HelenOS sources

root/uspace/srv/locsrv/locsrv.c

DEFINITIONS

1. loc_create_id
2. loc_fqsn_split
3. loc_namespace_find_name
4. loc_namespace_find_id
5. loc_service_find_name
6. loc_service_find_id
7. loc_namespace_create
8. loc_namespace_destroy
9. loc_namespace_addref
10. loc_namespace_delref
11. loc_service_unregister_core
12. loc_server_register
13. loc_server_unregister
14. loc_service_register
15. loc_service_unregister
16. loc_category_get_name
17. loc_service_get_name
18. loc_service_get_server_name
19. loc_forward
20. loc_service_get_id
21. loc_namespace_get_id
22. loc_callback_create
23. loc_category_change_event
24. loc_category_get_id
25. loc_id_probe
26. loc_get_namespace_count
27. loc_get_service_count
28. loc_get_categories
29. loc_get_namespaces
30. loc_get_services
31. loc_category_get_svcs
32. loc_null_create
33. loc_null_destroy
34. loc_service_add_to_cat
35. loc_init
36. loc_connection_supplier
37. loc_connection_consumer
38. main

/*
 * Copyright (c) 2024 Jiri Svoboda
 * Copyright (c) 2007 Josef Cejka
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/**
 * @addtogroup locsrv
 * @{
 */

/** @file
 */

#include <ipc/services.h>
#include <ns.h>
#include <async.h>
#include <stdio.h>
#include <errno.h>
#include <stdbool.h>
#include <fibril_synch.h>
#include <macros.h>
#include <stdlib.h>
#include <str.h>
#include <str_error.h>
#include <ipc/loc.h>
#include <assert.h>

#include "category.h"
#include "locsrv.h"

#define NAME          "loc"
#define NULL_SERVICES  256

/** Callback session */
typedef struct {
        link_t cb_sess_list;
        async_sess_t *sess;
} cb_sess_t;

LIST_INITIALIZE(services_list);
LIST_INITIALIZE(namespaces_list);
LIST_INITIALIZE(servers_list);

/*
 * Locking order:
 *  servers_list_mutex
 *  services_list_mutex
 *  (loc_server_t *)->services_mutex
 *  create_id_mutex
 */

FIBRIL_MUTEX_INITIALIZE(services_list_mutex);
static FIBRIL_CONDVAR_INITIALIZE(services_list_cv);
static FIBRIL_MUTEX_INITIALIZE(servers_list_mutex);
static FIBRIL_MUTEX_INITIALIZE(create_id_mutex);
static FIBRIL_MUTEX_INITIALIZE(null_services_mutex);

static service_id_t last_id = 0;
static loc_service_t *null_services[NULL_SERVICES];

/*
 * Dummy list for null services. This is necessary so that null services can
 * be used just as any other services, e.g. in loc_service_unregister_core().
 */
static LIST_INITIALIZE(dummy_null_services);

/** Service directory ogranized by categories (yellow pages) */
static categ_dir_t cdir;

static FIBRIL_MUTEX_INITIALIZE(callback_sess_mutex);
static LIST_INITIALIZE(callback_sess_list);

service_id_t loc_create_id(void)
{
        /*
         * TODO: allow reusing old ids after their unregistration
         * and implement some version of LRU algorithm, avoid overflow
         */

        fibril_mutex_lock(&create_id_mutex);
        last_id++;
        fibril_mutex_unlock(&create_id_mutex);

        return last_id;
}

/** Convert fully qualified service name to namespace and service name.
 *
 * A fully qualified service name can be either a plain service name
 * (then the namespace is considered to be an empty string) or consist
 * of two components separated by a slash. No more than one slash
 * is allowed.
 *
 */
static bool loc_fqsn_split(const char *fqsn, char **ns_name, char **name)
{
        size_t cnt = 0;
        size_t slash_offset = 0;
        size_t slash_after = 0;

        size_t offset = 0;
        size_t offset_prev = 0;
        char32_t c;

        while ((c = str_decode(fqsn, &offset, STR_NO_LIMIT)) != 0) {
                if (c == '/') {
                        cnt++;
                        slash_offset = offset_prev;
                        slash_after = offset;
                }
                offset_prev = offset;
        }

        /* More than one slash */
        if (cnt > 1)
                return false;

        /* No slash -> namespace is empty */
        if (cnt == 0) {
                *ns_name = str_dup("");
                if (*ns_name == NULL)
                        return false;

                *name = str_dup(fqsn);
                if (*name == NULL) {
                        free(*ns_name);
                        return false;
                }

                if (str_cmp(*name, "") == 0) {
                        free(*name);
                        free(*ns_name);
                        return false;
                }

                return true;
        }

        /* Exactly one slash */
        *ns_name = str_ndup(fqsn, slash_offset);
        if (*ns_name == NULL)
                return false;

        *name = str_dup(fqsn + slash_after);
        if (*name == NULL) {
                free(*ns_name);
                return false;
        }

        if (str_cmp(*name, "") == 0) {
                free(*name);
                free(*ns_name);
                return false;
        }

        return true;
}

/** Find namespace with given name. */
static loc_namespace_t *loc_namespace_find_name(const char *name)
{
        assert(fibril_mutex_is_locked(&services_list_mutex));

        list_foreach(namespaces_list, namespaces, loc_namespace_t, namespace) {
                if (str_cmp(namespace->name, name) == 0)
                        return namespace;
        }

        return NULL;
}

/** Find namespace with given ID.
 *
 * @todo: use hash table
 *
 */
static loc_namespace_t *loc_namespace_find_id(service_id_t id)
{
        assert(fibril_mutex_is_locked(&services_list_mutex));

        list_foreach(namespaces_list, namespaces, loc_namespace_t, namespace) {
                if (namespace->id == id)
                        return namespace;
        }

        return NULL;
}

/** Find service with given name. */
static loc_service_t *loc_service_find_name(const char *ns_name,
    const char *name)
{
        assert(fibril_mutex_is_locked(&services_list_mutex));

        list_foreach(services_list, services, loc_service_t, service) {
                if ((str_cmp(service->namespace->name, ns_name) == 0) &&
                    (str_cmp(service->name, name) == 0))
                        return service;
        }

        return NULL;
}

/** Find service with given ID.
 *
 * @todo: use hash table
 *
 */
static loc_service_t *loc_service_find_id(service_id_t id)
{
        assert(fibril_mutex_is_locked(&services_list_mutex));

        list_foreach(services_list, services, loc_service_t, service) {
                if (service->id == id)
                        return service;
        }

        return NULL;
}

/** Create a namespace (if not already present). */
static loc_namespace_t *loc_namespace_create(const char *ns_name)
{
        loc_namespace_t *namespace;

        assert(fibril_mutex_is_locked(&services_list_mutex));

        namespace = loc_namespace_find_name(ns_name);
        if (namespace != NULL)
                return namespace;

        namespace = (loc_namespace_t *) malloc(sizeof(loc_namespace_t));
        if (namespace == NULL)
                return NULL;

        namespace->name = str_dup(ns_name);
        if (namespace->name == NULL) {
                free(namespace);
                return NULL;
        }

        namespace->id = loc_create_id();
        namespace->refcnt = 0;

        /*
         * Insert new namespace into list of registered namespaces
         */
        list_append(&(namespace->namespaces), &namespaces_list);

        return namespace;
}

/** Destroy a namespace (if it is no longer needed). */
static void loc_namespace_destroy(loc_namespace_t *namespace)
{
        assert(fibril_mutex_is_locked(&services_list_mutex));

        if (namespace->refcnt == 0) {
                list_remove(&(namespace->namespaces));

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

/** Increase namespace reference count by including service. */
static void loc_namespace_addref(loc_namespace_t *namespace,
    loc_service_t *service)
{
        assert(fibril_mutex_is_locked(&services_list_mutex));

        service->namespace = namespace;
        namespace->refcnt++;
}

/** Decrease namespace reference count. */
static void loc_namespace_delref(loc_namespace_t *namespace)
{
        assert(fibril_mutex_is_locked(&services_list_mutex));

        namespace->refcnt--;
        loc_namespace_destroy(namespace);
}

/** Unregister service and free it. */
static void loc_service_unregister_core(loc_service_t *service)
{
        assert(fibril_mutex_is_locked(&services_list_mutex));
        assert(fibril_mutex_is_locked(&cdir.mutex));

        loc_namespace_delref(service->namespace);
        list_remove(&(service->services));
        list_remove(&(service->server_services));

        /* Remove service from all categories. */
        while (!list_empty(&service->cat_memb)) {
                link_t *link = list_first(&service->cat_memb);
                svc_categ_t *memb = list_get_instance(link, svc_categ_t,
                    svc_link);
                category_t *cat = memb->cat;

                fibril_mutex_lock(&cat->mutex);
                category_remove_service(memb);
                fibril_mutex_unlock(&cat->mutex);
        }

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

/**
 * Read info about new server and add it into linked list of registered
 * servers.
 */
static loc_server_t *loc_server_register(void)
{
        ipc_call_t icall;
        async_get_call(&icall);

        if (ipc_get_imethod(&icall) != LOC_SERVER_REGISTER) {
                async_answer_0(&icall, EREFUSED);
                return NULL;
        }

        loc_server_t *server =
            (loc_server_t *) malloc(sizeof(loc_server_t));
        if (server == NULL) {
                async_answer_0(&icall, ENOMEM);
                return NULL;
        }

        /*
         * Get server name
         */
        errno_t rc = async_data_write_accept((void **) &server->name, true, 0,
            LOC_NAME_MAXLEN, 0, NULL);
        if (rc != EOK) {
                free(server);
                async_answer_0(&icall, rc);
                return NULL;
        }

        /*
         * Create connection to the server
         */
        server->sess = async_callback_receive(EXCHANGE_SERIALIZE);
        if (!server->sess) {
                free(server->name);
                free(server);
                async_answer_0(&icall, ENOTSUP);
                return NULL;
        }

        /*
         * Initialize mutex for list of services
         * supplied by this server
         */
        fibril_mutex_initialize(&server->services_mutex);

        /*
         * Initialize list of supplied services
         */
        list_initialize(&server->services);
        link_initialize(&server->servers);

        fibril_mutex_lock(&servers_list_mutex);

        /*
         * TODO:
         * Check that no server with name equal to
         * server->name is registered
         */

        /*
         * Insert new server into list of registered servers
         */
        list_append(&(server->servers), &servers_list);
        fibril_mutex_unlock(&servers_list_mutex);

        async_answer_0(&icall, EOK);

        return server;
}

/**
 * Unregister server, unregister all its services and free server
 * structure.
 *
 */
static errno_t loc_server_unregister(loc_server_t *server)
{
        if (server == NULL)
                return EEXIST;

        fibril_mutex_lock(&servers_list_mutex);

        if (server->sess)
                async_hangup(server->sess);

        /* Remove it from list of servers */
        list_remove(&(server->servers));

        /* Unregister all its services */
        fibril_mutex_lock(&services_list_mutex);
        fibril_mutex_lock(&server->services_mutex);
        fibril_mutex_lock(&cdir.mutex);

        while (!list_empty(&server->services)) {
                loc_service_t *service = list_get_instance(
                    list_first(&server->services), loc_service_t,
                    server_services);
                loc_service_unregister_core(service);
        }

        fibril_mutex_unlock(&cdir.mutex);
        fibril_mutex_unlock(&server->services_mutex);
        fibril_mutex_unlock(&services_list_mutex);
        fibril_mutex_unlock(&servers_list_mutex);

        /* Free name and server */
        if (server->name != NULL)
                free(server->name);

        free(server);

        loc_category_change_event();
        return EOK;
}

/** Register service
 *
 */
static void loc_service_register(ipc_call_t *icall, loc_server_t *server)
{
        if (server == NULL) {
                async_answer_0(icall, EREFUSED);
                return;
        }

        /* Create new service entry */
        loc_service_t *service =
            (loc_service_t *) malloc(sizeof(loc_service_t));
        if (service == NULL) {
                async_answer_0(icall, ENOMEM);
                return;
        }

        /* Get fqsn */
        char *fqsn;
        errno_t rc = async_data_write_accept((void **) &fqsn, true, 0,
            LOC_NAME_MAXLEN, 0, NULL);
        if (rc != EOK) {
                free(service);
                async_answer_0(icall, rc);
                return;
        }

        char *ns_name;
        if (!loc_fqsn_split(fqsn, &ns_name, &service->name)) {
                free(fqsn);
                free(service);
                async_answer_0(icall, EINVAL);
                return;
        }

        free(fqsn);

        fibril_mutex_lock(&services_list_mutex);

        loc_namespace_t *namespace = loc_namespace_create(ns_name);
        free(ns_name);
        if (namespace == NULL) {
                fibril_mutex_unlock(&services_list_mutex);
                free(service->name);
                free(service);
                async_answer_0(icall, ENOMEM);
                return;
        }

        link_initialize(&service->services);
        link_initialize(&service->server_services);
        list_initialize(&service->cat_memb);

        /* Check that service is not already registered */
        if (loc_service_find_name(namespace->name, service->name) != NULL) {
                printf("%s: Service '%s/%s' already registered\n", NAME,
                    namespace->name, service->name);
                loc_namespace_destroy(namespace);
                fibril_mutex_unlock(&services_list_mutex);
                free(service->name);
                free(service);
                async_answer_0(icall, EEXIST);
                return;
        }

        /* Get unique service ID */
        service->id = loc_create_id();

        loc_namespace_addref(namespace, service);
        service->server = server;

        /* Insert service into list of all services  */
        list_append(&service->services, &services_list);

        /* Insert service into list of services supplied by one server */
        fibril_mutex_lock(&service->server->services_mutex);

        list_append(&service->server_services, &service->server->services);

        fibril_mutex_unlock(&service->server->services_mutex);
        fibril_condvar_broadcast(&services_list_cv);
        fibril_mutex_unlock(&services_list_mutex);

        async_answer_1(icall, EOK, service->id);
}

/**
 *
 */
static void loc_service_unregister(ipc_call_t *icall, loc_server_t *server)
{
        loc_service_t *svc;

        fibril_mutex_lock(&services_list_mutex);
        svc = loc_service_find_id(ipc_get_arg1(icall));
        if (svc == NULL) {
                fibril_mutex_unlock(&services_list_mutex);
                async_answer_0(icall, ENOENT);
                return;
        }

        fibril_mutex_lock(&cdir.mutex);
        loc_service_unregister_core(svc);
        fibril_mutex_unlock(&cdir.mutex);
        fibril_mutex_unlock(&services_list_mutex);

        /*
         * First send out all notifications and only then answer the request.
         * Otherwise the current fibril might block and transitively wait for
         * the completion of requests that are routed to it via an IPC loop.
         */
        loc_category_change_event();
        async_answer_0(icall, EOK);
}

static void loc_category_get_name(ipc_call_t *icall)
{
        ipc_call_t call;
        size_t size;
        size_t act_size;
        category_t *cat;

        if (!async_data_read_receive(&call, &size)) {
                async_answer_0(&call, EREFUSED);
                async_answer_0(icall, EREFUSED);
                return;
        }

        fibril_mutex_lock(&cdir.mutex);

        cat = category_get(&cdir, ipc_get_arg1(icall));
        if (cat == NULL) {
                fibril_mutex_unlock(&cdir.mutex);
                async_answer_0(&call, ENOENT);
                async_answer_0(icall, ENOENT);
                return;
        }

        act_size = str_size(cat->name);
        if (act_size > size) {
                fibril_mutex_unlock(&cdir.mutex);
                async_answer_0(&call, EOVERFLOW);
                async_answer_0(icall, EOVERFLOW);
                return;
        }

        errno_t retval = async_data_read_finalize(&call, cat->name,
            min(size, act_size));

        fibril_mutex_unlock(&cdir.mutex);

        async_answer_0(icall, retval);
}

static void loc_service_get_name(ipc_call_t *icall)
{
        ipc_call_t call;
        size_t size;
        size_t act_size;
        loc_service_t *svc;
        char *fqn;

        if (!async_data_read_receive(&call, &size)) {
                async_answer_0(&call, EREFUSED);
                async_answer_0(icall, EREFUSED);
                return;
        }

        fibril_mutex_lock(&services_list_mutex);

        svc = loc_service_find_id(ipc_get_arg1(icall));
        if (svc == NULL) {
                fibril_mutex_unlock(&services_list_mutex);
                async_answer_0(&call, ENOENT);
                async_answer_0(icall, ENOENT);
                return;
        }

        if (asprintf(&fqn, "%s/%s", svc->namespace->name, svc->name) < 0) {
                fibril_mutex_unlock(&services_list_mutex);
                async_answer_0(&call, ENOMEM);
                async_answer_0(icall, ENOMEM);
                return;
        }

        act_size = str_size(fqn);
        if (act_size > size) {
                free(fqn);
                fibril_mutex_unlock(&services_list_mutex);
                async_answer_0(&call, EOVERFLOW);
                async_answer_0(icall, EOVERFLOW);
                return;
        }

        errno_t retval = async_data_read_finalize(&call, fqn,
            min(size, act_size));
        free(fqn);

        fibril_mutex_unlock(&services_list_mutex);

        async_answer_0(icall, retval);
}

static void loc_service_get_server_name(ipc_call_t *icall)
{
        ipc_call_t call;
        size_t size;
        size_t act_size;
        loc_service_t *svc;

        if (!async_data_read_receive(&call, &size)) {
                async_answer_0(&call, EREFUSED);
                async_answer_0(icall, EREFUSED);
                return;
        }

        fibril_mutex_lock(&services_list_mutex);

        svc = loc_service_find_id(ipc_get_arg1(icall));
        if (svc == NULL) {
                fibril_mutex_unlock(&services_list_mutex);
                async_answer_0(&call, ENOENT);
                async_answer_0(icall, ENOENT);
                return;
        }

        if (svc->server == NULL) {
                fibril_mutex_unlock(&services_list_mutex);
                async_answer_0(&call, EINVAL);
                async_answer_0(icall, EINVAL);
                return;
        }

        act_size = str_size(svc->server->name);
        if (act_size > size) {
                fibril_mutex_unlock(&services_list_mutex);
                async_answer_0(&call, EOVERFLOW);
                async_answer_0(icall, EOVERFLOW);
                return;
        }

        errno_t retval = async_data_read_finalize(&call, svc->server->name,
            min(size, act_size));

        fibril_mutex_unlock(&services_list_mutex);

        async_answer_0(icall, retval);
}

/** Connect client to the service.
 *
 * Find server supplying requested service and forward
 * the message to it.
 *
 */
static void loc_forward(ipc_call_t *call, void *arg)
{
        fibril_mutex_lock(&services_list_mutex);

        /*
         * Get ID from request
         */
        iface_t iface = ipc_get_arg1(call);
        service_id_t id = ipc_get_arg2(call);
        loc_service_t *svc = loc_service_find_id(id);

        if ((svc == NULL) || (svc->server == NULL) || (!svc->server->sess)) {
                fibril_mutex_unlock(&services_list_mutex);
                async_answer_0(call, ENOENT);
                return;
        }

        async_exch_t *exch = async_exchange_begin(svc->server->sess);
        async_forward_1(call, exch, iface, svc->id, IPC_FF_NONE);
        async_exchange_end(exch);

        fibril_mutex_unlock(&services_list_mutex);
}

/** Find ID for service identified by name.
 *
 * In answer will be send EOK and service ID in arg1 or a error
 * code from errno.h.
 *
 */
static void loc_service_get_id(ipc_call_t *icall)
{
        char *fqsn;

        /* Get fqsn */
        errno_t rc = async_data_write_accept((void **) &fqsn, true, 0,
            LOC_NAME_MAXLEN, 0, NULL);
        if (rc != EOK) {
                async_answer_0(icall, rc);
                return;
        }

        char *ns_name;
        char *name;
        if (!loc_fqsn_split(fqsn, &ns_name, &name)) {
                free(fqsn);
                async_answer_0(icall, EINVAL);
                return;
        }

        free(fqsn);

        fibril_mutex_lock(&services_list_mutex);
        const loc_service_t *svc;

recheck:

        /*
         * Find service name in the list of known services.
         */
        svc = loc_service_find_name(ns_name, name);

        /*
         * Device was not found.
         */
        if (svc == NULL) {
                if (ipc_get_arg1(icall) & IPC_FLAG_BLOCKING) {
                        /* Blocking lookup */
                        fibril_condvar_wait(&services_list_cv,
                            &services_list_mutex);
                        goto recheck;
                }

                async_answer_0(icall, ENOENT);
                free(ns_name);
                free(name);
                fibril_mutex_unlock(&services_list_mutex);
                return;
        }

        async_answer_1(icall, EOK, svc->id);

        fibril_mutex_unlock(&services_list_mutex);
        free(ns_name);
        free(name);
}

/** Find ID for namespace identified by name.
 *
 * In answer will be send EOK and service ID in arg1 or a error
 * code from errno.h.
 *
 */
static void loc_namespace_get_id(ipc_call_t *icall)
{
        char *name;

        /* Get service name */
        errno_t rc = async_data_write_accept((void **) &name, true, 0,
            LOC_NAME_MAXLEN, 0, NULL);
        if (rc != EOK) {
                async_answer_0(icall, rc);
                return;
        }

        fibril_mutex_lock(&services_list_mutex);
        const loc_namespace_t *namespace;

recheck:

        /*
         * Find namespace name in the list of known namespaces.
         */
        namespace = loc_namespace_find_name(name);

        /*
         * Namespace was not found.
         */
        if (namespace == NULL) {
                if (ipc_get_arg1(icall) & IPC_FLAG_BLOCKING) {
                        /* Blocking lookup */
                        fibril_condvar_wait(&services_list_cv,
                            &services_list_mutex);
                        goto recheck;
                }

                async_answer_0(icall, ENOENT);
                free(name);
                fibril_mutex_unlock(&services_list_mutex);
                return;
        }

        async_answer_1(icall, EOK, namespace->id);

        fibril_mutex_unlock(&services_list_mutex);
        free(name);
}

/** Create callback connection.
 *
 * Create callback connection which will be used to send category change
 * events.
 *
 * On success, answer will contain EOK errno_t retval.
 * On failure, error code will be sent in retval.
 *
 */
static void loc_callback_create(ipc_call_t *icall)
{
        cb_sess_t *cb_sess = calloc(1, sizeof(cb_sess_t));
        if (cb_sess == NULL) {
                async_answer_0(icall, ENOMEM);
                return;
        }

        async_sess_t *sess = async_callback_receive(EXCHANGE_SERIALIZE);
        if (sess == NULL) {
                free(cb_sess);
                async_answer_0(icall, ENOMEM);
                return;
        }

        cb_sess->sess = sess;
        link_initialize(&cb_sess->cb_sess_list);

        fibril_mutex_lock(&callback_sess_mutex);
        list_append(&cb_sess->cb_sess_list, &callback_sess_list);
        fibril_mutex_unlock(&callback_sess_mutex);

        async_answer_0(icall, EOK);
}

void loc_category_change_event(void)
{
        fibril_mutex_lock(&callback_sess_mutex);

        list_foreach(callback_sess_list, cb_sess_list, cb_sess_t, cb_sess) {
                async_exch_t *exch = async_exchange_begin(cb_sess->sess);
                async_msg_0(exch, LOC_EVENT_CAT_CHANGE);
                async_exchange_end(exch);
        }

        fibril_mutex_unlock(&callback_sess_mutex);
}

/** Find ID for category specified by name.
 *
 * On success, answer will contain EOK errno_t retval and service ID in arg1.
 * On failure, error code will be sent in retval.
 *
 */
static void loc_category_get_id(ipc_call_t *icall)
{
        char *name;
        category_t *cat;

        /* Get service name */
        errno_t rc = async_data_write_accept((void **) &name, true, 0,
            LOC_NAME_MAXLEN, 0, NULL);
        if (rc != EOK) {
                async_answer_0(icall, rc);
                return;
        }

        fibril_mutex_lock(&cdir.mutex);

        cat = category_find_by_name(&cdir, name);
        if (cat == NULL) {
                /* Category not found */
                async_answer_0(icall, ENOENT);
                goto cleanup;
        }

        async_answer_1(icall, EOK, cat->id);
cleanup:
        fibril_mutex_unlock(&cdir.mutex);
        free(name);
}

static void loc_id_probe(ipc_call_t *icall)
{
        fibril_mutex_lock(&services_list_mutex);

        loc_namespace_t *namespace =
            loc_namespace_find_id(ipc_get_arg1(icall));
        if (namespace == NULL) {
                loc_service_t *svc =
                    loc_service_find_id(ipc_get_arg1(icall));
                if (svc == NULL)
                        async_answer_1(icall, EOK, LOC_OBJECT_NONE);
                else
                        async_answer_1(icall, EOK, LOC_OBJECT_SERVICE);
        } else
                async_answer_1(icall, EOK, LOC_OBJECT_NAMESPACE);

        fibril_mutex_unlock(&services_list_mutex);
}

static void loc_get_namespace_count(ipc_call_t *icall)
{
        fibril_mutex_lock(&services_list_mutex);
        async_answer_1(icall, EOK, list_count(&namespaces_list));
        fibril_mutex_unlock(&services_list_mutex);
}

static void loc_get_service_count(ipc_call_t *icall)
{
        fibril_mutex_lock(&services_list_mutex);

        loc_namespace_t *namespace =
            loc_namespace_find_id(ipc_get_arg1(icall));
        if (namespace == NULL)
                async_answer_0(icall, EEXIST);
        else
                async_answer_1(icall, EOK, namespace->refcnt);

        fibril_mutex_unlock(&services_list_mutex);
}

static void loc_get_categories(ipc_call_t *icall)
{
        ipc_call_t call;
        size_t size;
        size_t act_size;
        errno_t rc;

        if (!async_data_read_receive(&call, &size)) {
                async_answer_0(&call, EREFUSED);
                async_answer_0(icall, EREFUSED);
                return;
        }

        category_id_t *id_buf = (category_id_t *) malloc(size);
        if (id_buf == NULL) {
                fibril_mutex_unlock(&cdir.mutex);
                async_answer_0(&call, ENOMEM);
                async_answer_0(icall, ENOMEM);
                return;
        }

        fibril_mutex_lock(&cdir.mutex);

        rc = categ_dir_get_categories(&cdir, id_buf, size, &act_size);
        if (rc != EOK) {
                fibril_mutex_unlock(&cdir.mutex);
                async_answer_0(&call, rc);
                async_answer_0(icall, rc);
                return;
        }

        fibril_mutex_unlock(&cdir.mutex);

        errno_t retval = async_data_read_finalize(&call, id_buf, size);
        free(id_buf);

        async_answer_1(icall, retval, act_size);
}

static void loc_get_namespaces(ipc_call_t *icall)
{
        ipc_call_t call;
        size_t size;
        if (!async_data_read_receive(&call, &size)) {
                async_answer_0(&call, EREFUSED);
                async_answer_0(icall, EREFUSED);
                return;
        }

        if ((size % sizeof(loc_sdesc_t)) != 0) {
                async_answer_0(&call, EINVAL);
                async_answer_0(icall, EINVAL);
                return;
        }

        fibril_mutex_lock(&services_list_mutex);

        size_t count = size / sizeof(loc_sdesc_t);
        if (count != list_count(&namespaces_list)) {
                fibril_mutex_unlock(&services_list_mutex);
                async_answer_0(&call, EOVERFLOW);
                async_answer_0(icall, EOVERFLOW);
                return;
        }

        loc_sdesc_t *desc = (loc_sdesc_t *) malloc(size);
        if (desc == NULL) {
                fibril_mutex_unlock(&services_list_mutex);
                async_answer_0(&call, ENOMEM);
                async_answer_0(icall, ENOMEM);
                return;
        }

        size_t pos = 0;
        list_foreach(namespaces_list, namespaces, loc_namespace_t, namespace) {
                desc[pos].id = namespace->id;
                str_cpy(desc[pos].name, LOC_NAME_MAXLEN, namespace->name);
                pos++;
        }

        errno_t retval = async_data_read_finalize(&call, desc, size);

        free(desc);
        fibril_mutex_unlock(&services_list_mutex);

        async_answer_0(icall, retval);
}

static void loc_get_services(ipc_call_t *icall)
{
        /*
         * FIXME: Use faster algorithm which can make better use
         * of namespaces
         */

        ipc_call_t call;
        size_t size;
        if (!async_data_read_receive(&call, &size)) {
                async_answer_0(&call, EREFUSED);
                async_answer_0(icall, EREFUSED);
                return;
        }

        if ((size % sizeof(loc_sdesc_t)) != 0) {
                async_answer_0(&call, EINVAL);
                async_answer_0(icall, EINVAL);
                return;
        }

        fibril_mutex_lock(&services_list_mutex);

        loc_namespace_t *namespace =
            loc_namespace_find_id(ipc_get_arg1(icall));
        if (namespace == NULL) {
                fibril_mutex_unlock(&services_list_mutex);
                async_answer_0(&call, ENOENT);
                async_answer_0(icall, ENOENT);
                return;
        }

        size_t count = size / sizeof(loc_sdesc_t);
        if (count != namespace->refcnt) {
                fibril_mutex_unlock(&services_list_mutex);
                async_answer_0(&call, EOVERFLOW);
                async_answer_0(icall, EOVERFLOW);
                return;
        }

        loc_sdesc_t *desc = (loc_sdesc_t *) malloc(size);
        if (desc == NULL) {
                fibril_mutex_unlock(&services_list_mutex);
                async_answer_0(&call, ENOMEM);
                async_answer_0(icall, EREFUSED);
                return;
        }

        size_t pos = 0;
        list_foreach(services_list, services, loc_service_t, service) {
                if (service->namespace == namespace) {
                        desc[pos].id = service->id;
                        str_cpy(desc[pos].name, LOC_NAME_MAXLEN, service->name);
                        pos++;
                }
        }

        errno_t retval = async_data_read_finalize(&call, desc, size);

        free(desc);
        fibril_mutex_unlock(&services_list_mutex);

        async_answer_0(icall, retval);
}

static void loc_category_get_svcs(ipc_call_t *icall)
{
        ipc_call_t call;
        size_t size;
        size_t act_size;
        errno_t rc;

        if (!async_data_read_receive(&call, &size)) {
                async_answer_0(&call, EREFUSED);
                async_answer_0(icall, EREFUSED);
                return;
        }

        fibril_mutex_lock(&cdir.mutex);

        category_t *cat = category_get(&cdir, ipc_get_arg1(icall));
        if (cat == NULL) {
                fibril_mutex_unlock(&cdir.mutex);
                async_answer_0(&call, ENOENT);
                async_answer_0(icall, ENOENT);
                return;
        }

        category_id_t *id_buf = (category_id_t *) malloc(size);
        if (id_buf == NULL) {
                fibril_mutex_unlock(&cdir.mutex);
                async_answer_0(&call, ENOMEM);
                async_answer_0(icall, ENOMEM);
                return;
        }

        fibril_mutex_lock(&cat->mutex);

        rc = category_get_services(cat, id_buf, size, &act_size);
        if (rc != EOK) {
                fibril_mutex_unlock(&cat->mutex);
                fibril_mutex_unlock(&cdir.mutex);
                async_answer_0(&call, rc);
                async_answer_0(icall, rc);
                return;
        }

        fibril_mutex_unlock(&cat->mutex);
        fibril_mutex_unlock(&cdir.mutex);

        errno_t retval = async_data_read_finalize(&call, id_buf, size);
        free(id_buf);

        async_answer_1(icall, retval, act_size);
}

static void loc_null_create(ipc_call_t *icall)
{
        fibril_mutex_lock(&null_services_mutex);

        unsigned int i;
        bool fnd = false;

        for (i = 0; i < NULL_SERVICES; i++) {
                if (null_services[i] == NULL) {
                        fnd = true;
                        break;
                }
        }

        if (!fnd) {
                fibril_mutex_unlock(&null_services_mutex);
                async_answer_0(icall, ENOMEM);
                return;
        }

        char null[LOC_NAME_MAXLEN];
        snprintf(null, LOC_NAME_MAXLEN, "%u", i);

        char *dev_name = str_dup(null);
        if (dev_name == NULL) {
                fibril_mutex_unlock(&null_services_mutex);
                async_answer_0(icall, ENOMEM);
                return;
        }

        loc_service_t *service =
            (loc_service_t *) malloc(sizeof(loc_service_t));
        if (service == NULL) {
                fibril_mutex_unlock(&null_services_mutex);
                async_answer_0(icall, ENOMEM);
                return;
        }

        fibril_mutex_lock(&services_list_mutex);

        loc_namespace_t *namespace = loc_namespace_create("null");
        if (namespace == NULL) {
                fibril_mutex_lock(&services_list_mutex);
                fibril_mutex_unlock(&null_services_mutex);
                async_answer_0(icall, ENOMEM);
                return;
        }

        link_initialize(&service->services);
        link_initialize(&service->server_services);
        list_initialize(&service->cat_memb);

        /* Get unique service ID */
        service->id = loc_create_id();
        service->server = NULL;

        loc_namespace_addref(namespace, service);
        service->name = dev_name;

        /*
         * Insert service into list of all services and into null services array.
         * Insert service into a dummy list of null server's services so that it
         * can be safely removed later.
         */
        list_append(&service->services, &services_list);
        list_append(&service->server_services, &dummy_null_services);
        null_services[i] = service;

        fibril_mutex_unlock(&services_list_mutex);
        fibril_mutex_unlock(&null_services_mutex);

        async_answer_1(icall, EOK, (sysarg_t) i);
}

static void loc_null_destroy(ipc_call_t *icall)
{
        sysarg_t i = ipc_get_arg1(icall);
        if (i >= NULL_SERVICES) {
                async_answer_0(icall, ELIMIT);
                return;
        }

        fibril_mutex_lock(&null_services_mutex);

        if (null_services[i] == NULL) {
                fibril_mutex_unlock(&null_services_mutex);
                async_answer_0(icall, ENOENT);
                return;
        }

        fibril_mutex_lock(&services_list_mutex);
        fibril_mutex_lock(&cdir.mutex);
        loc_service_unregister_core(null_services[i]);
        fibril_mutex_unlock(&cdir.mutex);
        fibril_mutex_unlock(&services_list_mutex);

        null_services[i] = NULL;

        fibril_mutex_unlock(&null_services_mutex);
        async_answer_0(icall, EOK);
}

static void loc_service_add_to_cat(ipc_call_t *icall)
{
        category_t *cat;
        loc_service_t *svc;
        catid_t cat_id;
        service_id_t svc_id;
        errno_t retval;

        svc_id = ipc_get_arg1(icall);
        cat_id = ipc_get_arg2(icall);

        fibril_mutex_lock(&services_list_mutex);
        fibril_mutex_lock(&cdir.mutex);

        cat = category_get(&cdir, cat_id);
        svc = loc_service_find_id(svc_id);

        if (cat == NULL || svc == NULL) {
                fibril_mutex_unlock(&cdir.mutex);
                fibril_mutex_unlock(&services_list_mutex);
                async_answer_0(icall, ENOENT);
                return;
        }

        fibril_mutex_lock(&cat->mutex);
        retval = category_add_service(cat, svc);

        fibril_mutex_unlock(&cat->mutex);
        fibril_mutex_unlock(&cdir.mutex);
        fibril_mutex_unlock(&services_list_mutex);

        /*
         * First send out all notifications and only then answer the request.
         * Otherwise the current fibril might block and transitively wait for
         * the completion of requests that are routed to it via an IPC loop.
         */
        loc_category_change_event();
        async_answer_0(icall, retval);
}

/** Initialize location service.
 *
 *
 */
static bool loc_init(void)
{
        unsigned int i;
        category_t *cat;

        for (i = 0; i < NULL_SERVICES; i++)
                null_services[i] = NULL;

        categ_dir_init(&cdir);

        cat = category_new("disk");
        categ_dir_add_cat(&cdir, cat);

        cat = category_new("partition");
        categ_dir_add_cat(&cdir, cat);

        cat = category_new("iplink");
        categ_dir_add_cat(&cdir, cat);

        cat = category_new("keyboard");
        categ_dir_add_cat(&cdir, cat);

        cat = category_new("mouse");
        categ_dir_add_cat(&cdir, cat);

        cat = category_new("led");
        categ_dir_add_cat(&cdir, cat);

        cat = category_new("serial");
        categ_dir_add_cat(&cdir, cat);

        cat = category_new("console");
        categ_dir_add_cat(&cdir, cat);

        cat = category_new("clock");
        categ_dir_add_cat(&cdir, cat);

        cat = category_new("tbarcfg-notif");
        categ_dir_add_cat(&cdir, cat);

        cat = category_new("test3");
        categ_dir_add_cat(&cdir, cat);

        cat = category_new("usbdiag");
        categ_dir_add_cat(&cdir, cat);

        cat = category_new("usbhc");
        categ_dir_add_cat(&cdir, cat);

        cat = category_new("virt-null");
        categ_dir_add_cat(&cdir, cat);

        cat = category_new("virtual");
        categ_dir_add_cat(&cdir, cat);

        cat = category_new("nic");
        categ_dir_add_cat(&cdir, cat);

        cat = category_new("ieee80211");
        categ_dir_add_cat(&cdir, cat);

        cat = category_new("irc");
        categ_dir_add_cat(&cdir, cat);

        cat = category_new("display-device");
        categ_dir_add_cat(&cdir, cat);

        cat = category_new("audio-pcm");
        categ_dir_add_cat(&cdir, cat);

        cat = category_new("printer-port");
        categ_dir_add_cat(&cdir, cat);

        cat = category_new("pci");
        categ_dir_add_cat(&cdir, cat);

        return true;
}

/** Handle connection on supplier port.
 *
 */
static void loc_connection_supplier(ipc_call_t *icall, void *arg)
{
        /* Accept connection */
        async_accept_0(icall);

        /*
         * Each connection begins by a LOC_SERVER_REGISTER, which precludes us
         * from using parallel exchanges.
         */
        static_assert((INTERFACE_LOC_SUPPLIER & IFACE_EXCHANGE_MASK) ==
            IFACE_EXCHANGE_SERIALIZE, "");

        loc_server_t *server = loc_server_register();
        if (server == NULL)
                return;

        while (true) {
                ipc_call_t call;
                async_get_call(&call);

                if (!ipc_get_imethod(&call)) {
                        async_answer_0(&call, EOK);
                        break;
                }

                switch (ipc_get_imethod(&call)) {
                case LOC_SERVER_UNREGISTER:
                        if (server == NULL)
                                async_answer_0(&call, ENOENT);
                        else
                                async_answer_0(&call, EOK);
                        break;
                case LOC_SERVICE_ADD_TO_CAT:
                        /* Add service to category */
                        loc_service_add_to_cat(&call);
                        break;
                case LOC_SERVICE_REGISTER:
                        /* Register one service */
                        loc_service_register(&call, server);
                        break;
                case LOC_SERVICE_UNREGISTER:
                        /* Remove one service */
                        loc_service_unregister(&call, server);
                        break;
                case LOC_SERVICE_GET_ID:
                        loc_service_get_id(&call);
                        break;
                case LOC_NAMESPACE_GET_ID:
                        loc_namespace_get_id(&call);
                        break;
                default:
                        async_answer_0(&call, ENOENT);
                }
        }

        if (server != NULL) {
                /*
                 * Unregister the server and all its services.
                 */
                loc_server_unregister(server);
                server = NULL;
        }
}

/** Handle connection on consumer port.
 *
 */
static void loc_connection_consumer(ipc_call_t *icall, void *arg)
{
        /* Accept connection */
        async_accept_0(icall);

        while (true) {
                ipc_call_t call;
                async_get_call(&call);

                if (!ipc_get_imethod(&call)) {
                        async_answer_0(&call, EOK);
                        break;
                }

                switch (ipc_get_imethod(&call)) {
                case LOC_SERVICE_GET_ID:
                        loc_service_get_id(&call);
                        break;
                case LOC_SERVICE_GET_NAME:
                        loc_service_get_name(&call);
                        break;
                case LOC_SERVICE_GET_SERVER_NAME:
                        loc_service_get_server_name(&call);
                        break;
                case LOC_NAMESPACE_GET_ID:
                        loc_namespace_get_id(&call);
                        break;
                case LOC_CALLBACK_CREATE:
                        loc_callback_create(&call);
                        break;
                case LOC_CATEGORY_GET_ID:
                        loc_category_get_id(&call);
                        break;
                case LOC_CATEGORY_GET_NAME:
                        loc_category_get_name(&call);
                        break;
                case LOC_CATEGORY_GET_SVCS:
                        loc_category_get_svcs(&call);
                        break;
                case LOC_ID_PROBE:
                        loc_id_probe(&call);
                        break;
                case LOC_NULL_CREATE:
                        loc_null_create(&call);
                        break;
                case LOC_NULL_DESTROY:
                        loc_null_destroy(&call);
                        break;
                case LOC_GET_NAMESPACE_COUNT:
                        loc_get_namespace_count(&call);
                        break;
                case LOC_GET_SERVICE_COUNT:
                        loc_get_service_count(&call);
                        break;
                case LOC_GET_CATEGORIES:
                        loc_get_categories(&call);
                        break;
                case LOC_GET_NAMESPACES:
                        loc_get_namespaces(&call);
                        break;
                case LOC_GET_SERVICES:
                        loc_get_services(&call);
                        break;
                default:
                        async_answer_0(&call, ENOENT);
                }
        }
}

/**
 *
 */
int main(int argc, char *argv[])
{
        printf("%s: HelenOS Location Service\n", NAME);

        if (!loc_init()) {
                printf("%s: Error while initializing service\n", NAME);
                return -1;
        }

        /* Register location service at naming service */
        errno_t rc = service_register(SERVICE_LOC, INTERFACE_LOC_SUPPLIER,
            loc_connection_supplier, NULL);
        if (rc != EOK) {
                printf("%s: Error while registering supplier service: %s\n", NAME, str_error(rc));
                return rc;
        }

        rc = service_register(SERVICE_LOC, INTERFACE_LOC_CONSUMER,
            loc_connection_consumer, NULL);
        if (rc != EOK) {
                printf("%s: Error while registering consumer service: %s\n", NAME, str_error(rc));
                return rc;
        }

        rc = service_register_broker(SERVICE_LOC, loc_forward, NULL);
        if (rc != EOK) {
                printf("%s: Error while registering broker service: %s\n", NAME, str_error(rc));
                return rc;
        }

        printf("%s: Accepting connections\n", NAME);
        async_manager();

        /* Never reached */
        return 0;
}

/**
 * @}
 */