#include "virt.h"
+
+static const UnitActiveState state_translation_table[_TIMER_STATE_MAX] = {
+        [TIMER_DEAD] = UNIT_INACTIVE,
+        [TIMER_WAITING] = UNIT_ACTIVE,
+        [TIMER_RUNNING] = UNIT_ACTIVE,
+        [TIMER_ELAPSED] = UNIT_ACTIVE,
+        [TIMER_FAILED] = UNIT_FAILED
+};
+
+static int timer_dispatch(sd_event_source *s, uint64_t usec, void *userdata);
+
+static void timer_init(Unit *u) {
+        Timer *t = TIMER(u);
+
+        assert(u);
+        assert(u->load_state == UNIT_STUB);
+
+        t->next_elapse_monotonic_or_boottime = USEC_INFINITY;
+        t->next_elapse_realtime = USEC_INFINITY;
+        t->accuracy_usec = u->manager->default_timer_accuracy_usec;
+        t->remain_after_elapse = true;
+}
+
+void timer_free_values(Timer *t) {
+        TimerValue *v;
+
+        assert(t);
+
+        while ((v = t->values)) {
+                LIST_REMOVE(value, t->values, v);
+                calendar_spec_free(v->calendar_spec);
+                free(v);
+        }
+}
+
+static void timer_done(Unit *u) {
+        Timer *t = TIMER(u);
+
+        assert(t);
+
+        timer_free_values(t);
+
+        t->monotonic_event_source = sd_event_source_disable_unref(t->monotonic_event_source);
+        t->realtime_event_source = sd_event_source_disable_unref(t->realtime_event_source);
+
+        t->stamp_path = mfree(t->stamp_path);
+}
+
+static int timer_verify(Timer *t) {
+        assert(t);
+        assert(UNIT(t)->load_state == UNIT_LOADED);
+
+        if (!t->values && !t->on_clock_change && !t->on_timezone_change)
+                return log_unit_error_errno(UNIT(t), SYNTHETIC_ERRNO(ENOEXEC), "Timer unit lacks value setting. Refusing.");
+
+        return 0;
+}
+
+static int timer_add_default_dependencies(Timer *t) {
+        int r;
+
+        assert(t);
+
+        if (!UNIT(t)->default_dependencies)
+                return 0;
+
+        r = unit_add_dependency_by_name(UNIT(t), UNIT_BEFORE, SPECIAL_TIMERS_TARGET, true, UNIT_DEPENDENCY_DEFAULT);
+        if (r < 0)
+                return r;
+
+        if (MANAGER_IS_SYSTEM(UNIT(t)->manager)) {
+                r = unit_add_two_dependencies_by_name(UNIT(t), UNIT_AFTER, UNIT_REQUIRES, SPECIAL_SYSINIT_TARGET, true, UNIT_DEPENDENCY_DEFAULT);
+                if (r < 0)
+                        return r;
+
+                LIST_FOREACH(value, v, t->values) {
+                        if (v->base != TIMER_CALENDAR)
+                                continue;
+
+                        FOREACH_STRING(target, SPECIAL_TIME_SYNC_TARGET, SPECIAL_TIME_SET_TARGET) {
+                                r = unit_add_dependency_by_name(UNIT(t), UNIT_AFTER, target, true, UNIT_DEPENDENCY_DEFAULT);
+                                if (r < 0)
+                                        return r;
+                        }
+
+                        break;
+                }
+        }
+
+        return unit_add_two_dependencies_by_name(UNIT(t), UNIT_BEFORE, UNIT_CONFLICTS, SPECIAL_SHUTDOWN_TARGET, true, UNIT_DEPENDENCY_DEFAULT);
+}
+
+static int timer_add_trigger_dependencies(Timer *t) {
+        Unit *x;
+        int r;
+
+        assert(t);
+
+        if (UNIT_TRIGGER(UNIT(t)))
+                return 0;
+
+        r = unit_load_related_unit(UNIT(t), ".service", &x);
+        if (r < 0)
+                return r;
+
+        return unit_add_two_dependencies(UNIT(t), UNIT_BEFORE, UNIT_TRIGGERS, x, true, UNIT_DEPENDENCY_IMPLICIT);
+}
+
+static int timer_setup_persistent(Timer *t) {
+        _cleanup_free_ char *stamp_path = NULL;
+        int r;
+
+        assert(t);
+
+        if (!t->persistent)
+                return 0;
+
+        if (MANAGER_IS_SYSTEM(UNIT(t)->manager)) {
+
+                r = unit_require_mounts_for(UNIT(t), "/var/lib/systemd/timers", UNIT_DEPENDENCY_FILE);
+                if (r < 0)
+                        return r;
+
+                stamp_path = strjoin("/var/lib/systemd/timers/stamp-", UNIT(t)->id);
+        } else {
+                const char *e;
+
+                e = getenv("XDG_DATA_HOME");
+                if (e)
+                        stamp_path = strjoin(e, "/systemd/timers/stamp-", UNIT(t)->id);
+                else {
+
+                        _cleanup_free_ char *h = NULL;
+
+                        r = get_home_dir(&h);
+                        if (r < 0)
+                                return log_unit_error_errno(UNIT(t), r, "Failed to determine home directory: %m");
+
+                        stamp_path = strjoin(h, "/.local/share/systemd/timers/stamp-", UNIT(t)->id);
+                }
+        }
+
+        if (!stamp_path)
+                return log_oom();
+
+        return free_and_replace(t->stamp_path, stamp_path);
+}
+
+static uint64_t timer_get_fixed_delay_hash(Timer *t) {
+        static const uint8_t hash_key[] = {
+                0x51, 0x0a, 0xdb, 0x76, 0x29, 0x51, 0x42, 0xc2,
+                0x80, 0x35, 0xea, 0xe6, 0x8e, 0x3a, 0x37, 0xbd
+        };
+
+        struct siphash state;
+        sd_id128_t machine_id;
+        uid_t uid;
+        int r;
+
+        assert(t);
+
+        uid = getuid();
+        r = sd_id128_get_machine(&machine_id);
+        if (r < 0) {
+                log_unit_debug_errno(UNIT(t), r,
+                                     "Failed to get machine ID for the fixed delay calculation, proceeding with 0: %m");
+                machine_id = SD_ID128_NULL;
+        }
+
+        siphash24_init(&state, hash_key);
+        siphash24_compress(&machine_id, sizeof(sd_id128_t), &state);
+        siphash24_compress_boolean(MANAGER_IS_SYSTEM(UNIT(t)->manager), &state);
+        siphash24_compress(&uid, sizeof(uid_t), &state);
+        siphash24_compress_string(UNIT(t)->id, &state);
+
+        return siphash24_finalize(&state);
+}
+
+static int timer_load(Unit *u) {
+        Timer *t = TIMER(u);
+        int r;
+
+        assert(u);
+        assert(u->load_state == UNIT_STUB);
+
+        r = unit_load_fragment_and_dropin(u, true);
+        if (r < 0)
+                return r;
+
+        if (u->load_state != UNIT_LOADED)
+                return 0;
+
+        /* This is a new unit? Then let's add in some extras */
+        r = timer_add_trigger_dependencies(t);
+        if (r < 0)
+                return r;
+
+        r = timer_setup_persistent(t);
+        if (r < 0)
+                return r;
+
+        r = timer_add_default_dependencies(t);
+        if (r < 0)
+                return r;
+
+        return timer_verify(t);
+}
+
+static void timer_dump(Unit *u, FILE *f, const char *prefix) {
+        Timer *t = TIMER(u);
+        Unit *trigger;
+
+        trigger = UNIT_TRIGGER(u);
+
+        fprintf(f,
+                "%sTimer State: %s\n"
+                "%sResult: %s\n"
+                "%sUnit: %s\n"
+                "%sPersistent: %s\n"
+                "%sWakeSystem: %s\n"
+                "%sAccuracy: %s\n"
+                "%sRemainAfterElapse: %s\n"
+                "%sFixedRandomDelay: %s\n"
+                "%sOnClockChange: %s\n"
+                "%sOnTimeZoneChange: %s\n",
+                prefix, timer_state_to_string(t->state),
+                prefix, timer_result_to_string(t->result),
+                prefix, trigger ? trigger->id : "n/a",
+                prefix, yes_no(t->persistent),
+                prefix, yes_no(t->wake_system),
+                prefix, FORMAT_TIMESPAN(t->accuracy_usec, 1),
+                prefix, yes_no(t->remain_after_elapse),
+                prefix, yes_no(t->fixed_random_delay),
+                prefix, yes_no(t->on_clock_change),
+                prefix, yes_no(t->on_timezone_change));
+
+        LIST_FOREACH(value, v, t->values)
+                if (v->base == TIMER_CALENDAR) {
+                        _cleanup_free_ char *p = NULL;
+
+                        (void) calendar_spec_to_string(v->calendar_spec, &p);
+
+                        fprintf(f,
+                                "%s%s: %s\n",
+                                prefix,
+                                timer_base_to_string(v->base),
+                                strna(p));
+                } else
+                        fprintf(f,
+                                "%s%s: %s\n",
+                                prefix,
+                                timer_base_to_string(v->base),
+                                FORMAT_TIMESPAN(v->value, 0));
+}
+
+static void timer_set_state(Timer *t, TimerState state) {
+        TimerState old_state;
+        assert(t);
+
+        if (t->state != state)
+                bus_unit_send_pending_change_signal(UNIT(t), false);
+
+        old_state = t->state;
+        t->state = state;
+
+        if (state != TIMER_WAITING) {
+                t->monotonic_event_source = sd_event_source_disable_unref(t->monotonic_event_source);
+                t->realtime_event_source = sd_event_source_disable_unref(t->realtime_event_source);
+                t->next_elapse_monotonic_or_boottime = USEC_INFINITY;
+                t->next_elapse_realtime = USEC_INFINITY;
+        }
+
+        if (state != old_state)
+                log_unit_debug(UNIT(t), "Changed %s -> %s", timer_state_to_string(old_state), timer_state_to_string(state));
+
+        unit_notify(UNIT(t), state_translation_table[old_state], state_translation_table[state], 0);
+}
+
+static void timer_enter_waiting(Timer *t, bool time_change);
+
+static int timer_coldplug(Unit *u) {
+        Timer *t = TIMER(u);
+
+        assert(t);
+        assert(t->state == TIMER_DEAD);
+
+        if (t->deserialized_state == t->state)
+                return 0;
+
+        if (t->deserialized_state == TIMER_WAITING)
+                timer_enter_waiting(t, false);
+        else
+                timer_set_state(t, t->deserialized_state);
+
+        return 0;
+}
+
+static void timer_enter_dead(Timer *t, TimerResult f) {
+        assert(t);
+
+        if (t->result == TIMER_SUCCESS)
+                t->result = f;
+
+        unit_log_result(UNIT(t), t->result == TIMER_SUCCESS, timer_result_to_string(t->result));
+        timer_set_state(t, t->result != TIMER_SUCCESS ? TIMER_FAILED : TIMER_DEAD);
+}
+
+static void timer_enter_elapsed(Timer *t, bool leave_around) {
+        assert(t);
+
+        /* If a unit is marked with RemainAfterElapse=yes we leave it
+         * around even after it elapsed once, so that starting it
+         * later again does not necessarily mean immediate
+         * retriggering. We unconditionally leave units with
+         * TIMER_UNIT_ACTIVE or TIMER_UNIT_INACTIVE triggers around,
+         * since they might be restarted automatically at any time
+         * later on. */
+
+        if (t->remain_after_elapse || leave_around)
+                timer_set_state(t, TIMER_ELAPSED);
+        else
+                timer_enter_dead(t, TIMER_SUCCESS);
+}
+
+static void add_random(Timer *t, usec_t *v) {
+        usec_t add;
+
+        assert(t);
+        assert(v);
+
+        if (t->random_usec == 0)
+                return;
+        if (*v == USEC_INFINITY)
+                return;
+
+        add = (t->fixed_random_delay ? timer_get_fixed_delay_hash(t) : random_u64()) % t->random_usec;
+
+        if (*v + add < *v) /* overflow */
+                *v = (usec_t) -2; /* Highest possible value, that is not USEC_INFINITY */
+        else
+                *v += add;
+
+        log_unit_debug(UNIT(t), "Adding %s random time.", FORMAT_TIMESPAN(add, 0));
+}
+
+static void timer_enter_waiting(Timer *t, bool time_change) {
+        bool found_monotonic = false, found_realtime = false;
+        bool leave_around = false;
+        triple_timestamp ts;
+        Unit *trigger;
+        int r;
+
+        assert(t);
+
+        trigger = UNIT_TRIGGER(UNIT(t));
+        if (!trigger) {
+                log_unit_error(UNIT(t), "Unit to trigger vanished.");
+                timer_enter_dead(t, TIMER_FAILURE_RESOURCES);
+                return;
+        }
+
+        triple_timestamp_get(&ts);
+        t->next_elapse_monotonic_or_boottime = t->next_elapse_realtime = 0;
+
+        LIST_FOREACH(value, v, t->values) {
+                if (v->disabled)
+                        continue;
+
+                if (v->base == TIMER_CALENDAR) {
+                        usec_t b, rebased;
+
+                        /* If we know the last time this was
+                         * triggered, schedule the job based relative
+                         * to that. If we don't, just start from
+                         * the activation time. */
+
+                        if (dual_timestamp_is_set(&t->last_trigger))
+                                b = t->last_trigger.realtime;
+                        else if (dual_timestamp_is_set(&UNIT(t)->inactive_exit_timestamp))
+                                b = UNIT(t)->inactive_exit_timestamp.realtime;
+                        else
+                                b = ts.realtime;
+
+                        r = calendar_spec_next_usec(v->calendar_spec, b, &v->next_elapse);
+                        if (r < 0)
+                                continue;
+
+                        /* To make the delay due to RandomizedDelaySec= work even at boot, if the scheduled
+                         * time has already passed, set the time when systemd first started as the scheduled
+                         * time. Note that we base this on the monotonic timestamp of the boot, not the
+                         * realtime one, since the wallclock might have been off during boot. */
+                        rebased = map_clock_usec(UNIT(t)->manager->timestamps[MANAGER_TIMESTAMP_USERSPACE].monotonic,
+                                                 CLOCK_MONOTONIC, CLOCK_REALTIME);
+                        if (v->next_elapse < rebased)
+                                v->next_elapse = rebased;
+
+                        if (!found_realtime)
+                                t->next_elapse_realtime = v->next_elapse;
+                        else
+                                t->next_elapse_realtime = MIN(t->next_elapse_realtime, v->next_elapse);
+
+                        found_realtime = true;
+
+                } else {
+                        usec_t base;
+
+                        switch (v->base) {
+
+                        case TIMER_ACTIVE:
+                                if (state_translation_table[t->state] == UNIT_ACTIVE)
+                                        base = UNIT(t)->inactive_exit_timestamp.monotonic;
+                                else
+                                        base = ts.monotonic;
+                                break;
+
+                        case TIMER_BOOT:
+                                if (detect_container() <= 0) {
+                                        /* CLOCK_MONOTONIC equals the uptime on Linux */
+                                        base = 0;
+                                        break;
+                                }
+                                /* In a container we don't want to include the time the host
+                                 * was already up when the container started, so count from
+                                 * our own startup. */
+                                _fallthrough_;
+                        case TIMER_STARTUP:
+                                base = UNIT(t)->manager->timestamps[MANAGER_TIMESTAMP_USERSPACE].monotonic;
+                                break;
+
+                        case TIMER_UNIT_ACTIVE:
+                                leave_around = true;
+                                base = MAX(trigger->inactive_exit_timestamp.monotonic, t->last_trigger.monotonic);
+                                if (base <= 0)
+                                        continue;
+                                break;
+
+                        case TIMER_UNIT_INACTIVE:
+                                leave_around = true;
+                                base = MAX(trigger->inactive_enter_timestamp.monotonic, t->last_trigger.monotonic);
+                                if (base <= 0)
+                                        continue;
+                                break;
+
+                        default:
+                                assert_not_reached();
+                        }
+
+                        v->next_elapse = usec_add(usec_shift_clock(base, CLOCK_MONOTONIC, TIMER_MONOTONIC_CLOCK(t)), v->value);
+
+                        if (dual_timestamp_is_set(&t->last_trigger) &&
+                            !time_change &&
+                            v->next_elapse < triple_timestamp_by_clock(&ts, TIMER_MONOTONIC_CLOCK(t)) &&
+                            IN_SET(v->base, TIMER_ACTIVE, TIMER_BOOT, TIMER_STARTUP)) {
+                                /* This is a one time trigger, disable it now */
+                                v->disabled = true;
+                                continue;
+                        }
+
+                        if (!found_monotonic)
+                                t->next_elapse_monotonic_or_boottime = v->next_elapse;
+                        else
+                                t->next_elapse_monotonic_or_boottime = MIN(t->next_elapse_monotonic_or_boottime, v->next_elapse);
+
+                        found_monotonic = true;
+                }
+        }
+
+        if (!found_monotonic && !found_realtime && !t->on_timezone_change && !t->on_clock_change) {
+                log_unit_debug(UNIT(t), "Timer is elapsed.");
+                timer_enter_elapsed(t, leave_around);
+                return;
+        }
+
+        if (found_monotonic) {
+                usec_t left;
+
+                add_random(t, &t->next_elapse_monotonic_or_boottime);
+
+                left = usec_sub_unsigned(t->next_elapse_monotonic_or_boottime, triple_timestamp_by_clock(&ts, TIMER_MONOTONIC_CLOCK(t)));
+                log_unit_debug(UNIT(t), "Monotonic timer elapses in %s.", FORMAT_TIMESPAN(left, 0));
+
+                if (t->monotonic_event_source) {
+                        r = sd_event_source_set_time(t->monotonic_event_source, t->next_elapse_monotonic_or_boottime);
+                        if (r < 0)
+                                goto fail;
+
+                        r = sd_event_source_set_enabled(t->monotonic_event_source, SD_EVENT_ONESHOT);
+                        if (r < 0)
+                                goto fail;
+                } else {
+
+                        r = sd_event_add_time(
+                                        UNIT(t)->manager->event,
+                                        &t->monotonic_event_source,
+                                        t->wake_system ? CLOCK_BOOTTIME_ALARM : CLOCK_MONOTONIC,
+                                        t->next_elapse_monotonic_or_boottime, t->accuracy_usec,
+                                        timer_dispatch, t);
+                        if (r < 0)
+                                goto fail;
+
+                        (void) sd_event_source_set_description(t->monotonic_event_source, "timer-monotonic");
+                }
+
+        } else if (t->monotonic_event_source) {
+
+                r = sd_event_source_set_enabled(t->monotonic_event_source, SD_EVENT_OFF);
+                if (r < 0)
+                        goto fail;
+        }
+
+        if (found_realtime) {
+                add_random(t, &t->next_elapse_realtime);
+
+                log_unit_debug(UNIT(t), "Realtime timer elapses at %s.", FORMAT_TIMESTAMP(t->next_elapse_realtime));
+
+                if (t->realtime_event_source) {
+                        r = sd_event_source_set_time(t->realtime_event_source, t->next_elapse_realtime);
+                        if (r < 0)
+                                goto fail;
+
+                        r = sd_event_source_set_enabled(t->realtime_event_source, SD_EVENT_ONESHOT);
+                        if (r < 0)
+                                goto fail;
+                } else {
+                        r = sd_event_add_time(
+                                        UNIT(t)->manager->event,
+                                        &t->realtime_event_source,
+                                        t->wake_system ? CLOCK_REALTIME_ALARM : CLOCK_REALTIME,
+                                        t->next_elapse_realtime, t->accuracy_usec,
+                                        timer_dispatch, t);
+                        if (r < 0)
+                                goto fail;
+
+                        (void) sd_event_source_set_description(t->realtime_event_source, "timer-realtime");
+                }
+
+        } else if (t->realtime_event_source) {
+
+                r = sd_event_source_set_enabled(t->realtime_event_source, SD_EVENT_OFF);
+                if (r < 0)
+                        goto fail;
+        }
+
+        timer_set_state(t, TIMER_WAITING);
+        return;
+
+fail:
+        log_unit_warning_errno(UNIT(t), r, "Failed to enter waiting state: %m");
+        timer_enter_dead(t, TIMER_FAILURE_RESOURCES);
+}
+
+static void timer_enter_running(Timer *t) {
+        _cleanup_(activation_details_unrefp) ActivationDetails *details = NULL;
+        _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
+        Unit *trigger;
+        Job *job;
+        int r;
+
+        assert(t);
+
+        /* Don't start job if we are supposed to go down */
+        if (unit_stop_pending(UNIT(t)))
+                return;
+
+        trigger = UNIT_TRIGGER(UNIT(t));
+        if (!trigger) {
+                log_unit_error(UNIT(t), "Unit to trigger vanished.");
+                timer_enter_dead(t, TIMER_FAILURE_RESOURCES);
+                return;
+        }
+
+        details = activation_details_new(UNIT(t));
+        if (!details) {
+                r = -ENOMEM;
+                goto fail;
+        }
+
+        r = manager_add_job(UNIT(t)->manager, JOB_START, trigger, JOB_REPLACE, NULL, &error, &job);
+        if (r < 0)
+                goto fail;
+
+        dual_timestamp_get(&t->last_trigger);
+        ACTIVATION_DETAILS_TIMER(details)->last_trigger = t->last_trigger;
+
+        job_set_activation_details(job, details);
+
+        if (t->stamp_path)
+                touch_file(t->stamp_path, true, t->last_trigger.realtime, UID_INVALID, GID_INVALID, MODE_INVALID);
+
+        timer_set_state(t, TIMER_RUNNING);
+        return;
+
+fail:
+        log_unit_warning(UNIT(t), "Failed to queue unit startup job: %s", bus_error_message(&error, r));
+        timer_enter_dead(t, TIMER_FAILURE_RESOURCES);
+}
+
+static int timer_start(Unit *u) {
+        Timer *t = TIMER(u);
+        int r;
+
+        assert(t);
+        assert(IN_SET(t->state, TIMER_DEAD, TIMER_FAILED));
+
+        r = unit_test_trigger_loaded(u);
+        if (r < 0)
+                return r;
+
+        r = unit_acquire_invocation_id(u);
+        if (r < 0)
+                return r;
+
+        t->last_trigger = DUAL_TIMESTAMP_NULL;
+
+        /* Reenable all timers that depend on unit activation time */
+        LIST_FOREACH(value, v, t->values)
+                if (v->base == TIMER_ACTIVE)
+                        v->disabled = false;
+
+        if (t->stamp_path) {
+                struct stat st;
+
+                if (stat(t->stamp_path, &st) >= 0) {
+                        usec_t ft;
+
+                        /* Load the file timestamp, but only if it is actually in the past. If it is in the future,
+                         * something is wrong with the system clock. */
+
+                        ft = timespec_load(&st.st_mtim);
+                        if (ft < now(CLOCK_REALTIME))
+                                t->last_trigger.realtime = ft;
+                        else
+                                log_unit_warning(u, "Not using persistent file timestamp %s as it is in the future.",
+                                                 FORMAT_TIMESTAMP(ft));
+
+                } else if (errno == ENOENT)
+                        /* The timer has never run before, make sure a stamp file exists. */
+                        (void) touch_file(t->stamp_path, true, USEC_INFINITY, UID_INVALID, GID_INVALID, MODE_INVALID);
+        }
+
+        t->result = TIMER_SUCCESS;
+        timer_enter_waiting(t, false);
+        return 1;
+}
+
+static int timer_stop(Unit *u) {
+        Timer *t = TIMER(u);
+
+        assert(t);
+        assert(IN_SET(t->state, TIMER_WAITING, TIMER_RUNNING, TIMER_ELAPSED));
+
+        timer_enter_dead(t, TIMER_SUCCESS);
+        return 1;
+}
+
+static int timer_serialize(Unit *u, FILE *f, FDSet *fds) {
+        Timer *t = TIMER(u);
+
+        assert(u);
+        assert(f);
+        assert(fds);
+
+        (void) serialize_item(f, "state", timer_state_to_string(t->state));
+        (void) serialize_item(f, "result", timer_result_to_string(t->result));
+
+        if (t->last_trigger.realtime > 0)
+                (void) serialize_usec(f, "last-trigger-realtime", t->last_trigger.realtime);
+
+        if (t->last_trigger.monotonic > 0)
+                (void) serialize_usec(f, "last-trigger-monotonic", t->last_trigger.monotonic);
+
+        return 0;
+}
+
+static int timer_deserialize_item(Unit *u, const char *key, const char *value, FDSet *fds) {
+        Timer *t = TIMER(u);
+
+        assert(u);
+        assert(key);
+        assert(value);
+        assert(fds);
+
+        if (streq(key, "state")) {
+                TimerState state;
+
+                state = timer_state_from_string(value);
+                if (state < 0)
+                        log_unit_debug(u, "Failed to parse state value: %s", value);
+                else
+                        t->deserialized_state = state;
+
+        } else if (streq(key, "result")) {
+                TimerResult f;
+
+                f = timer_result_from_string(value);
+                if (f < 0)
+                        log_unit_debug(u, "Failed to parse result value: %s", value);
+                else if (f != TIMER_SUCCESS)
+                        t->result = f;
+
+        } else if (streq(key, "last-trigger-realtime"))
+                (void) deserialize_usec(value, &t->last_trigger.realtime);
+        else if (streq(key, "last-trigger-monotonic"))
+                (void) deserialize_usec(value, &t->last_trigger.monotonic);
+        else
+                log_unit_debug(u, "Unknown serialization key: %s", key);
+
+        return 0;
+}
+
+_pure_ static UnitActiveState timer_active_state(Unit *u) {
+        assert(u);
+
+        return state_translation_table[TIMER(u)->state];
+}
+
+_pure_ static const char *timer_sub_state_to_string(Unit *u) {
+        assert(u);
+
+        return timer_state_to_string(TIMER(u)->state);
+}
+
+static int timer_dispatch(sd_event_source *s, uint64_t usec, void *userdata) {
+        Timer *t = TIMER(userdata);
+
+        assert(t);
+
+        if (t->state != TIMER_WAITING)
+                return 0;
+
+        log_unit_debug(UNIT(t), "Timer elapsed.");
+        timer_enter_running(t);
+        return 0;
+}
+
+static void timer_trigger_notify(Unit *u, Unit *other) {
+        Timer *t = TIMER(u);
+
+        assert(u);
+        assert(other);
+
+        /* Filter out invocations with bogus state */
+        assert(UNIT_IS_LOAD_COMPLETE(other->load_state));
+
+        /* Reenable all timers that depend on unit state */
+        LIST_FOREACH(value, v, t->values)
+                if (IN_SET(v->base, TIMER_UNIT_ACTIVE, TIMER_UNIT_INACTIVE))
+                        v->disabled = false;
+
+        switch (t->state) {
+
+        case TIMER_WAITING:
+        case TIMER_ELAPSED:
+
+                /* Recalculate sleep time */
+                timer_enter_waiting(t, false);
+                break;
+
+        case TIMER_RUNNING:
+
+                if (UNIT_IS_INACTIVE_OR_FAILED(unit_active_state(other))) {
+                        log_unit_debug(UNIT(t), "Got notified about unit deactivation.");
+                        timer_enter_waiting(t, false);
+                }
+                break;
+
+        case TIMER_DEAD:
+        case TIMER_FAILED:
+                break;
+
+        default:
+                assert_not_reached();
+        }
+}
+
+static void timer_reset_failed(Unit *u) {
+        Timer *t = TIMER(u);
+
+        assert(t);
+
+        if (t->state == TIMER_FAILED)
+                timer_set_state(t, TIMER_DEAD);
+
+        t->result = TIMER_SUCCESS;
+}
+
+static void timer_time_change(Unit *u) {
+        Timer *t = TIMER(u);
+        usec_t ts;
+
+        assert(u);
+
+        if (t->state != TIMER_WAITING)
+                return;
+
+        /* If we appear to have triggered in the future, the system clock must
+         * have been set backwards.  So let's rewind our own clock and allow
+         * the future triggers to happen again :).  Exactly the same as when
+         * you start a timer unit with Persistent=yes. */
+        ts = now(CLOCK_REALTIME);
+        if (t->last_trigger.realtime > ts)
+                t->last_trigger.realtime = ts;
+
+        if (t->on_clock_change) {
+                log_unit_debug(u, "Time change, triggering activation.");
+                timer_enter_running(t);
+        } else {
+                log_unit_debug(u, "Time change, recalculating next elapse.");
+                timer_enter_waiting(t, true);
+        }
+}
+
+static void timer_timezone_change(Unit *u) {
+        Timer *t = TIMER(u);
+
+        assert(u);
+
+        if (t->state != TIMER_WAITING)
+                return;
+
+        if (t->on_timezone_change) {
+                log_unit_debug(u, "Timezone change, triggering activation.");
+                timer_enter_running(t);
+        } else {
+                log_unit_debug(u, "Timezone change, recalculating next elapse.");
+                timer_enter_waiting(t, false);
+        }
+}
+
+static int timer_clean(Unit *u, ExecCleanMask mask) {
+        Timer *t = TIMER(u);
+        int r;
+
+        assert(t);
+        assert(mask != 0);
+
+        if (t->state != TIMER_DEAD)
+                return -EBUSY;
+
+        if (!IN_SET(mask, EXEC_CLEAN_STATE))
+                return -EUNATCH;
+
+        r = timer_setup_persistent(t);
+        if (r < 0)
+                return r;
+
+        if (!t->stamp_path)
+                return -EUNATCH;
+
+        if (unlink(t->stamp_path) && errno != ENOENT)
+                return log_unit_error_errno(u, errno, "Failed to clean stamp file of timer: %m");
+
+        return 0;
+}
+
+static int timer_can_clean(Unit *u, ExecCleanMask *ret) {
+        Timer *t = TIMER(u);
+
+        assert(t);
+
+        *ret = t->persistent ? EXEC_CLEAN_STATE : 0;
+        return 0;
+}
+
+static int timer_can_start(Unit *u) {
+        Timer *t = TIMER(u);
+        int r;
+
+        assert(t);
+
+        r = unit_test_start_limit(u);
+        if (r < 0) {
+                timer_enter_dead(t, TIMER_FAILURE_START_LIMIT_HIT);
+                return r;
+        }
+
+        return 1;
+}
+
+static void activation_details_timer_serialize(ActivationDetails *details, FILE *f) {
+        ActivationDetailsTimer *t = ACTIVATION_DETAILS_TIMER(details);
+
+        assert(details);
+        assert(f);
+        assert(t);
+
+        (void) serialize_dual_timestamp(f, "activation-details-timer-last-trigger", &t->last_trigger);
+}
+
+static int activation_details_timer_deserialize(const char *key, const char *value, ActivationDetails **details) {
+        int r;
+
+        assert(key);
+        assert(value);
+
+        if (!details || !*details)
+                return -EINVAL;
+
+        ActivationDetailsTimer *t = ACTIVATION_DETAILS_TIMER(*details);
+        if (!t)
+                return -EINVAL;
+
+        if (!streq(key, "activation-details-timer-last-trigger"))
+                return -EINVAL;
+
+        r = deserialize_dual_timestamp(value, &t->last_trigger);
+        if (r < 0)
+                return r;
+
+        return 0;
+}
+
+static int activation_details_timer_append_env(ActivationDetails *details, char ***strv) {
+        ActivationDetailsTimer *t = ACTIVATION_DETAILS_TIMER(details);
+        int r;
+
+        assert(details);
+        assert(strv);
+        assert(t);
+
+        if (!dual_timestamp_is_set(&t->last_trigger))
+                return 0;
+
+        r = strv_extendf(strv, "TRIGGER_TIMER_REALTIME_USEC=" USEC_FMT, t->last_trigger.realtime);
+        if (r < 0)
+                return r;
+
+        r = strv_extendf(strv, "TRIGGER_TIMER_MONOTONIC_USEC=" USEC_FMT, t->last_trigger.monotonic);
+        if (r < 0)
+                return r;
+
+        return 2; /* Return the number of variables added to the env block */
+}
+
+static int activation_details_timer_append_pair(ActivationDetails *details, char ***strv) {
+        ActivationDetailsTimer *t = ACTIVATION_DETAILS_TIMER(details);
+        int r;
+
+        assert(details);
+        assert(strv);
+        assert(t);
+
+        if (!dual_timestamp_is_set(&t->last_trigger))
+                return 0;
+
+        r = strv_extend(strv, "trigger_timer_realtime_usec");
+        if (r < 0)
+                return r;
+
+        r = strv_extendf(strv, USEC_FMT, t->last_trigger.realtime);
+        if (r < 0)
+                return r;
+
+        r = strv_extend(strv, "trigger_timer_monotonic_usec");
+        if (r < 0)
+                return r;
+
+        r = strv_extendf(strv, USEC_FMT, t->last_trigger.monotonic);
+        if (r < 0)
+                return r;
+
+        return 2; /* Return the number of pairs added to the env block */
+}
+
+static const char* const timer_base_table[_TIMER_BASE_MAX] = {
+        [TIMER_ACTIVE]        = "OnActiveSec",
+        [TIMER_BOOT]          = "OnBootSec",
+        [TIMER_STARTUP]       = "OnStartupSec",
+        [TIMER_UNIT_ACTIVE]   = "OnUnitActiveSec",
+        [TIMER_UNIT_INACTIVE] = "OnUnitInactiveSec",
+        [TIMER_CALENDAR]      = "OnCalendar"
+};
+
+DEFINE_STRING_TABLE_LOOKUP(timer_base, TimerBase);
+
+static const char* const timer_result_table[_TIMER_RESULT_MAX] = {
+        [TIMER_SUCCESS]                 = "success",
+        [TIMER_FAILURE_RESOURCES]       = "resources",
+        [TIMER_FAILURE_START_LIMIT_HIT] = "start-limit-hit",
+};
+
+DEFINE_STRING_TABLE_LOOKUP(timer_result, TimerResult);
+
+const UnitVTable timer_vtable = {
+        .object_size = sizeof(Timer),
+
+        .sections =
+                "Unit\0"
+                "Timer\0"
+                "Install\0",
+        .private_section = "Timer",
+
+        .can_transient = true,
+        .can_fail = true,
+        .can_trigger = true,
+
+        .init = timer_init,
+        .done = timer_done,
+        .load = timer_load,
+
+        .coldplug = timer_coldplug,
+
+        .dump = timer_dump,
+
+        .start = timer_start,
+        .stop = timer_stop,
+
+        .clean = timer_clean,
+        .can_clean = timer_can_clean,
+
+        .serialize = timer_serialize,
+        .deserialize_item = timer_deserialize_item,
+
+        .active_state = timer_active_state,
+        .sub_state_to_string = timer_sub_state_to_string,
+
+        .trigger_notify = timer_trigger_notify,
+
+        .reset_failed = timer_reset_failed,
+        .time_change = timer_time_change,
+        .timezone_change = timer_timezone_change,
+
+        .bus_set_property = bus_timer_set_property,
+
+        .can_start = timer_can_start,
+};
+
+const ActivationDetailsVTable activation_details_timer_vtable = {
+        .object_size = sizeof(ActivationDetailsTimer),
+
+        .serialize = activation_details_timer_serialize,
+        .deserialize = activation_details_timer_deserialize,
+        .append_env = activation_details_timer_append_env,
+        .append_pair = activation_details_timer_append_pair,
+};