pid1: include the source unit in UnitRef

[thirdparty/systemd.git] / src / core / unit.c

/* SPDX-License-Identifier: LGPL-2.1+ */
/***
  This file is part of systemd.

  Copyright 2010 Lennart Poettering

  systemd is free software; you can redistribute it and/or modify it
  under the terms of the GNU Lesser General Public License as published by
  the Free Software Foundation; either version 2.1 of the License, or
  (at your option) any later version.

  systemd is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public License
  along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/

#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <sys/prctl.h>
#include <sys/stat.h>
#include <unistd.h>

#include "sd-id128.h"
#include "sd-messages.h"

#include "alloc-util.h"
#include "bus-common-errors.h"
#include "bus-util.h"
#include "cgroup-util.h"
#include "dbus-unit.h"
#include "dbus.h"
#include "dropin.h"
#include "escape.h"
#include "execute.h"
#include "fd-util.h"
#include "fileio-label.h"
#include "format-util.h"
#include "fs-util.h"
#include "id128-util.h"
#include "io-util.h"
#include "load-dropin.h"
#include "load-fragment.h"
#include "log.h"
#include "macro.h"
#include "missing.h"
#include "mkdir.h"
#include "parse-util.h"
#include "path-util.h"
#include "process-util.h"
#include "set.h"
#include "signal-util.h"
#include "sparse-endian.h"
#include "special.h"
#include "specifier.h"
#include "stat-util.h"
#include "stdio-util.h"
#include "string-table.h"
#include "string-util.h"
#include "strv.h"
#include "umask-util.h"
#include "unit-name.h"
#include "unit.h"
#include "user-util.h"
#include "virt.h"

const UnitVTable * const unit_vtable[_UNIT_TYPE_MAX] = {
        [UNIT_SERVICE] = &service_vtable,
        [UNIT_SOCKET] = &socket_vtable,
        [UNIT_TARGET] = &target_vtable,
        [UNIT_DEVICE] = &device_vtable,
        [UNIT_MOUNT] = &mount_vtable,
        [UNIT_AUTOMOUNT] = &automount_vtable,
        [UNIT_SWAP] = &swap_vtable,
        [UNIT_TIMER] = &timer_vtable,
        [UNIT_PATH] = &path_vtable,
        [UNIT_SLICE] = &slice_vtable,
        [UNIT_SCOPE] = &scope_vtable,
};

static void maybe_warn_about_dependency(Unit *u, const char *other, UnitDependency dependency);

Unit *unit_new(Manager *m, size_t size) {
        Unit *u;

        assert(m);
        assert(size >= sizeof(Unit));

        u = malloc0(size);
        if (!u)
                return NULL;

        u->names = set_new(&string_hash_ops);
        if (!u->names)
                return mfree(u);

        u->manager = m;
        u->type = _UNIT_TYPE_INVALID;
        u->default_dependencies = true;
        u->unit_file_state = _UNIT_FILE_STATE_INVALID;
        u->unit_file_preset = -1;
        u->on_failure_job_mode = JOB_REPLACE;
        u->cgroup_inotify_wd = -1;
        u->job_timeout = USEC_INFINITY;
        u->job_running_timeout = USEC_INFINITY;
        u->ref_uid = UID_INVALID;
        u->ref_gid = GID_INVALID;
        u->cpu_usage_last = NSEC_INFINITY;
        u->cgroup_bpf_state = UNIT_CGROUP_BPF_INVALIDATED;

        u->ip_accounting_ingress_map_fd = -1;
        u->ip_accounting_egress_map_fd = -1;
        u->ipv4_allow_map_fd = -1;
        u->ipv6_allow_map_fd = -1;
        u->ipv4_deny_map_fd = -1;
        u->ipv6_deny_map_fd = -1;

        u->last_section_private = -1;

        RATELIMIT_INIT(u->start_limit, m->default_start_limit_interval, m->default_start_limit_burst);
        RATELIMIT_INIT(u->auto_stop_ratelimit, 10 * USEC_PER_SEC, 16);

        return u;
}

int unit_new_for_name(Manager *m, size_t size, const char *name, Unit **ret) {
        Unit *u;
        int r;

        u = unit_new(m, size);
        if (!u)
                return -ENOMEM;

        r = unit_add_name(u, name);
        if (r < 0) {
                unit_free(u);
                return r;
        }

        *ret = u;
        return r;
}

bool unit_has_name(Unit *u, const char *name) {
        assert(u);
        assert(name);

        return set_contains(u->names, (char*) name);
}

static void unit_init(Unit *u) {
        CGroupContext *cc;
        ExecContext *ec;
        KillContext *kc;

        assert(u);
        assert(u->manager);
        assert(u->type >= 0);

        cc = unit_get_cgroup_context(u);
        if (cc) {
                cgroup_context_init(cc);

                /* Copy in the manager defaults into the cgroup
                 * context, _before_ the rest of the settings have
                 * been initialized */

                cc->cpu_accounting = u->manager->default_cpu_accounting;
                cc->io_accounting = u->manager->default_io_accounting;
                cc->ip_accounting = u->manager->default_ip_accounting;
                cc->blockio_accounting = u->manager->default_blockio_accounting;
                cc->memory_accounting = u->manager->default_memory_accounting;
                cc->tasks_accounting = u->manager->default_tasks_accounting;
                cc->ip_accounting = u->manager->default_ip_accounting;

                if (u->type != UNIT_SLICE)
                        cc->tasks_max = u->manager->default_tasks_max;
        }

        ec = unit_get_exec_context(u);
        if (ec) {
                exec_context_init(ec);

                ec->keyring_mode = MANAGER_IS_SYSTEM(u->manager) ?
                        EXEC_KEYRING_PRIVATE : EXEC_KEYRING_INHERIT;
        }

        kc = unit_get_kill_context(u);
        if (kc)
                kill_context_init(kc);

        if (UNIT_VTABLE(u)->init)
                UNIT_VTABLE(u)->init(u);
}

int unit_add_name(Unit *u, const char *text) {
        _cleanup_free_ char *s = NULL, *i = NULL;
        UnitType t;
        int r;

        assert(u);
        assert(text);

        if (unit_name_is_valid(text, UNIT_NAME_TEMPLATE)) {

                if (!u->instance)
                        return -EINVAL;

                r = unit_name_replace_instance(text, u->instance, &s);
                if (r < 0)
                        return r;
        } else {
                s = strdup(text);
                if (!s)
                        return -ENOMEM;
        }

        if (set_contains(u->names, s))
                return 0;
        if (hashmap_contains(u->manager->units, s))
                return -EEXIST;

        if (!unit_name_is_valid(s, UNIT_NAME_PLAIN|UNIT_NAME_INSTANCE))
                return -EINVAL;

        t = unit_name_to_type(s);
        if (t < 0)
                return -EINVAL;

        if (u->type != _UNIT_TYPE_INVALID && t != u->type)
                return -EINVAL;

        r = unit_name_to_instance(s, &i);
        if (r < 0)
                return r;

        if (i && !unit_type_may_template(t))
                return -EINVAL;

        /* Ensure that this unit is either instanced or not instanced,
         * but not both. Note that we do allow names with different
         * instance names however! */
        if (u->type != _UNIT_TYPE_INVALID && !u->instance != !i)
                return -EINVAL;

        if (!unit_type_may_alias(t) && !set_isempty(u->names))
                return -EEXIST;

        if (hashmap_size(u->manager->units) >= MANAGER_MAX_NAMES)
                return -E2BIG;

        r = set_put(u->names, s);
        if (r < 0)
                return r;
        assert(r > 0);

        r = hashmap_put(u->manager->units, s, u);
        if (r < 0) {
                (void) set_remove(u->names, s);
                return r;
        }

        if (u->type == _UNIT_TYPE_INVALID) {
                u->type = t;
                u->id = s;
                u->instance = i;

                LIST_PREPEND(units_by_type, u->manager->units_by_type[t], u);

                unit_init(u);

                i = NULL;
        }

        s = NULL;

        unit_add_to_dbus_queue(u);
        return 0;
}

int unit_choose_id(Unit *u, const char *name) {
        _cleanup_free_ char *t = NULL;
        char *s, *i;
        int r;

        assert(u);
        assert(name);

        if (unit_name_is_valid(name, UNIT_NAME_TEMPLATE)) {

                if (!u->instance)
                        return -EINVAL;

                r = unit_name_replace_instance(name, u->instance, &t);
                if (r < 0)
                        return r;

                name = t;
        }

        /* Selects one of the names of this unit as the id */
        s = set_get(u->names, (char*) name);
        if (!s)
                return -ENOENT;

        /* Determine the new instance from the new id */
        r = unit_name_to_instance(s, &i);
        if (r < 0)
                return r;

        u->id = s;

        free(u->instance);
        u->instance = i;

        unit_add_to_dbus_queue(u);

        return 0;
}

int unit_set_description(Unit *u, const char *description) {
        int r;

        assert(u);

        r = free_and_strdup(&u->description, empty_to_null(description));
        if (r < 0)
                return r;
        if (r > 0)
                unit_add_to_dbus_queue(u);

        return 0;
}

bool unit_may_gc(Unit *u) {
        UnitActiveState state;
        int r;

        assert(u);

        /* Checks whether the unit is ready to be unloaded for garbage collection.
         * Returns true when the unit may be collected, and false if there's some
         * reason to keep it loaded. */

        if (u->job)
                return false;

        if (u->nop_job)
                return false;

        state = unit_active_state(u);

        /* If the unit is inactive and failed and no job is queued for it, then release its runtime resources */
        if (UNIT_IS_INACTIVE_OR_FAILED(state) &&
            UNIT_VTABLE(u)->release_resources)
                UNIT_VTABLE(u)->release_resources(u);

        if (u->perpetual)
                return false;

        if (u->refs_by_target)
                return false;

        if (sd_bus_track_count(u->bus_track) > 0)
                return false;

        /* But we keep the unit object around for longer when it is referenced or configured to not be gc'ed */
        switch (u->collect_mode) {

        case COLLECT_INACTIVE:
                if (state != UNIT_INACTIVE)
                        return false;

                break;

        case COLLECT_INACTIVE_OR_FAILED:
                if (!IN_SET(state, UNIT_INACTIVE, UNIT_FAILED))
                        return false;

                break;

        default:
                assert_not_reached("Unknown garbage collection mode");
        }

        if (u->cgroup_path) {
                /* If the unit has a cgroup, then check whether there's anything in it. If so, we should stay
                 * around. Units with active processes should never be collected. */

                r = cg_is_empty_recursive(SYSTEMD_CGROUP_CONTROLLER, u->cgroup_path);
                if (r < 0)
                        log_unit_debug_errno(u, r, "Failed to determine whether cgroup %s is empty: %m", u->cgroup_path);
                if (r <= 0)
                        return false;
        }

        if (UNIT_VTABLE(u)->may_gc && !UNIT_VTABLE(u)->may_gc(u))
                return false;

        return true;
}

void unit_add_to_load_queue(Unit *u) {
        assert(u);
        assert(u->type != _UNIT_TYPE_INVALID);

        if (u->load_state != UNIT_STUB || u->in_load_queue)
                return;

        LIST_PREPEND(load_queue, u->manager->load_queue, u);
        u->in_load_queue = true;
}

void unit_add_to_cleanup_queue(Unit *u) {
        assert(u);

        if (u->in_cleanup_queue)
                return;

        LIST_PREPEND(cleanup_queue, u->manager->cleanup_queue, u);
        u->in_cleanup_queue = true;
}

void unit_add_to_gc_queue(Unit *u) {
        assert(u);

        if (u->in_gc_queue || u->in_cleanup_queue)
                return;

        if (!unit_may_gc(u))
                return;

        LIST_PREPEND(gc_queue, u->manager->gc_unit_queue, u);
        u->in_gc_queue = true;
}

void unit_add_to_dbus_queue(Unit *u) {
        assert(u);
        assert(u->type != _UNIT_TYPE_INVALID);

        if (u->load_state == UNIT_STUB || u->in_dbus_queue)
                return;

        /* Shortcut things if nobody cares */
        if (sd_bus_track_count(u->manager->subscribed) <= 0 &&
            sd_bus_track_count(u->bus_track) <= 0 &&
            set_isempty(u->manager->private_buses)) {
                u->sent_dbus_new_signal = true;
                return;
        }

        LIST_PREPEND(dbus_queue, u->manager->dbus_unit_queue, u);
        u->in_dbus_queue = true;
}

static void bidi_set_free(Unit *u, Hashmap *h) {
        Unit *other;
        Iterator i;
        void *v;

        assert(u);

        /* Frees the hashmap and makes sure we are dropped from the inverse pointers */

        HASHMAP_FOREACH_KEY(v, other, h, i) {
                UnitDependency d;

                for (d = 0; d < _UNIT_DEPENDENCY_MAX; d++)
                        hashmap_remove(other->dependencies[d], u);

                unit_add_to_gc_queue(other);
        }

        hashmap_free(h);
}

static void unit_remove_transient(Unit *u) {
        char **i;

        assert(u);

        if (!u->transient)
                return;

        if (u->fragment_path)
                (void) unlink(u->fragment_path);

        STRV_FOREACH(i, u->dropin_paths) {
                _cleanup_free_ char *p = NULL, *pp = NULL;

                p = dirname_malloc(*i); /* Get the drop-in directory from the drop-in file */
                if (!p)
                        continue;

                pp = dirname_malloc(p); /* Get the config directory from the drop-in directory */
                if (!pp)
                        continue;

                /* Only drop transient drop-ins */
                if (!path_equal(u->manager->lookup_paths.transient, pp))
                        continue;

                (void) unlink(*i);
                (void) rmdir(p);
        }
}

static void unit_free_requires_mounts_for(Unit *u) {
        assert(u);

        for (;;) {
                _cleanup_free_ char *path;

                path = hashmap_steal_first_key(u->requires_mounts_for);
                if (!path)
                        break;
                else {
                        char s[strlen(path) + 1];

                        PATH_FOREACH_PREFIX_MORE(s, path) {
                                char *y;
                                Set *x;

                                x = hashmap_get2(u->manager->units_requiring_mounts_for, s, (void**) &y);
                                if (!x)
                                        continue;

                                (void) set_remove(x, u);

                                if (set_isempty(x)) {
                                        (void) hashmap_remove(u->manager->units_requiring_mounts_for, y);
                                        free(y);
                                        set_free(x);
                                }
                        }
                }
        }

        u->requires_mounts_for = hashmap_free(u->requires_mounts_for);
}

static void unit_done(Unit *u) {
        ExecContext *ec;
        CGroupContext *cc;

        assert(u);

        if (u->type < 0)
                return;

        if (UNIT_VTABLE(u)->done)
                UNIT_VTABLE(u)->done(u);

        ec = unit_get_exec_context(u);
        if (ec)
                exec_context_done(ec);

        cc = unit_get_cgroup_context(u);
        if (cc)
                cgroup_context_done(cc);
}

void unit_free(Unit *u) {
        UnitDependency d;
        Iterator i;
        char *t;

        if (!u)
                return;

        u->transient_file = safe_fclose(u->transient_file);

        if (!MANAGER_IS_RELOADING(u->manager))
                unit_remove_transient(u);

        bus_unit_send_removed_signal(u);

        unit_done(u);

        sd_bus_slot_unref(u->match_bus_slot);

        sd_bus_track_unref(u->bus_track);
        u->deserialized_refs = strv_free(u->deserialized_refs);

        unit_free_requires_mounts_for(u);

        SET_FOREACH(t, u->names, i)
                hashmap_remove_value(u->manager->units, t, u);

        if (!sd_id128_is_null(u->invocation_id))
                hashmap_remove_value(u->manager->units_by_invocation_id, &u->invocation_id, u);

        if (u->job) {
                Job *j = u->job;
                job_uninstall(j);
                job_free(j);
        }

        if (u->nop_job) {
                Job *j = u->nop_job;
                job_uninstall(j);
                job_free(j);
        }

        for (d = 0; d < _UNIT_DEPENDENCY_MAX; d++)
                bidi_set_free(u, u->dependencies[d]);

        if (u->type != _UNIT_TYPE_INVALID)
                LIST_REMOVE(units_by_type, u->manager->units_by_type[u->type], u);

        if (u->in_load_queue)
                LIST_REMOVE(load_queue, u->manager->load_queue, u);

        if (u->in_dbus_queue)
                LIST_REMOVE(dbus_queue, u->manager->dbus_unit_queue, u);

        if (u->in_cleanup_queue)
                LIST_REMOVE(cleanup_queue, u->manager->cleanup_queue, u);

        if (u->in_gc_queue)
                LIST_REMOVE(gc_queue, u->manager->gc_unit_queue, u);

        if (u->in_cgroup_realize_queue)
                LIST_REMOVE(cgroup_realize_queue, u->manager->cgroup_realize_queue, u);

        if (u->in_cgroup_empty_queue)
                LIST_REMOVE(cgroup_empty_queue, u->manager->cgroup_empty_queue, u);

        if (u->on_console)
                manager_unref_console(u->manager);

        unit_release_cgroup(u);

        if (!MANAGER_IS_RELOADING(u->manager))
                unit_unlink_state_files(u);

        unit_unref_uid_gid(u, false);

        (void) manager_update_failed_units(u->manager, u, false);
        set_remove(u->manager->startup_units, u);

        free(u->description);
        strv_free(u->documentation);
        free(u->fragment_path);
        free(u->source_path);
        strv_free(u->dropin_paths);
        free(u->instance);

        free(u->job_timeout_reboot_arg);

        set_free_free(u->names);

        unit_unwatch_all_pids(u);

        condition_free_list(u->conditions);
        condition_free_list(u->asserts);

        free(u->reboot_arg);

        unit_ref_unset(&u->slice);
        while (u->refs_by_target)
                unit_ref_unset(u->refs_by_target);

        safe_close(u->ip_accounting_ingress_map_fd);
        safe_close(u->ip_accounting_egress_map_fd);

        safe_close(u->ipv4_allow_map_fd);
        safe_close(u->ipv6_allow_map_fd);
        safe_close(u->ipv4_deny_map_fd);
        safe_close(u->ipv6_deny_map_fd);

        bpf_program_unref(u->ip_bpf_ingress);
        bpf_program_unref(u->ip_bpf_egress);

        free(u);
}

UnitActiveState unit_active_state(Unit *u) {
        assert(u);

        if (u->load_state == UNIT_MERGED)
                return unit_active_state(unit_follow_merge(u));

        /* After a reload it might happen that a unit is not correctly
         * loaded but still has a process around. That's why we won't
         * shortcut failed loading to UNIT_INACTIVE_FAILED. */

        return UNIT_VTABLE(u)->active_state(u);
}

const char* unit_sub_state_to_string(Unit *u) {
        assert(u);

        return UNIT_VTABLE(u)->sub_state_to_string(u);
}

static int set_complete_move(Set **s, Set **other) {
        assert(s);
        assert(other);

        if (!other)
                return 0;

        if (*s)
                return set_move(*s, *other);
        else {
                *s = *other;
                *other = NULL;
        }

        return 0;
}

static int hashmap_complete_move(Hashmap **s, Hashmap **other) {
        assert(s);
        assert(other);

        if (!*other)
                return 0;

        if (*s)
                return hashmap_move(*s, *other);
        else {
                *s = *other;
                *other = NULL;
        }

        return 0;
}

static int merge_names(Unit *u, Unit *other) {
        char *t;
        Iterator i;
        int r;

        assert(u);
        assert(other);

        r = set_complete_move(&u->names, &other->names);
        if (r < 0)
                return r;

        set_free_free(other->names);
        other->names = NULL;
        other->id = NULL;

        SET_FOREACH(t, u->names, i)
                assert_se(hashmap_replace(u->manager->units, t, u) == 0);

        return 0;
}

static int reserve_dependencies(Unit *u, Unit *other, UnitDependency d) {
        unsigned n_reserve;

        assert(u);
        assert(other);
        assert(d < _UNIT_DEPENDENCY_MAX);

        /*
         * If u does not have this dependency set allocated, there is no need
         * to reserve anything. In that case other's set will be transferred
         * as a whole to u by complete_move().
         */
        if (!u->dependencies[d])
                return 0;

        /* merge_dependencies() will skip a u-on-u dependency */
        n_reserve = hashmap_size(other->dependencies[d]) - !!hashmap_get(other->dependencies[d], u);

        return hashmap_reserve(u->dependencies[d], n_reserve);
}

static void merge_dependencies(Unit *u, Unit *other, const char *other_id, UnitDependency d) {
        Iterator i;
        Unit *back;
        void *v;
        int r;

        /* Merges all dependencies of type 'd' of the unit 'other' into the deps of the unit 'u' */

        assert(u);
        assert(other);
        assert(d < _UNIT_DEPENDENCY_MAX);

        /* Fix backwards pointers. Let's iterate through all dependendent units of the other unit. */
        HASHMAP_FOREACH_KEY(v, back, other->dependencies[d], i) {
                UnitDependency k;

                /* Let's now iterate through the dependencies of that dependencies of the other units, looking for
                 * pointers back, and let's fix them up, to instead point to 'u'. */

                for (k = 0; k < _UNIT_DEPENDENCY_MAX; k++) {
                        if (back == u) {
                                /* Do not add dependencies between u and itself. */
                                if (hashmap_remove(back->dependencies[k], other))
                                        maybe_warn_about_dependency(u, other_id, k);
                        } else {
                                UnitDependencyInfo di_u, di_other, di_merged;

                                /* Let's drop this dependency between "back" and "other", and let's create it between
                                 * "back" and "u" instead. Let's merge the bit masks of the dependency we are moving,
                                 * and any such dependency which might already exist */

                                di_other.data = hashmap_get(back->dependencies[k], other);
                                if (!di_other.data)
                                        continue; /* dependency isn't set, let's try the next one */

                                di_u.data = hashmap_get(back->dependencies[k], u);

                                di_merged = (UnitDependencyInfo) {
                                        .origin_mask = di_u.origin_mask | di_other.origin_mask,
                                        .destination_mask = di_u.destination_mask | di_other.destination_mask,
                                };

                                r = hashmap_remove_and_replace(back->dependencies[k], other, u, di_merged.data);
                                if (r < 0)
                                        log_warning_errno(r, "Failed to remove/replace: back=%s other=%s u=%s: %m", back->id, other_id, u->id);
                                assert(r >= 0);

                                /* assert_se(hashmap_remove_and_replace(back->dependencies[k], other, u, di_merged.data) >= 0); */
                        }
                }

        }

        /* Also do not move dependencies on u to itself */
        back = hashmap_remove(other->dependencies[d], u);
        if (back)
                maybe_warn_about_dependency(u, other_id, d);

        /* The move cannot fail. The caller must have performed a reservation. */
        assert_se(hashmap_complete_move(&u->dependencies[d], &other->dependencies[d]) == 0);

        other->dependencies[d] = hashmap_free(other->dependencies[d]);
}

int unit_merge(Unit *u, Unit *other) {
        UnitDependency d;
        const char *other_id = NULL;
        int r;

        assert(u);
        assert(other);
        assert(u->manager == other->manager);
        assert(u->type != _UNIT_TYPE_INVALID);

        other = unit_follow_merge(other);

        if (other == u)
                return 0;

        if (u->type != other->type)
                return -EINVAL;

        if (!u->instance != !other->instance)
                return -EINVAL;

        if (!unit_type_may_alias(u->type)) /* Merging only applies to unit names that support aliases */
                return -EEXIST;

        if (!IN_SET(other->load_state, UNIT_STUB, UNIT_NOT_FOUND))
                return -EEXIST;

        if (other->job)
                return -EEXIST;

        if (other->nop_job)
                return -EEXIST;

        if (!UNIT_IS_INACTIVE_OR_FAILED(unit_active_state(other)))
                return -EEXIST;

        if (other->id)
                other_id = strdupa(other->id);

        /* Make reservations to ensure merge_dependencies() won't fail */
        for (d = 0; d < _UNIT_DEPENDENCY_MAX; d++) {
                r = reserve_dependencies(u, other, d);
                /*
                 * We don't rollback reservations if we fail. We don't have
                 * a way to undo reservations. A reservation is not a leak.
                 */
                if (r < 0)
                        return r;
        }

        /* Merge names */
        r = merge_names(u, other);
        if (r < 0)
                return r;

        /* Redirect all references */
        while (other->refs_by_target)
                unit_ref_set(other->refs_by_target, other->refs_by_target->source, u);

        /* Merge dependencies */
        for (d = 0; d < _UNIT_DEPENDENCY_MAX; d++)
                merge_dependencies(u, other, other_id, d);

        other->load_state = UNIT_MERGED;
        other->merged_into = u;

        /* If there is still some data attached to the other node, we
         * don't need it anymore, and can free it. */
        if (other->load_state != UNIT_STUB)
                if (UNIT_VTABLE(other)->done)
                        UNIT_VTABLE(other)->done(other);

        unit_add_to_dbus_queue(u);
        unit_add_to_cleanup_queue(other);

        return 0;
}

int unit_merge_by_name(Unit *u, const char *name) {
        _cleanup_free_ char *s = NULL;
        Unit *other;
        int r;

        assert(u);
        assert(name);

        if (unit_name_is_valid(name, UNIT_NAME_TEMPLATE)) {
                if (!u->instance)
                        return -EINVAL;

                r = unit_name_replace_instance(name, u->instance, &s);
                if (r < 0)
                        return r;

                name = s;
        }

        other = manager_get_unit(u->manager, name);
        if (other)
                return unit_merge(u, other);

        return unit_add_name(u, name);
}

Unit* unit_follow_merge(Unit *u) {
        assert(u);

        while (u->load_state == UNIT_MERGED)
                assert_se(u = u->merged_into);

        return u;
}

int unit_add_exec_dependencies(Unit *u, ExecContext *c) {
        ExecDirectoryType dt;
        char **dp;
        int r;

        assert(u);
        assert(c);

        if (c->working_directory) {
                r = unit_require_mounts_for(u, c->working_directory, UNIT_DEPENDENCY_FILE);
                if (r < 0)
                        return r;
        }

        if (c->root_directory) {
                r = unit_require_mounts_for(u, c->root_directory, UNIT_DEPENDENCY_FILE);
                if (r < 0)
                        return r;
        }

        if (c->root_image) {
                r = unit_require_mounts_for(u, c->root_image, UNIT_DEPENDENCY_FILE);
                if (r < 0)
                        return r;
        }

        for (dt = 0; dt < _EXEC_DIRECTORY_TYPE_MAX; dt++) {
                if (!u->manager->prefix[dt])
                        continue;

                STRV_FOREACH(dp, c->directories[dt].paths) {
                        _cleanup_free_ char *p;

                        p = strjoin(u->manager->prefix[dt], "/", *dp);
                        if (!p)
                                return -ENOMEM;

                        r = unit_require_mounts_for(u, p, UNIT_DEPENDENCY_FILE);
                        if (r < 0)
                                return r;
                }
        }

        if (!MANAGER_IS_SYSTEM(u->manager))
                return 0;

        if (c->private_tmp) {
                const char *p;

                FOREACH_STRING(p, "/tmp", "/var/tmp") {
                        r = unit_require_mounts_for(u, p, UNIT_DEPENDENCY_FILE);
                        if (r < 0)
                                return r;
                }

                r = unit_add_dependency_by_name(u, UNIT_AFTER, SPECIAL_TMPFILES_SETUP_SERVICE, NULL, true, UNIT_DEPENDENCY_FILE);
                if (r < 0)
                        return r;
        }

        if (!IN_SET(c->std_output,
                    EXEC_OUTPUT_JOURNAL, EXEC_OUTPUT_JOURNAL_AND_CONSOLE,
                    EXEC_OUTPUT_KMSG, EXEC_OUTPUT_KMSG_AND_CONSOLE,
                    EXEC_OUTPUT_SYSLOG, EXEC_OUTPUT_SYSLOG_AND_CONSOLE) &&
            !IN_SET(c->std_error,
                    EXEC_OUTPUT_JOURNAL, EXEC_OUTPUT_JOURNAL_AND_CONSOLE,
                    EXEC_OUTPUT_KMSG, EXEC_OUTPUT_KMSG_AND_CONSOLE,
                    EXEC_OUTPUT_SYSLOG, EXEC_OUTPUT_SYSLOG_AND_CONSOLE))
                return 0;

        /* If syslog or kernel logging is requested, make sure our own
         * logging daemon is run first. */

        r = unit_add_dependency_by_name(u, UNIT_AFTER, SPECIAL_JOURNALD_SOCKET, NULL, true, UNIT_DEPENDENCY_FILE);
        if (r < 0)
                return r;

        return 0;
}

const char *unit_description(Unit *u) {
        assert(u);

        if (u->description)
                return u->description;

        return strna(u->id);
}

static void print_unit_dependency_mask(FILE *f, const char *kind, UnitDependencyMask mask, bool *space) {
        const struct {
                UnitDependencyMask mask;
                const char *name;
        } table[] = {
                { UNIT_DEPENDENCY_FILE,               "file"               },
                { UNIT_DEPENDENCY_IMPLICIT,           "implicit"           },
                { UNIT_DEPENDENCY_DEFAULT,            "default"            },
                { UNIT_DEPENDENCY_UDEV,               "udev"               },
                { UNIT_DEPENDENCY_PATH,               "path"               },
                { UNIT_DEPENDENCY_MOUNTINFO_IMPLICIT, "mountinfo-implicit" },
                { UNIT_DEPENDENCY_MOUNTINFO_DEFAULT,  "mountinfo-default"  },
                { UNIT_DEPENDENCY_PROC_SWAP,          "proc-swap"          },
        };
        size_t i;

        assert(f);
        assert(kind);
        assert(space);

        for (i = 0; i < ELEMENTSOF(table); i++) {

                if (mask == 0)
                        break;

                if ((mask & table[i].mask) == table[i].mask) {
                        if (*space)
                                fputc(' ', f);
                        else
                                *space = true;

                        fputs(kind, f);
                        fputs("-", f);
                        fputs(table[i].name, f);

                        mask &= ~table[i].mask;
                }
        }

        assert(mask == 0);
}

void unit_dump(Unit *u, FILE *f, const char *prefix) {
        char *t, **j;
        UnitDependency d;
        Iterator i;
        const char *prefix2;
        char
                timestamp0[FORMAT_TIMESTAMP_MAX],
                timestamp1[FORMAT_TIMESTAMP_MAX],
                timestamp2[FORMAT_TIMESTAMP_MAX],
                timestamp3[FORMAT_TIMESTAMP_MAX],
                timestamp4[FORMAT_TIMESTAMP_MAX],
                timespan[FORMAT_TIMESPAN_MAX];
        Unit *following;
        _cleanup_set_free_ Set *following_set = NULL;
        const char *n;
        CGroupMask m;
        int r;

        assert(u);
        assert(u->type >= 0);

        prefix = strempty(prefix);
        prefix2 = strjoina(prefix, "\t");

        fprintf(f,
                "%s-> Unit %s:\n"
                "%s\tDescription: %s\n"
                "%s\tInstance: %s\n"
                "%s\tUnit Load State: %s\n"
                "%s\tUnit Active State: %s\n"
                "%s\tState Change Timestamp: %s\n"
                "%s\tInactive Exit Timestamp: %s\n"
                "%s\tActive Enter Timestamp: %s\n"
                "%s\tActive Exit Timestamp: %s\n"
                "%s\tInactive Enter Timestamp: %s\n"
                "%s\tMay GC: %s\n"
                "%s\tNeed Daemon Reload: %s\n"
                "%s\tTransient: %s\n"
                "%s\tPerpetual: %s\n"
                "%s\tGarbage Collection Mode: %s\n"
                "%s\tSlice: %s\n"
                "%s\tCGroup: %s\n"
                "%s\tCGroup realized: %s\n",
                prefix, u->id,
                prefix, unit_description(u),
                prefix, strna(u->instance),
                prefix, unit_load_state_to_string(u->load_state),
                prefix, unit_active_state_to_string(unit_active_state(u)),
                prefix, strna(format_timestamp(timestamp0, sizeof(timestamp0), u->state_change_timestamp.realtime)),
                prefix, strna(format_timestamp(timestamp1, sizeof(timestamp1), u->inactive_exit_timestamp.realtime)),
                prefix, strna(format_timestamp(timestamp2, sizeof(timestamp2), u->active_enter_timestamp.realtime)),
                prefix, strna(format_timestamp(timestamp3, sizeof(timestamp3), u->active_exit_timestamp.realtime)),
                prefix, strna(format_timestamp(timestamp4, sizeof(timestamp4), u->inactive_enter_timestamp.realtime)),
                prefix, yes_no(unit_may_gc(u)),
                prefix, yes_no(unit_need_daemon_reload(u)),
                prefix, yes_no(u->transient),
                prefix, yes_no(u->perpetual),
                prefix, collect_mode_to_string(u->collect_mode),
                prefix, strna(unit_slice_name(u)),
                prefix, strna(u->cgroup_path),
                prefix, yes_no(u->cgroup_realized));

        if (u->cgroup_realized_mask != 0) {
                _cleanup_free_ char *s = NULL;
                (void) cg_mask_to_string(u->cgroup_realized_mask, &s);
                fprintf(f, "%s\tCGroup realized mask: %s\n", prefix, strnull(s));
        }
        if (u->cgroup_enabled_mask != 0) {
                _cleanup_free_ char *s = NULL;
                (void) cg_mask_to_string(u->cgroup_enabled_mask, &s);
                fprintf(f, "%s\tCGroup enabled mask: %s\n", prefix, strnull(s));
        }
        m = unit_get_own_mask(u);
        if (m != 0) {
                _cleanup_free_ char *s = NULL;
                (void) cg_mask_to_string(m, &s);
                fprintf(f, "%s\tCGroup own mask: %s\n", prefix, strnull(s));
        }
        m = unit_get_members_mask(u);
        if (m != 0) {
                _cleanup_free_ char *s = NULL;
                (void) cg_mask_to_string(m, &s);
                fprintf(f, "%s\tCGroup members mask: %s\n", prefix, strnull(s));
        }

        SET_FOREACH(t, u->names, i)
                fprintf(f, "%s\tName: %s\n", prefix, t);

        if (!sd_id128_is_null(u->invocation_id))
                fprintf(f, "%s\tInvocation ID: " SD_ID128_FORMAT_STR "\n",
                        prefix, SD_ID128_FORMAT_VAL(u->invocation_id));

        STRV_FOREACH(j, u->documentation)
                fprintf(f, "%s\tDocumentation: %s\n", prefix, *j);

        following = unit_following(u);
        if (following)
                fprintf(f, "%s\tFollowing: %s\n", prefix, following->id);

        r = unit_following_set(u, &following_set);
        if (r >= 0) {
                Unit *other;

                SET_FOREACH(other, following_set, i)
                        fprintf(f, "%s\tFollowing Set Member: %s\n", prefix, other->id);
        }

        if (u->fragment_path)
                fprintf(f, "%s\tFragment Path: %s\n", prefix, u->fragment_path);

        if (u->source_path)
                fprintf(f, "%s\tSource Path: %s\n", prefix, u->source_path);

        STRV_FOREACH(j, u->dropin_paths)
                fprintf(f, "%s\tDropIn Path: %s\n", prefix, *j);

        if (u->failure_action != EMERGENCY_ACTION_NONE)
                fprintf(f, "%s\tFailure Action: %s\n", prefix, emergency_action_to_string(u->failure_action));
        if (u->success_action != EMERGENCY_ACTION_NONE)
                fprintf(f, "%s\tSuccess Action: %s\n", prefix, emergency_action_to_string(u->success_action));

        if (u->job_timeout != USEC_INFINITY)
                fprintf(f, "%s\tJob Timeout: %s\n", prefix, format_timespan(timespan, sizeof(timespan), u->job_timeout, 0));

        if (u->job_timeout_action != EMERGENCY_ACTION_NONE)
                fprintf(f, "%s\tJob Timeout Action: %s\n", prefix, emergency_action_to_string(u->job_timeout_action));

        if (u->job_timeout_reboot_arg)
                fprintf(f, "%s\tJob Timeout Reboot Argument: %s\n", prefix, u->job_timeout_reboot_arg);

        condition_dump_list(u->conditions, f, prefix, condition_type_to_string);
        condition_dump_list(u->asserts, f, prefix, assert_type_to_string);

        if (dual_timestamp_is_set(&u->condition_timestamp))
                fprintf(f,
                        "%s\tCondition Timestamp: %s\n"
                        "%s\tCondition Result: %s\n",
                        prefix, strna(format_timestamp(timestamp1, sizeof(timestamp1), u->condition_timestamp.realtime)),
                        prefix, yes_no(u->condition_result));

        if (dual_timestamp_is_set(&u->assert_timestamp))
                fprintf(f,
                        "%s\tAssert Timestamp: %s\n"
                        "%s\tAssert Result: %s\n",
                        prefix, strna(format_timestamp(timestamp1, sizeof(timestamp1), u->assert_timestamp.realtime)),
                        prefix, yes_no(u->assert_result));

        for (d = 0; d < _UNIT_DEPENDENCY_MAX; d++) {
                UnitDependencyInfo di;
                Unit *other;

                HASHMAP_FOREACH_KEY(di.data, other, u->dependencies[d], i) {
                        bool space = false;

                        fprintf(f, "%s\t%s: %s (", prefix, unit_dependency_to_string(d), other->id);

                        print_unit_dependency_mask(f, "origin", di.origin_mask, &space);
                        print_unit_dependency_mask(f, "destination", di.destination_mask, &space);

                        fputs(")\n", f);
                }
        }

        if (!hashmap_isempty(u->requires_mounts_for)) {
                UnitDependencyInfo di;
                const char *path;

                HASHMAP_FOREACH_KEY(di.data, path, u->requires_mounts_for, i) {
                        bool space = false;

                        fprintf(f, "%s\tRequiresMountsFor: %s (", prefix, path);

                        print_unit_dependency_mask(f, "origin", di.origin_mask, &space);
                        print_unit_dependency_mask(f, "destination", di.destination_mask, &space);

                        fputs(")\n", f);
                }
        }

        if (u->load_state == UNIT_LOADED) {

                fprintf(f,
                        "%s\tStopWhenUnneeded: %s\n"
                        "%s\tRefuseManualStart: %s\n"
                        "%s\tRefuseManualStop: %s\n"
                        "%s\tDefaultDependencies: %s\n"
                        "%s\tOnFailureJobMode: %s\n"
                        "%s\tIgnoreOnIsolate: %s\n",
                        prefix, yes_no(u->stop_when_unneeded),
                        prefix, yes_no(u->refuse_manual_start),
                        prefix, yes_no(u->refuse_manual_stop),
                        prefix, yes_no(u->default_dependencies),
                        prefix, job_mode_to_string(u->on_failure_job_mode),
                        prefix, yes_no(u->ignore_on_isolate));

                if (UNIT_VTABLE(u)->dump)
                        UNIT_VTABLE(u)->dump(u, f, prefix2);

        } else if (u->load_state == UNIT_MERGED)
                fprintf(f,
                        "%s\tMerged into: %s\n",
                        prefix, u->merged_into->id);
        else if (u->load_state == UNIT_ERROR)
                fprintf(f, "%s\tLoad Error Code: %s\n", prefix, strerror(-u->load_error));

        for (n = sd_bus_track_first(u->bus_track); n; n = sd_bus_track_next(u->bus_track))
                fprintf(f, "%s\tBus Ref: %s\n", prefix, n);

        if (u->job)
                job_dump(u->job, f, prefix2);

        if (u->nop_job)
                job_dump(u->nop_job, f, prefix2);
}

/* Common implementation for multiple backends */
int unit_load_fragment_and_dropin(Unit *u) {
        int r;

        assert(u);

        /* Load a .{service,socket,...} file */
        r = unit_load_fragment(u);
        if (r < 0)
                return r;

        if (u->load_state == UNIT_STUB)
                return -ENOENT;

        /* Load drop-in directory data. If u is an alias, we might be reloading the
         * target unit needlessly. But we cannot be sure which drops-ins have already
         * been loaded and which not, at least without doing complicated book-keeping,
         * so let's always reread all drop-ins. */
        return unit_load_dropin(unit_follow_merge(u));
}

/* Common implementation for multiple backends */
int unit_load_fragment_and_dropin_optional(Unit *u) {
        int r;

        assert(u);

        /* Same as unit_load_fragment_and_dropin(), but whether
         * something can be loaded or not doesn't matter. */

        /* Load a .service file */
        r = unit_load_fragment(u);
        if (r < 0)
                return r;

        if (u->load_state == UNIT_STUB)
                u->load_state = UNIT_LOADED;

        /* Load drop-in directory data */
        return unit_load_dropin(unit_follow_merge(u));
}

int unit_add_default_target_dependency(Unit *u, Unit *target) {
        assert(u);
        assert(target);

        if (target->type != UNIT_TARGET)
                return 0;

        /* Only add the dependency if both units are loaded, so that
         * that loop check below is reliable */
        if (u->load_state != UNIT_LOADED ||
            target->load_state != UNIT_LOADED)
                return 0;

        /* If either side wants no automatic dependencies, then let's
         * skip this */
        if (!u->default_dependencies ||
            !target->default_dependencies)
                return 0;

        /* Don't create loops */
        if (hashmap_get(target->dependencies[UNIT_BEFORE], u))
                return 0;

        return unit_add_dependency(target, UNIT_AFTER, u, true, UNIT_DEPENDENCY_DEFAULT);
}

static int unit_add_target_dependencies(Unit *u) {

        static const UnitDependency deps[] = {
                UNIT_REQUIRED_BY,
                UNIT_REQUISITE_OF,
                UNIT_WANTED_BY,
                UNIT_BOUND_BY
        };

        unsigned k;
        int r = 0;

        assert(u);

        for (k = 0; k < ELEMENTSOF(deps); k++) {
                Unit *target;
                Iterator i;
                void *v;

                HASHMAP_FOREACH_KEY(v, target, u->dependencies[deps[k]], i) {
                        r = unit_add_default_target_dependency(u, target);
                        if (r < 0)
                                return r;
                }
        }

        return r;
}

static int unit_add_slice_dependencies(Unit *u) {
        UnitDependencyMask mask;
        assert(u);

        if (!UNIT_HAS_CGROUP_CONTEXT(u))
                return 0;

        /* Slice units are implicitly ordered against their parent slices (as this relationship is encoded in the
           name), while all other units are ordered based on configuration (as in their case Slice= configures the
           relationship). */
        mask = u->type == UNIT_SLICE ? UNIT_DEPENDENCY_IMPLICIT : UNIT_DEPENDENCY_FILE;

        if (UNIT_ISSET(u->slice))
                return unit_add_two_dependencies(u, UNIT_AFTER, UNIT_REQUIRES, UNIT_DEREF(u->slice), true, mask);

        if (unit_has_name(u, SPECIAL_ROOT_SLICE))
                return 0;

        return unit_add_two_dependencies_by_name(u, UNIT_AFTER, UNIT_REQUIRES, SPECIAL_ROOT_SLICE, NULL, true, mask);
}

static int unit_add_mount_dependencies(Unit *u) {
        UnitDependencyInfo di;
        const char *path;
        Iterator i;
        int r;

        assert(u);

        HASHMAP_FOREACH_KEY(di.data, path, u->requires_mounts_for, i) {
                char prefix[strlen(path) + 1];

                PATH_FOREACH_PREFIX_MORE(prefix, path) {
                        _cleanup_free_ char *p = NULL;
                        Unit *m;

                        r = unit_name_from_path(prefix, ".mount", &p);
                        if (r < 0)
                                return r;

                        m = manager_get_unit(u->manager, p);
                        if (!m) {
                                /* Make sure to load the mount unit if
                                 * it exists. If so the dependencies
                                 * on this unit will be added later
                                 * during the loading of the mount
                                 * unit. */
                                (void) manager_load_unit_prepare(u->manager, p, NULL, NULL, &m);
                                continue;
                        }
                        if (m == u)
                                continue;

                        if (m->load_state != UNIT_LOADED)
                                continue;

                        r = unit_add_dependency(u, UNIT_AFTER, m, true, di.origin_mask);
                        if (r < 0)
                                return r;

                        if (m->fragment_path) {
                                r = unit_add_dependency(u, UNIT_REQUIRES, m, true, di.origin_mask);
                                if (r < 0)
                                        return r;
                        }
                }
        }

        return 0;
}

static int unit_add_startup_units(Unit *u) {
        CGroupContext *c;
        int r;

        c = unit_get_cgroup_context(u);
        if (!c)
                return 0;

        if (c->startup_cpu_shares == CGROUP_CPU_SHARES_INVALID &&
            c->startup_io_weight == CGROUP_WEIGHT_INVALID &&
            c->startup_blockio_weight == CGROUP_BLKIO_WEIGHT_INVALID)
                return 0;

        r = set_ensure_allocated(&u->manager->startup_units, NULL);
        if (r < 0)
                return r;

        return set_put(u->manager->startup_units, u);
}

int unit_load(Unit *u) {
        int r;

        assert(u);

        if (u->in_load_queue) {
                LIST_REMOVE(load_queue, u->manager->load_queue, u);
                u->in_load_queue = false;
        }

        if (u->type == _UNIT_TYPE_INVALID)
                return -EINVAL;

        if (u->load_state != UNIT_STUB)
                return 0;

        if (u->transient_file) {
                r = fflush_and_check(u->transient_file);
                if (r < 0)
                        goto fail;

                u->transient_file = safe_fclose(u->transient_file);
                u->fragment_mtime = now(CLOCK_REALTIME);
        }

        if (UNIT_VTABLE(u)->load) {
                r = UNIT_VTABLE(u)->load(u);
                if (r < 0)
                        goto fail;
        }

        if (u->load_state == UNIT_STUB) {
                r = -ENOENT;
                goto fail;
        }

        if (u->load_state == UNIT_LOADED) {

                r = unit_add_target_dependencies(u);
                if (r < 0)
                        goto fail;

                r = unit_add_slice_dependencies(u);
                if (r < 0)
                        goto fail;

                r = unit_add_mount_dependencies(u);
                if (r < 0)
                        goto fail;

                r = unit_add_startup_units(u);
                if (r < 0)
                        goto fail;

                if (u->on_failure_job_mode == JOB_ISOLATE && hashmap_size(u->dependencies[UNIT_ON_FAILURE]) > 1) {
                        log_unit_error(u, "More than one OnFailure= dependencies specified but OnFailureJobMode=isolate set. Refusing.");
                        r = -EINVAL;
                        goto fail;
                }

                if (u->job_running_timeout != USEC_INFINITY && u->job_running_timeout > u->job_timeout)
                        log_unit_warning(u, "JobRunningTimeoutSec= is greater than JobTimeoutSec=, it has no effect.");

                unit_update_cgroup_members_masks(u);
        }

        assert((u->load_state != UNIT_MERGED) == !u->merged_into);

        unit_add_to_dbus_queue(unit_follow_merge(u));
        unit_add_to_gc_queue(u);

        return 0;

fail:
        u->load_state = u->load_state == UNIT_STUB ? UNIT_NOT_FOUND : UNIT_ERROR;
        u->load_error = r;
        unit_add_to_dbus_queue(u);
        unit_add_to_gc_queue(u);

        log_unit_debug_errno(u, r, "Failed to load configuration: %m");

        return r;
}

static bool unit_condition_test_list(Unit *u, Condition *first, const char *(*to_string)(ConditionType t)) {
        Condition *c;
        int triggered = -1;

        assert(u);
        assert(to_string);

        /* If the condition list is empty, then it is true */
        if (!first)
                return true;

        /* Otherwise, if all of the non-trigger conditions apply and
         * if any of the trigger conditions apply (unless there are
         * none) we return true */
        LIST_FOREACH(conditions, c, first) {
                int r;

                r = condition_test(c);
                if (r < 0)
                        log_unit_warning(u,
                                         "Couldn't determine result for %s=%s%s%s, assuming failed: %m",
                                         to_string(c->type),
                                         c->trigger ? "|" : "",
                                         c->negate ? "!" : "",
                                         c->parameter);
                else
                        log_unit_debug(u,
                                       "%s=%s%s%s %s.",
                                       to_string(c->type),
                                       c->trigger ? "|" : "",
                                       c->negate ? "!" : "",
                                       c->parameter,
                                       condition_result_to_string(c->result));

                if (!c->trigger && r <= 0)
                        return false;

                if (c->trigger && triggered <= 0)
                        triggered = r > 0;
        }

        return triggered != 0;
}

static bool unit_condition_test(Unit *u) {
        assert(u);

        dual_timestamp_get(&u->condition_timestamp);
        u->condition_result = unit_condition_test_list(u, u->conditions, condition_type_to_string);

        return u->condition_result;
}

static bool unit_assert_test(Unit *u) {
        assert(u);

        dual_timestamp_get(&u->assert_timestamp);
        u->assert_result = unit_condition_test_list(u, u->asserts, assert_type_to_string);

        return u->assert_result;
}

void unit_status_printf(Unit *u, const char *status, const char *unit_status_msg_format) {
        DISABLE_WARNING_FORMAT_NONLITERAL;
        manager_status_printf(u->manager, STATUS_TYPE_NORMAL, status, unit_status_msg_format, unit_description(u));
        REENABLE_WARNING;
}

_pure_ static const char* unit_get_status_message_format(Unit *u, JobType t) {
        const char *format;
        const UnitStatusMessageFormats *format_table;

        assert(u);
        assert(IN_SET(t, JOB_START, JOB_STOP, JOB_RELOAD));

        if (t != JOB_RELOAD) {
                format_table = &UNIT_VTABLE(u)->status_message_formats;
                if (format_table) {
                        format = format_table->starting_stopping[t == JOB_STOP];
                        if (format)
                                return format;
                }
        }

        /* Return generic strings */
        if (t == JOB_START)
                return "Starting %s.";
        else if (t == JOB_STOP)
                return "Stopping %s.";
        else
                return "Reloading %s.";
}

static void unit_status_print_starting_stopping(Unit *u, JobType t) {
        const char *format;

        assert(u);

        /* Reload status messages have traditionally not been printed to console. */
        if (!IN_SET(t, JOB_START, JOB_STOP))
                return;

        format = unit_get_status_message_format(u, t);

        DISABLE_WARNING_FORMAT_NONLITERAL;
        unit_status_printf(u, "", format);
        REENABLE_WARNING;
}

static void unit_status_log_starting_stopping_reloading(Unit *u, JobType t) {
        const char *format, *mid;
        char buf[LINE_MAX];

        assert(u);

        if (!IN_SET(t, JOB_START, JOB_STOP, JOB_RELOAD))
                return;

        if (log_on_console())
                return;

        /* We log status messages for all units and all operations. */

        format = unit_get_status_message_format(u, t);

        DISABLE_WARNING_FORMAT_NONLITERAL;
        xsprintf(buf, format, unit_description(u));
        REENABLE_WARNING;

        mid = t == JOB_START ? "MESSAGE_ID=" SD_MESSAGE_UNIT_STARTING_STR :
              t == JOB_STOP  ? "MESSAGE_ID=" SD_MESSAGE_UNIT_STOPPING_STR :
                               "MESSAGE_ID=" SD_MESSAGE_UNIT_RELOADING_STR;

        /* Note that we deliberately use LOG_MESSAGE() instead of
         * LOG_UNIT_MESSAGE() here, since this is supposed to mimic
         * closely what is written to screen using the status output,
         * which is supposed the highest level, friendliest output
         * possible, which means we should avoid the low-level unit
         * name. */
        log_struct(LOG_INFO,
                   LOG_MESSAGE("%s", buf),
                   LOG_UNIT_ID(u),
                   LOG_UNIT_INVOCATION_ID(u),
                   mid,
                   NULL);
}

void unit_status_emit_starting_stopping_reloading(Unit *u, JobType t) {
        assert(u);
        assert(t >= 0);
        assert(t < _JOB_TYPE_MAX);

        unit_status_log_starting_stopping_reloading(u, t);
        unit_status_print_starting_stopping(u, t);
}

int unit_start_limit_test(Unit *u) {
        assert(u);

        if (ratelimit_test(&u->start_limit)) {
                u->start_limit_hit = false;
                return 0;
        }

        log_unit_warning(u, "Start request repeated too quickly.");
        u->start_limit_hit = true;

        return emergency_action(u->manager, u->start_limit_action, u->reboot_arg, "unit failed");
}

bool unit_shall_confirm_spawn(Unit *u) {
        assert(u);

        if (manager_is_confirm_spawn_disabled(u->manager))
                return false;

        /* For some reasons units remaining in the same process group
         * as PID 1 fail to acquire the console even if it's not used
         * by any process. So skip the confirmation question for them. */
        return !unit_get_exec_context(u)->same_pgrp;
}

static bool unit_verify_deps(Unit *u) {
        Unit *other;
        Iterator j;
        void *v;

        assert(u);

        /* Checks whether all BindsTo= dependencies of this unit are fulfilled — if they are also combined with
         * After=. We do not check Requires= or Requisite= here as they only should have an effect on the job
         * processing, but do not have any effect afterwards. We don't check BindsTo= dependencies that are not used in
         * conjunction with After= as for them any such check would make things entirely racy. */

        HASHMAP_FOREACH_KEY(v, other, u->dependencies[UNIT_BINDS_TO], j) {

                if (!hashmap_contains(u->dependencies[UNIT_AFTER], other))
                        continue;

                if (!UNIT_IS_ACTIVE_OR_RELOADING(unit_active_state(other))) {
                        log_unit_notice(u, "Bound to unit %s, but unit isn't active.", other->id);
                        return false;
                }
        }

        return true;
}

/* Errors:
 *         -EBADR:      This unit type does not support starting.
 *         -EALREADY:   Unit is already started.
 *         -EAGAIN:     An operation is already in progress. Retry later.
 *         -ECANCELED:  Too many requests for now.
 *         -EPROTO:     Assert failed
 *         -EINVAL:     Unit not loaded
 *         -EOPNOTSUPP: Unit type not supported
 *         -ENOLINK:    The necessary dependencies are not fulfilled.
 */
int unit_start(Unit *u) {
        UnitActiveState state;
        Unit *following;

        assert(u);

        /* If this is already started, then this will succeed. Note
         * that this will even succeed if this unit is not startable
         * by the user. This is relied on to detect when we need to
         * wait for units and when waiting is finished. */
        state = unit_active_state(u);
        if (UNIT_IS_ACTIVE_OR_RELOADING(state))
                return -EALREADY;

        /* Units that aren't loaded cannot be started */
        if (u->load_state != UNIT_LOADED)
                return -EINVAL;

        /* If the conditions failed, don't do anything at all. If we
         * already are activating this call might still be useful to
         * speed up activation in case there is some hold-off time,
         * but we don't want to recheck the condition in that case. */
        if (state != UNIT_ACTIVATING &&
            !unit_condition_test(u)) {
                log_unit_debug(u, "Starting requested but condition failed. Not starting unit.");
                return -EALREADY;
        }

        /* If the asserts failed, fail the entire job */
        if (state != UNIT_ACTIVATING &&
            !unit_assert_test(u)) {
                log_unit_notice(u, "Starting requested but asserts failed.");
                return -EPROTO;
        }

        /* Units of types that aren't supported cannot be
         * started. Note that we do this test only after the condition
         * checks, so that we rather return condition check errors
         * (which are usually not considered a true failure) than "not
         * supported" errors (which are considered a failure).
         */
        if (!unit_supported(u))
                return -EOPNOTSUPP;

        /* Let's make sure that the deps really are in order before we start this. Normally the job engine should have
         * taken care of this already, but let's check this here again. After all, our dependencies might not be in
         * effect anymore, due to a reload or due to a failed condition. */
        if (!unit_verify_deps(u))
                return -ENOLINK;

        /* Forward to the main object, if we aren't it. */
        following = unit_following(u);
        if (following) {
                log_unit_debug(u, "Redirecting start request from %s to %s.", u->id, following->id);
                return unit_start(following);
        }

        /* If it is stopped, but we cannot start it, then fail */
        if (!UNIT_VTABLE(u)->start)
                return -EBADR;

        /* We don't suppress calls to ->start() here when we are
         * already starting, to allow this request to be used as a
         * "hurry up" call, for example when the unit is in some "auto
         * restart" state where it waits for a holdoff timer to elapse
         * before it will start again. */

        unit_add_to_dbus_queue(u);

        return UNIT_VTABLE(u)->start(u);
}

bool unit_can_start(Unit *u) {
        assert(u);

        if (u->load_state != UNIT_LOADED)
                return false;

        if (!unit_supported(u))
                return false;

        return !!UNIT_VTABLE(u)->start;
}

bool unit_can_isolate(Unit *u) {
        assert(u);

        return unit_can_start(u) &&
                u->allow_isolate;
}

/* Errors:
 *         -EBADR:    This unit type does not support stopping.
 *         -EALREADY: Unit is already stopped.
 *         -EAGAIN:   An operation is already in progress. Retry later.
 */
int unit_stop(Unit *u) {
        UnitActiveState state;
        Unit *following;

        assert(u);

        state = unit_active_state(u);
        if (UNIT_IS_INACTIVE_OR_FAILED(state))
                return -EALREADY;

        following = unit_following(u);
        if (following) {
                log_unit_debug(u, "Redirecting stop request from %s to %s.", u->id, following->id);
                return unit_stop(following);
        }

        if (!UNIT_VTABLE(u)->stop)
                return -EBADR;

        unit_add_to_dbus_queue(u);

        return UNIT_VTABLE(u)->stop(u);
}

bool unit_can_stop(Unit *u) {
        assert(u);

        if (!unit_supported(u))
                return false;

        if (u->perpetual)
                return false;

        return !!UNIT_VTABLE(u)->stop;
}

/* Errors:
 *         -EBADR:    This unit type does not support reloading.
 *         -ENOEXEC:  Unit is not started.
 *         -EAGAIN:   An operation is already in progress. Retry later.
 */
int unit_reload(Unit *u) {
        UnitActiveState state;
        Unit *following;

        assert(u);

        if (u->load_state != UNIT_LOADED)
                return -EINVAL;

        if (!unit_can_reload(u))
                return -EBADR;

        state = unit_active_state(u);
        if (state == UNIT_RELOADING)
                return -EALREADY;

        if (state != UNIT_ACTIVE) {
                log_unit_warning(u, "Unit cannot be reloaded because it is inactive.");
                return -ENOEXEC;
        }

        following = unit_following(u);
        if (following) {
                log_unit_debug(u, "Redirecting reload request from %s to %s.", u->id, following->id);
                return unit_reload(following);
        }

        unit_add_to_dbus_queue(u);

        if (!UNIT_VTABLE(u)->reload) {
                /* Unit doesn't have a reload function, but we need to propagate the reload anyway */
                unit_notify(u, unit_active_state(u), unit_active_state(u), true);
                return 0;
        }

        return UNIT_VTABLE(u)->reload(u);
}

bool unit_can_reload(Unit *u) {
        assert(u);

        if (UNIT_VTABLE(u)->can_reload)
                return UNIT_VTABLE(u)->can_reload(u);

        if (!hashmap_isempty(u->dependencies[UNIT_PROPAGATES_RELOAD_TO]))
                return true;

        return UNIT_VTABLE(u)->reload;
}

static void unit_check_unneeded(Unit *u) {

        _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;

        static const UnitDependency needed_dependencies[] = {
                UNIT_REQUIRED_BY,
                UNIT_REQUISITE_OF,
                UNIT_WANTED_BY,
                UNIT_BOUND_BY,
        };

        unsigned j;
        int r;

        assert(u);

        /* If this service shall be shut down when unneeded then do
         * so. */

        if (!u->stop_when_unneeded)
                return;

        if (!UNIT_IS_ACTIVE_OR_ACTIVATING(unit_active_state(u)))
                return;

        for (j = 0; j < ELEMENTSOF(needed_dependencies); j++) {
                Unit *other;
                Iterator i;
                void *v;

                HASHMAP_FOREACH_KEY(v, other, u->dependencies[needed_dependencies[j]], i)
                        if (unit_active_or_pending(other) || unit_will_restart(other))
                                return;
        }

        /* If stopping a unit fails continuously we might enter a stop
         * loop here, hence stop acting on the service being
         * unnecessary after a while. */
        if (!ratelimit_test(&u->auto_stop_ratelimit)) {
                log_unit_warning(u, "Unit not needed anymore, but not stopping since we tried this too often recently.");
                return;
        }

        log_unit_info(u, "Unit not needed anymore. Stopping.");

        /* Ok, nobody needs us anymore. Sniff. Then let's commit suicide */
        r = manager_add_job(u->manager, JOB_STOP, u, JOB_FAIL, &error, NULL);
        if (r < 0)
                log_unit_warning_errno(u, r, "Failed to enqueue stop job, ignoring: %s", bus_error_message(&error, r));
}

static void unit_check_binds_to(Unit *u) {
        _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
        bool stop = false;
        Unit *other;
        Iterator i;
        void *v;
        int r;

        assert(u);

        if (u->job)
                return;

        if (unit_active_state(u) != UNIT_ACTIVE)
                return;

        HASHMAP_FOREACH_KEY(v, other, u->dependencies[UNIT_BINDS_TO], i) {
                if (other->job)
                        continue;

                if (!other->coldplugged)
                        /* We might yet create a job for the other unit… */
                        continue;

                if (!UNIT_IS_INACTIVE_OR_FAILED(unit_active_state(other)))
                        continue;

                stop = true;
                break;
        }

        if (!stop)
                return;

        /* If stopping a unit fails continuously we might enter a stop
         * loop here, hence stop acting on the service being
         * unnecessary after a while. */
        if (!ratelimit_test(&u->auto_stop_ratelimit)) {
                log_unit_warning(u, "Unit is bound to inactive unit %s, but not stopping since we tried this too often recently.", other->id);
                return;
        }

        assert(other);
        log_unit_info(u, "Unit is bound to inactive unit %s. Stopping, too.", other->id);

        /* A unit we need to run is gone. Sniff. Let's stop this. */
        r = manager_add_job(u->manager, JOB_STOP, u, JOB_FAIL, &error, NULL);
        if (r < 0)
                log_unit_warning_errno(u, r, "Failed to enqueue stop job, ignoring: %s", bus_error_message(&error, r));
}

static void retroactively_start_dependencies(Unit *u) {
        Iterator i;
        Unit *other;
        void *v;

        assert(u);
        assert(UNIT_IS_ACTIVE_OR_ACTIVATING(unit_active_state(u)));

        HASHMAP_FOREACH_KEY(v, other, u->dependencies[UNIT_REQUIRES], i)
                if (!hashmap_get(u->dependencies[UNIT_AFTER], other) &&
                    !UNIT_IS_ACTIVE_OR_ACTIVATING(unit_active_state(other)))
                        manager_add_job(u->manager, JOB_START, other, JOB_REPLACE, NULL, NULL);

        HASHMAP_FOREACH_KEY(v, other, u->dependencies[UNIT_BINDS_TO], i)
                if (!hashmap_get(u->dependencies[UNIT_AFTER], other) &&
                    !UNIT_IS_ACTIVE_OR_ACTIVATING(unit_active_state(other)))
                        manager_add_job(u->manager, JOB_START, other, JOB_REPLACE, NULL, NULL);

        HASHMAP_FOREACH_KEY(v, other, u->dependencies[UNIT_WANTS], i)
                if (!hashmap_get(u->dependencies[UNIT_AFTER], other) &&
                    !UNIT_IS_ACTIVE_OR_ACTIVATING(unit_active_state(other)))
                        manager_add_job(u->manager, JOB_START, other, JOB_FAIL, NULL, NULL);

        HASHMAP_FOREACH_KEY(v, other, u->dependencies[UNIT_CONFLICTS], i)
                if (!UNIT_IS_INACTIVE_OR_DEACTIVATING(unit_active_state(other)))
                        manager_add_job(u->manager, JOB_STOP, other, JOB_REPLACE, NULL, NULL);

        HASHMAP_FOREACH_KEY(v, other, u->dependencies[UNIT_CONFLICTED_BY], i)
                if (!UNIT_IS_INACTIVE_OR_DEACTIVATING(unit_active_state(other)))
                        manager_add_job(u->manager, JOB_STOP, other, JOB_REPLACE, NULL, NULL);
}

static void retroactively_stop_dependencies(Unit *u) {
        Unit *other;
        Iterator i;
        void *v;

        assert(u);
        assert(UNIT_IS_INACTIVE_OR_DEACTIVATING(unit_active_state(u)));

        /* Pull down units which are bound to us recursively if enabled */
        HASHMAP_FOREACH_KEY(v, other, u->dependencies[UNIT_BOUND_BY], i)
                if (!UNIT_IS_INACTIVE_OR_DEACTIVATING(unit_active_state(other)))
                        manager_add_job(u->manager, JOB_STOP, other, JOB_REPLACE, NULL, NULL);
}

static void check_unneeded_dependencies(Unit *u) {
        Unit *other;
        Iterator i;
        void *v;

        assert(u);
        assert(UNIT_IS_INACTIVE_OR_DEACTIVATING(unit_active_state(u)));

        /* Garbage collect services that might not be needed anymore, if enabled */
        HASHMAP_FOREACH_KEY(v, other, u->dependencies[UNIT_REQUIRES], i)
                if (!UNIT_IS_INACTIVE_OR_DEACTIVATING(unit_active_state(other)))
                        unit_check_unneeded(other);
        HASHMAP_FOREACH_KEY(v, other, u->dependencies[UNIT_WANTS], i)
                if (!UNIT_IS_INACTIVE_OR_DEACTIVATING(unit_active_state(other)))
                        unit_check_unneeded(other);
        HASHMAP_FOREACH_KEY(v, other, u->dependencies[UNIT_REQUISITE], i)
                if (!UNIT_IS_INACTIVE_OR_DEACTIVATING(unit_active_state(other)))
                        unit_check_unneeded(other);
        HASHMAP_FOREACH_KEY(v, other, u->dependencies[UNIT_BINDS_TO], i)
                if (!UNIT_IS_INACTIVE_OR_DEACTIVATING(unit_active_state(other)))
                        unit_check_unneeded(other);
}

void unit_start_on_failure(Unit *u) {
        Unit *other;
        Iterator i;
        void *v;

        assert(u);

        if (hashmap_size(u->dependencies[UNIT_ON_FAILURE]) <= 0)
                return;

        log_unit_info(u, "Triggering OnFailure= dependencies.");

        HASHMAP_FOREACH_KEY(v, other, u->dependencies[UNIT_ON_FAILURE], i) {
                int r;

                r = manager_add_job(u->manager, JOB_START, other, u->on_failure_job_mode, NULL, NULL);
                if (r < 0)
                        log_unit_error_errno(u, r, "Failed to enqueue OnFailure= job: %m");
        }
}

void unit_trigger_notify(Unit *u) {
        Unit *other;
        Iterator i;
        void *v;

        assert(u);

        HASHMAP_FOREACH_KEY(v, other, u->dependencies[UNIT_TRIGGERED_BY], i)
                if (UNIT_VTABLE(other)->trigger_notify)
                        UNIT_VTABLE(other)->trigger_notify(other, u);
}

static int unit_log_resources(Unit *u) {

        struct iovec iovec[1 + _CGROUP_IP_ACCOUNTING_METRIC_MAX + 4];
        size_t n_message_parts = 0, n_iovec = 0;
        char* message_parts[3 + 1], *t;
        nsec_t nsec = NSEC_INFINITY;
        CGroupIPAccountingMetric m;
        size_t i;
        int r;
        const char* const ip_fields[_CGROUP_IP_ACCOUNTING_METRIC_MAX] = {
                [CGROUP_IP_INGRESS_BYTES]   = "IP_METRIC_INGRESS_BYTES",
                [CGROUP_IP_INGRESS_PACKETS] = "IP_METRIC_INGRESS_PACKETS",
                [CGROUP_IP_EGRESS_BYTES]    = "IP_METRIC_EGRESS_BYTES",
                [CGROUP_IP_EGRESS_PACKETS]  = "IP_METRIC_EGRESS_PACKETS",
        };

        assert(u);

        /* Invoked whenever a unit enters failed or dead state. Logs information about consumed resources if resource
         * accounting was enabled for a unit. It does this in two ways: a friendly human readable string with reduced
         * information and the complete data in structured fields. */

        (void) unit_get_cpu_usage(u, &nsec);
        if (nsec != NSEC_INFINITY) {
                char buf[FORMAT_TIMESPAN_MAX] = "";

                /* Format the CPU time for inclusion in the structured log message */
                if (asprintf(&t, "CPU_USAGE_NSEC=%" PRIu64, nsec) < 0) {
                        r = log_oom();
                        goto finish;
                }
                iovec[n_iovec++] = IOVEC_MAKE_STRING(t);

                /* Format the CPU time for inclusion in the human language message string */
                format_timespan(buf, sizeof(buf), nsec / NSEC_PER_USEC, USEC_PER_MSEC);
                t = strjoin(n_message_parts > 0 ? "consumed " : "Consumed ", buf, " CPU time");
                if (!t) {
                        r = log_oom();
                        goto finish;
                }

                message_parts[n_message_parts++] = t;
        }

        for (m = 0; m < _CGROUP_IP_ACCOUNTING_METRIC_MAX; m++) {
                char buf[FORMAT_BYTES_MAX] = "";
                uint64_t value = UINT64_MAX;

                assert(ip_fields[m]);

                (void) unit_get_ip_accounting(u, m, &value);
                if (value == UINT64_MAX)
                        continue;

                /* Format IP accounting data for inclusion in the structured log message */
                if (asprintf(&t, "%s=%" PRIu64, ip_fields[m], value) < 0) {
                        r = log_oom();
                        goto finish;
                }
                iovec[n_iovec++] = IOVEC_MAKE_STRING(t);

                /* Format the IP accounting data for inclusion in the human language message string, but only for the
                 * bytes counters (and not for the packets counters) */
                if (m == CGROUP_IP_INGRESS_BYTES)
                        t = strjoin(n_message_parts > 0 ? "received " : "Received ",
                                    format_bytes(buf, sizeof(buf), value),
                                    " IP traffic");
                else if (m == CGROUP_IP_EGRESS_BYTES)
                        t = strjoin(n_message_parts > 0 ? "sent " : "Sent ",
                                    format_bytes(buf, sizeof(buf), value),
                                    " IP traffic");
                else
                        continue;
                if (!t) {
                        r = log_oom();
                        goto finish;
                }

                message_parts[n_message_parts++] = t;
        }

        /* Is there any accounting data available at all? */
        if (n_iovec == 0) {
                r = 0;
                goto finish;
        }

        if (n_message_parts == 0)
                t = strjoina("MESSAGE=", u->id, ": Completed");
        else {
                _cleanup_free_ char *joined;

                message_parts[n_message_parts] = NULL;

                joined = strv_join(message_parts, ", ");
                if (!joined) {
                        r = log_oom();
                        goto finish;
                }

                t = strjoina("MESSAGE=", u->id, ": ", joined);
        }

        /* The following four fields we allocate on the stack or are static strings, we hence don't want to free them,
         * and hence don't increase n_iovec for them */
        iovec[n_iovec] = IOVEC_MAKE_STRING(t);
        iovec[n_iovec + 1] = IOVEC_MAKE_STRING("MESSAGE_ID=" SD_MESSAGE_UNIT_RESOURCES_STR);

        t = strjoina(u->manager->unit_log_field, u->id);
        iovec[n_iovec + 2] = IOVEC_MAKE_STRING(t);

        t = strjoina(u->manager->invocation_log_field, u->invocation_id_string);
        iovec[n_iovec + 3] = IOVEC_MAKE_STRING(t);

        log_struct_iovec(LOG_INFO, iovec, n_iovec + 4);
        r = 0;

finish:
        for (i = 0; i < n_message_parts; i++)
                free(message_parts[i]);

        for (i = 0; i < n_iovec; i++)
                free(iovec[i].iov_base);

        return r;

}

static void unit_update_on_console(Unit *u) {
        bool b;

        assert(u);

        b = unit_needs_console(u);
        if (u->on_console == b)
                return;

        u->on_console = b;
        if (b)
                manager_ref_console(u->manager);
        else
                manager_unref_console(u->manager);

}

void unit_notify(Unit *u, UnitActiveState os, UnitActiveState ns, bool reload_success) {
        Manager *m;
        bool unexpected;

        assert(u);
        assert(os < _UNIT_ACTIVE_STATE_MAX);
        assert(ns < _UNIT_ACTIVE_STATE_MAX);

        /* Note that this is called for all low-level state changes,
         * even if they might map to the same high-level
         * UnitActiveState! That means that ns == os is an expected
         * behavior here. For example: if a mount point is remounted
         * this function will be called too! */

        m = u->manager;

        /* Update timestamps for state changes */
        if (!MANAGER_IS_RELOADING(m)) {
                dual_timestamp_get(&u->state_change_timestamp);

                if (UNIT_IS_INACTIVE_OR_FAILED(os) && !UNIT_IS_INACTIVE_OR_FAILED(ns))
                        u->inactive_exit_timestamp = u->state_change_timestamp;
                else if (!UNIT_IS_INACTIVE_OR_FAILED(os) && UNIT_IS_INACTIVE_OR_FAILED(ns))
                        u->inactive_enter_timestamp = u->state_change_timestamp;

                if (!UNIT_IS_ACTIVE_OR_RELOADING(os) && UNIT_IS_ACTIVE_OR_RELOADING(ns))
                        u->active_enter_timestamp = u->state_change_timestamp;
                else if (UNIT_IS_ACTIVE_OR_RELOADING(os) && !UNIT_IS_ACTIVE_OR_RELOADING(ns))
                        u->active_exit_timestamp = u->state_change_timestamp;
        }

        /* Keep track of failed units */
        (void) manager_update_failed_units(u->manager, u, ns == UNIT_FAILED);

        /* Make sure the cgroup and state files are always removed when we become inactive */
        if (UNIT_IS_INACTIVE_OR_FAILED(ns)) {
                unit_prune_cgroup(u);
                unit_unlink_state_files(u);
        }

        unit_update_on_console(u);

        if (u->job) {
                unexpected = false;

                if (u->job->state == JOB_WAITING)

                        /* So we reached a different state for this
                         * job. Let's see if we can run it now if it
                         * failed previously due to EAGAIN. */
                        job_add_to_run_queue(u->job);

                /* Let's check whether this state change constitutes a
                 * finished job, or maybe contradicts a running job and
                 * hence needs to invalidate jobs. */

                switch (u->job->type) {

                case JOB_START:
                case JOB_VERIFY_ACTIVE:

                        if (UNIT_IS_ACTIVE_OR_RELOADING(ns))
                                job_finish_and_invalidate(u->job, JOB_DONE, true, false);
                        else if (u->job->state == JOB_RUNNING && ns != UNIT_ACTIVATING) {
                                unexpected = true;

                                if (UNIT_IS_INACTIVE_OR_FAILED(ns))
                                        job_finish_and_invalidate(u->job, ns == UNIT_FAILED ? JOB_FAILED : JOB_DONE, true, false);
                        }

                        break;

                case JOB_RELOAD:
                case JOB_RELOAD_OR_START:
                case JOB_TRY_RELOAD:

                        if (u->job->state == JOB_RUNNING) {
                                if (ns == UNIT_ACTIVE)
                                        job_finish_and_invalidate(u->job, reload_success ? JOB_DONE : JOB_FAILED, true, false);
                                else if (!IN_SET(ns, UNIT_ACTIVATING, UNIT_RELOADING)) {
                                        unexpected = true;

                                        if (UNIT_IS_INACTIVE_OR_FAILED(ns))
                                                job_finish_and_invalidate(u->job, ns == UNIT_FAILED ? JOB_FAILED : JOB_DONE, true, false);
                                }
                        }

                        break;

                case JOB_STOP:
                case JOB_RESTART:
                case JOB_TRY_RESTART:

                        if (UNIT_IS_INACTIVE_OR_FAILED(ns))
                                job_finish_and_invalidate(u->job, JOB_DONE, true, false);
                        else if (u->job->state == JOB_RUNNING && ns != UNIT_DEACTIVATING) {
                                unexpected = true;
                                job_finish_and_invalidate(u->job, JOB_FAILED, true, false);
                        }

                        break;

                default:
                        assert_not_reached("Job type unknown");
                }

        } else
                unexpected = true;

        if (!MANAGER_IS_RELOADING(m)) {

                /* If this state change happened without being
                 * requested by a job, then let's retroactively start
                 * or stop dependencies. We skip that step when
                 * deserializing, since we don't want to create any
                 * additional jobs just because something is already
                 * activated. */

                if (unexpected) {
                        if (UNIT_IS_INACTIVE_OR_FAILED(os) && UNIT_IS_ACTIVE_OR_ACTIVATING(ns))
                                retroactively_start_dependencies(u);
                        else if (UNIT_IS_ACTIVE_OR_ACTIVATING(os) && UNIT_IS_INACTIVE_OR_DEACTIVATING(ns))
                                retroactively_stop_dependencies(u);
                }

                /* stop unneeded units regardless if going down was expected or not */
                if (UNIT_IS_INACTIVE_OR_DEACTIVATING(ns))
                        check_unneeded_dependencies(u);

                if (ns != os && ns == UNIT_FAILED) {
                        log_unit_debug(u, "Unit entered failed state.");
                        unit_start_on_failure(u);
                }
        }

        /* Some names are special */
        if (UNIT_IS_ACTIVE_OR_RELOADING(ns)) {

                if (unit_has_name(u, SPECIAL_DBUS_SERVICE))
                        /* The bus might have just become available,
                         * hence try to connect to it, if we aren't
                         * yet connected. */
                        bus_init(m, true);

                if (u->type == UNIT_SERVICE &&
                    !UNIT_IS_ACTIVE_OR_RELOADING(os) &&
                    !MANAGER_IS_RELOADING(m)) {
                        /* Write audit record if we have just finished starting up */
                        manager_send_unit_audit(m, u, AUDIT_SERVICE_START, true);
                        u->in_audit = true;
                }

                if (!UNIT_IS_ACTIVE_OR_RELOADING(os))
                        manager_send_unit_plymouth(m, u);

        } else {
                /* We don't care about D-Bus going down here, since we'll get an asynchronous notification for it
                 * anyway. */

                if (UNIT_IS_INACTIVE_OR_FAILED(ns) &&
                    !UNIT_IS_INACTIVE_OR_FAILED(os)
                    && !MANAGER_IS_RELOADING(m)) {

                        /* This unit just stopped/failed. */
                        if (u->type == UNIT_SERVICE) {

                                /* Hmm, if there was no start record written
                                 * write it now, so that we always have a nice
                                 * pair */
                                if (!u->in_audit) {
                                        manager_send_unit_audit(m, u, AUDIT_SERVICE_START, ns == UNIT_INACTIVE);

                                        if (ns == UNIT_INACTIVE)
                                                manager_send_unit_audit(m, u, AUDIT_SERVICE_STOP, true);
                                } else
                                        /* Write audit record if we have just finished shutting down */
                                        manager_send_unit_audit(m, u, AUDIT_SERVICE_STOP, ns == UNIT_INACTIVE);

                                u->in_audit = false;
                        }

                        /* Write a log message about consumed resources */
                        unit_log_resources(u);
                }
        }

        manager_recheck_journal(m);
        unit_trigger_notify(u);

        if (!MANAGER_IS_RELOADING(u->manager)) {
                /* Maybe we finished startup and are now ready for
                 * being stopped because unneeded? */
                unit_check_unneeded(u);

                /* Maybe we finished startup, but something we needed
                 * has vanished? Let's die then. (This happens when
                 * something BindsTo= to a Type=oneshot unit, as these
                 * units go directly from starting to inactive,
                 * without ever entering started.) */
                unit_check_binds_to(u);

                if (os != UNIT_FAILED && ns == UNIT_FAILED)
                        (void) emergency_action(u->manager, u->failure_action, u->reboot_arg, "unit failed");
                else if (!UNIT_IS_INACTIVE_OR_FAILED(os) && ns == UNIT_INACTIVE)
                        (void) emergency_action(u->manager, u->success_action, u->reboot_arg, "unit succeeded");
        }

        unit_add_to_dbus_queue(u);
        unit_add_to_gc_queue(u);
}

int unit_watch_pid(Unit *u, pid_t pid) {
        int r;

        assert(u);
        assert(pid_is_valid(pid));

        /* Watch a specific PID */

        r = set_ensure_allocated(&u->pids, NULL);
        if (r < 0)
                return r;

        r = hashmap_ensure_allocated(&u->manager->watch_pids, NULL);
        if (r < 0)
                return r;

        /* First try, let's add the unit keyed by "pid". */
        r = hashmap_put(u->manager->watch_pids, PID_TO_PTR(pid), u);
        if (r == -EEXIST)  {
                Unit **array;
                bool found = false;
                size_t n = 0;

                /* OK, the "pid" key is already assigned to a different unit. Let's see if the "-pid" key (which points
                 * to an array of Units rather than just a Unit), lists us already. */

                array = hashmap_get(u->manager->watch_pids, PID_TO_PTR(-pid));
                if (array)
                        for (; array[n]; n++)
                                if (array[n] == u)
                                        found = true;

                if (found) /* Found it already? if so, do nothing */
                        r = 0;
                else {
                        Unit **new_array;

                        /* Allocate a new array */
                        new_array = new(Unit*, n + 2);
                        if (!new_array)
                                return -ENOMEM;

                        memcpy_safe(new_array, array, sizeof(Unit*) * n);
                        new_array[n] = u;
                        new_array[n+1] = NULL;

                        /* Add or replace the old array */
                        r = hashmap_replace(u->manager->watch_pids, PID_TO_PTR(-pid), new_array);
                        if (r < 0) {
                                free(new_array);
                                return r;
                        }

                        free(array);
                }
        } else if (r < 0)
                return r;

        r = set_put(u->pids, PID_TO_PTR(pid));
        if (r < 0)
                return r;

        return 0;
}

void unit_unwatch_pid(Unit *u, pid_t pid) {
        Unit **array;

        assert(u);
        assert(pid_is_valid(pid));

        /* First let's drop the unit in case it's keyed as "pid". */
        (void) hashmap_remove_value(u->manager->watch_pids, PID_TO_PTR(pid), u);

        /* Then, let's also drop the unit, in case it's in the array keyed by -pid */
        array = hashmap_get(u->manager->watch_pids, PID_TO_PTR(-pid));
        if (array) {
                size_t n, m = 0;

                /* Let's iterate through the array, dropping our own entry */
                for (n = 0; array[n]; n++)
                        if (array[n] != u)
                                array[m++] = array[n];
                array[m] = NULL;

                if (m == 0) {
                        /* The array is now empty, remove the entire entry */
                        assert(hashmap_remove(u->manager->watch_pids, PID_TO_PTR(-pid)) == array);
                        free(array);
                }
        }

        (void) set_remove(u->pids, PID_TO_PTR(pid));
}

void unit_unwatch_all_pids(Unit *u) {
        assert(u);

        while (!set_isempty(u->pids))
                unit_unwatch_pid(u, PTR_TO_PID(set_first(u->pids)));

        u->pids = set_free(u->pids);
}

void unit_tidy_watch_pids(Unit *u, pid_t except1, pid_t except2) {
        Iterator i;
        void *e;

        assert(u);

        /* Cleans dead PIDs from our list */

        SET_FOREACH(e, u->pids, i) {
                pid_t pid = PTR_TO_PID(e);

                if (pid == except1 || pid == except2)
                        continue;

                if (!pid_is_unwaited(pid))
                        unit_unwatch_pid(u, pid);
        }
}

bool unit_job_is_applicable(Unit *u, JobType j) {
        assert(u);
        assert(j >= 0 && j < _JOB_TYPE_MAX);

        switch (j) {

        case JOB_VERIFY_ACTIVE:
        case JOB_START:
        case JOB_NOP:
                /* Note that we don't check unit_can_start() here. That's because .device units and suchlike are not
                 * startable by us but may appear due to external events, and it thus makes sense to permit enqueing
                 * jobs for it. */
                return true;

        case JOB_STOP:
                /* Similar as above. However, perpetual units can never be stopped (neither explicitly nor due to
                 * external events), hence it makes no sense to permit enqueing such a request either. */
                return !u->perpetual;

        case JOB_RESTART:
        case JOB_TRY_RESTART:
                return unit_can_stop(u) && unit_can_start(u);

        case JOB_RELOAD:
        case JOB_TRY_RELOAD:
                return unit_can_reload(u);

        case JOB_RELOAD_OR_START:
                return unit_can_reload(u) && unit_can_start(u);

        default:
                assert_not_reached("Invalid job type");
        }
}

static void maybe_warn_about_dependency(Unit *u, const char *other, UnitDependency dependency) {
        assert(u);

        /* Only warn about some unit types */
        if (!IN_SET(dependency, UNIT_CONFLICTS, UNIT_CONFLICTED_BY, UNIT_BEFORE, UNIT_AFTER, UNIT_ON_FAILURE, UNIT_TRIGGERS, UNIT_TRIGGERED_BY))
                return;

        if (streq_ptr(u->id, other))
                log_unit_warning(u, "Dependency %s=%s dropped", unit_dependency_to_string(dependency), u->id);
        else
                log_unit_warning(u, "Dependency %s=%s dropped, merged into %s", unit_dependency_to_string(dependency), strna(other), u->id);
}

static int unit_add_dependency_hashmap(
                Hashmap **h,
                Unit *other,
                UnitDependencyMask origin_mask,
                UnitDependencyMask destination_mask) {

        UnitDependencyInfo info;
        int r;

        assert(h);
        assert(other);
        assert(origin_mask < _UNIT_DEPENDENCY_MASK_FULL);
        assert(destination_mask < _UNIT_DEPENDENCY_MASK_FULL);
        assert(origin_mask > 0 || destination_mask > 0);

        r = hashmap_ensure_allocated(h, NULL);
        if (r < 0)
                return r;

        assert_cc(sizeof(void*) == sizeof(info));

        info.data = hashmap_get(*h, other);
        if (info.data) {
                /* Entry already exists. Add in our mask. */

                if ((info.origin_mask & origin_mask) == info.origin_mask &&
                    (info.destination_mask & destination_mask) == info.destination_mask)
                        return 0; /* NOP */

                info.origin_mask |= origin_mask;
                info.destination_mask |= destination_mask;

                r = hashmap_update(*h, other, info.data);
        } else {
                info = (UnitDependencyInfo) {
                        .origin_mask = origin_mask,
                        .destination_mask = destination_mask,
                };

                r = hashmap_put(*h, other, info.data);
        }
        if (r < 0)
                return r;

        return 1;
}

int unit_add_dependency(
                Unit *u,
                UnitDependency d,
                Unit *other,
                bool add_reference,
                UnitDependencyMask mask) {

        static const UnitDependency inverse_table[_UNIT_DEPENDENCY_MAX] = {
                [UNIT_REQUIRES] = UNIT_REQUIRED_BY,
                [UNIT_WANTS] = UNIT_WANTED_BY,
                [UNIT_REQUISITE] = UNIT_REQUISITE_OF,
                [UNIT_BINDS_TO] = UNIT_BOUND_BY,
                [UNIT_PART_OF] = UNIT_CONSISTS_OF,
                [UNIT_REQUIRED_BY] = UNIT_REQUIRES,
                [UNIT_REQUISITE_OF] = UNIT_REQUISITE,
                [UNIT_WANTED_BY] = UNIT_WANTS,
                [UNIT_BOUND_BY] = UNIT_BINDS_TO,
                [UNIT_CONSISTS_OF] = UNIT_PART_OF,
                [UNIT_CONFLICTS] = UNIT_CONFLICTED_BY,
                [UNIT_CONFLICTED_BY] = UNIT_CONFLICTS,
                [UNIT_BEFORE] = UNIT_AFTER,
                [UNIT_AFTER] = UNIT_BEFORE,
                [UNIT_ON_FAILURE] = _UNIT_DEPENDENCY_INVALID,
                [UNIT_REFERENCES] = UNIT_REFERENCED_BY,
                [UNIT_REFERENCED_BY] = UNIT_REFERENCES,
                [UNIT_TRIGGERS] = UNIT_TRIGGERED_BY,
                [UNIT_TRIGGERED_BY] = UNIT_TRIGGERS,
                [UNIT_PROPAGATES_RELOAD_TO] = UNIT_RELOAD_PROPAGATED_FROM,
                [UNIT_RELOAD_PROPAGATED_FROM] = UNIT_PROPAGATES_RELOAD_TO,
                [UNIT_JOINS_NAMESPACE_OF] = UNIT_JOINS_NAMESPACE_OF,
        };
        Unit *original_u = u, *original_other = other;
        int r;

        assert(u);
        assert(d >= 0 && d < _UNIT_DEPENDENCY_MAX);
        assert(other);

        u = unit_follow_merge(u);
        other = unit_follow_merge(other);

        /* We won't allow dependencies on ourselves. We will not
         * consider them an error however. */
        if (u == other) {
                maybe_warn_about_dependency(original_u, original_other->id, d);
                return 0;
        }

        if ((d == UNIT_BEFORE && other->type == UNIT_DEVICE) ||
            (d == UNIT_AFTER && u->type == UNIT_DEVICE)) {
                log_unit_warning(u, "Dependency Before=%s ignored (.device units cannot be delayed)", other->id);
                return 0;
        }

        r = unit_add_dependency_hashmap(u->dependencies + d, other, mask, 0);
        if (r < 0)
                return r;

        if (inverse_table[d] != _UNIT_DEPENDENCY_INVALID && inverse_table[d] != d) {
                r = unit_add_dependency_hashmap(other->dependencies + inverse_table[d], u, 0, mask);
                if (r < 0)
                        return r;
        }

        if (add_reference) {
                r = unit_add_dependency_hashmap(u->dependencies + UNIT_REFERENCES, other, mask, 0);
                if (r < 0)
                        return r;

                r = unit_add_dependency_hashmap(other->dependencies + UNIT_REFERENCED_BY, u, 0, mask);
                if (r < 0)
                        return r;
        }

        unit_add_to_dbus_queue(u);
        return 0;
}

int unit_add_two_dependencies(Unit *u, UnitDependency d, UnitDependency e, Unit *other, bool add_reference, UnitDependencyMask mask) {
        int r;

        assert(u);

        r = unit_add_dependency(u, d, other, add_reference, mask);
        if (r < 0)
                return r;

        return unit_add_dependency(u, e, other, add_reference, mask);
}

static int resolve_template(Unit *u, const char *name, const char*path, char **buf, const char **ret) {
        int r;

        assert(u);
        assert(name || path);
        assert(buf);
        assert(ret);

        if (!name)
                name = basename(path);

        if (!unit_name_is_valid(name, UNIT_NAME_TEMPLATE)) {
                *buf = NULL;
                *ret = name;
                return 0;
        }

        if (u->instance)
                r = unit_name_replace_instance(name, u->instance, buf);
        else {
                _cleanup_free_ char *i = NULL;

                r = unit_name_to_prefix(u->id, &i);
                if (r < 0)
                        return r;

                r = unit_name_replace_instance(name, i, buf);
        }
        if (r < 0)
                return r;

        *ret = *buf;
        return 0;
}

int unit_add_dependency_by_name(Unit *u, UnitDependency d, const char *name, const char *path, bool add_reference, UnitDependencyMask mask) {
        _cleanup_free_ char *buf = NULL;
        Unit *other;
        int r;

        assert(u);
        assert(name || path);

        r = resolve_template(u, name, path, &buf, &name);
        if (r < 0)
                return r;

        r = manager_load_unit(u->manager, name, path, NULL, &other);
        if (r < 0)
                return r;

        return unit_add_dependency(u, d, other, add_reference, mask);
}

int unit_add_two_dependencies_by_name(Unit *u, UnitDependency d, UnitDependency e, const char *name, const char *path, bool add_reference, UnitDependencyMask mask) {
        _cleanup_free_ char *buf = NULL;
        Unit *other;
        int r;

        assert(u);
        assert(name || path);

        r = resolve_template(u, name, path, &buf, &name);
        if (r < 0)
                return r;

        r = manager_load_unit(u->manager, name, path, NULL, &other);
        if (r < 0)
                return r;

        return unit_add_two_dependencies(u, d, e, other, add_reference, mask);
}

int set_unit_path(const char *p) {
        /* This is mostly for debug purposes */
        if (setenv("SYSTEMD_UNIT_PATH", p, 1) < 0)
                return -errno;

        return 0;
}

char *unit_dbus_path(Unit *u) {
        assert(u);

        if (!u->id)
                return NULL;

        return unit_dbus_path_from_name(u->id);
}

char *unit_dbus_path_invocation_id(Unit *u) {
        assert(u);

        if (sd_id128_is_null(u->invocation_id))
                return NULL;

        return unit_dbus_path_from_name(u->invocation_id_string);
}

int unit_set_slice(Unit *u, Unit *slice) {
        assert(u);
        assert(slice);

        /* Sets the unit slice if it has not been set before. Is extra
         * careful, to only allow this for units that actually have a
         * cgroup context. Also, we don't allow to set this for slices
         * (since the parent slice is derived from the name). Make
         * sure the unit we set is actually a slice. */

        if (!UNIT_HAS_CGROUP_CONTEXT(u))
                return -EOPNOTSUPP;

        if (u->type == UNIT_SLICE)
                return -EINVAL;

        if (unit_active_state(u) != UNIT_INACTIVE)
                return -EBUSY;

        if (slice->type != UNIT_SLICE)
                return -EINVAL;

        if (unit_has_name(u, SPECIAL_INIT_SCOPE) &&
            !unit_has_name(slice, SPECIAL_ROOT_SLICE))
                return -EPERM;

        if (UNIT_DEREF(u->slice) == slice)
                return 0;

        /* Disallow slice changes if @u is already bound to cgroups */
        if (UNIT_ISSET(u->slice) && u->cgroup_realized)
                return -EBUSY;

        unit_ref_set(&u->slice, u, slice);
        return 1;
}

int unit_set_default_slice(Unit *u) {
        _cleanup_free_ char *b = NULL;
        const char *slice_name;
        Unit *slice;
        int r;

        assert(u);

        if (UNIT_ISSET(u->slice))
                return 0;

        if (u->instance) {
                _cleanup_free_ char *prefix = NULL, *escaped = NULL;

                /* Implicitly place all instantiated units in their
                 * own per-template slice */

                r = unit_name_to_prefix(u->id, &prefix);
                if (r < 0)
                        return r;

                /* The prefix is already escaped, but it might include
                 * "-" which has a special meaning for slice units,
                 * hence escape it here extra. */
                escaped = unit_name_escape(prefix);
                if (!escaped)
                        return -ENOMEM;

                if (MANAGER_IS_SYSTEM(u->manager))
                        b = strjoin("system-", escaped, ".slice");
                else
                        b = strappend(escaped, ".slice");
                if (!b)
                        return -ENOMEM;

                slice_name = b;
        } else
                slice_name =
                        MANAGER_IS_SYSTEM(u->manager) && !unit_has_name(u, SPECIAL_INIT_SCOPE)
                        ? SPECIAL_SYSTEM_SLICE
                        : SPECIAL_ROOT_SLICE;

        r = manager_load_unit(u->manager, slice_name, NULL, NULL, &slice);
        if (r < 0)
                return r;

        return unit_set_slice(u, slice);
}

const char *unit_slice_name(Unit *u) {
        assert(u);

        if (!UNIT_ISSET(u->slice))
                return NULL;

        return UNIT_DEREF(u->slice)->id;
}

int unit_load_related_unit(Unit *u, const char *type, Unit **_found) {
        _cleanup_free_ char *t = NULL;
        int r;

        assert(u);
        assert(type);
        assert(_found);

        r = unit_name_change_suffix(u->id, type, &t);
        if (r < 0)
                return r;
        if (unit_has_name(u, t))
                return -EINVAL;

        r = manager_load_unit(u->manager, t, NULL, NULL, _found);
        assert(r < 0 || *_found != u);
        return r;
}

static int signal_name_owner_changed(sd_bus_message *message, void *userdata, sd_bus_error *error) {
        const char *name, *old_owner, *new_owner;
        Unit *u = userdata;
        int r;

        assert(message);
        assert(u);

        r = sd_bus_message_read(message, "sss", &name, &old_owner, &new_owner);
        if (r < 0) {
                bus_log_parse_error(r);
                return 0;
        }

        old_owner = empty_to_null(old_owner);
        new_owner = empty_to_null(new_owner);

        if (UNIT_VTABLE(u)->bus_name_owner_change)
                UNIT_VTABLE(u)->bus_name_owner_change(u, name, old_owner, new_owner);

        return 0;
}

int unit_install_bus_match(Unit *u, sd_bus *bus, const char *name) {
        const char *match;

        assert(u);
        assert(bus);
        assert(name);

        if (u->match_bus_slot)
                return -EBUSY;

        match = strjoina("type='signal',"
                         "sender='org.freedesktop.DBus',"
                         "path='/org/freedesktop/DBus',"
                         "interface='org.freedesktop.DBus',"
                         "member='NameOwnerChanged',"
                         "arg0='", name, "'");

        return sd_bus_add_match_async(bus, &u->match_bus_slot, match, signal_name_owner_changed, NULL, u);
}

int unit_watch_bus_name(Unit *u, const char *name) {
        int r;

        assert(u);
        assert(name);

        /* Watch a specific name on the bus. We only support one unit
         * watching each name for now. */

        if (u->manager->api_bus) {
                /* If the bus is already available, install the match directly.
                 * Otherwise, just put the name in the list. bus_setup_api() will take care later. */
                r = unit_install_bus_match(u, u->manager->api_bus, name);
                if (r < 0)
                        return log_warning_errno(r, "Failed to subscribe to NameOwnerChanged signal for '%s': %m", name);
        }

        r = hashmap_put(u->manager->watch_bus, name, u);
        if (r < 0) {
                u->match_bus_slot = sd_bus_slot_unref(u->match_bus_slot);
                return log_warning_errno(r, "Failed to put bus name to hashmap: %m");
        }

        return 0;
}

void unit_unwatch_bus_name(Unit *u, const char *name) {
        assert(u);
        assert(name);

        (void) hashmap_remove_value(u->manager->watch_bus, name, u);
        u->match_bus_slot = sd_bus_slot_unref(u->match_bus_slot);
}

bool unit_can_serialize(Unit *u) {
        assert(u);

        return UNIT_VTABLE(u)->serialize && UNIT_VTABLE(u)->deserialize_item;
}

static int unit_serialize_cgroup_mask(FILE *f, const char *key, CGroupMask mask) {
        _cleanup_free_ char *s = NULL;
        int r = 0;

        assert(f);
        assert(key);

        if (mask != 0) {
                r = cg_mask_to_string(mask, &s);
                if (r >= 0) {
                        fputs(key, f);
                        fputc('=', f);
                        fputs(s, f);
                        fputc('\n', f);
                }
        }
        return r;
}

static const char *ip_accounting_metric_field[_CGROUP_IP_ACCOUNTING_METRIC_MAX] = {
        [CGROUP_IP_INGRESS_BYTES] = "ip-accounting-ingress-bytes",
        [CGROUP_IP_INGRESS_PACKETS] = "ip-accounting-ingress-packets",
        [CGROUP_IP_EGRESS_BYTES] = "ip-accounting-egress-bytes",
        [CGROUP_IP_EGRESS_PACKETS] = "ip-accounting-egress-packets",
};

int unit_serialize(Unit *u, FILE *f, FDSet *fds, bool serialize_jobs) {
        CGroupIPAccountingMetric m;
        int r;

        assert(u);
        assert(f);
        assert(fds);

        if (unit_can_serialize(u)) {
                r = UNIT_VTABLE(u)->serialize(u, f, fds);
                if (r < 0)
                        return r;
        }

        dual_timestamp_serialize(f, "state-change-timestamp", &u->state_change_timestamp);

        dual_timestamp_serialize(f, "inactive-exit-timestamp", &u->inactive_exit_timestamp);
        dual_timestamp_serialize(f, "active-enter-timestamp", &u->active_enter_timestamp);
        dual_timestamp_serialize(f, "active-exit-timestamp", &u->active_exit_timestamp);
        dual_timestamp_serialize(f, "inactive-enter-timestamp", &u->inactive_enter_timestamp);

        dual_timestamp_serialize(f, "condition-timestamp", &u->condition_timestamp);
        dual_timestamp_serialize(f, "assert-timestamp", &u->assert_timestamp);

        if (dual_timestamp_is_set(&u->condition_timestamp))
                unit_serialize_item(u, f, "condition-result", yes_no(u->condition_result));

        if (dual_timestamp_is_set(&u->assert_timestamp))
                unit_serialize_item(u, f, "assert-result", yes_no(u->assert_result));

        unit_serialize_item(u, f, "transient", yes_no(u->transient));

        unit_serialize_item(u, f, "exported-invocation-id", yes_no(u->exported_invocation_id));
        unit_serialize_item(u, f, "exported-log-level-max", yes_no(u->exported_log_level_max));
        unit_serialize_item(u, f, "exported-log-extra-fields", yes_no(u->exported_log_extra_fields));

        unit_serialize_item_format(u, f, "cpu-usage-base", "%" PRIu64, u->cpu_usage_base);
        if (u->cpu_usage_last != NSEC_INFINITY)
                unit_serialize_item_format(u, f, "cpu-usage-last", "%" PRIu64, u->cpu_usage_last);

        if (u->cgroup_path)
                unit_serialize_item(u, f, "cgroup", u->cgroup_path);
        unit_serialize_item(u, f, "cgroup-realized", yes_no(u->cgroup_realized));
        (void) unit_serialize_cgroup_mask(f, "cgroup-realized-mask", u->cgroup_realized_mask);
        (void) unit_serialize_cgroup_mask(f, "cgroup-enabled-mask", u->cgroup_enabled_mask);
        unit_serialize_item_format(u, f, "cgroup-bpf-realized", "%i", u->cgroup_bpf_state);

        if (uid_is_valid(u->ref_uid))
                unit_serialize_item_format(u, f, "ref-uid", UID_FMT, u->ref_uid);
        if (gid_is_valid(u->ref_gid))
                unit_serialize_item_format(u, f, "ref-gid", GID_FMT, u->ref_gid);

        if (!sd_id128_is_null(u->invocation_id))
                unit_serialize_item_format(u, f, "invocation-id", SD_ID128_FORMAT_STR, SD_ID128_FORMAT_VAL(u->invocation_id));

        bus_track_serialize(u->bus_track, f, "ref");

        for (m = 0; m < _CGROUP_IP_ACCOUNTING_METRIC_MAX; m++) {
                uint64_t v;

                r = unit_get_ip_accounting(u, m, &v);
                if (r >= 0)
                        unit_serialize_item_format(u, f, ip_accounting_metric_field[m], "%" PRIu64, v);
        }

        if (serialize_jobs) {
                if (u->job) {
                        fprintf(f, "job\n");
                        job_serialize(u->job, f);
                }

                if (u->nop_job) {
                        fprintf(f, "job\n");
                        job_serialize(u->nop_job, f);
                }
        }

        /* End marker */
        fputc('\n', f);
        return 0;
}

int unit_serialize_item(Unit *u, FILE *f, const char *key, const char *value) {
        assert(u);
        assert(f);
        assert(key);

        if (!value)
                return 0;

        fputs(key, f);
        fputc('=', f);
        fputs(value, f);
        fputc('\n', f);

        return 1;
}

int unit_serialize_item_escaped(Unit *u, FILE *f, const char *key, const char *value) {
        _cleanup_free_ char *c = NULL;

        assert(u);
        assert(f);
        assert(key);

        if (!value)
                return 0;

        c = cescape(value);
        if (!c)
                return -ENOMEM;

        fputs(key, f);
        fputc('=', f);
        fputs(c, f);
        fputc('\n', f);

        return 1;
}

int unit_serialize_item_fd(Unit *u, FILE *f, FDSet *fds, const char *key, int fd) {
        int copy;

        assert(u);
        assert(f);
        assert(key);

        if (fd < 0)
                return 0;

        copy = fdset_put_dup(fds, fd);
        if (copy < 0)
                return copy;

        fprintf(f, "%s=%i\n", key, copy);
        return 1;
}

void unit_serialize_item_format(Unit *u, FILE *f, const char *key, const char *format, ...) {
        va_list ap;

        assert(u);
        assert(f);
        assert(key);
        assert(format);

        fputs(key, f);
        fputc('=', f);

        va_start(ap, format);
        vfprintf(f, format, ap);
        va_end(ap);

        fputc('\n', f);
}

int unit_deserialize(Unit *u, FILE *f, FDSet *fds) {
        int r;

        assert(u);
        assert(f);
        assert(fds);

        for (;;) {
                char line[LINE_MAX], *l, *v;
                CGroupIPAccountingMetric m;
                size_t k;

                if (!fgets(line, sizeof(line), f)) {
                        if (feof(f))
                                return 0;
                        return -errno;
                }

                char_array_0(line);
                l = strstrip(line);

                /* End marker */
                if (isempty(l))
                        break;

                k = strcspn(l, "=");

                if (l[k] == '=') {
                        l[k] = 0;
                        v = l+k+1;
                } else
                        v = l+k;

                if (streq(l, "job")) {
                        if (v[0] == '\0') {
                                /* new-style serialized job */
                                Job *j;

                                j = job_new_raw(u);
                                if (!j)
                                        return log_oom();

                                r = job_deserialize(j, f);
                                if (r < 0) {
                                        job_free(j);
                                        return r;
                                }

                                r = hashmap_put(u->manager->jobs, UINT32_TO_PTR(j->id), j);
                                if (r < 0) {
                                        job_free(j);
                                        return r;
                                }

                                r = job_install_deserialized(j);
                                if (r < 0) {
                                        hashmap_remove(u->manager->jobs, UINT32_TO_PTR(j->id));
                                        job_free(j);
                                        return r;
                                }
                        } else  /* legacy for pre-44 */
                                log_unit_warning(u, "Update from too old systemd versions are unsupported, cannot deserialize job: %s", v);
                        continue;
                } else if (streq(l, "state-change-timestamp")) {
                        dual_timestamp_deserialize(v, &u->state_change_timestamp);
                        continue;
                } else if (streq(l, "inactive-exit-timestamp")) {
                        dual_timestamp_deserialize(v, &u->inactive_exit_timestamp);
                        continue;
                } else if (streq(l, "active-enter-timestamp")) {
                        dual_timestamp_deserialize(v, &u->active_enter_timestamp);
                        continue;
                } else if (streq(l, "active-exit-timestamp")) {
                        dual_timestamp_deserialize(v, &u->active_exit_timestamp);
                        continue;
                } else if (streq(l, "inactive-enter-timestamp")) {
                        dual_timestamp_deserialize(v, &u->inactive_enter_timestamp);
                        continue;
                } else if (streq(l, "condition-timestamp")) {
                        dual_timestamp_deserialize(v, &u->condition_timestamp);
                        continue;
                } else if (streq(l, "assert-timestamp")) {
                        dual_timestamp_deserialize(v, &u->assert_timestamp);
                        continue;
                } else if (streq(l, "condition-result")) {

                        r = parse_boolean(v);
                        if (r < 0)
                                log_unit_debug(u, "Failed to parse condition result value %s, ignoring.", v);
                        else
                                u->condition_result = r;

                        continue;

                } else if (streq(l, "assert-result")) {

                        r = parse_boolean(v);
                        if (r < 0)
                                log_unit_debug(u, "Failed to parse assert result value %s, ignoring.", v);
                        else
                                u->assert_result = r;

                        continue;

                } else if (streq(l, "transient")) {

                        r = parse_boolean(v);
                        if (r < 0)
                                log_unit_debug(u, "Failed to parse transient bool %s, ignoring.", v);
                        else
                                u->transient = r;

                        continue;

                } else if (streq(l, "exported-invocation-id")) {

                        r = parse_boolean(v);
                        if (r < 0)
                                log_unit_debug(u, "Failed to parse exported invocation ID bool %s, ignoring.", v);
                        else
                                u->exported_invocation_id = r;

                        continue;

                } else if (streq(l, "exported-log-level-max")) {

                        r = parse_boolean(v);
                        if (r < 0)
                                log_unit_debug(u, "Failed to parse exported log level max bool %s, ignoring.", v);
                        else
                                u->exported_log_level_max = r;

                        continue;

                } else if (streq(l, "exported-log-extra-fields")) {

                        r = parse_boolean(v);
                        if (r < 0)
                                log_unit_debug(u, "Failed to parse exported log extra fields bool %s, ignoring.", v);
                        else
                                u->exported_log_extra_fields = r;

                        continue;

                } else if (STR_IN_SET(l, "cpu-usage-base", "cpuacct-usage-base")) {

                        r = safe_atou64(v, &u->cpu_usage_base);
                        if (r < 0)
                                log_unit_debug(u, "Failed to parse CPU usage base %s, ignoring.", v);

                        continue;

                } else if (streq(l, "cpu-usage-last")) {

                        r = safe_atou64(v, &u->cpu_usage_last);
                        if (r < 0)
                                log_unit_debug(u, "Failed to read CPU usage last %s, ignoring.", v);

                        continue;

                } else if (streq(l, "cgroup")) {

                        r = unit_set_cgroup_path(u, v);
                        if (r < 0)
                                log_unit_debug_errno(u, r, "Failed to set cgroup path %s, ignoring: %m", v);

                        (void) unit_watch_cgroup(u);

                        continue;
                } else if (streq(l, "cgroup-realized")) {
                        int b;

                        b = parse_boolean(v);
                        if (b < 0)
                                log_unit_debug(u, "Failed to parse cgroup-realized bool %s, ignoring.", v);
                        else
                                u->cgroup_realized = b;

                        continue;

                } else if (streq(l, "cgroup-realized-mask")) {

                        r = cg_mask_from_string(v, &u->cgroup_realized_mask);
                        if (r < 0)
                                log_unit_debug(u, "Failed to parse cgroup-realized-mask %s, ignoring.", v);
                        continue;

                } else if (streq(l, "cgroup-enabled-mask")) {

                        r = cg_mask_from_string(v, &u->cgroup_enabled_mask);
                        if (r < 0)
                                log_unit_debug(u, "Failed to parse cgroup-enabled-mask %s, ignoring.", v);
                        continue;

                } else if (streq(l, "cgroup-bpf-realized")) {
                        int i;

                        r = safe_atoi(v, &i);
                        if (r < 0)
                                log_unit_debug(u, "Failed to parse cgroup BPF state %s, ignoring.", v);
                        else
                                u->cgroup_bpf_state =
                                        i < 0 ? UNIT_CGROUP_BPF_INVALIDATED :
                                        i > 0 ? UNIT_CGROUP_BPF_ON :
                                        UNIT_CGROUP_BPF_OFF;

                        continue;

                } else if (streq(l, "ref-uid")) {
                        uid_t uid;

                        r = parse_uid(v, &uid);
                        if (r < 0)
                                log_unit_debug(u, "Failed to parse referenced UID %s, ignoring.", v);
                        else
                                unit_ref_uid_gid(u, uid, GID_INVALID);

                        continue;

                } else if (streq(l, "ref-gid")) {
                        gid_t gid;

                        r = parse_gid(v, &gid);
                        if (r < 0)
                                log_unit_debug(u, "Failed to parse referenced GID %s, ignoring.", v);
                        else
                                unit_ref_uid_gid(u, UID_INVALID, gid);

                } else if (streq(l, "ref")) {

                        r = strv_extend(&u->deserialized_refs, v);
                        if (r < 0)
                                log_oom();

                        continue;
                } else if (streq(l, "invocation-id")) {
                        sd_id128_t id;

                        r = sd_id128_from_string(v, &id);
                        if (r < 0)
                                log_unit_debug(u, "Failed to parse invocation id %s, ignoring.", v);
                        else {
                                r = unit_set_invocation_id(u, id);
                                if (r < 0)
                                        log_unit_warning_errno(u, r, "Failed to set invocation ID for unit: %m");
                        }

                        continue;
                }

                /* Check if this is an IP accounting metric serialization field */
                for (m = 0; m < _CGROUP_IP_ACCOUNTING_METRIC_MAX; m++)
                        if (streq(l, ip_accounting_metric_field[m]))
                                break;
                if (m < _CGROUP_IP_ACCOUNTING_METRIC_MAX) {
                        uint64_t c;

                        r = safe_atou64(v, &c);
                        if (r < 0)
                                log_unit_debug(u, "Failed to parse IP accounting value %s, ignoring.", v);
                        else
                                u->ip_accounting_extra[m] = c;
                        continue;
                }

                if (unit_can_serialize(u)) {
                        r = exec_runtime_deserialize_compat(u, l, v, fds);
                        if (r < 0) {
                                log_unit_warning(u, "Failed to deserialize runtime parameter '%s', ignoring.", l);
                                continue;
                        }

                        /* Returns positive if key was handled by the call */
                        if (r > 0)
                                continue;

                        r = UNIT_VTABLE(u)->deserialize_item(u, l, v, fds);
                        if (r < 0)
                                log_unit_warning(u, "Failed to deserialize unit parameter '%s', ignoring.", l);
                }
        }

        /* Versions before 228 did not carry a state change timestamp. In this case, take the current time. This is
         * useful, so that timeouts based on this timestamp don't trigger too early, and is in-line with the logic from
         * before 228 where the base for timeouts was not persistent across reboots. */

        if (!dual_timestamp_is_set(&u->state_change_timestamp))
                dual_timestamp_get(&u->state_change_timestamp);

        /* Let's make sure that everything that is deserialized also gets any potential new cgroup settings applied
         * after we are done. For that we invalidate anything already realized, so that we can realize it again. */
        unit_invalidate_cgroup(u, _CGROUP_MASK_ALL);
        unit_invalidate_cgroup_bpf(u);

        return 0;
}

void unit_deserialize_skip(FILE *f) {
        assert(f);

        /* Skip serialized data for this unit. We don't know what it is. */

        for (;;) {
                char line[LINE_MAX], *l;

                if (!fgets(line, sizeof line, f))
                        return;

                char_array_0(line);
                l = strstrip(line);

                /* End marker */
                if (isempty(l))
                        return;
        }
}


int unit_add_node_dependency(Unit *u, const char *what, bool wants, UnitDependency dep, UnitDependencyMask mask) {
        Unit *device;
        _cleanup_free_ char *e = NULL;
        int r;

        assert(u);

        /* Adds in links to the device node that this unit is based on */
        if (isempty(what))
                return 0;

        if (!is_device_path(what))
                return 0;

        /* When device units aren't supported (such as in a
         * container), don't create dependencies on them. */
        if (!unit_type_supported(UNIT_DEVICE))
                return 0;

        r = unit_name_from_path(what, ".device", &e);
        if (r < 0)
                return r;

        r = manager_load_unit(u->manager, e, NULL, NULL, &device);
        if (r < 0)
                return r;

        if (dep == UNIT_REQUIRES && device_shall_be_bound_by(device, u))
                dep = UNIT_BINDS_TO;

        r = unit_add_two_dependencies(u, UNIT_AFTER,
                                      MANAGER_IS_SYSTEM(u->manager) ? dep : UNIT_WANTS,
                                      device, true, mask);
        if (r < 0)
                return r;

        if (wants) {
                r = unit_add_dependency(device, UNIT_WANTS, u, false, mask);
                if (r < 0)
                        return r;
        }

        return 0;
}

int unit_coldplug(Unit *u) {
        int r = 0, q;
        char **i;

        assert(u);

        /* Make sure we don't enter a loop, when coldplugging
         * recursively. */
        if (u->coldplugged)
                return 0;

        u->coldplugged = true;

        STRV_FOREACH(i, u->deserialized_refs) {
                q = bus_unit_track_add_name(u, *i);
                if (q < 0 && r >= 0)
                        r = q;
        }
        u->deserialized_refs = strv_free(u->deserialized_refs);

        if (UNIT_VTABLE(u)->coldplug) {
                q = UNIT_VTABLE(u)->coldplug(u);
                if (q < 0 && r >= 0)
                        r = q;
        }

        if (u->job) {
                q = job_coldplug(u->job);
                if (q < 0 && r >= 0)
                        r = q;
        }

        return r;
}

static bool fragment_mtime_newer(const char *path, usec_t mtime, bool path_masked) {
        struct stat st;

        if (!path)
                return false;

        /* If the source is some virtual kernel file system, then we assume we watch it anyway, and hence pretend we
         * are never out-of-date. */
        if (PATH_STARTSWITH_SET(path, "/proc", "/sys"))
                return false;

        if (stat(path, &st) < 0)
                /* What, cannot access this anymore? */
                return true;

        if (path_masked)
                /* For masked files check if they are still so */
                return !null_or_empty(&st);
        else
                /* For non-empty files check the mtime */
                return timespec_load(&st.st_mtim) > mtime;

        return false;
}

bool unit_need_daemon_reload(Unit *u) {
        _cleanup_strv_free_ char **t = NULL;
        char **path;

        assert(u);

        /* For unit files, we allow masking… */
        if (fragment_mtime_newer(u->fragment_path, u->fragment_mtime,
                                 u->load_state == UNIT_MASKED))
                return true;

        /* Source paths should not be masked… */
        if (fragment_mtime_newer(u->source_path, u->source_mtime, false))
                return true;

        if (u->load_state == UNIT_LOADED)
                (void) unit_find_dropin_paths(u, &t);
        if (!strv_equal(u->dropin_paths, t))
                return true;

        /* … any drop-ins that are masked are simply omitted from the list. */
        STRV_FOREACH(path, u->dropin_paths)
                if (fragment_mtime_newer(*path, u->dropin_mtime, false))
                        return true;

        return false;
}

void unit_reset_failed(Unit *u) {
        assert(u);

        if (UNIT_VTABLE(u)->reset_failed)
                UNIT_VTABLE(u)->reset_failed(u);

        RATELIMIT_RESET(u->start_limit);
        u->start_limit_hit = false;
}

Unit *unit_following(Unit *u) {
        assert(u);

        if (UNIT_VTABLE(u)->following)
                return UNIT_VTABLE(u)->following(u);

        return NULL;
}

bool unit_stop_pending(Unit *u) {
        assert(u);

        /* This call does check the current state of the unit. It's
         * hence useful to be called from state change calls of the
         * unit itself, where the state isn't updated yet. This is
         * different from unit_inactive_or_pending() which checks both
         * the current state and for a queued job. */

        return u->job && u->job->type == JOB_STOP;
}

bool unit_inactive_or_pending(Unit *u) {
        assert(u);

        /* Returns true if the unit is inactive or going down */

        if (UNIT_IS_INACTIVE_OR_DEACTIVATING(unit_active_state(u)))
                return true;

        if (unit_stop_pending(u))
                return true;

        return false;
}

bool unit_active_or_pending(Unit *u) {
        assert(u);

        /* Returns true if the unit is active or going up */

        if (UNIT_IS_ACTIVE_OR_ACTIVATING(unit_active_state(u)))
                return true;

        if (u->job &&
            IN_SET(u->job->type, JOB_START, JOB_RELOAD_OR_START, JOB_RESTART))
                return true;

        return false;
}

bool unit_will_restart(Unit *u) {
        assert(u);

        if (!UNIT_VTABLE(u)->will_restart)
                return false;

        return UNIT_VTABLE(u)->will_restart(u);
}

int unit_kill(Unit *u, KillWho w, int signo, sd_bus_error *error) {
        assert(u);
        assert(w >= 0 && w < _KILL_WHO_MAX);
        assert(SIGNAL_VALID(signo));

        if (!UNIT_VTABLE(u)->kill)
                return -EOPNOTSUPP;

        return UNIT_VTABLE(u)->kill(u, w, signo, error);
}

static Set *unit_pid_set(pid_t main_pid, pid_t control_pid) {
        Set *pid_set;
        int r;

        pid_set = set_new(NULL);
        if (!pid_set)
                return NULL;

        /* Exclude the main/control pids from being killed via the cgroup */
        if (main_pid > 0) {
                r = set_put(pid_set, PID_TO_PTR(main_pid));
                if (r < 0)
                        goto fail;
        }

        if (control_pid > 0) {
                r = set_put(pid_set, PID_TO_PTR(control_pid));
                if (r < 0)
                        goto fail;
        }

        return pid_set;

fail:
        set_free(pid_set);
        return NULL;
}

int unit_kill_common(
                Unit *u,
                KillWho who,
                int signo,
                pid_t main_pid,
                pid_t control_pid,
                sd_bus_error *error) {

        int r = 0;
        bool killed = false;

        if (IN_SET(who, KILL_MAIN, KILL_MAIN_FAIL)) {
                if (main_pid < 0)
                        return sd_bus_error_setf(error, BUS_ERROR_NO_SUCH_PROCESS, "%s units have no main processes", unit_type_to_string(u->type));
                else if (main_pid == 0)
                        return sd_bus_error_set_const(error, BUS_ERROR_NO_SUCH_PROCESS, "No main process to kill");
        }

        if (IN_SET(who, KILL_CONTROL, KILL_CONTROL_FAIL)) {
                if (control_pid < 0)
                        return sd_bus_error_setf(error, BUS_ERROR_NO_SUCH_PROCESS, "%s units have no control processes", unit_type_to_string(u->type));
                else if (control_pid == 0)
                        return sd_bus_error_set_const(error, BUS_ERROR_NO_SUCH_PROCESS, "No control process to kill");
        }

        if (IN_SET(who, KILL_CONTROL, KILL_CONTROL_FAIL, KILL_ALL, KILL_ALL_FAIL))
                if (control_pid > 0) {
                        if (kill(control_pid, signo) < 0)
                                r = -errno;
                        else
                                killed = true;
                }

        if (IN_SET(who, KILL_MAIN, KILL_MAIN_FAIL, KILL_ALL, KILL_ALL_FAIL))
                if (main_pid > 0) {
                        if (kill(main_pid, signo) < 0)
                                r = -errno;
                        else
                                killed = true;
                }

        if (IN_SET(who, KILL_ALL, KILL_ALL_FAIL) && u->cgroup_path) {
                _cleanup_set_free_ Set *pid_set = NULL;
                int q;

                /* Exclude the main/control pids from being killed via the cgroup */
                pid_set = unit_pid_set(main_pid, control_pid);
                if (!pid_set)
                        return -ENOMEM;

                q = cg_kill_recursive(SYSTEMD_CGROUP_CONTROLLER, u->cgroup_path, signo, 0, pid_set, NULL, NULL);
                if (q < 0 && !IN_SET(q, -EAGAIN, -ESRCH, -ENOENT))
                        r = q;
                else
                        killed = true;
        }

        if (r == 0 && !killed && IN_SET(who, KILL_ALL_FAIL, KILL_CONTROL_FAIL))
                return -ESRCH;

        return r;
}

int unit_following_set(Unit *u, Set **s) {
        assert(u);
        assert(s);

        if (UNIT_VTABLE(u)->following_set)
                return UNIT_VTABLE(u)->following_set(u, s);

        *s = NULL;
        return 0;
}

UnitFileState unit_get_unit_file_state(Unit *u) {
        int r;

        assert(u);

        if (u->unit_file_state < 0 && u->fragment_path) {
                r = unit_file_get_state(
                                u->manager->unit_file_scope,
                                NULL,
                                u->id,
                                &u->unit_file_state);
                if (r < 0)
                        u->unit_file_state = UNIT_FILE_BAD;
        }

        return u->unit_file_state;
}

int unit_get_unit_file_preset(Unit *u) {
        assert(u);

        if (u->unit_file_preset < 0 && u->fragment_path)
                u->unit_file_preset = unit_file_query_preset(
                                u->manager->unit_file_scope,
                                NULL,
                                basename(u->fragment_path));

        return u->unit_file_preset;
}

Unit* unit_ref_set(UnitRef *ref, Unit *source, Unit *target) {
        assert(ref);
        assert(source);
        assert(target);

        if (ref->target)
                unit_ref_unset(ref);

        ref->source = source;
        ref->target = target;
        LIST_PREPEND(refs_by_target, target->refs_by_target, ref);
        return target;
}

void unit_ref_unset(UnitRef *ref) {
        assert(ref);

        if (!ref->target)
                return;

        /* We are about to drop a reference to the unit, make sure the garbage collection has a look at it as it might
         * be unreferenced now. */
        unit_add_to_gc_queue(ref->target);

        LIST_REMOVE(refs_by_target, ref->target->refs_by_target, ref);
        ref->source = ref->target = NULL;
}

static int user_from_unit_name(Unit *u, char **ret) {

        static const uint8_t hash_key[] = {
                0x58, 0x1a, 0xaf, 0xe6, 0x28, 0x58, 0x4e, 0x96,
                0xb4, 0x4e, 0xf5, 0x3b, 0x8c, 0x92, 0x07, 0xec
        };

        _cleanup_free_ char *n = NULL;
        int r;

        r = unit_name_to_prefix(u->id, &n);
        if (r < 0)
                return r;

        if (valid_user_group_name(n)) {
                *ret = n;
                n = NULL;
                return 0;
        }

        /* If we can't use the unit name as a user name, then let's hash it and use that */
        if (asprintf(ret, "_du%016" PRIx64, siphash24(n, strlen(n), hash_key)) < 0)
                return -ENOMEM;

        return 0;
}

int unit_patch_contexts(Unit *u) {
        CGroupContext *cc;
        ExecContext *ec;
        unsigned i;
        int r;

        assert(u);

        /* Patch in the manager defaults into the exec and cgroup
         * contexts, _after_ the rest of the settings have been
         * initialized */

        ec = unit_get_exec_context(u);
        if (ec) {
                /* This only copies in the ones that need memory */
                for (i = 0; i < _RLIMIT_MAX; i++)
                        if (u->manager->rlimit[i] && !ec->rlimit[i]) {
                                ec->rlimit[i] = newdup(struct rlimit, u->manager->rlimit[i], 1);
                                if (!ec->rlimit[i])
                                        return -ENOMEM;
                        }

                if (MANAGER_IS_USER(u->manager) &&
                    !ec->working_directory) {

                        r = get_home_dir(&ec->working_directory);
                        if (r < 0)
                                return r;

                        /* Allow user services to run, even if the
                         * home directory is missing */
                        ec->working_directory_missing_ok = true;
                }

                if (ec->private_devices)
                        ec->capability_bounding_set &= ~((UINT64_C(1) << CAP_MKNOD) | (UINT64_C(1) << CAP_SYS_RAWIO));

                if (ec->protect_kernel_modules)
                        ec->capability_bounding_set &= ~(UINT64_C(1) << CAP_SYS_MODULE);

                if (ec->dynamic_user) {
                        if (!ec->user) {
                                r = user_from_unit_name(u, &ec->user);
                                if (r < 0)
                                        return r;
                        }

                        if (!ec->group) {
                                ec->group = strdup(ec->user);
                                if (!ec->group)
                                        return -ENOMEM;
                        }

                        /* If the dynamic user option is on, let's make sure that the unit can't leave its UID/GID
                         * around in the file system or on IPC objects. Hence enforce a strict sandbox. */

                        ec->private_tmp = true;
                        ec->remove_ipc = true;
                        ec->protect_system = PROTECT_SYSTEM_STRICT;
                        if (ec->protect_home == PROTECT_HOME_NO)
                                ec->protect_home = PROTECT_HOME_READ_ONLY;
                }
        }

        cc = unit_get_cgroup_context(u);
        if (cc) {

                if (ec &&
                    ec->private_devices &&
                    cc->device_policy == CGROUP_AUTO)
                        cc->device_policy = CGROUP_CLOSED;
        }

        return 0;
}

ExecContext *unit_get_exec_context(Unit *u) {
        size_t offset;
        assert(u);

        if (u->type < 0)
                return NULL;

        offset = UNIT_VTABLE(u)->exec_context_offset;
        if (offset <= 0)
                return NULL;

        return (ExecContext*) ((uint8_t*) u + offset);
}

KillContext *unit_get_kill_context(Unit *u) {
        size_t offset;
        assert(u);

        if (u->type < 0)
                return NULL;

        offset = UNIT_VTABLE(u)->kill_context_offset;
        if (offset <= 0)
                return NULL;

        return (KillContext*) ((uint8_t*) u + offset);
}

CGroupContext *unit_get_cgroup_context(Unit *u) {
        size_t offset;

        if (u->type < 0)
                return NULL;

        offset = UNIT_VTABLE(u)->cgroup_context_offset;
        if (offset <= 0)
                return NULL;

        return (CGroupContext*) ((uint8_t*) u + offset);
}

ExecRuntime *unit_get_exec_runtime(Unit *u) {
        size_t offset;

        if (u->type < 0)
                return NULL;

        offset = UNIT_VTABLE(u)->exec_runtime_offset;
        if (offset <= 0)
                return NULL;

        return *(ExecRuntime**) ((uint8_t*) u + offset);
}

static const char* unit_drop_in_dir(Unit *u, UnitWriteFlags flags) {
        assert(u);

        if (UNIT_WRITE_FLAGS_NOOP(flags))
                return NULL;

        if (u->transient) /* Redirect drop-ins for transient units always into the transient directory. */
                return u->manager->lookup_paths.transient;

        if (flags & UNIT_PERSISTENT)
                return u->manager->lookup_paths.persistent_control;

        if (flags & UNIT_RUNTIME)
                return u->manager->lookup_paths.runtime_control;

        return NULL;
}

char* unit_escape_setting(const char *s, UnitWriteFlags flags, char **buf) {
        char *ret = NULL;

        if (!s)
                return NULL;

        /* Escapes the input string as requested. Returns the escaped string. If 'buf' is specified then the allocated
         * return buffer pointer is also written to *buf, except if no escaping was necessary, in which case *buf is
         * set to NULL, and the input pointer is returned as-is. This means the return value always contains a properly
         * escaped version, but *buf when passed only contains a pointer if an allocation was necessary. If *buf is
         * not specified, then the return value always needs to be freed. Callers can use this to optimize memory
         * allocations. */

        if (flags & UNIT_ESCAPE_SPECIFIERS) {
                ret = specifier_escape(s);
                if (!ret)
                        return NULL;

                s = ret;
        }

        if (flags & UNIT_ESCAPE_C) {
                char *a;

                a = cescape(s);
                free(ret);
                if (!a)
                        return NULL;

                ret = a;
        }

        if (buf) {
                *buf = ret;
                return ret ?: (char*) s;
        }

        return ret ?: strdup(s);
}

char* unit_concat_strv(char **l, UnitWriteFlags flags) {
        _cleanup_free_ char *result = NULL;
        size_t n = 0, allocated = 0;
        char **i, *ret;

        /* Takes a list of strings, escapes them, and concatenates them. This may be used to format command lines in a
         * way suitable for ExecStart= stanzas */

        STRV_FOREACH(i, l) {
                _cleanup_free_ char *buf = NULL;
                const char *p;
                size_t a;
                char *q;

                p = unit_escape_setting(*i, flags, &buf);
                if (!p)
                        return NULL;

                a = (n > 0) + 1 + strlen(p) + 1; /* separating space + " + entry + " */
                if (!GREEDY_REALLOC(result, allocated, n + a + 1))
                        return NULL;

                q = result + n;
                if (n > 0)
                        *(q++) = ' ';

                *(q++) = '"';
                q = stpcpy(q, p);
                *(q++) = '"';

                n += a;
        }

        if (!GREEDY_REALLOC(result, allocated, n + 1))
                return NULL;

        result[n] = 0;

        ret = result;
        result = NULL;

        return ret;
}

int unit_write_setting(Unit *u, UnitWriteFlags flags, const char *name, const char *data) {
        _cleanup_free_ char *p = NULL, *q = NULL, *escaped = NULL;
        const char *dir, *wrapped;
        int r;

        assert(u);
        assert(name);
        assert(data);

        if (UNIT_WRITE_FLAGS_NOOP(flags))
                return 0;

        data = unit_escape_setting(data, flags, &escaped);
        if (!data)
                return -ENOMEM;

        /* Prefix the section header. If we are writing this out as transient file, then let's suppress this if the
         * previous section header is the same */

        if (flags & UNIT_PRIVATE) {
                if (!UNIT_VTABLE(u)->private_section)
                        return -EINVAL;

                if (!u->transient_file || u->last_section_private < 0)
                        data = strjoina("[", UNIT_VTABLE(u)->private_section, "]\n", data);
                else if (u->last_section_private == 0)
                        data = strjoina("\n[", UNIT_VTABLE(u)->private_section, "]\n", data);
        } else {
                if (!u->transient_file || u->last_section_private < 0)
                        data = strjoina("[Unit]\n", data);
                else if (u->last_section_private > 0)
                        data = strjoina("\n[Unit]\n", data);
        }

        if (u->transient_file) {
                /* When this is a transient unit file in creation, then let's not create a new drop-in but instead
                 * write to the transient unit file. */
                fputs(data, u->transient_file);

                if (!endswith(data, "\n"))
                        fputc('\n', u->transient_file);

                /* Remember which section we wrote this entry to */
                u->last_section_private = !!(flags & UNIT_PRIVATE);
                return 0;
        }

        dir = unit_drop_in_dir(u, flags);
        if (!dir)
                return -EINVAL;

        wrapped = strjoina("# This is a drop-in unit file extension, created via \"systemctl set-property\"\n"
                           "# or an equivalent operation. Do not edit.\n",
                           data,
                           "\n");

        r = drop_in_file(dir, u->id, 50, name, &p, &q);
        if (r < 0)
                return r;

        (void) mkdir_p_label(p, 0755);
        r = write_string_file_atomic_label(q, wrapped);
        if (r < 0)
                return r;

        r = strv_push(&u->dropin_paths, q);
        if (r < 0)
                return r;
        q = NULL;

        strv_uniq(u->dropin_paths);

        u->dropin_mtime = now(CLOCK_REALTIME);

        return 0;
}

int unit_write_settingf(Unit *u, UnitWriteFlags flags, const char *name, const char *format, ...) {
        _cleanup_free_ char *p = NULL;
        va_list ap;
        int r;

        assert(u);
        assert(name);
        assert(format);

        if (UNIT_WRITE_FLAGS_NOOP(flags))
                return 0;

        va_start(ap, format);
        r = vasprintf(&p, format, ap);
        va_end(ap);

        if (r < 0)
                return -ENOMEM;

        return unit_write_setting(u, flags, name, p);
}

int unit_make_transient(Unit *u) {
        _cleanup_free_ char *path = NULL;
        FILE *f;

        assert(u);

        if (!UNIT_VTABLE(u)->can_transient)
                return -EOPNOTSUPP;

        (void) mkdir_p_label(u->manager->lookup_paths.transient, 0755);

        path = strjoin(u->manager->lookup_paths.transient, "/", u->id);
        if (!path)
                return -ENOMEM;

        /* Let's open the file we'll write the transient settings into. This file is kept open as long as we are
         * creating the transient, and is closed in unit_load(), as soon as we start loading the file. */

        RUN_WITH_UMASK(0022) {
                f = fopen(path, "we");
                if (!f)
                        return -errno;
        }

        safe_fclose(u->transient_file);
        u->transient_file = f;

        free_and_replace(u->fragment_path, path);

        u->source_path = mfree(u->source_path);
        u->dropin_paths = strv_free(u->dropin_paths);
        u->fragment_mtime = u->source_mtime = u->dropin_mtime = 0;

        u->load_state = UNIT_STUB;
        u->load_error = 0;
        u->transient = true;

        unit_add_to_dbus_queue(u);
        unit_add_to_gc_queue(u);

        fputs("# This is a transient unit file, created programmatically via the systemd API. Do not edit.\n",
              u->transient_file);

        return 0;
}

static void log_kill(pid_t pid, int sig, void *userdata) {
        _cleanup_free_ char *comm = NULL;

        (void) get_process_comm(pid, &comm);

        /* Don't log about processes marked with brackets, under the assumption that these are temporary processes
           only, like for example systemd's own PAM stub process. */
        if (comm && comm[0] == '(')
                return;

        log_unit_notice(userdata,
                        "Killing process " PID_FMT " (%s) with signal SIG%s.",
                        pid,
                        strna(comm),
                        signal_to_string(sig));
}

static int operation_to_signal(KillContext *c, KillOperation k) {
        assert(c);

        switch (k) {

        case KILL_TERMINATE:
        case KILL_TERMINATE_AND_LOG:
                return c->kill_signal;

        case KILL_KILL:
                return SIGKILL;

        case KILL_ABORT:
                return SIGABRT;

        default:
                assert_not_reached("KillOperation unknown");
        }
}

int unit_kill_context(
                Unit *u,
                KillContext *c,
                KillOperation k,
                pid_t main_pid,
                pid_t control_pid,
                bool main_pid_alien) {

        bool wait_for_exit = false, send_sighup;
        cg_kill_log_func_t log_func = NULL;
        int sig, r;

        assert(u);
        assert(c);

        /* Kill the processes belonging to this unit, in preparation for shutting the unit down.
         * Returns > 0 if we killed something worth waiting for, 0 otherwise. */

        if (c->kill_mode == KILL_NONE)
                return 0;

        sig = operation_to_signal(c, k);

        send_sighup =
                c->send_sighup &&
                IN_SET(k, KILL_TERMINATE, KILL_TERMINATE_AND_LOG) &&
                sig != SIGHUP;

        if (k != KILL_TERMINATE || IN_SET(sig, SIGKILL, SIGABRT))
                log_func = log_kill;

        if (main_pid > 0) {
                if (log_func)
                        log_func(main_pid, sig, u);

                r = kill_and_sigcont(main_pid, sig);
                if (r < 0 && r != -ESRCH) {
                        _cleanup_free_ char *comm = NULL;
                        (void) get_process_comm(main_pid, &comm);

                        log_unit_warning_errno(u, r, "Failed to kill main process " PID_FMT " (%s), ignoring: %m", main_pid, strna(comm));
                } else {
                        if (!main_pid_alien)
                                wait_for_exit = true;

                        if (r != -ESRCH && send_sighup)
                                (void) kill(main_pid, SIGHUP);
                }
        }

        if (control_pid > 0) {
                if (log_func)
                        log_func(control_pid, sig, u);

                r = kill_and_sigcont(control_pid, sig);
                if (r < 0 && r != -ESRCH) {
                        _cleanup_free_ char *comm = NULL;
                        (void) get_process_comm(control_pid, &comm);

                        log_unit_warning_errno(u, r, "Failed to kill control process " PID_FMT " (%s), ignoring: %m", control_pid, strna(comm));
                } else {
                        wait_for_exit = true;

                        if (r != -ESRCH && send_sighup)
                                (void) kill(control_pid, SIGHUP);
                }
        }

        if (u->cgroup_path &&
            (c->kill_mode == KILL_CONTROL_GROUP || (c->kill_mode == KILL_MIXED && k == KILL_KILL))) {
                _cleanup_set_free_ Set *pid_set = NULL;

                /* Exclude the main/control pids from being killed via the cgroup */
                pid_set = unit_pid_set(main_pid, control_pid);
                if (!pid_set)
                        return -ENOMEM;

                r = cg_kill_recursive(SYSTEMD_CGROUP_CONTROLLER, u->cgroup_path,
                                      sig,
                                      CGROUP_SIGCONT|CGROUP_IGNORE_SELF,
                                      pid_set,
                                      log_func, u);
                if (r < 0) {
                        if (!IN_SET(r, -EAGAIN, -ESRCH, -ENOENT))
                                log_unit_warning_errno(u, r, "Failed to kill control group %s, ignoring: %m", u->cgroup_path);

                } else if (r > 0) {

                        /* FIXME: For now, on the legacy hierarchy, we
                         * will not wait for the cgroup members to die
                         * if we are running in a container or if this
                         * is a delegation unit, simply because cgroup
                         * notification is unreliable in these
                         * cases. It doesn't work at all in
                         * containers, and outside of containers it
                         * can be confused easily by left-over
                         * directories in the cgroup — which however
                         * should not exist in non-delegated units. On
                         * the unified hierarchy that's different,
                         * there we get proper events. Hence rely on
                         * them. */

                        if (cg_unified_controller(SYSTEMD_CGROUP_CONTROLLER) > 0 ||
                            (detect_container() == 0 && !UNIT_CGROUP_BOOL(u, delegate)))
                                wait_for_exit = true;

                        if (send_sighup) {
                                set_free(pid_set);

                                pid_set = unit_pid_set(main_pid, control_pid);
                                if (!pid_set)
                                        return -ENOMEM;

                                cg_kill_recursive(SYSTEMD_CGROUP_CONTROLLER, u->cgroup_path,
                                                  SIGHUP,
                                                  CGROUP_IGNORE_SELF,
                                                  pid_set,
                                                  NULL, NULL);
                        }
                }
        }

        return wait_for_exit;
}

int unit_require_mounts_for(Unit *u, const char *path, UnitDependencyMask mask) {
        char prefix[strlen(path) + 1], *p;
        UnitDependencyInfo di;
        int r;

        assert(u);
        assert(path);

        /* Registers a unit for requiring a certain path and all its prefixes. We keep a hashtable of these paths in
         * the unit (from the path to the UnitDependencyInfo structure indicating how to the dependency came to
         * be). However, we build a prefix table for all possible prefixes so that new appearing mount units can easily
         * determine which units to make themselves a dependency of. */

        if (!path_is_absolute(path))
                return -EINVAL;

        r = hashmap_ensure_allocated(&u->requires_mounts_for, &string_hash_ops);
        if (r < 0)
                return r;

        p = strdup(path);
        if (!p)
                return -ENOMEM;

        path_kill_slashes(p);

        if (!path_is_normalized(p)) {
                free(p);
                return -EPERM;
        }

        if (hashmap_contains(u->requires_mounts_for, p)) {
                free(p);
                return 0;
        }

        di = (UnitDependencyInfo) {
                .origin_mask = mask
        };

        r = hashmap_put(u->requires_mounts_for, p, di.data);
        if (r < 0) {
                free(p);
                return r;
        }

        PATH_FOREACH_PREFIX_MORE(prefix, p) {
                Set *x;

                x = hashmap_get(u->manager->units_requiring_mounts_for, prefix);
                if (!x) {
                        char *q;

                        r = hashmap_ensure_allocated(&u->manager->units_requiring_mounts_for, &string_hash_ops);
                        if (r < 0)
                                return r;

                        q = strdup(prefix);
                        if (!q)
                                return -ENOMEM;

                        x = set_new(NULL);
                        if (!x) {
                                free(q);
                                return -ENOMEM;
                        }

                        r = hashmap_put(u->manager->units_requiring_mounts_for, q, x);
                        if (r < 0) {
                                free(q);
                                set_free(x);
                                return r;
                        }
                }

                r = set_put(x, u);
                if (r < 0)
                        return r;
        }

        return 0;
}

int unit_setup_exec_runtime(Unit *u) {
        ExecRuntime **rt;
        size_t offset;
        Unit *other;
        Iterator i;
        void *v;
        int r;

        offset = UNIT_VTABLE(u)->exec_runtime_offset;
        assert(offset > 0);

        /* Check if there already is an ExecRuntime for this unit? */
        rt = (ExecRuntime**) ((uint8_t*) u + offset);
        if (*rt)
                return 0;

        /* Try to get it from somebody else */
        HASHMAP_FOREACH_KEY(v, other, u->dependencies[UNIT_JOINS_NAMESPACE_OF], i) {
                r = exec_runtime_acquire(u->manager, NULL, other->id, false, rt);
                if (r == 1)
                        return 1;
        }

        return exec_runtime_acquire(u->manager, unit_get_exec_context(u), u->id, true, rt);
}

int unit_setup_dynamic_creds(Unit *u) {
        ExecContext *ec;
        DynamicCreds *dcreds;
        size_t offset;

        assert(u);

        offset = UNIT_VTABLE(u)->dynamic_creds_offset;
        assert(offset > 0);
        dcreds = (DynamicCreds*) ((uint8_t*) u + offset);

        ec = unit_get_exec_context(u);
        assert(ec);

        if (!ec->dynamic_user)
                return 0;

        return dynamic_creds_acquire(dcreds, u->manager, ec->user, ec->group);
}

bool unit_type_supported(UnitType t) {
        if (_unlikely_(t < 0))
                return false;
        if (_unlikely_(t >= _UNIT_TYPE_MAX))
                return false;

        if (!unit_vtable[t]->supported)
                return true;

        return unit_vtable[t]->supported();
}

void unit_warn_if_dir_nonempty(Unit *u, const char* where) {
        int r;

        assert(u);
        assert(where);

        r = dir_is_empty(where);
        if (r > 0 || r == -ENOTDIR)
                return;
        if (r < 0) {
                log_unit_warning_errno(u, r, "Failed to check directory %s: %m", where);
                return;
        }

        log_struct(LOG_NOTICE,
                   "MESSAGE_ID=" SD_MESSAGE_OVERMOUNTING_STR,
                   LOG_UNIT_ID(u),
                   LOG_UNIT_INVOCATION_ID(u),
                   LOG_UNIT_MESSAGE(u, "Directory %s to mount over is not empty, mounting anyway.", where),
                   "WHERE=%s", where,
                   NULL);
}

int unit_fail_if_noncanonical(Unit *u, const char* where) {
        _cleanup_free_ char *canonical_where;
        int r;

        assert(u);
        assert(where);

        r = chase_symlinks(where, NULL, CHASE_NONEXISTENT, &canonical_where);
        if (r < 0) {
                log_unit_debug_errno(u, r, "Failed to check %s for symlinks, ignoring: %m", where);
                return 0;
        }

        /* We will happily ignore a trailing slash (or any redundant slashes) */
        if (path_equal(where, canonical_where))
                return 0;

        /* No need to mention "." or "..", they would already have been rejected by unit_name_from_path() */
        log_struct(LOG_ERR,
                   "MESSAGE_ID=" SD_MESSAGE_OVERMOUNTING_STR,
                   LOG_UNIT_ID(u),
                   LOG_UNIT_INVOCATION_ID(u),
                   LOG_UNIT_MESSAGE(u, "Mount path %s is not canonical (contains a symlink).", where),
                   "WHERE=%s", where,
                   NULL);

        return -ELOOP;
}

bool unit_is_pristine(Unit *u) {
        assert(u);

        /* Check if the unit already exists or is already around,
         * in a number of different ways. Note that to cater for unit
         * types such as slice, we are generally fine with units that
         * are marked UNIT_LOADED even though nothing was
         * actually loaded, as those unit types don't require a file
         * on disk to validly load. */

        return !(!IN_SET(u->load_state, UNIT_NOT_FOUND, UNIT_LOADED) ||
                 u->fragment_path ||
                 u->source_path ||
                 !strv_isempty(u->dropin_paths) ||
                 u->job ||
                 u->merged_into);
}

pid_t unit_control_pid(Unit *u) {
        assert(u);

        if (UNIT_VTABLE(u)->control_pid)
                return UNIT_VTABLE(u)->control_pid(u);

        return 0;
}

pid_t unit_main_pid(Unit *u) {
        assert(u);

        if (UNIT_VTABLE(u)->main_pid)
                return UNIT_VTABLE(u)->main_pid(u);

        return 0;
}

static void unit_unref_uid_internal(
                Unit *u,
                uid_t *ref_uid,
                bool destroy_now,
                void (*_manager_unref_uid)(Manager *m, uid_t uid, bool destroy_now)) {

        assert(u);
        assert(ref_uid);
        assert(_manager_unref_uid);

        /* Generic implementation of both unit_unref_uid() and unit_unref_gid(), under the assumption that uid_t and
         * gid_t are actually the same time, with the same validity rules.
         *
         * Drops a reference to UID/GID from a unit. */

        assert_cc(sizeof(uid_t) == sizeof(gid_t));
        assert_cc(UID_INVALID == (uid_t) GID_INVALID);

        if (!uid_is_valid(*ref_uid))
                return;

        _manager_unref_uid(u->manager, *ref_uid, destroy_now);
        *ref_uid = UID_INVALID;
}

void unit_unref_uid(Unit *u, bool destroy_now) {
        unit_unref_uid_internal(u, &u->ref_uid, destroy_now, manager_unref_uid);
}

void unit_unref_gid(Unit *u, bool destroy_now) {
        unit_unref_uid_internal(u, (uid_t*) &u->ref_gid, destroy_now, manager_unref_gid);
}

static int unit_ref_uid_internal(
                Unit *u,
                uid_t *ref_uid,
                uid_t uid,
                bool clean_ipc,
                int (*_manager_ref_uid)(Manager *m, uid_t uid, bool clean_ipc)) {

        int r;

        assert(u);
        assert(ref_uid);
        assert(uid_is_valid(uid));
        assert(_manager_ref_uid);

        /* Generic implementation of both unit_ref_uid() and unit_ref_guid(), under the assumption that uid_t and gid_t
         * are actually the same type, and have the same validity rules.
         *
         * Adds a reference on a specific UID/GID to this unit. Each unit referencing the same UID/GID maintains a
         * reference so that we can destroy the UID/GID's IPC resources as soon as this is requested and the counter
         * drops to zero. */

        assert_cc(sizeof(uid_t) == sizeof(gid_t));
        assert_cc(UID_INVALID == (uid_t) GID_INVALID);

        if (*ref_uid == uid)
                return 0;

        if (uid_is_valid(*ref_uid)) /* Already set? */
                return -EBUSY;

        r = _manager_ref_uid(u->manager, uid, clean_ipc);
        if (r < 0)
                return r;

        *ref_uid = uid;
        return 1;
}

int unit_ref_uid(Unit *u, uid_t uid, bool clean_ipc) {
        return unit_ref_uid_internal(u, &u->ref_uid, uid, clean_ipc, manager_ref_uid);
}

int unit_ref_gid(Unit *u, gid_t gid, bool clean_ipc) {
        return unit_ref_uid_internal(u, (uid_t*) &u->ref_gid, (uid_t) gid, clean_ipc, manager_ref_gid);
}

static int unit_ref_uid_gid_internal(Unit *u, uid_t uid, gid_t gid, bool clean_ipc) {
        int r = 0, q = 0;

        assert(u);

        /* Reference both a UID and a GID in one go. Either references both, or neither. */

        if (uid_is_valid(uid)) {
                r = unit_ref_uid(u, uid, clean_ipc);
                if (r < 0)
                        return r;
        }

        if (gid_is_valid(gid)) {
                q = unit_ref_gid(u, gid, clean_ipc);
                if (q < 0) {
                        if (r > 0)
                                unit_unref_uid(u, false);

                        return q;
                }
        }

        return r > 0 || q > 0;
}

int unit_ref_uid_gid(Unit *u, uid_t uid, gid_t gid) {
        ExecContext *c;
        int r;

        assert(u);

        c = unit_get_exec_context(u);

        r = unit_ref_uid_gid_internal(u, uid, gid, c ? c->remove_ipc : false);
        if (r < 0)
                return log_unit_warning_errno(u, r, "Couldn't add UID/GID reference to unit, proceeding without: %m");

        return r;
}

void unit_unref_uid_gid(Unit *u, bool destroy_now) {
        assert(u);

        unit_unref_uid(u, destroy_now);
        unit_unref_gid(u, destroy_now);
}

void unit_notify_user_lookup(Unit *u, uid_t uid, gid_t gid) {
        int r;

        assert(u);

        /* This is invoked whenever one of the forked off processes let's us know the UID/GID its user name/group names
         * resolved to. We keep track of which UID/GID is currently assigned in order to be able to destroy its IPC
         * objects when no service references the UID/GID anymore. */

        r = unit_ref_uid_gid(u, uid, gid);
        if (r > 0)
                bus_unit_send_change_signal(u);
}

int unit_set_invocation_id(Unit *u, sd_id128_t id) {
        int r;

        assert(u);

        /* Set the invocation ID for this unit. If we cannot, this will not roll back, but reset the whole thing. */

        if (sd_id128_equal(u->invocation_id, id))
                return 0;

        if (!sd_id128_is_null(u->invocation_id))
                (void) hashmap_remove_value(u->manager->units_by_invocation_id, &u->invocation_id, u);

        if (sd_id128_is_null(id)) {
                r = 0;
                goto reset;
        }

        r = hashmap_ensure_allocated(&u->manager->units_by_invocation_id, &id128_hash_ops);
        if (r < 0)
                goto reset;

        u->invocation_id = id;
        sd_id128_to_string(id, u->invocation_id_string);

        r = hashmap_put(u->manager->units_by_invocation_id, &u->invocation_id, u);
        if (r < 0)
                goto reset;

        return 0;

reset:
        u->invocation_id = SD_ID128_NULL;
        u->invocation_id_string[0] = 0;
        return r;
}

int unit_acquire_invocation_id(Unit *u) {
        sd_id128_t id;
        int r;

        assert(u);

        r = sd_id128_randomize(&id);
        if (r < 0)
                return log_unit_error_errno(u, r, "Failed to generate invocation ID for unit: %m");

        r = unit_set_invocation_id(u, id);
        if (r < 0)
                return log_unit_error_errno(u, r, "Failed to set invocation ID for unit: %m");

        return 0;
}

void unit_set_exec_params(Unit *u, ExecParameters *p) {
        assert(u);
        assert(p);

        p->cgroup_path = u->cgroup_path;
        SET_FLAG(p->flags, EXEC_CGROUP_DELEGATE, UNIT_CGROUP_BOOL(u, delegate));
}

int unit_fork_helper_process(Unit *u, const char *name, pid_t *ret) {
        int r;

        assert(u);
        assert(ret);

        /* Forks off a helper process and makes sure it is a member of the unit's cgroup. Returns == 0 in the child,
         * and > 0 in the parent. The pid parameter is always filled in with the child's PID. */

        (void) unit_realize_cgroup(u);

        r = safe_fork(name, FORK_REOPEN_LOG, ret);
        if (r != 0)
                return r;

        (void) default_signals(SIGNALS_CRASH_HANDLER, SIGNALS_IGNORE, -1);
        (void) ignore_signals(SIGPIPE, -1);

        (void) prctl(PR_SET_PDEATHSIG, SIGTERM);

        if (u->cgroup_path) {
                r = cg_attach_everywhere(u->manager->cgroup_supported, u->cgroup_path, 0, NULL, NULL);
                if (r < 0) {
                        log_unit_error_errno(u, r, "Failed to join unit cgroup %s: %m", u->cgroup_path);
                        _exit(EXIT_CGROUP);
                }
        }

        return 0;
}

static void unit_update_dependency_mask(Unit *u, UnitDependency d, Unit *other, UnitDependencyInfo di) {
        assert(u);
        assert(d >= 0);
        assert(d < _UNIT_DEPENDENCY_MAX);
        assert(other);

        if (di.origin_mask == 0 && di.destination_mask == 0) {
                /* No bit set anymore, let's drop the whole entry */
                assert_se(hashmap_remove(u->dependencies[d], other));
                log_unit_debug(u, "%s lost dependency %s=%s", u->id, unit_dependency_to_string(d), other->id);
        } else
                /* Mask was reduced, let's update the entry */
                assert_se(hashmap_update(u->dependencies[d], other, di.data) == 0);
}

void unit_remove_dependencies(Unit *u, UnitDependencyMask mask) {
        UnitDependency d;

        assert(u);

        /* Removes all dependencies u has on other units marked for ownership by 'mask'. */

        if (mask == 0)
                return;

        for (d = 0; d < _UNIT_DEPENDENCY_MAX; d++) {
                bool done;

                do {
                        UnitDependencyInfo di;
                        Unit *other;
                        Iterator i;

                        done = true;

                        HASHMAP_FOREACH_KEY(di.data, other, u->dependencies[d], i) {
                                UnitDependency q;

                                if ((di.origin_mask & ~mask) == di.origin_mask)
                                        continue;
                                di.origin_mask &= ~mask;
                                unit_update_dependency_mask(u, d, other, di);

                                /* We updated the dependency from our unit to the other unit now. But most dependencies
                                 * imply a reverse dependency. Hence, let's delete that one too. For that we go through
                                 * all dependency types on the other unit and delete all those which point to us and
                                 * have the right mask set. */

                                for (q = 0; q < _UNIT_DEPENDENCY_MAX; q++) {
                                        UnitDependencyInfo dj;

                                        dj.data = hashmap_get(other->dependencies[q], u);
                                        if ((dj.destination_mask & ~mask) == dj.destination_mask)
                                                continue;
                                        dj.destination_mask &= ~mask;

                                        unit_update_dependency_mask(other, q, u, dj);
                                }

                                unit_add_to_gc_queue(other);

                                done = false;
                                break;
                        }

                } while (!done);
        }
}

static int unit_export_invocation_id(Unit *u) {
        const char *p;
        int r;

        assert(u);

        if (u->exported_invocation_id)
                return 0;

        if (sd_id128_is_null(u->invocation_id))
                return 0;

        p = strjoina("/run/systemd/units/invocation:", u->id);
        r = symlink_atomic(u->invocation_id_string, p);
        if (r < 0)
                return log_unit_debug_errno(u, r, "Failed to create invocation ID symlink %s: %m", p);

        u->exported_invocation_id = true;
        return 0;
}

static int unit_export_log_level_max(Unit *u, const ExecContext *c) {
        const char *p;
        char buf[2];
        int r;

        assert(u);
        assert(c);

        if (u->exported_log_level_max)
                return 0;

        if (c->log_level_max < 0)
                return 0;

        assert(c->log_level_max <= 7);

        buf[0] = '0' + c->log_level_max;
        buf[1] = 0;

        p = strjoina("/run/systemd/units/log-level-max:", u->id);
        r = symlink_atomic(buf, p);
        if (r < 0)
                return log_unit_debug_errno(u, r, "Failed to create maximum log level symlink %s: %m", p);

        u->exported_log_level_max = true;
        return 0;
}

static int unit_export_log_extra_fields(Unit *u, const ExecContext *c) {
        _cleanup_close_ int fd = -1;
        struct iovec *iovec;
        const char *p;
        char *pattern;
        le64_t *sizes;
        ssize_t n;
        size_t i;
        int r;

        if (u->exported_log_extra_fields)
                return 0;

        if (c->n_log_extra_fields <= 0)
                return 0;

        sizes = newa(le64_t, c->n_log_extra_fields);
        iovec = newa(struct iovec, c->n_log_extra_fields * 2);

        for (i = 0; i < c->n_log_extra_fields; i++) {
                sizes[i] = htole64(c->log_extra_fields[i].iov_len);

                iovec[i*2] = IOVEC_MAKE(sizes + i, sizeof(le64_t));
                iovec[i*2+1] = c->log_extra_fields[i];
        }

        p = strjoina("/run/systemd/units/log-extra-fields:", u->id);
        pattern = strjoina(p, ".XXXXXX");

        fd = mkostemp_safe(pattern);
        if (fd < 0)
                return log_unit_debug_errno(u, fd, "Failed to create extra fields file %s: %m", p);

        n = writev(fd, iovec, c->n_log_extra_fields*2);
        if (n < 0) {
                r = log_unit_debug_errno(u, errno, "Failed to write extra fields: %m");
                goto fail;
        }

        (void) fchmod(fd, 0644);

        if (rename(pattern, p) < 0) {
                r = log_unit_debug_errno(u, errno, "Failed to rename extra fields file: %m");
                goto fail;
        }

        u->exported_log_extra_fields = true;
        return 0;

fail:
        (void) unlink(pattern);
        return r;
}

void unit_export_state_files(Unit *u) {
        const ExecContext *c;

        assert(u);

        if (!u->id)
                return;

        if (!MANAGER_IS_SYSTEM(u->manager))
                return;

        /* Exports a couple of unit properties to /run/systemd/units/, so that journald can quickly query this data
         * from there. Ideally, journald would use IPC to query this, like everybody else, but that's hard, as long as
         * the IPC system itself and PID 1 also log to the journal.
         *
         * Note that these files really shouldn't be considered API for anyone else, as use a runtime file system as
         * IPC replacement is not compatible with today's world of file system namespaces. However, this doesn't really
         * apply to communication between the journal and systemd, as we assume that these two daemons live in the same
         * namespace at least.
         *
         * Note that some of the "files" exported here are actually symlinks and not regular files. Symlinks work
         * better for storing small bits of data, in particular as we can write them with two system calls, and read
         * them with one. */

        (void) unit_export_invocation_id(u);

        c = unit_get_exec_context(u);
        if (c) {
                (void) unit_export_log_level_max(u, c);
                (void) unit_export_log_extra_fields(u, c);
        }
}

void unit_unlink_state_files(Unit *u) {
        const char *p;

        assert(u);

        if (!u->id)
                return;

        if (!MANAGER_IS_SYSTEM(u->manager))
                return;

        /* Undoes the effect of unit_export_state() */

        if (u->exported_invocation_id) {
                p = strjoina("/run/systemd/units/invocation:", u->id);
                (void) unlink(p);

                u->exported_invocation_id = false;
        }

        if (u->exported_log_level_max) {
                p = strjoina("/run/systemd/units/log-level-max:", u->id);
                (void) unlink(p);

                u->exported_log_level_max = false;
        }

        if (u->exported_log_extra_fields) {
                p = strjoina("/run/systemd/units/extra-fields:", u->id);
                (void) unlink(p);

                u->exported_log_extra_fields = false;
        }
}

int unit_prepare_exec(Unit *u) {
        int r;

        assert(u);

        /* Prepares everything so that we can fork of a process for this unit */

        (void) unit_realize_cgroup(u);

        if (u->reset_accounting) {
                (void) unit_reset_cpu_accounting(u);
                (void) unit_reset_ip_accounting(u);
                u->reset_accounting = false;
        }

        unit_export_state_files(u);

        r = unit_setup_exec_runtime(u);
        if (r < 0)
                return r;

        r = unit_setup_dynamic_creds(u);
        if (r < 0)
                return r;

        return 0;
}

static void log_leftover(pid_t pid, int sig, void *userdata) {
        _cleanup_free_ char *comm = NULL;

        (void) get_process_comm(pid, &comm);

        if (comm && comm[0] == '(') /* Most likely our own helper process (PAM?), ignore */
                return;

        log_unit_warning(userdata,
                         "Found left-over process " PID_FMT " (%s) in control group while starting unit. Ignoring.\n"
                         "This usually indicates unclean termination of a previous run, or service implementation deficiencies.",
                         pid, strna(comm));
}

void unit_warn_leftover_processes(Unit *u) {
        assert(u);

        (void) unit_pick_cgroup_path(u);

        if (!u->cgroup_path)
                return;

        (void) cg_kill_recursive(SYSTEMD_CGROUP_CONTROLLER, u->cgroup_path, 0, 0, NULL, log_leftover, u);
}

bool unit_needs_console(Unit *u) {
        ExecContext *ec;
        UnitActiveState state;

        assert(u);

        state = unit_active_state(u);

        if (UNIT_IS_INACTIVE_OR_FAILED(state))
                return false;

        if (UNIT_VTABLE(u)->needs_console)
                return UNIT_VTABLE(u)->needs_console(u);

        /* If this unit type doesn't implement this call, let's use a generic fallback implementation: */
        ec = unit_get_exec_context(u);
        if (!ec)
                return false;

        return exec_context_may_touch_console(ec);
}

const char *unit_label_path(Unit *u) {
        const char *p;

        /* Returns the file system path to use for MAC access decisions, i.e. the file to read the SELinux label off
         * when validating access checks. */

        p = u->source_path ?: u->fragment_path;
        if (!p)
                return NULL;

        /* If a unit is masked, then don't read the SELinux label of /dev/null, as that really makes no sense */
        if (path_equal(p, "/dev/null"))
                return NULL;

        return p;
}

static const char* const collect_mode_table[_COLLECT_MODE_MAX] = {
        [COLLECT_INACTIVE] = "inactive",
        [COLLECT_INACTIVE_OR_FAILED] = "inactive-or-failed",
};

DEFINE_STRING_TABLE_LOOKUP(collect_mode, CollectMode);