/* SPDX-License-Identifier: LGPL-2.1-or-later */

#include <errno.h>

#include "alloc-util.h"
#include "dbus-slice.h"
#include "dbus-unit.h"
#include "fd-util.h"
#include "log.h"
#include "serialize.h"
#include "slice.h"
#include "special.h"
#include "string-util.h"
#include "strv.h"
#include "unit-name.h"
#include "unit.h"

static const UnitActiveState state_translation_table[_SLICE_STATE_MAX] = {
        [SLICE_DEAD]   = UNIT_INACTIVE,
        [SLICE_ACTIVE] = UNIT_ACTIVE,
};

static void slice_init(Unit *u) {
        assert(u);
        assert(u->load_state == UNIT_STUB);

        u->ignore_on_isolate = true;
}

static void slice_set_state(Slice *s, SliceState state) {
        SliceState old_state;

        assert(s);

        if (s->state != state)
                bus_unit_send_pending_change_signal(UNIT(s), false);

        old_state = s->state;
        s->state = state;

        if (state != old_state)
                log_unit_debug(UNIT(s), "Changed %s -> %s",
                               slice_state_to_string(old_state), slice_state_to_string(state));

        unit_notify(UNIT(s), state_translation_table[old_state], state_translation_table[state], /* reload_success = */ true);
}

static int slice_add_parent_slice(Slice *s) {
        Unit *u = UNIT(ASSERT_PTR(s));
        _cleanup_free_ char *a = NULL;
        int r;

        if (UNIT_GET_SLICE(u))
                return 0;

        r = slice_build_parent_slice(u->id, &a);
        if (r <= 0) /* 0 means root slice */
                return r;

        return unit_add_dependency_by_name(u, UNIT_IN_SLICE, a, true, UNIT_DEPENDENCY_IMPLICIT);
}

static int slice_add_default_dependencies(Slice *s) {
        int r;

        assert(s);

        if (!UNIT(s)->default_dependencies)
                return 0;

        /* Make sure slices are unloaded on shutdown */
        r = unit_add_two_dependencies_by_name(
                        UNIT(s),
                        UNIT_BEFORE, UNIT_CONFLICTS,
                        SPECIAL_SHUTDOWN_TARGET, true, UNIT_DEPENDENCY_DEFAULT);
        if (r < 0)
                return r;

        return 0;
}

static int slice_verify(Slice *s) {
        _cleanup_free_ char *parent = NULL;
        int r;

        assert(s);
        assert(UNIT(s)->load_state == UNIT_LOADED);

        if (!slice_name_is_valid(UNIT(s)->id))
                return log_unit_error_errno(UNIT(s), SYNTHETIC_ERRNO(ENOEXEC), "Slice name %s is not valid. Refusing.", UNIT(s)->id);

        r = slice_build_parent_slice(UNIT(s)->id, &parent);
        if (r < 0)
                return log_unit_error_errno(UNIT(s), r, "Failed to determine parent slice: %m");

        /* If recursive errors are to be ignored, the parent slice should not be verified */
        if (UNIT(s)->manager && FLAGS_SET(UNIT(s)->manager->test_run_flags, MANAGER_TEST_RUN_IGNORE_DEPENDENCIES))
                return 0;

        if (parent ? !unit_has_name(UNIT_GET_SLICE(UNIT(s)), parent) : !!UNIT_GET_SLICE(UNIT(s)))
                return log_unit_error_errno(UNIT(s), SYNTHETIC_ERRNO(ENOEXEC), "Located outside of parent slice. Refusing.");

        return 0;
}

static int slice_load_root_slice(Unit *u) {
        assert(u);

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

        u->perpetual = true;

        /* The root slice is a bit special. For example it is always running and cannot be terminated. Because of its
         * special semantics we synthesize it here, instead of relying on the unit file on disk. */

        u->default_dependencies = false;

        if (!u->description)
                u->description = strdup("Root Slice");
        if (!u->documentation)
                u->documentation = strv_new("man:systemd.special(7)");

        return 1;
}

static int slice_load_system_slice(Unit *u) {
        assert(u);

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

        u->perpetual = true;

        /* The system slice is a bit special. For example it is always running and cannot be terminated. Because of its
         * special semantics we synthesize it here, instead of relying on the unit file on disk. */

        u->default_dependencies = false;

        if (!u->description)
                u->description = strdup("System Slice");
        if (!u->documentation)
                u->documentation = strv_new("man:systemd.special(7)");

        return 1;
}

static int slice_load(Unit *u) {
        Slice *s = ASSERT_PTR(SLICE(u));
        int r;

        assert(u->load_state == UNIT_STUB);

        r = slice_load_root_slice(u);
        if (r < 0)
                return r;
        r = slice_load_system_slice(u);
        if (r < 0)
                return r;

        r = unit_load_fragment_and_dropin(u, false);
        if (r < 0)
                return r;

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

        /* This is a new unit? Then let's add in some extras */
        r = unit_patch_contexts(u);
        if (r < 0)
                return r;

        r = slice_add_parent_slice(s);
        if (r < 0)
                return r;

        r = slice_add_default_dependencies(s);
        if (r < 0)
                return r;

        if (!u->description) {
                _cleanup_free_ char *tmp = NULL;

                r = unit_name_to_path(u->id, &tmp);
                if (r >= 0)  /* Failure is ignored… */
                        u->description = strjoin("Slice ", tmp);
        }

        return slice_verify(s);
}

static int slice_coldplug(Unit *u) {
        Slice *s = ASSERT_PTR(SLICE(u));

        assert(s->state == SLICE_DEAD);

        if (s->deserialized_state != s->state)
                slice_set_state(s, s->deserialized_state);

        return 0;
}

static void slice_dump(Unit *u, FILE *f, const char *prefix) {
        Slice *s = ASSERT_PTR(SLICE(u));

        assert(s);
        assert(f);
        assert(prefix);

        fprintf(f,
                "%sSlice State: %s\n",
                prefix, slice_state_to_string(s->state));

        cgroup_context_dump(u, f, prefix);
}

static int slice_start(Unit *u) {
        Slice *s = ASSERT_PTR(SLICE(u));
        int r;

        assert(s->state == SLICE_DEAD);

        r = unit_acquire_invocation_id(u);
        if (r < 0)
                return r;

        (void) unit_realize_cgroup(u);
        (void) unit_reset_accounting(u);

        slice_set_state(s, SLICE_ACTIVE);
        return 1;
}

static int slice_stop(Unit *u) {
        Slice *s = ASSERT_PTR(SLICE(u));

        assert(s->state == SLICE_ACTIVE);

        /* We do not need to destroy the cgroup explicitly,
         * unit_notify() will do that for us anyway. */

        slice_set_state(s, SLICE_DEAD);
        return 1;
}

static int slice_serialize(Unit *u, FILE *f, FDSet *fds) {
        Slice *s = ASSERT_PTR(SLICE(u));

        assert(f);
        assert(fds);

        (void) serialize_item(f, "state", slice_state_to_string(s->state));

        return 0;
}

static int slice_deserialize_item(Unit *u, const char *key, const char *value, FDSet *fds) {
        Slice *s = ASSERT_PTR(SLICE(u));

        assert(key);
        assert(value);
        assert(fds);

        if (streq(key, "state")) {
                SliceState state;

                state = slice_state_from_string(value);
                if (state < 0)
                        log_unit_debug(u, "Failed to parse state: %s", value);
                else
                        s->deserialized_state = state;

        } else
                log_unit_debug(u, "Unknown serialization key: %s", key);

        return 0;
}

static UnitActiveState slice_active_state(Unit *u) {
        Slice *s = ASSERT_PTR(SLICE(u));

        return state_translation_table[s->state];
}

static const char *slice_sub_state_to_string(Unit *u) {
        Slice *s = ASSERT_PTR(SLICE(u));

        return slice_state_to_string(s->state);
}

static int slice_make_perpetual(Manager *m, const char *name, Unit **ret) {
        Unit *u;
        int r;

        assert(m);
        assert(name);

        u = manager_get_unit(m, name);
        if (!u) {
                r = unit_new_for_name(m, sizeof(Slice), name, &u);
                if (r < 0)
                        return log_error_errno(r, "Failed to allocate the special %s unit: %m", name);
        }

        u->perpetual = true;
        SLICE(u)->deserialized_state = SLICE_ACTIVE;

        unit_add_to_load_queue(u);
        unit_add_to_dbus_queue(u);

        if (ret)
                *ret = u;

        return 0;
}

static void slice_enumerate_perpetual(Manager *m) {
        Unit *u;
        int r;

        assert(m);

        r = slice_make_perpetual(m, SPECIAL_ROOT_SLICE, &u);
        if (r >= 0 && manager_owns_host_root_cgroup(m)) {
                Slice *s = SLICE(u);

                /* If we are managing the root cgroup then this means our root slice covers the whole system, which
                 * means the kernel will track CPU/tasks/memory for us anyway, and it is all available in /proc. Let's
                 * hence turn accounting on here, so that our APIs to query this data are available. */

                s->cgroup_context.cpu_accounting = true;
                s->cgroup_context.tasks_accounting = true;
                s->cgroup_context.memory_accounting = true;
        }

        if (MANAGER_IS_SYSTEM(m))
                (void) slice_make_perpetual(m, SPECIAL_SYSTEM_SLICE, NULL);
}

static bool slice_can_freeze(Unit *s) {
        Unit *member;

        assert(s);

        UNIT_FOREACH_DEPENDENCY(member, s, UNIT_ATOM_SLICE_OF)
                if (!unit_can_freeze(member))
                        return false;
        return true;
}

static int slice_freezer_action(Unit *s, FreezerAction action) {
        FreezerAction child_action;
        Unit *member;
        int r;

        assert(s);
        assert(IN_SET(action, FREEZER_FREEZE, FREEZER_PARENT_FREEZE,
                      FREEZER_THAW, FREEZER_PARENT_THAW));

        if (action == FREEZER_FREEZE && !slice_can_freeze(s)) {
                /* We're intentionally only checking for FREEZER_FREEZE here and ignoring the
                 * _BY_PARENT variant. If we're being frozen by parent, that means someone has
                 * already checked if we can be frozen further up the call stack. No point to
                 * redo that work */
                log_unit_warning(s, "Requested freezer operation is not supported by all children of the slice");
                return 0;
        }

        if (action == FREEZER_FREEZE)
                child_action = FREEZER_PARENT_FREEZE;
        else if (action == FREEZER_THAW)
                child_action = FREEZER_PARENT_THAW;
        else
                child_action = action;

        UNIT_FOREACH_DEPENDENCY(member, s, UNIT_ATOM_SLICE_OF) {
                if (UNIT_VTABLE(member)->freezer_action)
                        r = UNIT_VTABLE(member)->freezer_action(member, child_action);
                else
                        /* Only thawing will reach here, since freezing checks for a method in can_freeze */
                        r = 0;
                if (r < 0)
                        return r;
        }

        return unit_cgroup_freezer_action(s, action);
}

const UnitVTable slice_vtable = {
        .object_size = sizeof(Slice),
        .cgroup_context_offset = offsetof(Slice, cgroup_context),
        .cgroup_runtime_offset = offsetof(Slice, cgroup_runtime),

        .sections =
                "Unit\0"
                "Slice\0"
                "Install\0",
        .private_section = "Slice",

        .can_transient = true,
        .can_set_managed_oom = true,

        .init = slice_init,
        .load = slice_load,

        .coldplug = slice_coldplug,

        .dump = slice_dump,

        .start = slice_start,
        .stop = slice_stop,

        .freezer_action = slice_freezer_action,
        .can_freeze = slice_can_freeze,

        .serialize = slice_serialize,
        .deserialize_item = slice_deserialize_item,

        .active_state = slice_active_state,
        .sub_state_to_string = slice_sub_state_to_string,

        .bus_set_property = bus_slice_set_property,
        .bus_commit_properties = bus_slice_commit_properties,

        .enumerate_perpetual = slice_enumerate_perpetual,

        .status_message_formats = {
                .finished_start_job = {
                        [JOB_DONE]       = "Created slice %s.",
                },
                .finished_stop_job = {
                        [JOB_DONE]       = "Removed slice %s.",
                },
        },
};