src/core/unit.h

/* SPDX-License-Identifier: LGPL-2.1+ */
#pragma once

#include <stdbool.h>
#include <stdlib.h>
#include <unistd.h>

#include "bpf-program.h"
#include "condition.h"
#include "emergency-action.h"
#include "install.h"
#include "list.h"
#include "unit-name.h"
#include "cgroup.h"

typedef struct UnitRef UnitRef;

typedef enum KillOperation {
        KILL_TERMINATE,
        KILL_TERMINATE_AND_LOG,
        KILL_KILL,
        KILL_ABORT,
        _KILL_OPERATION_MAX,
        _KILL_OPERATION_INVALID = -1
} KillOperation;

typedef enum CollectMode {
        COLLECT_INACTIVE,
        COLLECT_INACTIVE_OR_FAILED,
        _COLLECT_MODE_MAX,
        _COLLECT_MODE_INVALID = -1,
} CollectMode;

static inline bool UNIT_IS_ACTIVE_OR_RELOADING(UnitActiveState t) {
        return IN_SET(t, UNIT_ACTIVE, UNIT_RELOADING);
}

static inline bool UNIT_IS_ACTIVE_OR_ACTIVATING(UnitActiveState t) {
        return IN_SET(t, UNIT_ACTIVE, UNIT_ACTIVATING, UNIT_RELOADING);
}

static inline bool UNIT_IS_INACTIVE_OR_DEACTIVATING(UnitActiveState t) {
        return IN_SET(t, UNIT_INACTIVE, UNIT_FAILED, UNIT_DEACTIVATING);
}

static inline bool UNIT_IS_INACTIVE_OR_FAILED(UnitActiveState t) {
        return IN_SET(t, UNIT_INACTIVE, UNIT_FAILED);
}

/* Stores the 'reason' a dependency was created as a bit mask, i.e. due to which configuration source it came to be. We
 * use this so that we can selectively flush out parts of dependencies again. Note that the same dependency might be
 * created as a result of multiple "reasons", hence the bitmask. */
typedef enum UnitDependencyMask {
        /* Configured directly by the unit file, .wants/.requries symlink or drop-in, or as an immediate result of a
         * non-dependency option configured that way.  */
        UNIT_DEPENDENCY_FILE               = 1 << 0,

        /* As unconditional implicit dependency (not affected by unit configuration — except by the unit name and
         * type) */
        UNIT_DEPENDENCY_IMPLICIT           = 1 << 1,

        /* A dependency effected by DefaultDependencies=yes. Note that dependencies marked this way are conceptually
         * just a subset of UNIT_DEPENDENCY_FILE, as DefaultDependencies= is itself a unit file setting that can only
         * be set in unit files. We make this two separate bits only to help debugging how dependencies came to be. */
        UNIT_DEPENDENCY_DEFAULT            = 1 << 2,

        /* A dependency created from udev rules */
        UNIT_DEPENDENCY_UDEV               = 1 << 3,

        /* A dependency created because of some unit's RequiresMountsFor= setting */
        UNIT_DEPENDENCY_PATH               = 1 << 4,

        /* A dependency created because of data read from /proc/self/mountinfo and no other configuration source */
        UNIT_DEPENDENCY_MOUNTINFO_IMPLICIT = 1 << 5,

        /* A dependency created because of data read from /proc/self/mountinfo, but conditionalized by
         * DefaultDependencies= and thus also involving configuration from UNIT_DEPENDENCY_FILE sources */
        UNIT_DEPENDENCY_MOUNTINFO_DEFAULT  = 1 << 6,

        /* A dependency created because of data read from /proc/swaps and no other configuration source */
        UNIT_DEPENDENCY_PROC_SWAP          = 1 << 7,

        _UNIT_DEPENDENCY_MASK_FULL         = (1 << 8) - 1,
} UnitDependencyMask;

/* The Unit's dependencies[] hashmaps use this structure as value. It has the same size as a void pointer, and thus can
 * be stored directly as hashmap value, without any indirection. Note that this stores two masks, as both the origin
 * and the destination of a dependency might have created it. */
typedef union UnitDependencyInfo {
        void *data;
        struct {
                UnitDependencyMask origin_mask:16;
                UnitDependencyMask destination_mask:16;
        } _packed_;
} UnitDependencyInfo;

#include "job.h"

struct UnitRef {
        /* Keeps tracks of references to a unit. This is useful so
         * that we can merge two units if necessary and correct all
         * references to them */

        Unit *source, *target;
        LIST_FIELDS(UnitRef, refs_by_target);
};

typedef enum UnitCGroupBPFState {
        UNIT_CGROUP_BPF_OFF = 0,
        UNIT_CGROUP_BPF_ON = 1,
        UNIT_CGROUP_BPF_INVALIDATED = -1,
} UnitCGroupBPFState;

typedef struct Unit {
        Manager *manager;

        UnitType type;
        UnitLoadState load_state;
        Unit *merged_into;

        char *id; /* One name is special because we use it for identification. Points to an entry in the names set */
        char *instance;

        Set *names;

        /* For each dependency type we maintain a Hashmap whose key is the Unit* object, and the value encodes why the
         * dependency exists, using the UnitDependencyInfo type */
        Hashmap *dependencies[_UNIT_DEPENDENCY_MAX];

        /* Similar, for RequiresMountsFor= path dependencies. The key is the path, the value the UnitDependencyInfo type */
        Hashmap *requires_mounts_for;

        char *description;
        char **documentation;

        char *fragment_path; /* if loaded from a config file this is the primary path to it */
        char *source_path; /* if converted, the source file */
        char **dropin_paths;

        usec_t fragment_mtime;
        usec_t source_mtime;
        usec_t dropin_mtime;

        /* If this is a transient unit we are currently writing, this is where we are writing it to */
        FILE *transient_file;

        /* If there is something to do with this unit, then this is the installed job for it */
        Job *job;

        /* JOB_NOP jobs are special and can be installed without disturbing the real job. */
        Job *nop_job;

        /* The slot used for watching NameOwnerChanged signals */
        sd_bus_slot *match_bus_slot;

        /* References to this unit from clients */
        sd_bus_track *bus_track;
        char **deserialized_refs;

        /* Job timeout and action to take */
        usec_t job_timeout;
        usec_t job_running_timeout;
        bool job_running_timeout_set:1;
        EmergencyAction job_timeout_action;
        char *job_timeout_reboot_arg;

        /* References to this */
        LIST_HEAD(UnitRef, refs_by_target);

        /* Conditions to check */
        LIST_HEAD(Condition, conditions);
        LIST_HEAD(Condition, asserts);

        dual_timestamp condition_timestamp;
        dual_timestamp assert_timestamp;

        /* Updated whenever the low-level state changes */
        dual_timestamp state_change_timestamp;

        /* Updated whenever the (high-level) active state enters or leaves the active or inactive states */
        dual_timestamp inactive_exit_timestamp;
        dual_timestamp active_enter_timestamp;
        dual_timestamp active_exit_timestamp;
        dual_timestamp inactive_enter_timestamp;

        UnitRef slice;

        /* Per type list */
        LIST_FIELDS(Unit, units_by_type);

        /* All units which have requires_mounts_for set */
        LIST_FIELDS(Unit, has_requires_mounts_for);

        /* Load queue */
        LIST_FIELDS(Unit, load_queue);

        /* D-Bus queue */
        LIST_FIELDS(Unit, dbus_queue);

        /* Cleanup queue */
        LIST_FIELDS(Unit, cleanup_queue);

        /* GC queue */
        LIST_FIELDS(Unit, gc_queue);

        /* CGroup realize members queue */
        LIST_FIELDS(Unit, cgroup_realize_queue);

        /* cgroup empty queue */
        LIST_FIELDS(Unit, cgroup_empty_queue);

        /* Target dependencies queue */
        LIST_FIELDS(Unit, target_deps_queue);

        /* PIDs we keep an eye on. Note that a unit might have many
         * more, but these are the ones we care enough about to
         * process SIGCHLD for */
        Set *pids;

        /* Used in SIGCHLD and sd_notify() message event invocation logic to avoid that we dispatch the same event
         * multiple times on the same unit. */
        unsigned sigchldgen;
        unsigned notifygen;

        /* Used during GC sweeps */
        unsigned gc_marker;

        /* Error code when we didn't manage to load the unit (negative) */
        int load_error;

        /* Put a ratelimit on unit starting */
        RateLimit start_limit;
        EmergencyAction start_limit_action;

        EmergencyAction failure_action;
        EmergencyAction success_action;
        char *reboot_arg;

        /* Make sure we never enter endless loops with the check unneeded logic, or the BindsTo= logic */
        RateLimit auto_stop_ratelimit;

        /* Reference to a specific UID/GID */
        uid_t ref_uid;
        gid_t ref_gid;

        /* Cached unit file state and preset */
        UnitFileState unit_file_state;
        int unit_file_preset;

        /* Where the cpu.stat or cpuacct.usage was at the time the unit was started */
        nsec_t cpu_usage_base;
        nsec_t cpu_usage_last; /* the most recently read value */

        /* Counterparts in the cgroup filesystem */
        char *cgroup_path;
        CGroupMask cgroup_realized_mask;
        CGroupMask cgroup_enabled_mask;
        CGroupMask cgroup_subtree_mask;
        CGroupMask cgroup_members_mask;
        int cgroup_inotify_wd;

        /* IP BPF Firewalling/accounting */
        int ip_accounting_ingress_map_fd;
        int ip_accounting_egress_map_fd;

        int ipv4_allow_map_fd;
        int ipv6_allow_map_fd;
        int ipv4_deny_map_fd;
        int ipv6_deny_map_fd;

        BPFProgram *ip_bpf_ingress, *ip_bpf_ingress_installed;
        BPFProgram *ip_bpf_egress, *ip_bpf_egress_installed;

        uint64_t ip_accounting_extra[_CGROUP_IP_ACCOUNTING_METRIC_MAX];

        /* Low-priority event source which is used to remove watched PIDs that have gone away, and subscribe to any new
         * ones which might have appeared. */
        sd_event_source *rewatch_pids_event_source;

        /* How to start OnFailure units */
        JobMode on_failure_job_mode;

        /* Tweaking the GC logic */
        CollectMode collect_mode;

        /* The current invocation ID */
        sd_id128_t invocation_id;
        char invocation_id_string[SD_ID128_STRING_MAX]; /* useful when logging */

        /* Garbage collect us we nobody wants or requires us anymore */
        bool stop_when_unneeded;

        /* Create default dependencies */
        bool default_dependencies;

        /* Refuse manual starting, allow starting only indirectly via dependency. */
        bool refuse_manual_start;

        /* Don't allow the user to stop this unit manually, allow stopping only indirectly via dependency. */
        bool refuse_manual_stop;

        /* Allow isolation requests */
        bool allow_isolate;

        /* Ignore this unit when isolating */
        bool ignore_on_isolate;

        /* Did the last condition check succeed? */
        bool condition_result;
        bool assert_result;

        /* Is this a transient unit? */
        bool transient;

        /* Is this a unit that is always running and cannot be stopped? */
        bool perpetual;

        bool in_load_queue:1;
        bool in_dbus_queue:1;
        bool in_cleanup_queue:1;
        bool in_gc_queue:1;
        bool in_cgroup_realize_queue:1;
        bool in_cgroup_empty_queue:1;
        bool in_target_deps_queue:1;

        bool sent_dbus_new_signal:1;

        bool in_audit:1;
        bool on_console:1;

        bool cgroup_realized:1;
        bool cgroup_members_mask_valid:1;
        bool cgroup_subtree_mask_valid:1;

        UnitCGroupBPFState cgroup_bpf_state:2;

        /* Reset cgroup accounting next time we fork something off */
        bool reset_accounting:1;

        bool start_limit_hit:1;

        /* Did we already invoke unit_coldplug() for this unit? */
        bool coldplugged:1;

        /* For transient units: whether to add a bus track reference after creating the unit */
        bool bus_track_add:1;

        /* Remember which unit state files we created */
        bool exported_invocation_id:1;
        bool exported_log_level_max:1;
        bool exported_log_extra_fields:1;

        /* When writing transient unit files, stores which section we stored last. If < 0, we didn't write any yet. If
         * == 0 we are in the [Unit] section, if > 0 we are in the unit type-specific section. */
        int last_section_private:2;
} Unit;

typedef struct UnitStatusMessageFormats {
        const char *starting_stopping[2];
        const char *finished_start_job[_JOB_RESULT_MAX];
        const char *finished_stop_job[_JOB_RESULT_MAX];
} UnitStatusMessageFormats;

/* Flags used when writing drop-in files or transient unit files */
typedef enum UnitWriteFlags {
        /* Write a runtime unit file or drop-in (i.e. one below /run) */
        UNIT_RUNTIME           = 1 << 0,

        /* Write a persistent drop-in (i.e. one below /etc) */
        UNIT_PERSISTENT        = 1 << 1,

        /* Place this item in the per-unit-type private section, instead of [Unit] */
        UNIT_PRIVATE           = 1 << 2,

        /* Apply specifier escaping before writing */
        UNIT_ESCAPE_SPECIFIERS = 1 << 3,

        /* Apply C escaping before writing */
        UNIT_ESCAPE_C          = 1 << 4,
} UnitWriteFlags;

/* Returns true if neither persistent, nor runtime storage is requested, i.e. this is a check invocation only */
#define UNIT_WRITE_FLAGS_NOOP(flags) (((flags) & (UNIT_RUNTIME|UNIT_PERSISTENT)) == 0)

#include "kill.h"

typedef struct UnitVTable {
        /* How much memory does an object of this unit type need */
        size_t object_size;

        /* If greater than 0, the offset into the object where
         * ExecContext is found, if the unit type has that */
        size_t exec_context_offset;

        /* If greater than 0, the offset into the object where
         * CGroupContext is found, if the unit type has that */
        size_t cgroup_context_offset;

        /* If greater than 0, the offset into the object where
         * KillContext is found, if the unit type has that */
        size_t kill_context_offset;

        /* If greater than 0, the offset into the object where the
         * pointer to ExecRuntime is found, if the unit type has
         * that */
        size_t exec_runtime_offset;

        /* If greater than 0, the offset into the object where the pointer to DynamicCreds is found, if the unit type
         * has that. */
        size_t dynamic_creds_offset;

        /* The name of the configuration file section with the private settings of this unit */
        const char *private_section;

        /* Config file sections this unit type understands, separated
         * by NUL chars */
        const char *sections;

        /* This should reset all type-specific variables. This should
         * not allocate memory, and is called with zero-initialized
         * data. It should hence only initialize variables that need
         * to be set != 0. */
        void (*init)(Unit *u);

        /* This should free all type-specific variables. It should be
         * idempotent. */
        void (*done)(Unit *u);

        /* Actually load data from disk. This may fail, and should set
         * load_state to UNIT_LOADED, UNIT_MERGED or leave it at
         * UNIT_STUB if no configuration could be found. */
        int (*load)(Unit *u);

        /* During deserialization we only record the intended state to return to. With coldplug() we actually put the
         * deserialized state in effect. This is where unit_notify() should be called to start things up. */
        int (*coldplug)(Unit *u);

        /* This is called shortly after all units' coldplug() call was invoked. It's supposed to catch up state changes
         * we missed so far (for example because they took place while we were reloading/reexecing) */
        void (*catchup)(Unit *u);

        void (*dump)(Unit *u, FILE *f, const char *prefix);

        int (*start)(Unit *u);
        int (*stop)(Unit *u);
        int (*reload)(Unit *u);

        int (*kill)(Unit *u, KillWho w, int signo, sd_bus_error *error);

        bool (*can_reload)(Unit *u);

        /* Write all data that cannot be restored from other sources
         * away using unit_serialize_item() */
        int (*serialize)(Unit *u, FILE *f, FDSet *fds);

        /* Restore one item from the serialization */
        int (*deserialize_item)(Unit *u, const char *key, const char *data, FDSet *fds);

        /* Try to match up fds with what we need for this unit */
        void (*distribute_fds)(Unit *u, FDSet *fds);

        /* Boils down the more complex internal state of this unit to
         * a simpler one that the engine can understand */
        UnitActiveState (*active_state)(Unit *u);

        /* Returns the substate specific to this unit type as
         * string. This is purely information so that we can give the
         * user a more fine grained explanation in which actual state a
         * unit is in. */
        const char* (*sub_state_to_string)(Unit *u);

        /* Additionally to UnitActiveState determine whether unit is to be restarted. */
        bool (*will_restart)(Unit *u);

        /* Return false when there is a reason to prevent this unit from being gc'ed
         * even though nothing references it and it isn't active in any way. */
        bool (*may_gc)(Unit *u);

        /* When the unit is not running and no job for it queued we shall release its runtime resources */
        void (*release_resources)(Unit *u);

        /* Invoked on every child that died */
        void (*sigchld_event)(Unit *u, pid_t pid, int code, int status);

        /* Reset failed state if we are in failed state */
        void (*reset_failed)(Unit *u);

        /* Called whenever any of the cgroups this unit watches for
         * ran empty */
        void (*notify_cgroup_empty)(Unit *u);

        /* Called whenever a process of this unit sends us a message */
        void (*notify_message)(Unit *u, const struct ucred *ucred, char **tags, FDSet *fds);

        /* Called whenever a name this Unit registered for comes or goes away. */
        void (*bus_name_owner_change)(Unit *u, const char *name, const char *old_owner, const char *new_owner);

        /* Called for each property that is being set */
        int (*bus_set_property)(Unit *u, const char *name, sd_bus_message *message, UnitWriteFlags flags, sd_bus_error *error);

        /* Called after at least one property got changed to apply the necessary change */
        int (*bus_commit_properties)(Unit *u);

        /* Return the unit this unit is following */
        Unit *(*following)(Unit *u);

        /* Return the set of units that are following each other */
        int (*following_set)(Unit *u, Set **s);

        /* Invoked each time a unit this unit is triggering changes
         * state or gains/loses a job */
        void (*trigger_notify)(Unit *u, Unit *trigger);

        /* Called whenever CLOCK_REALTIME made a jump */
        void (*time_change)(Unit *u);

        /* Called whenever /etc/localtime was modified */
        void (*timezone_change)(Unit *u);

        /* Returns the next timeout of a unit */
        int (*get_timeout)(Unit *u, usec_t *timeout);

        /* Returns the main PID if there is any defined, or 0. */
        pid_t (*main_pid)(Unit *u);

        /* Returns the main PID if there is any defined, or 0. */
        pid_t (*control_pid)(Unit *u);

        /* Returns true if the unit currently needs access to the console */
        bool (*needs_console)(Unit *u);

        /* Like the enumerate() callback further down, but only enumerates the perpetual units, i.e. all units that
         * unconditionally exist and are always active. The main reason to keep both enumeration functions separate is
         * philosophical: the state of perpetual units should be put in place by coldplug(), while the state of those
         * discovered through regular enumeration should be put in place by catchup(), see below. */
        void (*enumerate_perpetual)(Manager *m);

        /* This is called for each unit type and should be used to enumerate units already existing in the system
         * internally and load them. However, everything that is loaded here should still stay in inactive state. It is
         * the job of the catchup() call above to put the units into the discovered state. */
        void (*enumerate)(Manager *m);

        /* Type specific cleanups. */
        void (*shutdown)(Manager *m);

        /* If this function is set and return false all jobs for units
         * of this type will immediately fail. */
        bool (*supported)(void);

        /* The bus vtable */
        const sd_bus_vtable *bus_vtable;

        /* The strings to print in status messages */
        UnitStatusMessageFormats status_message_formats;

        /* True if transient units of this type are OK */
        bool can_transient:1;

        /* True if cgroup delegation is permissible */
        bool can_delegate:1;

        /* True if units of this type shall be startable only once and then never again */
        bool once_only:1;

        /* True if queued jobs of this type should be GC'ed if no other job needs them anymore */
        bool gc_jobs:1;
} UnitVTable;

extern const UnitVTable * const unit_vtable[_UNIT_TYPE_MAX];

#define UNIT_VTABLE(u) unit_vtable[(u)->type]

/* For casting a unit into the various unit types */
#define DEFINE_CAST(UPPERCASE, MixedCase)                               \
        static inline MixedCase* UPPERCASE(Unit *u) {                   \
                if (_unlikely_(!u || u->type != UNIT_##UPPERCASE))      \
                        return NULL;                                    \
                                                                        \
                return (MixedCase*) u;                                  \
        }

/* For casting the various unit types into a unit */
#define UNIT(u) (&(u)->meta)

#define UNIT_HAS_EXEC_CONTEXT(u) (UNIT_VTABLE(u)->exec_context_offset > 0)
#define UNIT_HAS_CGROUP_CONTEXT(u) (UNIT_VTABLE(u)->cgroup_context_offset > 0)
#define UNIT_HAS_KILL_CONTEXT(u) (UNIT_VTABLE(u)->kill_context_offset > 0)

#define UNIT_TRIGGER(u) ((Unit*) hashmap_first_key((u)->dependencies[UNIT_TRIGGERS]))

Unit *unit_new(Manager *m, size_t size);
void unit_free(Unit *u);
DEFINE_TRIVIAL_CLEANUP_FUNC(Unit *, unit_free);

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

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

int unit_add_dependency_by_name(Unit *u, UnitDependency d, const char *name, const char *filename, bool add_reference, UnitDependencyMask 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);

int unit_add_exec_dependencies(Unit *u, ExecContext *c);

int unit_choose_id(Unit *u, const char *name);
int unit_set_description(Unit *u, const char *description);

bool unit_may_gc(Unit *u);

void unit_add_to_load_queue(Unit *u);
void unit_add_to_dbus_queue(Unit *u);
void unit_add_to_cleanup_queue(Unit *u);
void unit_add_to_gc_queue(Unit *u);
void unit_add_to_target_deps_queue(Unit *u);

int unit_merge(Unit *u, Unit *other);
int unit_merge_by_name(Unit *u, const char *other);

Unit *unit_follow_merge(Unit *u) _pure_;

int unit_load_fragment_and_dropin(Unit *u);
int unit_load_fragment_and_dropin_optional(Unit *u);
int unit_load(Unit *unit);

int unit_set_slice(Unit *u, Unit *slice);
int unit_set_default_slice(Unit *u);

const char *unit_description(Unit *u) _pure_;

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

UnitActiveState unit_active_state(Unit *u);

const char* unit_sub_state_to_string(Unit *u);

void unit_dump(Unit *u, FILE *f, const char *prefix);

bool unit_can_reload(Unit *u) _pure_;
bool unit_can_start(Unit *u) _pure_;
bool unit_can_stop(Unit *u) _pure_;
bool unit_can_isolate(Unit *u) _pure_;

int unit_start(Unit *u);
int unit_stop(Unit *u);
int unit_reload(Unit *u);

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

typedef enum UnitNotifyFlags {
        UNIT_NOTIFY_RELOAD_FAILURE    = 1 << 0,
        UNIT_NOTIFY_WILL_AUTO_RESTART = 1 << 1,
} UnitNotifyFlags;

void unit_notify(Unit *u, UnitActiveState os, UnitActiveState ns, UnitNotifyFlags flags);

int unit_watch_pid(Unit *u, pid_t pid);
void unit_unwatch_pid(Unit *u, pid_t pid);
void unit_unwatch_all_pids(Unit *u);

int unit_enqueue_rewatch_pids(Unit *u);
void unit_dequeue_rewatch_pids(Unit *u);

int unit_install_bus_match(Unit *u, sd_bus *bus, const char *name);
int unit_watch_bus_name(Unit *u, const char *name);
void unit_unwatch_bus_name(Unit *u, const char *name);

bool unit_job_is_applicable(Unit *u, JobType j);

int set_unit_path(const char *p);

char *unit_dbus_path(Unit *u);
char *unit_dbus_path_invocation_id(Unit *u);

int unit_load_related_unit(Unit *u, const char *type, Unit **_found);

bool unit_can_serialize(Unit *u) _pure_;

int unit_serialize(Unit *u, FILE *f, FDSet *fds, bool serialize_jobs);
int unit_deserialize(Unit *u, FILE *f, FDSet *fds);
void unit_deserialize_skip(FILE *f);

int unit_serialize_item(Unit *u, FILE *f, const char *key, const char *value);
int unit_serialize_item_escaped(Unit *u, FILE *f, const char *key, const char *value);
int unit_serialize_item_fd(Unit *u, FILE *f, FDSet *fds, const char *key, int fd);
void unit_serialize_item_format(Unit *u, FILE *f, const char *key, const char *value, ...) _printf_(4,5);

int unit_add_node_dependency(Unit *u, const char *what, bool wants, UnitDependency d, UnitDependencyMask mask);

int unit_coldplug(Unit *u);
void unit_catchup(Unit *u);

void unit_status_printf(Unit *u, const char *status, const char *unit_status_msg_format) _printf_(3, 0);
void unit_status_emit_starting_stopping_reloading(Unit *u, JobType t);

bool unit_need_daemon_reload(Unit *u);

void unit_reset_failed(Unit *u);

Unit *unit_following(Unit *u);
int unit_following_set(Unit *u, Set **s);

const char *unit_slice_name(Unit *u);

bool unit_stop_pending(Unit *u) _pure_;
bool unit_inactive_or_pending(Unit *u) _pure_;
bool unit_active_or_pending(Unit *u);
bool unit_will_restart(Unit *u);

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

void unit_start_on_failure(Unit *u);
void unit_trigger_notify(Unit *u);

UnitFileState unit_get_unit_file_state(Unit *u);
int unit_get_unit_file_preset(Unit *u);

Unit* unit_ref_set(UnitRef *ref, Unit *source, Unit *target);
void unit_ref_unset(UnitRef *ref);

#define UNIT_DEREF(ref) ((ref).target)
#define UNIT_ISSET(ref) (!!(ref).target)

int unit_patch_contexts(Unit *u);

ExecContext *unit_get_exec_context(Unit *u) _pure_;
KillContext *unit_get_kill_context(Unit *u) _pure_;
CGroupContext *unit_get_cgroup_context(Unit *u) _pure_;

ExecRuntime *unit_get_exec_runtime(Unit *u) _pure_;

int unit_setup_exec_runtime(Unit *u);
int unit_setup_dynamic_creds(Unit *u);

char* unit_escape_setting(const char *s, UnitWriteFlags flags, char **buf);
char* unit_concat_strv(char **l, UnitWriteFlags flags);

int unit_write_setting(Unit *u, UnitWriteFlags flags, const char *name, const char *data);
int unit_write_settingf(Unit *u, UnitWriteFlags mode, const char *name, const char *format, ...) _printf_(4,5);

int unit_kill_context(Unit *u, KillContext *c, KillOperation k, pid_t main_pid, pid_t control_pid, bool main_pid_alien);

int unit_make_transient(Unit *u);

int unit_require_mounts_for(Unit *u, const char *path, UnitDependencyMask mask);

bool unit_type_supported(UnitType t);

bool unit_is_pristine(Unit *u);

pid_t unit_control_pid(Unit *u);
pid_t unit_main_pid(Unit *u);

static inline bool unit_supported(Unit *u) {
        return unit_type_supported(u->type);
}

void unit_warn_if_dir_nonempty(Unit *u, const char* where);
int unit_fail_if_noncanonical(Unit *u, const char* where);

int unit_start_limit_test(Unit *u);

void unit_unref_uid(Unit *u, bool destroy_now);
int unit_ref_uid(Unit *u, uid_t uid, bool clean_ipc);

void unit_unref_gid(Unit *u, bool destroy_now);
int unit_ref_gid(Unit *u, gid_t gid, bool clean_ipc);

int unit_ref_uid_gid(Unit *u, uid_t uid, gid_t gid);
void unit_unref_uid_gid(Unit *u, bool destroy_now);

void unit_notify_user_lookup(Unit *u, uid_t uid, gid_t gid);

int unit_set_invocation_id(Unit *u, sd_id128_t id);
int unit_acquire_invocation_id(Unit *u);

bool unit_shall_confirm_spawn(Unit *u);

void unit_set_exec_params(Unit *s, ExecParameters *p);

int unit_fork_helper_process(Unit *u, const char *name, pid_t *ret);

void unit_remove_dependencies(Unit *u, UnitDependencyMask mask);

void unit_export_state_files(Unit *u);
void unit_unlink_state_files(Unit *u);

int unit_prepare_exec(Unit *u);

void unit_warn_leftover_processes(Unit *u);

bool unit_needs_console(Unit *u);

const char *unit_label_path(Unit *u);

int unit_pid_attachable(Unit *unit, pid_t pid, sd_bus_error *error);

/* Macros which append UNIT= or USER_UNIT= to the message */

#define log_unit_full(unit, level, error, ...)                          \
        ({                                                              \
                const Unit *_u = (unit);                                \
                _u ? log_object_internal(level, error, __FILE__, __LINE__, __func__, _u->manager->unit_log_field, _u->id, _u->manager->invocation_log_field, _u->invocation_id_string, ##__VA_ARGS__) : \
                        log_internal(level, error, __FILE__, __LINE__, __func__, ##__VA_ARGS__); \
        })

#define log_unit_debug(unit, ...)   log_unit_full(unit, LOG_DEBUG, 0, ##__VA_ARGS__)
#define log_unit_info(unit, ...)    log_unit_full(unit, LOG_INFO, 0, ##__VA_ARGS__)
#define log_unit_notice(unit, ...)  log_unit_full(unit, LOG_NOTICE, 0, ##__VA_ARGS__)
#define log_unit_warning(unit, ...) log_unit_full(unit, LOG_WARNING, 0, ##__VA_ARGS__)
#define log_unit_error(unit, ...)   log_unit_full(unit, LOG_ERR, 0, ##__VA_ARGS__)

#define log_unit_debug_errno(unit, error, ...)   log_unit_full(unit, LOG_DEBUG, error, ##__VA_ARGS__)
#define log_unit_info_errno(unit, error, ...)    log_unit_full(unit, LOG_INFO, error, ##__VA_ARGS__)
#define log_unit_notice_errno(unit, error, ...)  log_unit_full(unit, LOG_NOTICE, error, ##__VA_ARGS__)
#define log_unit_warning_errno(unit, error, ...) log_unit_full(unit, LOG_WARNING, error, ##__VA_ARGS__)
#define log_unit_error_errno(unit, error, ...)   log_unit_full(unit, LOG_ERR, error, ##__VA_ARGS__)

#define LOG_UNIT_MESSAGE(unit, fmt, ...) "MESSAGE=%s: " fmt, (unit)->id, ##__VA_ARGS__
#define LOG_UNIT_ID(unit) (unit)->manager->unit_log_format_string, (unit)->id
#define LOG_UNIT_INVOCATION_ID(unit) (unit)->manager->invocation_log_format_string, (unit)->invocation_id_string

const char* collect_mode_to_string(CollectMode m) _const_;
CollectMode collect_mode_from_string(const char *s) _pure_;