Force usage of assert() condition when NDEBUG is defined

[lttng-tools.git] / src / common / trigger.c

/*
 * Copyright (C) 2017 Jérémie Galarneau <jeremie.galarneau@efficios.com>
 *
 * SPDX-License-Identifier: LGPL-2.1-only
 *
 */

#include <common/credentials.h>
#include <common/dynamic-array.h>
#include <common/error.h>
#include <common/mi-lttng.h>
#include <common/optional.h>
#include <common/payload-view.h>
#include <common/payload.h>
#include <inttypes.h>
#include <lttng/action/action-internal.h>
#include <lttng/condition/buffer-usage.h>
#include <lttng/condition/condition-internal.h>
#include <lttng/condition/event-rule-matches-internal.h>
#include <lttng/condition/event-rule-matches.h>
#include <lttng/domain.h>
#include <lttng/error-query-internal.h>
#include <lttng/event-expr-internal.h>
#include <lttng/event-rule/event-rule-internal.h>
#include <lttng/trigger/trigger-internal.h>
#include <pthread.h>

LTTNG_HIDDEN
bool lttng_trigger_validate(const struct lttng_trigger *trigger)
{
        bool valid;

        if (!trigger) {
                valid = false;
                goto end;
        }

        if (!trigger->creds.uid.is_set) {
                valid = false;
                goto end;
        }

        valid = lttng_condition_validate(trigger->condition) &&
                        lttng_action_validate(trigger->action);
end:
        return valid;
}

struct lttng_trigger *lttng_trigger_create(
                struct lttng_condition *condition,
                struct lttng_action *action)
{
        struct lttng_trigger *trigger = NULL;

        if (!condition || !action) {
                goto end;
        }

        trigger = zmalloc(sizeof(struct lttng_trigger));
        if (!trigger) {
                goto end;
        }

        urcu_ref_init(&trigger->ref);

        lttng_condition_get(condition);
        trigger->condition = condition;

        lttng_action_get(action);
        trigger->action = action;

        pthread_mutex_init(&trigger->lock, NULL);
        trigger->registered = false;

end:
        return trigger;
}

/*
 * Note: the lack of reference counting 'get' on the condition object is normal.
 * This API was exposed as such in 2.11. The client is not expected to call
 * lttng_condition_destroy on the returned object.
 */
struct lttng_condition *lttng_trigger_get_condition(
                struct lttng_trigger *trigger)
{
        return trigger ? trigger->condition : NULL;
}

const struct lttng_condition *lttng_trigger_get_const_condition(
                const struct lttng_trigger *trigger)
{
        return trigger ? trigger->condition : NULL;
}

/*
 * Note: the lack of reference counting 'get' on the action object is normal.
 * This API was exposed as such in 2.11. The client is not expected to call
 * lttng_action_destroy on the returned object.
 */
struct lttng_action *lttng_trigger_get_action(
                struct lttng_trigger *trigger)
{
        return trigger ? trigger->action : NULL;
}

const struct lttng_action *lttng_trigger_get_const_action(
                const struct lttng_trigger *trigger)
{
        return trigger ? trigger->action : NULL;
}

static void trigger_destroy_ref(struct urcu_ref *ref)
{
        struct lttng_trigger *trigger =
                        container_of(ref, struct lttng_trigger, ref);
        struct lttng_action *action = lttng_trigger_get_action(trigger);
        struct lttng_condition *condition =
                        lttng_trigger_get_condition(trigger);

        LTTNG_ASSERT(action);
        LTTNG_ASSERT(condition);

        /* Release ownership. */
        lttng_action_put(action);
        lttng_condition_put(condition);

        pthread_mutex_destroy(&trigger->lock);

        free(trigger->name);
        free(trigger);
}

void lttng_trigger_destroy(struct lttng_trigger *trigger)
{
        lttng_trigger_put(trigger);
}

LTTNG_HIDDEN
ssize_t lttng_trigger_create_from_payload(
                struct lttng_payload_view *src_view,
                struct lttng_trigger **_trigger)
{
        ssize_t ret, offset = 0, condition_size, action_size, name_size = 0;
        struct lttng_condition *condition = NULL;
        struct lttng_action *action = NULL;
        const struct lttng_trigger_comm *trigger_comm;
        const char *name = NULL;
        struct lttng_credentials creds = {
                .uid = LTTNG_OPTIONAL_INIT_UNSET,
                .gid = LTTNG_OPTIONAL_INIT_UNSET,
        };
        struct lttng_trigger *trigger = NULL;
        const struct lttng_payload_view trigger_comm_view =
                        lttng_payload_view_from_view(
                                        src_view, 0, sizeof(*trigger_comm));

        if (!src_view || !_trigger) {
                ret = -1;
                goto end;
        }

        if (!lttng_payload_view_is_valid(&trigger_comm_view)) {
                /* Payload not large enough to contain the header. */
                ret = -1;
                goto end;
        }

        /* lttng_trigger_comm header */
        trigger_comm = (typeof(trigger_comm)) trigger_comm_view.buffer.data;

        /* Set the trigger's creds. */
        if (trigger_comm->uid > (uint64_t) ((uid_t) -1)) {
                /* UID out of range for this platform. */
                ret = -1;
                goto end;
        }

        LTTNG_OPTIONAL_SET(&creds.uid, trigger_comm->uid);

        offset += sizeof(*trigger_comm);

        if (trigger_comm->name_length != 0) {
                /* Name. */
                const struct lttng_payload_view name_view =
                                lttng_payload_view_from_view(
                                                src_view, offset,
                                                trigger_comm->name_length);

                if (!lttng_payload_view_is_valid(&name_view)) {
                        ret = -1;
                        goto end;
                }

                name = name_view.buffer.data;
                if (!lttng_buffer_view_contains_string(&name_view.buffer, name,
                                    trigger_comm->name_length)) {
                        ret = -1;
                        goto end;
                }

                offset += trigger_comm->name_length;
                name_size = trigger_comm->name_length;
        }

        {
                /* struct lttng_condition */
                struct lttng_payload_view condition_view =
                                lttng_payload_view_from_view(
                                                src_view, offset, -1);

                condition_size = lttng_condition_create_from_payload(&condition_view,
                                &condition);
        }

        if (condition_size < 0) {
                ret = condition_size;
                goto end;
        }

        offset += condition_size;
        {
                /* struct lttng_action */
                struct lttng_payload_view action_view =
                                lttng_payload_view_from_view(
                                        src_view, offset, -1);

                action_size = lttng_action_create_from_payload(&action_view, &action);
        }

        if (action_size < 0) {
                ret = action_size;
                goto end;
        }
        offset += action_size;

        /* Unexpected size of inner-elements; the buffer is corrupted. */
        if ((ssize_t) trigger_comm->length != condition_size + action_size + name_size) {
                ret = -1;
                goto error;
        }

        trigger = lttng_trigger_create(condition, action);
        if (!trigger) {
                ret = -1;
                goto error;
        }

        lttng_trigger_set_credentials(trigger, &creds);

        /*
         * The trigger object owns references to the action and condition
         * objects.
         */
        lttng_condition_put(condition);
        condition = NULL;

        lttng_action_put(action);
        action = NULL;

        if (name) {
                const enum lttng_trigger_status status =
                                lttng_trigger_set_name(trigger, name);

                if (status != LTTNG_TRIGGER_STATUS_OK) {
                        ret = -1;
                        goto end;
                }
        }

        ret = offset;

error:
        lttng_condition_put(condition);
        lttng_action_put(action);
end:
        if (ret >= 0) {
                *_trigger = trigger;
        } else {
                lttng_trigger_put(trigger);
        }

        return ret;
}

/*
 * Both elements are stored contiguously, see their "*_comm" structure
 * for the detailed format.
 */
LTTNG_HIDDEN
int lttng_trigger_serialize(const struct lttng_trigger *trigger,
                struct lttng_payload *payload)
{
        int ret;
        size_t header_offset, size_before_payload, size_name;
        struct lttng_trigger_comm trigger_comm = {};
        struct lttng_trigger_comm *header;
        const struct lttng_credentials *creds = NULL;

        creds = lttng_trigger_get_credentials(trigger);
        LTTNG_ASSERT(creds);

        trigger_comm.uid = LTTNG_OPTIONAL_GET(creds->uid);

        if (trigger->name != NULL) {
                size_name = strlen(trigger->name) + 1;
        } else {
                size_name = 0;
        }

        trigger_comm.name_length = size_name;

        header_offset = payload->buffer.size;
        ret = lttng_dynamic_buffer_append(&payload->buffer, &trigger_comm,
                        sizeof(trigger_comm));
        if (ret) {
                goto end;
        }

        size_before_payload = payload->buffer.size;

        /* Trigger name. */
        ret = lttng_dynamic_buffer_append(
                        &payload->buffer, trigger->name, size_name);
        if (ret) {
                goto end;
        }

        ret = lttng_condition_serialize(trigger->condition, payload);
        if (ret) {
                goto end;
        }

        ret = lttng_action_serialize(trigger->action, payload);
        if (ret) {
                goto end;
        }

        /* Update payload size. */
        header = (typeof(header)) (payload->buffer.data + header_offset);
        header->length = payload->buffer.size - size_before_payload;
end:
        return ret;
}

LTTNG_HIDDEN
bool lttng_trigger_is_equal(
                const struct lttng_trigger *a, const struct lttng_trigger *b)
{
        if (!!a->name != !!b->name) {
                /* Both must be either anonymous or named. */
                return false;
        }

        if (a->name && strcmp(a->name, b->name) != 0) {
                return false;
        }

        if (!lttng_condition_is_equal(a->condition, b->condition)) {
                return false;
        }

        if (!lttng_action_is_equal(a->action, b->action)) {
                return false;
        }

        if (!lttng_credentials_is_equal(lttng_trigger_get_credentials(a),
                        lttng_trigger_get_credentials(b))) {
                return false;
        }

        if (a->is_hidden != b->is_hidden) {
                return false;
        }

        return true;
}

LTTNG_HIDDEN
bool lttng_trigger_is_hidden(const struct lttng_trigger *trigger)
{
        return trigger->is_hidden;
}

LTTNG_HIDDEN
void lttng_trigger_set_hidden(struct lttng_trigger *trigger)
{
        LTTNG_ASSERT(!trigger->is_hidden);
        trigger->is_hidden = true;
}

LTTNG_HIDDEN
enum lttng_trigger_status lttng_trigger_set_name(struct lttng_trigger *trigger,
                const char* name)
{
        char *name_copy = NULL;
        enum lttng_trigger_status status = LTTNG_TRIGGER_STATUS_OK;

        if (!trigger) {
                status = LTTNG_TRIGGER_STATUS_INVALID;
                goto end;
        }

        if (name) {
                name_copy = strdup(name);
                if (!name_copy) {
                        status = LTTNG_TRIGGER_STATUS_ERROR;
                        goto end;
                }
        }

        free(trigger->name);

        trigger->name = name_copy;
        name_copy = NULL;
end:
        return status;
}

enum lttng_trigger_status lttng_trigger_get_name(
                const struct lttng_trigger *trigger, const char **name)
{
        enum lttng_trigger_status status = LTTNG_TRIGGER_STATUS_OK;

        if (!trigger || !name) {
                status = LTTNG_TRIGGER_STATUS_INVALID;
                goto end;
        }

        if (!trigger->name) {
                status = LTTNG_TRIGGER_STATUS_UNSET;
        }

        *name = trigger->name;
end:
        return status;
}

LTTNG_HIDDEN
int lttng_trigger_assign_name(struct lttng_trigger *dst,
                const struct lttng_trigger *src)
{
        int ret = 0;
        enum lttng_trigger_status status;

        status = lttng_trigger_set_name(dst, src->name);
        if (status != LTTNG_TRIGGER_STATUS_OK) {
                ret = -1;
                ERR("Failed to set name for trigger");
                goto end;
        }
end:
        return ret;
}

LTTNG_HIDDEN
void lttng_trigger_set_tracer_token(struct lttng_trigger *trigger,
                uint64_t token)
{
        LTTNG_ASSERT(trigger);
        LTTNG_OPTIONAL_SET(&trigger->tracer_token, token);
}

LTTNG_HIDDEN
uint64_t lttng_trigger_get_tracer_token(const struct lttng_trigger *trigger)
{
        LTTNG_ASSERT(trigger);

        return LTTNG_OPTIONAL_GET(trigger->tracer_token);
}

LTTNG_HIDDEN
int lttng_trigger_generate_name(struct lttng_trigger *trigger,
                uint64_t unique_id)
{
        int ret = 0;
        char *generated_name = NULL;

        ret = asprintf(&generated_name, "trigger%" PRIu64 "", unique_id);
        if (ret < 0) {
                ERR("Failed to generate trigger name");
                ret = -1;
                goto end;
        }

        ret = 0;
        free(trigger->name);
        trigger->name = generated_name;
end:
        return ret;
}

LTTNG_HIDDEN
void lttng_trigger_get(struct lttng_trigger *trigger)
{
        urcu_ref_get(&trigger->ref);
}

LTTNG_HIDDEN
void lttng_trigger_put(struct lttng_trigger *trigger)
{
        if (!trigger) {
                return;
        }

        urcu_ref_put(&trigger->ref , trigger_destroy_ref);
}

static void delete_trigger_array_element(void *ptr)
{
        struct lttng_trigger *trigger = ptr;

        lttng_trigger_put(trigger);
}

LTTNG_HIDDEN
struct lttng_triggers *lttng_triggers_create(void)
{
        struct lttng_triggers *triggers = NULL;

        triggers = zmalloc(sizeof(*triggers));
        if (!triggers) {
                goto end;
        }

        lttng_dynamic_pointer_array_init(&triggers->array, delete_trigger_array_element);

end:
        return triggers;
}

LTTNG_HIDDEN
struct lttng_trigger *lttng_triggers_borrow_mutable_at_index(
                const struct lttng_triggers *triggers, unsigned int index)
{
        struct lttng_trigger *trigger = NULL;

        LTTNG_ASSERT(triggers);
        if (index >= lttng_dynamic_pointer_array_get_count(&triggers->array)) {
                goto end;
        }

        trigger = (struct lttng_trigger *)
                        lttng_dynamic_pointer_array_get_pointer(
                                        &triggers->array, index);
end:
        return trigger;
}

LTTNG_HIDDEN
int lttng_triggers_add(
                struct lttng_triggers *triggers, struct lttng_trigger *trigger)
{
        int ret;

        LTTNG_ASSERT(triggers);
        LTTNG_ASSERT(trigger);

        lttng_trigger_get(trigger);

        ret = lttng_dynamic_pointer_array_add_pointer(&triggers->array, trigger);
        if (ret) {
                lttng_trigger_put(trigger);
        }

        return ret;
}

LTTNG_HIDDEN
int lttng_triggers_remove_hidden_triggers(struct lttng_triggers *triggers)
{
        int ret;
        unsigned int trigger_count, i = 0;
        enum lttng_trigger_status trigger_status;

        LTTNG_ASSERT(triggers);

        trigger_status = lttng_triggers_get_count(triggers, &trigger_count);
        LTTNG_ASSERT(trigger_status == LTTNG_TRIGGER_STATUS_OK);

        while (i < trigger_count) {
                const struct lttng_trigger *trigger =
                                lttng_triggers_get_at_index(triggers, i);

                if (lttng_trigger_is_hidden(trigger)) {
                        ret = lttng_dynamic_pointer_array_remove_pointer(
                                        &triggers->array, i);
                        if (ret) {
                                goto end;
                        }

                        trigger_count--;
                } else {
                        i++;
                }
        }

        ret = 0;
end:
        return ret;
}

const struct lttng_trigger *lttng_triggers_get_at_index(
                const struct lttng_triggers *triggers, unsigned int index)
{
        return lttng_triggers_borrow_mutable_at_index(triggers, index);
}

enum lttng_trigger_status lttng_triggers_get_count(const struct lttng_triggers *triggers, unsigned int *count)
{
        enum lttng_trigger_status status = LTTNG_TRIGGER_STATUS_OK;

        if (!triggers || !count) {
                status = LTTNG_TRIGGER_STATUS_INVALID;
                goto end;
        }

        *count = lttng_dynamic_pointer_array_get_count(&triggers->array);
end:
        return status;
}

void lttng_triggers_destroy(struct lttng_triggers *triggers)
{
        if (!triggers) {
                return;
        }

        lttng_dynamic_pointer_array_reset(&triggers->array);
        free(triggers);
}

int lttng_triggers_serialize(const struct lttng_triggers *triggers,
                struct lttng_payload *payload)
{
        int ret;
        unsigned int i, count;
        size_t size_before_payload;
        struct lttng_triggers_comm triggers_comm = {};
        struct lttng_triggers_comm *header;
        enum lttng_trigger_status status;
        const size_t header_offset = payload->buffer.size;

        status = lttng_triggers_get_count(triggers, &count);
        if (status != LTTNG_TRIGGER_STATUS_OK) {
                ret = LTTNG_ERR_INVALID;
                goto end;
        }

        triggers_comm.count = count;

        /* Placeholder header; updated at the end. */
        ret = lttng_dynamic_buffer_append(&payload->buffer, &triggers_comm,
                        sizeof(triggers_comm));
        if (ret) {
                goto end;
        }

        size_before_payload = payload->buffer.size;

        for (i = 0; i < count; i++) {
                const struct lttng_trigger *trigger =
                                lttng_triggers_get_at_index(triggers, i);

                LTTNG_ASSERT(trigger);

                ret = lttng_trigger_serialize(trigger, payload);
                if (ret) {
                        goto end;
                }
        }

        /* Update payload size. */
        header = (struct lttng_triggers_comm *) ((char *) payload->buffer.data + header_offset);
        header->length = payload->buffer.size - size_before_payload;
end:
        return ret;
}

LTTNG_HIDDEN
ssize_t lttng_triggers_create_from_payload(
                struct lttng_payload_view *src_view,
                struct lttng_triggers **triggers)
{
        ssize_t ret, offset = 0, triggers_size = 0;
        unsigned int i;
        const struct lttng_triggers_comm *triggers_comm;
        struct lttng_triggers *local_triggers = NULL;

        if (!src_view || !triggers) {
                ret = -1;
                goto error;
        }

        /* lttng_trigger_comms header */
        triggers_comm = (const struct lttng_triggers_comm *) src_view->buffer.data;
        offset += sizeof(*triggers_comm);

        local_triggers = lttng_triggers_create();
        if (!local_triggers) {
                ret = -1;
                goto error;
        }

        for (i = 0; i < triggers_comm->count; i++) {
                struct lttng_trigger *trigger = NULL;
                struct lttng_payload_view trigger_view =
                                lttng_payload_view_from_view(src_view, offset, -1);
                ssize_t trigger_size;

                trigger_size = lttng_trigger_create_from_payload(
                                &trigger_view, &trigger);
                if (trigger_size < 0) {
                        ret = trigger_size;
                        goto error;
                }

                /* Transfer ownership of the trigger to the collection. */
                ret = lttng_triggers_add(local_triggers, trigger);
                lttng_trigger_put(trigger);
                if (ret < 0) {
                        ret = -1;
                        goto error;
                }

                offset += trigger_size;
                triggers_size += trigger_size;
        }

        /* Unexpected size of inner-elements; the buffer is corrupted. */
        if ((ssize_t) triggers_comm->length != triggers_size) {
                ret = -1;
                goto error;
        }

        /* Pass ownership to caller. */
        *triggers = local_triggers;
        local_triggers = NULL;

        ret = offset;
error:

        lttng_triggers_destroy(local_triggers);
        return ret;
}

LTTNG_HIDDEN
const struct lttng_credentials *lttng_trigger_get_credentials(
                const struct lttng_trigger *trigger)
{
        return &trigger->creds;
}

LTTNG_HIDDEN
void lttng_trigger_set_credentials(struct lttng_trigger *trigger,
                const struct lttng_credentials *creds)
{
        LTTNG_ASSERT(creds);
        trigger->creds = *creds;
}

enum lttng_trigger_status lttng_trigger_set_owner_uid(
                struct lttng_trigger *trigger, uid_t uid)
{
        enum lttng_trigger_status ret = LTTNG_TRIGGER_STATUS_OK;
        const uid_t euid = geteuid();
        const struct lttng_credentials creds = {
                .uid = LTTNG_OPTIONAL_INIT_VALUE(uid),
                .gid = LTTNG_OPTIONAL_INIT_UNSET,
        };

        if (!trigger) {
                ret = LTTNG_TRIGGER_STATUS_INVALID;
                goto end;
        }

        /* Client-side validation only to report a clearer error. */
        if (euid != 0 && euid != uid) {
                ret = LTTNG_TRIGGER_STATUS_PERMISSION_DENIED;
                goto end;
        }

        lttng_trigger_set_credentials(trigger, &creds);

end:
        return ret;
}

enum lttng_trigger_status lttng_trigger_get_owner_uid(
                const struct lttng_trigger *trigger, uid_t *uid)
{
        enum lttng_trigger_status ret = LTTNG_TRIGGER_STATUS_OK;
        const struct lttng_credentials *creds = NULL;

        if (!trigger || !uid ) {
                ret = LTTNG_TRIGGER_STATUS_INVALID;
                goto end;
        }

        if (!trigger->creds.uid.is_set ) {
                ret = LTTNG_TRIGGER_STATUS_UNSET;
                goto end;
        }

        creds = lttng_trigger_get_credentials(trigger);
        *uid = lttng_credentials_get_uid(creds);

end:
        return ret;
}

LTTNG_HIDDEN
enum lttng_domain_type lttng_trigger_get_underlying_domain_type_restriction(
                const struct lttng_trigger *trigger)
{
        enum lttng_domain_type type = LTTNG_DOMAIN_NONE;
        const struct lttng_event_rule *event_rule;
        enum lttng_condition_status c_status;
        enum lttng_condition_type c_type;

        LTTNG_ASSERT(trigger);
        LTTNG_ASSERT(trigger->condition);

        c_type = lttng_condition_get_type(trigger->condition);
        assert (c_type != LTTNG_CONDITION_TYPE_UNKNOWN);

        switch (c_type) {
        case LTTNG_CONDITION_TYPE_SESSION_CONSUMED_SIZE:
        case LTTNG_CONDITION_TYPE_SESSION_ROTATION_ONGOING:
        case LTTNG_CONDITION_TYPE_SESSION_ROTATION_COMPLETED:
                /* Apply to any domain. */
                type = LTTNG_DOMAIN_NONE;
                break;
        case LTTNG_CONDITION_TYPE_EVENT_RULE_MATCHES:
                /* Return the domain of the event rule. */
                c_status = lttng_condition_event_rule_matches_get_rule(
                                trigger->condition, &event_rule);
                LTTNG_ASSERT(c_status == LTTNG_CONDITION_STATUS_OK);
                type = lttng_event_rule_get_domain_type(event_rule);
                break;
        case LTTNG_CONDITION_TYPE_BUFFER_USAGE_HIGH:
        case LTTNG_CONDITION_TYPE_BUFFER_USAGE_LOW:
                /* Return the domain of the channel being monitored. */
                c_status = lttng_condition_buffer_usage_get_domain_type(
                                trigger->condition, &type);
                LTTNG_ASSERT(c_status == LTTNG_CONDITION_STATUS_OK);
                break;
        default:
                abort();
        }

        return type;
}

/*
 * Generate bytecode related to the trigger.
 * On success LTTNG_OK. On error, returns lttng_error code.
 */
LTTNG_HIDDEN
enum lttng_error_code lttng_trigger_generate_bytecode(
                struct lttng_trigger *trigger,
                const struct lttng_credentials *creds)
{
        enum lttng_error_code ret;
        struct lttng_condition *condition = NULL;

        condition = lttng_trigger_get_condition(trigger);
        if (!condition) {
                ret = LTTNG_ERR_INVALID_TRIGGER;
                goto end;
        }

        switch (lttng_condition_get_type(condition)) {
        case LTTNG_CONDITION_TYPE_EVENT_RULE_MATCHES:
        {
                struct lttng_event_rule *event_rule;
                const enum lttng_condition_status condition_status =
                                lttng_condition_event_rule_matches_borrow_rule_mutable(
                                                condition, &event_rule);

                LTTNG_ASSERT(condition_status == LTTNG_CONDITION_STATUS_OK);

                /* Generate the filter bytecode. */
                ret = lttng_event_rule_generate_filter_bytecode(
                                event_rule, creds);
                if (ret != LTTNG_OK) {
                        goto end;
                }

                /* Generate the capture bytecode. */
                ret = lttng_condition_event_rule_matches_generate_capture_descriptor_bytecode(
                                condition);
                if (ret != LTTNG_OK) {
                        goto end;
                }

                ret = LTTNG_OK;
                break;
        }
        default:
                ret = LTTNG_OK;
                break;
        }
end:
        return ret;
}

LTTNG_HIDDEN
struct lttng_trigger *lttng_trigger_copy(const struct lttng_trigger *trigger)
{
        int ret;
        struct lttng_payload copy_buffer;
        struct lttng_condition *condition_copy = NULL;
        struct lttng_action *action_copy = NULL;
        struct lttng_trigger *copy = NULL;
        enum lttng_trigger_status trigger_status;
        const char *trigger_name;
        uid_t trigger_owner_uid;

        lttng_payload_init(&copy_buffer);

        ret = lttng_condition_serialize(trigger->condition, &copy_buffer);
        if (ret < 0) {
                goto end;
        }

        {
                struct lttng_payload_view view =
                                lttng_payload_view_from_payload(
                                                &copy_buffer, 0, -1);

                ret = lttng_condition_create_from_payload(
                                &view, &condition_copy);
                if (ret < 0) {
                        goto end;
                }
        }

        lttng_payload_clear(&copy_buffer);

        ret = lttng_action_serialize(trigger->action, &copy_buffer);
        if (ret < 0) {
                goto end;
        }

        {
                struct lttng_payload_view view =
                                lttng_payload_view_from_payload(
                                                &copy_buffer, 0, -1);

                ret = lttng_action_create_from_payload(
                                &view, &action_copy);
                if (ret < 0) {
                        goto end;
                }
        }

        copy = lttng_trigger_create(condition_copy, action_copy);
        if (!copy) {
                ERR("Failed to allocate trigger during trigger copy");
                goto end;
        }

        trigger_status = lttng_trigger_get_name(trigger, &trigger_name);
        switch (trigger_status) {
        case LTTNG_TRIGGER_STATUS_OK:
                trigger_status = lttng_trigger_set_name(copy, trigger_name);
                if (trigger_status != LTTNG_TRIGGER_STATUS_OK) {
                        ERR("Failed to set name of new trigger during copy");
                        goto error_cleanup_trigger;
                }
                break;
        case LTTNG_TRIGGER_STATUS_UNSET:
                break;
        default:
                ERR("Failed to get name of original trigger during copy");
                goto error_cleanup_trigger;
        }

        trigger_status = lttng_trigger_get_owner_uid(
                        trigger, &trigger_owner_uid);
        switch (trigger_status) {
        case LTTNG_TRIGGER_STATUS_OK:
                LTTNG_OPTIONAL_SET(&copy->creds.uid, trigger_owner_uid);
                break;
        case LTTNG_TRIGGER_STATUS_UNSET:
                break;
        default:
                ERR("Failed to get owner uid of original trigger during copy");
                goto error_cleanup_trigger;
        }

        copy->tracer_token = trigger->tracer_token;
        copy->registered = trigger->registered;
        copy->is_hidden = trigger->is_hidden;
        goto end;

error_cleanup_trigger:
        lttng_trigger_destroy(copy);
        copy = NULL;
end:
        lttng_condition_put(condition_copy);
        lttng_action_put(action_copy);
        lttng_payload_reset(&copy_buffer);
        return copy;
}

LTTNG_HIDDEN
bool lttng_trigger_needs_tracer_notifier(const struct lttng_trigger *trigger)
{
        bool needs_tracer_notifier = false;
        const struct lttng_condition *condition =
                        lttng_trigger_get_const_condition(trigger);

        switch (lttng_condition_get_type(condition)) {
        case LTTNG_CONDITION_TYPE_EVENT_RULE_MATCHES:
                needs_tracer_notifier = true;
                goto end;
        case LTTNG_CONDITION_TYPE_SESSION_CONSUMED_SIZE:
        case LTTNG_CONDITION_TYPE_BUFFER_USAGE_HIGH:
        case LTTNG_CONDITION_TYPE_BUFFER_USAGE_LOW:
        case LTTNG_CONDITION_TYPE_SESSION_ROTATION_ONGOING:
        case LTTNG_CONDITION_TYPE_SESSION_ROTATION_COMPLETED:
                goto end;
        case LTTNG_CONDITION_TYPE_UNKNOWN:
        default:
                abort();
        }
end:
        return needs_tracer_notifier;
}

LTTNG_HIDDEN
void lttng_trigger_set_as_registered(struct lttng_trigger *trigger)
{
        pthread_mutex_lock(&trigger->lock);
        trigger->registered = true;
        pthread_mutex_unlock(&trigger->lock);
}

LTTNG_HIDDEN
void lttng_trigger_set_as_unregistered(struct lttng_trigger *trigger)
{
        pthread_mutex_lock(&trigger->lock);
        trigger->registered = false;
        pthread_mutex_unlock(&trigger->lock);
}

/*
 * The trigger must be locked before calling lttng_trigger_registered.
 * The lock is necessary since a trigger can be unregistered at anytime.
 * Manipulations requiring that the trigger be registered must always acquire
 * the trigger lock for the duration of the manipulation using
 * `lttng_trigger_lock` and `lttng_trigger_unlock`.
 */
LTTNG_HIDDEN
bool lttng_trigger_is_registered(struct lttng_trigger *trigger)
{
        ASSERT_LOCKED(trigger->lock);
        return trigger->registered;
}

LTTNG_HIDDEN
void lttng_trigger_lock(struct lttng_trigger *trigger)
{
        pthread_mutex_lock(&trigger->lock);
}

LTTNG_HIDDEN
void lttng_trigger_unlock(struct lttng_trigger *trigger)
{
        pthread_mutex_unlock(&trigger->lock);
}

LTTNG_HIDDEN
enum lttng_error_code lttng_trigger_mi_serialize(const struct lttng_trigger *trigger,
                struct mi_writer *writer,
                const struct mi_lttng_error_query_callbacks
                                *error_query_callbacks)
{
        int ret;
        enum lttng_error_code ret_code;
        enum lttng_trigger_status trigger_status;
        const struct lttng_condition *condition = NULL;
        const struct lttng_action *action = NULL;
        struct lttng_dynamic_array action_path_indexes;
        uid_t owner_uid;

        LTTNG_ASSERT(trigger);
        LTTNG_ASSERT(writer);

        lttng_dynamic_array_init(&action_path_indexes, sizeof(uint64_t), NULL);

        /* Open trigger element. */
        ret = mi_lttng_writer_open_element(writer, mi_lttng_element_trigger);
        if (ret) {
                goto mi_error;
        }

        trigger_status = lttng_trigger_get_owner_uid(trigger, &owner_uid);
        LTTNG_ASSERT(trigger_status == LTTNG_TRIGGER_STATUS_OK);

        /* Name. */
        ret = mi_lttng_writer_write_element_string(
                        writer, config_element_name, trigger->name);
        if (ret) {
                goto mi_error;
        }

        /* Owner uid. */
        ret = mi_lttng_writer_write_element_signed_int(writer,
                        mi_lttng_element_trigger_owner_uid,
                        (int64_t) owner_uid);
        if (ret) {
                goto mi_error;
        }

        /* Condition. */
        condition = lttng_trigger_get_const_condition(trigger);
        LTTNG_ASSERT(condition);
        ret_code = lttng_condition_mi_serialize(
                        trigger, condition, writer, error_query_callbacks);
        if (ret_code != LTTNG_OK) {
                goto end;
        }

        /* Action. */
        action = lttng_trigger_get_const_action(trigger);
        LTTNG_ASSERT(action);
        ret_code = lttng_action_mi_serialize(trigger, action, writer,
                        error_query_callbacks, &action_path_indexes);
        if (ret_code != LTTNG_OK) {
                goto end;
        }

        if (error_query_callbacks && error_query_callbacks->trigger_cb) {
                struct lttng_error_query_results *results = NULL;

                ret_code = error_query_callbacks->trigger_cb(trigger, &results);
                if (ret_code != LTTNG_OK) {
                        goto end;
                }

                ret_code = lttng_error_query_results_mi_serialize(
                                results, writer);
                lttng_error_query_results_destroy(results);
                if (ret_code != LTTNG_OK) {
                        goto end;
                }
        }

        /* Close trigger element. */
        ret = mi_lttng_writer_close_element(writer);
        if (ret) {
                goto mi_error;
        }

        ret_code = LTTNG_OK;
        goto end;

mi_error:
        ret_code = LTTNG_ERR_MI_IO_FAIL;
end:
        lttng_dynamic_array_reset(&action_path_indexes);
        return ret_code;
}

/* Used by qsort, which expects the semantics of strcmp(). */
static int compare_triggers_by_name(const void *a, const void *b)
{
        const struct lttng_trigger *trigger_a =
                        *((const struct lttng_trigger **) a);
        const struct lttng_trigger *trigger_b =
                        *((const struct lttng_trigger **) b);
        const char *name_a, *name_b;
        enum lttng_trigger_status trigger_status;

        /* Anonymous triggers are not reachable here. */
        trigger_status = lttng_trigger_get_name(trigger_a, &name_a);
        LTTNG_ASSERT(trigger_status == LTTNG_TRIGGER_STATUS_OK);

        trigger_status = lttng_trigger_get_name(trigger_b, &name_b);
        LTTNG_ASSERT(trigger_status == LTTNG_TRIGGER_STATUS_OK);

        return strcmp(name_a, name_b);
}

LTTNG_HIDDEN
enum lttng_error_code lttng_triggers_mi_serialize(const struct lttng_triggers *triggers,
                struct mi_writer *writer,
                const struct mi_lttng_error_query_callbacks
                                *error_query_callbacks)
{
        int ret;
        enum lttng_error_code ret_code;
        enum lttng_trigger_status status;
        unsigned int count, i;
        struct lttng_dynamic_pointer_array sorted_triggers;

        LTTNG_ASSERT(triggers);
        LTTNG_ASSERT(writer);

        /*
         * Sort trigger by name to ensure an order at the MI level and ignore
         * any anonymous trigger present.
         */
        lttng_dynamic_pointer_array_init(&sorted_triggers, NULL);

        status = lttng_triggers_get_count(triggers, &count);
        LTTNG_ASSERT(status == LTTNG_TRIGGER_STATUS_OK);

        for (i = 0; i < count; i++) {
                int add_ret;
                const char *unused_name;
                const struct lttng_trigger *trigger =
                                lttng_triggers_get_at_index(triggers, i);

                status = lttng_trigger_get_name(trigger, &unused_name);
                switch (status) {
                case LTTNG_TRIGGER_STATUS_OK:
                        break;
                case LTTNG_TRIGGER_STATUS_UNSET:
                        /* Don't list anonymous triggers. */
                        continue;
                default:
                        abort();
                }

                add_ret = lttng_dynamic_pointer_array_add_pointer(
                                &sorted_triggers, (void *) trigger);

                if (add_ret) {
                        ERR("Failed to lttng_trigger to sorting array.");
                        ret_code = LTTNG_ERR_NOMEM;
                        goto error;
                }
        }

        qsort(sorted_triggers.array.buffer.data, count,
                        sizeof(struct lttng_trigger *),
                        compare_triggers_by_name);

        /* Open triggers element. */
        ret = mi_lttng_writer_open_element(writer, mi_lttng_element_triggers);
        if (ret) {
                ret_code = LTTNG_ERR_MI_IO_FAIL;
                goto error;
        }

        for (i = 0; i < lttng_dynamic_pointer_array_get_count(&sorted_triggers); i++) {
                const struct lttng_trigger *trigger =
                                (const struct lttng_trigger *)
                                lttng_dynamic_pointer_array_get_pointer(
                                                &sorted_triggers, i);

                lttng_trigger_mi_serialize(trigger, writer, error_query_callbacks);
        }

        /* Close triggers element. */
        ret = mi_lttng_writer_close_element(writer);
        if (ret) {
                ret_code = LTTNG_ERR_MI_IO_FAIL;
                goto error;
        }

        ret_code = LTTNG_OK;

error:
        lttng_dynamic_pointer_array_reset(&sorted_triggers);
        return ret_code;
}