/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */ /* dbus-bus.c Convenience functions for communicating with the bus. * * Copyright (C) 2003 CodeFactory AB * Copyright (C) 2003 Red Hat, Inc. * * Licensed under the Academic Free License version 2.1 * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA * */ #include #include "dbus-bus.h" #include "dbus-protocol.h" #include "dbus-internals.h" #include "dbus-message.h" #include "dbus-marshal-validate.h" #include "dbus-threads-internal.h" #include "dbus-connection-internal.h" #include "dbus-string.h" /** * @defgroup DBusBus Message bus APIs * @ingroup DBus * @brief Functions for communicating with the message bus * * dbus_bus_get() allows all modules and libraries in a given * process to share the same connection to the bus daemon by storing * the connection globally. * * All other functions in this module are just convenience functions; * most of them invoke methods on the bus daemon, by sending method * call messages to #DBUS_SERVICE_DBUS. These convenience functions * often make blocking method calls. If you don't want to block, * you can send the method call messages manually in the same way * you would any other method call message. * * This module is the only one in libdbus that's specific to * communicating with the message bus daemon. The rest of the API can * also be used for connecting to another application directly. * * @todo right now the default address of the system bus is hardcoded, * so if you change it in the global config file suddenly you have to * set DBUS_SYSTEM_BUS_ADDRESS env variable. Might be nice if the * client lib somehow read the config file, or if the bus on startup * somehow wrote out its address to a well-known spot, but might also * not be worth it. */ /** * @defgroup DBusBusInternals Message bus APIs internals * @ingroup DBusInternals * @brief Internals of functions for communicating with the message bus * * @{ */ /** * Block of message-bus-related data we attach to each * #DBusConnection used with these convenience functions. * */ typedef struct { DBusConnection *connection; /**< Connection we're associated with */ char *unique_name; /**< Unique name of this connection */ unsigned int is_well_known : 1; /**< Is one of the well-known connections in our global array */ } BusData; /** The slot we have reserved to store BusData. */ static dbus_int32_t bus_data_slot = -1; /** Number of bus types */ #define N_BUS_TYPES 3 static DBusConnection *bus_connections[N_BUS_TYPES]; static char *bus_connection_addresses[N_BUS_TYPES] = { NULL, NULL, NULL }; static DBusBusType activation_bus_type = DBUS_BUS_STARTER; static dbus_bool_t initialized = FALSE; /** * Lock for globals in this file */ _DBUS_DEFINE_GLOBAL_LOCK (bus); /** * Global lock covering all BusData on any connection. The bet is * that some lock contention is better than more memory * for a per-connection lock, but it's tough to imagine it mattering * either way. */ _DBUS_DEFINE_GLOBAL_LOCK (bus_datas); static void addresses_shutdown_func (void *data) { int i; i = 0; while (i < N_BUS_TYPES) { if (bus_connections[i] != NULL) _dbus_warn_check_failed ("dbus_shutdown() called but connections were still live. This probably means the application did not drop all its references to bus connections.\n"); dbus_free (bus_connection_addresses[i]); bus_connection_addresses[i] = NULL; ++i; } activation_bus_type = DBUS_BUS_STARTER; initialized = FALSE; } static dbus_bool_t get_from_env (char **connection_p, const char *env_var) { const char *s; _dbus_assert (*connection_p == NULL); s = _dbus_getenv (env_var); if (s == NULL || *s == '\0') return TRUE; /* successfully didn't use the env var */ else { *connection_p = _dbus_strdup (s); return *connection_p != NULL; } } static dbus_bool_t init_session_address (void) { dbus_bool_t retval; retval = FALSE; /* First, look in the environment. This is the normal case on * freedesktop.org/Unix systems. */ get_from_env (&bus_connection_addresses[DBUS_BUS_SESSION], "DBUS_SESSION_BUS_ADDRESS"); if (bus_connection_addresses[DBUS_BUS_SESSION] == NULL) { dbus_bool_t supported; DBusString addr; DBusError error = DBUS_ERROR_INIT; if (!_dbus_string_init (&addr)) return FALSE; supported = FALSE; /* So it's not in the environment - let's try a platform-specific method. * On MacOS, this involves asking launchd. On Windows (not specified yet) * we might do a COM lookup. * Ignore errors - if we failed, fall back to autolaunch. */ retval = _dbus_lookup_session_address (&supported, &addr, &error); if (supported && retval) { retval =_dbus_string_steal_data (&addr, &bus_connection_addresses[DBUS_BUS_SESSION]); } else if (supported && !retval) { if (dbus_error_is_set(&error)) _dbus_warn ("Dynamic session lookup supported but failed: %s\n", error.message); else _dbus_warn ("Dynamic session lookup supported but failed silently\n"); } _dbus_string_free (&addr); } else retval = TRUE; if (!retval) return FALSE; /* The DBUS_SESSION_BUS_DEFAULT_ADDRESS should have really been named * DBUS_SESSION_BUS_FALLBACK_ADDRESS. */ if (bus_connection_addresses[DBUS_BUS_SESSION] == NULL) bus_connection_addresses[DBUS_BUS_SESSION] = _dbus_strdup (DBUS_SESSION_BUS_DEFAULT_ADDRESS); if (bus_connection_addresses[DBUS_BUS_SESSION] == NULL) return FALSE; return TRUE; } static dbus_bool_t init_connections_unlocked (void) { if (!initialized) { const char *s; int i; i = 0; while (i < N_BUS_TYPES) { bus_connections[i] = NULL; ++i; } /* Don't init these twice, we may run this code twice if * init_connections_unlocked() fails midway through. * In practice, each block below should contain only one * "return FALSE" or running through twice may not * work right. */ if (bus_connection_addresses[DBUS_BUS_SYSTEM] == NULL) { _dbus_verbose ("Filling in system bus address...\n"); if (!get_from_env (&bus_connection_addresses[DBUS_BUS_SYSTEM], "DBUS_SYSTEM_BUS_ADDRESS")) return FALSE; } if (bus_connection_addresses[DBUS_BUS_SYSTEM] == NULL) { /* Use default system bus address if none set in environment */ bus_connection_addresses[DBUS_BUS_SYSTEM] = _dbus_strdup (DBUS_SYSTEM_BUS_DEFAULT_ADDRESS); if (bus_connection_addresses[DBUS_BUS_SYSTEM] == NULL) return FALSE; _dbus_verbose (" used default system bus \"%s\"\n", bus_connection_addresses[DBUS_BUS_SYSTEM]); } else _dbus_verbose (" used env var system bus \"%s\"\n", bus_connection_addresses[DBUS_BUS_SYSTEM]); if (bus_connection_addresses[DBUS_BUS_SESSION] == NULL) { _dbus_verbose ("Filling in session bus address...\n"); if (!init_session_address ()) return FALSE; _dbus_verbose (" \"%s\"\n", bus_connection_addresses[DBUS_BUS_SESSION] ? bus_connection_addresses[DBUS_BUS_SESSION] : "none set"); } if (bus_connection_addresses[DBUS_BUS_STARTER] == NULL) { _dbus_verbose ("Filling in activation bus address...\n"); if (!get_from_env (&bus_connection_addresses[DBUS_BUS_STARTER], "DBUS_STARTER_ADDRESS")) return FALSE; _dbus_verbose (" \"%s\"\n", bus_connection_addresses[DBUS_BUS_STARTER] ? bus_connection_addresses[DBUS_BUS_STARTER] : "none set"); } if (bus_connection_addresses[DBUS_BUS_STARTER] != NULL) { s = _dbus_getenv ("DBUS_STARTER_BUS_TYPE"); if (s != NULL) { _dbus_verbose ("Bus activation type was set to \"%s\"\n", s); if (strcmp (s, "system") == 0) activation_bus_type = DBUS_BUS_SYSTEM; else if (strcmp (s, "session") == 0) activation_bus_type = DBUS_BUS_SESSION; } } else { /* Default to the session bus instead if available */ if (bus_connection_addresses[DBUS_BUS_SESSION] != NULL) { bus_connection_addresses[DBUS_BUS_STARTER] = _dbus_strdup (bus_connection_addresses[DBUS_BUS_SESSION]); if (bus_connection_addresses[DBUS_BUS_STARTER] == NULL) return FALSE; } } /* If we return FALSE we have to be sure that restarting * the above code will work right */ if (!_dbus_setenv ("DBUS_ACTIVATION_ADDRESS", NULL)) return FALSE; if (!_dbus_setenv ("DBUS_ACTIVATION_BUS_TYPE", NULL)) return FALSE; if (!_dbus_register_shutdown_func (addresses_shutdown_func, NULL)) return FALSE; initialized = TRUE; } return initialized; } static void bus_data_free (void *data) { BusData *bd = data; if (bd->is_well_known) { int i; _DBUS_LOCK (bus); /* We may be stored in more than one slot */ /* This should now be impossible - these slots are supposed to * be cleared on disconnect, so should not need to be cleared on * finalize */ i = 0; while (i < N_BUS_TYPES) { if (bus_connections[i] == bd->connection) bus_connections[i] = NULL; ++i; } _DBUS_UNLOCK (bus); } dbus_free (bd->unique_name); dbus_free (bd); dbus_connection_free_data_slot (&bus_data_slot); } static BusData* ensure_bus_data (DBusConnection *connection) { BusData *bd; if (!dbus_connection_allocate_data_slot (&bus_data_slot)) return NULL; bd = dbus_connection_get_data (connection, bus_data_slot); if (bd == NULL) { bd = dbus_new0 (BusData, 1); if (bd == NULL) { dbus_connection_free_data_slot (&bus_data_slot); return NULL; } bd->connection = connection; if (!dbus_connection_set_data (connection, bus_data_slot, bd, bus_data_free)) { dbus_free (bd); dbus_connection_free_data_slot (&bus_data_slot); return NULL; } /* Data slot refcount now held by the BusData */ } else { dbus_connection_free_data_slot (&bus_data_slot); } return bd; } /** * Internal function that checks to see if this * is a shared connection owned by the bus and if it is unref it. * * @param connection a connection that has been disconnected. */ void _dbus_bus_notify_shared_connection_disconnected_unlocked (DBusConnection *connection) { int i; _DBUS_LOCK (bus); /* We are expecting to have the connection saved in only one of these * slots, but someone could in a pathological case set system and session * bus to the same bus or something. Or set one of them to the starter * bus without setting the starter bus type in the env variable. * So we don't break the loop as soon as we find a match. */ for (i = 0; i < N_BUS_TYPES; ++i) { if (bus_connections[i] == connection) { bus_connections[i] = NULL; } } _DBUS_UNLOCK (bus); } static DBusConnection * internal_bus_get (DBusBusType type, dbus_bool_t private, DBusError *error) { const char *address; DBusConnection *connection; BusData *bd; DBusBusType address_type; _dbus_return_val_if_fail (type >= 0 && type < N_BUS_TYPES, NULL); _dbus_return_val_if_error_is_set (error, NULL); _DBUS_LOCK (bus); if (!init_connections_unlocked ()) { _DBUS_UNLOCK (bus); _DBUS_SET_OOM (error); return NULL; } /* We want to use the activation address even if the * activating bus is the session or system bus, * per the spec. */ address_type = type; /* Use the real type of the activation bus for getting its * connection, but only if the real type's address is available. (If * the activating bus isn't a well-known bus then * activation_bus_type == DBUS_BUS_STARTER) */ if (type == DBUS_BUS_STARTER && bus_connection_addresses[activation_bus_type] != NULL) type = activation_bus_type; if (!private && bus_connections[type] != NULL) { connection = bus_connections[type]; dbus_connection_ref (connection); _DBUS_UNLOCK (bus); return connection; } address = bus_connection_addresses[address_type]; if (address == NULL) { dbus_set_error (error, DBUS_ERROR_FAILED, "Unable to determine the address of the message bus (try 'man dbus-launch' and 'man dbus-daemon' for help)"); _DBUS_UNLOCK (bus); return NULL; } if (private) connection = dbus_connection_open_private (address, error); else connection = dbus_connection_open (address, error); if (!connection) { _DBUS_ASSERT_ERROR_IS_SET (error); _DBUS_UNLOCK (bus); return NULL; } if (!dbus_bus_register (connection, error)) { _DBUS_ASSERT_ERROR_IS_SET (error); _dbus_connection_close_possibly_shared (connection); dbus_connection_unref (connection); _DBUS_UNLOCK (bus); return NULL; } if (!private) { /* store a weak ref to the connection (dbus-connection.c is * supposed to have a strong ref that it drops on disconnect, * since this is a shared connection) */ bus_connections[type] = connection; } /* By default we're bound to the lifecycle of * the message bus. */ dbus_connection_set_exit_on_disconnect (connection, TRUE); _DBUS_LOCK (bus_datas); bd = ensure_bus_data (connection); _dbus_assert (bd != NULL); /* it should have been created on register, so OOM not possible */ bd->is_well_known = TRUE; _DBUS_UNLOCK (bus_datas); _DBUS_UNLOCK (bus); /* Return a reference to the caller */ return connection; } /** @} */ /* end of implementation details docs */ /** * @addtogroup DBusBus * @{ */ /** * Connects to a bus daemon and registers the client with it. If a * connection to the bus already exists, then that connection is * returned. The caller of this function owns a reference to the bus. * * The caller may NOT call dbus_connection_close() on this connection; * see dbus_connection_open() and dbus_connection_close() for details * on that. * * If this function obtains a new connection object never before * returned from dbus_bus_get(), it will call * dbus_connection_set_exit_on_disconnect(), so the application * will exit if the connection closes. You can undo this * by calling dbus_connection_set_exit_on_disconnect() yourself * after you get the connection. * * dbus_bus_get() calls dbus_bus_register() for you. * * If returning a newly-created connection, this function will block * until authentication and bus registration are complete. * * @param type bus type * @param error address where an error can be returned. * @returns a #DBusConnection with new ref */ DBusConnection * dbus_bus_get (DBusBusType type, DBusError *error) { return internal_bus_get (type, FALSE, error); } /** * Connects to a bus daemon and registers the client with it as with * dbus_bus_register(). Unlike dbus_bus_get(), always creates a new * connection. This connection will not be saved or recycled by * libdbus. Caller owns a reference to the bus and must either close * it or know it to be closed prior to releasing this reference. * * See dbus_connection_open_private() for more details on when to * close and unref this connection. * * This function calls * dbus_connection_set_exit_on_disconnect() on the new connection, so the application * will exit if the connection closes. You can undo this * by calling dbus_connection_set_exit_on_disconnect() yourself * after you get the connection. * * dbus_bus_get_private() calls dbus_bus_register() for you. * * This function will block until authentication and bus registration * are complete. * * @param type bus type * @param error address where an error can be returned. * @returns a DBusConnection with new ref */ DBusConnection * dbus_bus_get_private (DBusBusType type, DBusError *error) { return internal_bus_get (type, TRUE, error); } /** * Registers a connection with the bus. This must be the first * thing an application does when connecting to the message bus. * If registration succeeds, the unique name will be set, * and can be obtained using dbus_bus_get_unique_name(). * * This function will block until registration is complete. * * If the connection has already registered with the bus * (determined by checking whether dbus_bus_get_unique_name() * returns a non-#NULL value), then this function does nothing. * * If you use dbus_bus_get() or dbus_bus_get_private() this * function will be called for you. * * @note Just use dbus_bus_get() or dbus_bus_get_private() instead of * dbus_bus_register() and save yourself some pain. Using * dbus_bus_register() manually is only useful if you have your * own custom message bus not found in #DBusBusType. * * If you open a bus connection with dbus_connection_open() or * dbus_connection_open_private() you will have to dbus_bus_register() * yourself, or make the appropriate registration method calls * yourself. If you send the method calls yourself, call * dbus_bus_set_unique_name() with the unique bus name you get from * the bus. * * For shared connections (created with dbus_connection_open()) in a * multithreaded application, you can't really make the registration * calls yourself, because you don't know whether some other thread is * also registering, and the bus will kick you off if you send two * registration messages. * * If you use dbus_bus_register() however, there is a lock that * keeps both apps from registering at the same time. * * The rule in a multithreaded app, then, is that dbus_bus_register() * must be used to register, or you need to have your own locks that * all threads in the app will respect. * * In a single-threaded application you can register by hand instead * of using dbus_bus_register(), as long as you check * dbus_bus_get_unique_name() to see if a unique name has already been * stored by another thread before you send the registration messages. * * @param connection the connection * @param error place to store errors * @returns #TRUE on success */ dbus_bool_t dbus_bus_register (DBusConnection *connection, DBusError *error) { DBusMessage *message, *reply; char *name; BusData *bd; dbus_bool_t retval; _dbus_return_val_if_fail (connection != NULL, FALSE); _dbus_return_val_if_error_is_set (error, FALSE); retval = FALSE; _DBUS_LOCK (bus_datas); bd = ensure_bus_data (connection); if (bd == NULL) { _DBUS_SET_OOM (error); _DBUS_UNLOCK (bus_datas); return FALSE; } if (bd->unique_name != NULL) { _dbus_verbose ("Ignoring attempt to register the same DBusConnection %s with the message bus a second time.\n", bd->unique_name); _DBUS_UNLOCK (bus_datas); /* Success! */ return TRUE; } message = dbus_message_new_method_call (DBUS_SERVICE_DBUS, DBUS_PATH_DBUS, DBUS_INTERFACE_DBUS, "Hello"); if (!message) { _DBUS_SET_OOM (error); _DBUS_UNLOCK (bus_datas); return FALSE; } reply = dbus_connection_send_with_reply_and_block (connection, message, -1, error); dbus_message_unref (message); if (reply == NULL) goto out; else if (dbus_set_error_from_message (error, reply)) goto out; else if (!dbus_message_get_args (reply, error, DBUS_TYPE_STRING, &name, DBUS_TYPE_INVALID)) goto out; bd->unique_name = _dbus_strdup (name); if (bd->unique_name == NULL) { _DBUS_SET_OOM (error); goto out; } retval = TRUE; out: if (reply) dbus_message_unref (reply); if (!retval) _DBUS_ASSERT_ERROR_IS_SET (error); _DBUS_UNLOCK (bus_datas); return retval; } /** * Sets the unique name of the connection, as assigned by the message * bus. Can only be used if you registered with the bus manually * (i.e. if you did not call dbus_bus_register()). Can only be called * once per connection. After the unique name is set, you can get it * with dbus_bus_get_unique_name(). * * The only reason to use this function is to re-implement the * equivalent of dbus_bus_register() yourself. One (probably unusual) * reason to do that might be to do the bus registration call * asynchronously instead of synchronously. * * @note Just use dbus_bus_get() or dbus_bus_get_private(), or worst * case dbus_bus_register(), instead of messing with this * function. There's really no point creating pain for yourself by * doing things manually. * * It's hard to use this function safely on shared connections * (created by dbus_connection_open()) in a multithreaded application, * because only one registration attempt can be sent to the bus. If * two threads are both sending the registration message, there is no * mechanism in libdbus itself to avoid sending it twice. * * Thus, you need a way to coordinate which thread sends the * registration attempt; which also means you know which thread * will call dbus_bus_set_unique_name(). If you don't know * about all threads in the app (for example, if some libraries * you're using might start libdbus-using threads), then you * need to avoid using this function on shared connections. * * @param connection the connection * @param unique_name the unique name * @returns #FALSE if not enough memory */ dbus_bool_t dbus_bus_set_unique_name (DBusConnection *connection, const char *unique_name) { BusData *bd; dbus_bool_t success; _dbus_return_val_if_fail (connection != NULL, FALSE); _dbus_return_val_if_fail (unique_name != NULL, FALSE); _DBUS_LOCK (bus_datas); bd = ensure_bus_data (connection); if (bd == NULL) return FALSE; _dbus_assert (bd->unique_name == NULL); bd->unique_name = _dbus_strdup (unique_name); success = bd->unique_name != NULL; _DBUS_UNLOCK (bus_datas); return success; } /** * Gets the unique name of the connection as assigned by the message * bus. Only possible after the connection has been registered with * the message bus. All connections returned by dbus_bus_get() or * dbus_bus_get_private() have been successfully registered. * * The name remains valid until the connection is freed, and * should not be freed by the caller. * * Other than dbus_bus_get(), there are two ways to set the unique * name; one is dbus_bus_register(), the other is * dbus_bus_set_unique_name(). You are responsible for calling * dbus_bus_set_unique_name() if you register by hand instead of using * dbus_bus_register(). * * @param connection the connection * @returns the unique name or #NULL on error */ const char* dbus_bus_get_unique_name (DBusConnection *connection) { BusData *bd; const char *unique_name; _dbus_return_val_if_fail (connection != NULL, NULL); _DBUS_LOCK (bus_datas); bd = ensure_bus_data (connection); if (bd == NULL) return NULL; unique_name = bd->unique_name; _DBUS_UNLOCK (bus_datas); return unique_name; } /** * Asks the bus to return the UID the named connection authenticated * as, if any. Only works on UNIX; only works for connections on the * same machine as the bus. If you are not on the same machine as the * bus, then calling this is probably a bad idea, since the UID will * mean little to your application. * * For the system message bus you're guaranteed to be on the same * machine since it only listens on a UNIX domain socket (at least, * as shipped by default). * * This function only works for connections that authenticated as * a UNIX user, right now that includes all bus connections, but * it's very possible to have connections with no associated UID. * So check for errors and do something sensible if they happen. * * This function will always return an error on Windows. * * @param connection the connection * @param name a name owned by the connection * @param error location to store the error * @returns the unix user id, or ((unsigned)-1) if error is set */ unsigned long dbus_bus_get_unix_user (DBusConnection *connection, const char *name, DBusError *error) { DBusMessage *message, *reply; dbus_uint32_t uid; _dbus_return_val_if_fail (connection != NULL, DBUS_UID_UNSET); _dbus_return_val_if_fail (name != NULL, DBUS_UID_UNSET); _dbus_return_val_if_fail (_dbus_check_is_valid_bus_name (name), DBUS_UID_UNSET); _dbus_return_val_if_error_is_set (error, DBUS_UID_UNSET); message = dbus_message_new_method_call (DBUS_SERVICE_DBUS, DBUS_PATH_DBUS, DBUS_INTERFACE_DBUS, "GetConnectionUnixUser"); if (message == NULL) { _DBUS_SET_OOM (error); return DBUS_UID_UNSET; } if (!dbus_message_append_args (message, DBUS_TYPE_STRING, &name, DBUS_TYPE_INVALID)) { dbus_message_unref (message); _DBUS_SET_OOM (error); return DBUS_UID_UNSET; } reply = dbus_connection_send_with_reply_and_block (connection, message, -1, error); dbus_message_unref (message); if (reply == NULL) { _DBUS_ASSERT_ERROR_IS_SET (error); return DBUS_UID_UNSET; } if (dbus_set_error_from_message (error, reply)) { _DBUS_ASSERT_ERROR_IS_SET (error); dbus_message_unref (reply); return DBUS_UID_UNSET; } if (!dbus_message_get_args (reply, error, DBUS_TYPE_UINT32, &uid, DBUS_TYPE_INVALID)) { _DBUS_ASSERT_ERROR_IS_SET (error); dbus_message_unref (reply); return DBUS_UID_UNSET; } dbus_message_unref (reply); return (unsigned long) uid; } /** * Asks the bus to return its globally unique ID, as described in the * D-Bus specification. For the session bus, this is useful as a way * to uniquely identify each user session. For the system bus, * probably the bus ID is not useful; instead, use the machine ID * since it's accessible without necessarily connecting to the bus and * may be persistent beyond a single bus instance (across reboots for * example). See dbus_get_local_machine_id(). * * In addition to an ID for each bus and an ID for each machine, there is * an ID for each address that the bus is listening on; that can * be retrieved with dbus_connection_get_server_id(), though it is * probably not very useful. * * @param connection the connection * @param error location to store the error * @returns the bus ID or #NULL if error is set */ char* dbus_bus_get_id (DBusConnection *connection, DBusError *error) { DBusMessage *message, *reply; char *id; const char *v_STRING; _dbus_return_val_if_fail (connection != NULL, NULL); _dbus_return_val_if_error_is_set (error, NULL); message = dbus_message_new_method_call (DBUS_SERVICE_DBUS, DBUS_PATH_DBUS, DBUS_INTERFACE_DBUS, "GetId"); if (message == NULL) { _DBUS_SET_OOM (error); return NULL; } reply = dbus_connection_send_with_reply_and_block (connection, message, -1, error); dbus_message_unref (message); if (reply == NULL) { _DBUS_ASSERT_ERROR_IS_SET (error); return NULL; } if (dbus_set_error_from_message (error, reply)) { _DBUS_ASSERT_ERROR_IS_SET (error); dbus_message_unref (reply); return NULL; } v_STRING = NULL; if (!dbus_message_get_args (reply, error, DBUS_TYPE_STRING, &v_STRING, DBUS_TYPE_INVALID)) { _DBUS_ASSERT_ERROR_IS_SET (error); dbus_message_unref (reply); return NULL; } id = _dbus_strdup (v_STRING); /* may be NULL */ dbus_message_unref (reply); if (id == NULL) _DBUS_SET_OOM (error); /* FIXME it might be nice to cache the ID locally */ return id; } /** * Asks the bus to assign the given name to this connection by invoking * the RequestName method on the bus. This method is fully documented * in the D-Bus specification. For quick reference, the flags and * result codes are discussed here, but the specification is the * canonical version of this information. * * First you should know that for each bus name, the bus stores * a queue of connections that would like to own it. Only * one owns it at a time - called the primary owner. If the primary * owner releases the name or disconnects, then the next owner in the * queue atomically takes over. * * So for example if you have an application org.freedesktop.TextEditor * and multiple instances of it can be run, you can have all of them * sitting in the queue. The first one to start up will receive messages * sent to org.freedesktop.TextEditor, but if that one exits another * will become the primary owner and receive messages. * * The queue means you don't need to manually watch for the current owner to * disappear and then request the name again. * * When requesting a name, you can specify several flags. * * #DBUS_NAME_FLAG_ALLOW_REPLACEMENT and #DBUS_NAME_FLAG_DO_NOT_QUEUE * are properties stored by the bus for this connection with respect to * each requested bus name. These properties are stored even if the * connection is queued and does not become the primary owner. * You can update these flags by calling RequestName again (even if * you already own the name). * * #DBUS_NAME_FLAG_ALLOW_REPLACEMENT means that another requestor of the * name can take it away from you by specifying #DBUS_NAME_FLAG_REPLACE_EXISTING. * * #DBUS_NAME_FLAG_DO_NOT_QUEUE means that if you aren't the primary owner, * you don't want to be queued up - you only care about being the * primary owner. * * Unlike the other two flags, #DBUS_NAME_FLAG_REPLACE_EXISTING is a property * of the individual RequestName call, i.e. the bus does not persistently * associate it with the connection-name pair. If a RequestName call includes * the #DBUS_NAME_FLAG_REPLACE_EXISTING flag, and the current primary * owner has #DBUS_NAME_FLAG_ALLOW_REPLACEMENT set, then the current primary * owner will be kicked off. * * If no flags are given, an application will receive the requested * name only if the name is currently unowned; and it will NOT give * up the name if another application asks to take it over using * #DBUS_NAME_FLAG_REPLACE_EXISTING. * * This function returns a result code. The possible result codes * are as follows. * * #DBUS_REQUEST_NAME_REPLY_PRIMARY_OWNER means that the name had no * existing owner, and the caller is now the primary owner; or that * the name had an owner, and the caller specified * #DBUS_NAME_FLAG_REPLACE_EXISTING, and the current owner * specified #DBUS_NAME_FLAG_ALLOW_REPLACEMENT. * * #DBUS_REQUEST_NAME_REPLY_IN_QUEUE happens only if the caller does NOT * specify #DBUS_NAME_FLAG_DO_NOT_QUEUE and either the current owner * did NOT specify #DBUS_NAME_FLAG_ALLOW_REPLACEMENT or the caller did NOT * specify #DBUS_NAME_FLAG_REPLACE_EXISTING. In this case the caller ends up * in a queue to own the name after the current owner gives it up. * * #DBUS_REQUEST_NAME_REPLY_EXISTS happens if the name has an owner * already and the caller specifies #DBUS_NAME_FLAG_DO_NOT_QUEUE * and either the current owner has NOT specified * #DBUS_NAME_FLAG_ALLOW_REPLACEMENT or the caller did NOT specify * #DBUS_NAME_FLAG_REPLACE_EXISTING. * * #DBUS_REQUEST_NAME_REPLY_ALREADY_OWNER happens if an application * requests a name it already owns. (Re-requesting a name is useful if * you want to change the #DBUS_NAME_FLAG_ALLOW_REPLACEMENT or * #DBUS_NAME_FLAG_DO_NOT_QUEUE settings.) * * When a service represents an application, say "text editor," then * it should specify #DBUS_NAME_FLAG_ALLOW_REPLACEMENT if it wants * the last editor started to be the user's editor vs. the first one * started. Then any editor that can be the user's editor should * specify #DBUS_NAME_FLAG_REPLACE_EXISTING to either take over * (last-started-wins) or be queued up (first-started-wins) according * to whether #DBUS_NAME_FLAG_ALLOW_REPLACEMENT was given. * * Conventionally, single-instance applications often offer a command * line option called --replace which means to replace the current * instance. To implement this, always set * #DBUS_NAME_FLAG_ALLOW_REPLACEMENT when you request your * application's bus name. When you lose ownership of your bus name, * you need to exit. Look for the signal "NameLost" from * #DBUS_SERVICE_DBUS and #DBUS_INTERFACE_DBUS (the signal's first * argument is the bus name that was lost). If starting up without * --replace, do not specify #DBUS_NAME_FLAG_REPLACE_EXISTING, and * exit if you fail to become the bus name owner. If --replace is * given, ask to replace the old owner. * * @param connection the connection * @param name the name to request * @param flags flags * @param error location to store the error * @returns a result code, -1 if error is set */ int dbus_bus_request_name (DBusConnection *connection, const char *name, unsigned int flags, DBusError *error) { DBusMessage *message, *reply; dbus_uint32_t result; _dbus_return_val_if_fail (connection != NULL, 0); _dbus_return_val_if_fail (name != NULL, 0); _dbus_return_val_if_fail (_dbus_check_is_valid_bus_name (name), 0); _dbus_return_val_if_error_is_set (error, 0); message = dbus_message_new_method_call (DBUS_SERVICE_DBUS, DBUS_PATH_DBUS, DBUS_INTERFACE_DBUS, "RequestName"); if (message == NULL) { _DBUS_SET_OOM (error); return -1; } if (!dbus_message_append_args (message, DBUS_TYPE_STRING, &name, DBUS_TYPE_UINT32, &flags, DBUS_TYPE_INVALID)) { dbus_message_unref (message); _DBUS_SET_OOM (error); return -1; } reply = dbus_connection_send_with_reply_and_block (connection, message, -1, error); dbus_message_unref (message); if (reply == NULL) { _DBUS_ASSERT_ERROR_IS_SET (error); return -1; } if (dbus_set_error_from_message (error, reply)) { _DBUS_ASSERT_ERROR_IS_SET (error); dbus_message_unref (reply); return -1; } if (!dbus_message_get_args (reply, error, DBUS_TYPE_UINT32, &result, DBUS_TYPE_INVALID)) { _DBUS_ASSERT_ERROR_IS_SET (error); dbus_message_unref (reply); return -1; } dbus_message_unref (reply); return result; } /** * Asks the bus to unassign the given name from this connection by * invoking the ReleaseName method on the bus. The "ReleaseName" * method is canonically documented in the D-Bus specification. * * Possible results are: #DBUS_RELEASE_NAME_REPLY_RELEASED * which means you owned the name or were in the queue to own it, * and and now you don't own it and aren't in the queue. * #DBUS_RELEASE_NAME_REPLY_NOT_OWNER which means someone else * owns the name so you can't release it. * #DBUS_RELEASE_NAME_REPLY_NON_EXISTENT * which means nobody owned the name. * * @param connection the connection * @param name the name to remove * @param error location to store the error * @returns a result code, -1 if error is set */ int dbus_bus_release_name (DBusConnection *connection, const char *name, DBusError *error) { DBusMessage *message, *reply; dbus_uint32_t result; _dbus_return_val_if_fail (connection != NULL, 0); _dbus_return_val_if_fail (name != NULL, 0); _dbus_return_val_if_fail (_dbus_check_is_valid_bus_name (name), 0); _dbus_return_val_if_error_is_set (error, 0); message = dbus_message_new_method_call (DBUS_SERVICE_DBUS, DBUS_PATH_DBUS, DBUS_INTERFACE_DBUS, "ReleaseName"); if (message == NULL) { _DBUS_SET_OOM (error); return -1; } if (!dbus_message_append_args (message, DBUS_TYPE_STRING, &name, DBUS_TYPE_INVALID)) { dbus_message_unref (message); _DBUS_SET_OOM (error); return -1; } reply = dbus_connection_send_with_reply_and_block (connection, message, -1, error); dbus_message_unref (message); if (reply == NULL) { _DBUS_ASSERT_ERROR_IS_SET (error); return -1; } if (dbus_set_error_from_message (error, reply)) { _DBUS_ASSERT_ERROR_IS_SET (error); dbus_message_unref (reply); return -1; } if (!dbus_message_get_args (reply, error, DBUS_TYPE_UINT32, &result, DBUS_TYPE_INVALID)) { _DBUS_ASSERT_ERROR_IS_SET (error); dbus_message_unref (reply); return -1; } dbus_message_unref (reply); return result; } /** * Asks the bus whether a certain name has an owner. * * Using this can easily result in a race condition, * since an owner can appear or disappear after you * call this. * * If you want to request a name, just request it; * if you want to avoid replacing a current owner, * don't specify #DBUS_NAME_FLAG_REPLACE_EXISTING and * you will get an error if there's already an owner. * * @param connection the connection * @param name the name * @param error location to store any errors * @returns #TRUE if the name exists, #FALSE if not or on error */ dbus_bool_t dbus_bus_name_has_owner (DBusConnection *connection, const char *name, DBusError *error) { DBusMessage *message, *reply; dbus_bool_t exists; _dbus_return_val_if_fail (connection != NULL, FALSE); _dbus_return_val_if_fail (name != NULL, FALSE); _dbus_return_val_if_fail (_dbus_check_is_valid_bus_name (name), FALSE); _dbus_return_val_if_error_is_set (error, FALSE); message = dbus_message_new_method_call (DBUS_SERVICE_DBUS, DBUS_PATH_DBUS, DBUS_INTERFACE_DBUS, "NameHasOwner"); if (message == NULL) { _DBUS_SET_OOM (error); return FALSE; } if (!dbus_message_append_args (message, DBUS_TYPE_STRING, &name, DBUS_TYPE_INVALID)) { dbus_message_unref (message); _DBUS_SET_OOM (error); return FALSE; } reply = dbus_connection_send_with_reply_and_block (connection, message, -1, error); dbus_message_unref (message); if (reply == NULL) { _DBUS_ASSERT_ERROR_IS_SET (error); return FALSE; } if (!dbus_message_get_args (reply, error, DBUS_TYPE_BOOLEAN, &exists, DBUS_TYPE_INVALID)) { _DBUS_ASSERT_ERROR_IS_SET (error); dbus_message_unref (reply); return FALSE; } dbus_message_unref (reply); return exists; } /** * Starts a service that will request ownership of the given name. * The returned result will be one of be one of * #DBUS_START_REPLY_SUCCESS or #DBUS_START_REPLY_ALREADY_RUNNING if * successful. Pass #NULL if you don't care about the result. * * The flags parameter is for future expansion, currently you should * specify 0. * * It's often easier to avoid explicitly starting services, and * just send a method call to the service's bus name instead. * Method calls start a service to handle them by default * unless you call dbus_message_set_auto_start() to disable this * behavior. * * @param connection the connection * @param name the name we want the new service to request * @param flags the flags (should always be 0 for now) * @param result a place to store the result or #NULL * @param error location to store any errors * @returns #TRUE if the activation succeeded, #FALSE if not */ dbus_bool_t dbus_bus_start_service_by_name (DBusConnection *connection, const char *name, dbus_uint32_t flags, dbus_uint32_t *result, DBusError *error) { DBusMessage *msg; DBusMessage *reply; _dbus_return_val_if_fail (connection != NULL, FALSE); _dbus_return_val_if_fail (_dbus_check_is_valid_bus_name (name), FALSE); msg = dbus_message_new_method_call (DBUS_SERVICE_DBUS, DBUS_PATH_DBUS, DBUS_INTERFACE_DBUS, "StartServiceByName"); if (!dbus_message_append_args (msg, DBUS_TYPE_STRING, &name, DBUS_TYPE_UINT32, &flags, DBUS_TYPE_INVALID)) { dbus_message_unref (msg); _DBUS_SET_OOM (error); return FALSE; } reply = dbus_connection_send_with_reply_and_block (connection, msg, -1, error); dbus_message_unref (msg); if (reply == NULL) { _DBUS_ASSERT_ERROR_IS_SET (error); return FALSE; } if (dbus_set_error_from_message (error, reply)) { _DBUS_ASSERT_ERROR_IS_SET (error); dbus_message_unref (reply); return FALSE; } if (result != NULL && !dbus_message_get_args (reply, error, DBUS_TYPE_UINT32, result, DBUS_TYPE_INVALID)) { _DBUS_ASSERT_ERROR_IS_SET (error); dbus_message_unref (reply); return FALSE; } dbus_message_unref (reply); return TRUE; } static void send_no_return_values (DBusConnection *connection, DBusMessage *msg, DBusError *error) { if (error) { /* Block to check success codepath */ DBusMessage *reply; reply = dbus_connection_send_with_reply_and_block (connection, msg, -1, error); if (reply == NULL) _DBUS_ASSERT_ERROR_IS_SET (error); else dbus_message_unref (reply); } else { /* Silently-fail nonblocking codepath */ dbus_message_set_no_reply (msg, TRUE); dbus_connection_send (connection, msg, NULL); } } /** * Adds a match rule to match messages going through the message bus. * The "rule" argument is the string form of a match rule. * * If you pass #NULL for the error, this function will not * block; the match thus won't be added until you flush the * connection, and if there's an error adding the match * (only possible error is lack of resources in the bus), * you won't find out about it. * * If you pass non-#NULL for the error this function will * block until it gets a reply. * * Normal API conventions would have the function return * a boolean value indicating whether the error was set, * but that would require blocking always to determine * the return value. * * The AddMatch method is fully documented in the D-Bus * specification. For quick reference, the format of the * match rules is discussed here, but the specification * is the canonical version of this information. * * Rules are specified as a string of comma separated * key/value pairs. An example is * "type='signal',sender='org.freedesktop.DBus', * interface='org.freedesktop.DBus',member='Foo', * path='/bar/foo',destination=':452345.34'" * * Possible keys you can match on are type, sender, * interface, member, path, destination and numbered * keys to match message args (keys are 'arg0', 'arg1', etc.). * Omitting a key from the rule indicates * a wildcard match. For instance omitting * the member from a match rule but adding a sender would * let all messages from that sender through regardless of * the member. * * Matches are inclusive not exclusive so as long as one * rule matches the message will get through. It is important * to note this because every time a message is received the * application will be paged into memory to process it. This * can cause performance problems such as draining batteries * on embedded platforms. * * If you match message args ('arg0', 'arg1', and so forth) * only string arguments will match. That is, arg0='5' means * match the string "5" not the integer 5. * * Currently there is no way to match against non-string arguments. * * A specialised form of wildcard matching on arguments is * supported for path-like namespaces. If your argument match has * a 'path' suffix (eg: "arg0path='/some/path/'") then it is * considered a match if the argument exactly matches the given * string or if one of them ends in a '/' and is a prefix of the * other. * * Matching on interface is tricky because method call * messages only optionally specify the interface. * If a message omits the interface, then it will NOT match * if the rule specifies an interface name. This means match * rules on method calls should not usually give an interface. * * However, signal messages are required to include the interface * so when matching signals usually you should specify the interface * in the match rule. * * For security reasons, you can match arguments only up to * #DBUS_MAXIMUM_MATCH_RULE_ARG_NUMBER. * * Match rules have a maximum length of #DBUS_MAXIMUM_MATCH_RULE_LENGTH * bytes. * * Both of these maximums are much higher than you're likely to need, * they only exist because the D-Bus bus daemon has fixed limits on * all resource usage. * * @param connection connection to the message bus * @param rule textual form of match rule * @param error location to store any errors */ void dbus_bus_add_match (DBusConnection *connection, const char *rule, DBusError *error) { DBusMessage *msg; _dbus_return_if_fail (rule != NULL); msg = dbus_message_new_method_call (DBUS_SERVICE_DBUS, DBUS_PATH_DBUS, DBUS_INTERFACE_DBUS, "AddMatch"); if (msg == NULL) { _DBUS_SET_OOM (error); return; } if (!dbus_message_append_args (msg, DBUS_TYPE_STRING, &rule, DBUS_TYPE_INVALID)) { dbus_message_unref (msg); _DBUS_SET_OOM (error); return; } send_no_return_values (connection, msg, error); dbus_message_unref (msg); } /** * Removes a previously-added match rule "by value" (the most * recently-added identical rule gets removed). The "rule" argument * is the string form of a match rule. * * The bus compares match rules semantically, not textually, so * whitespace and ordering don't have to be identical to * the rule you passed to dbus_bus_add_match(). * * If you pass #NULL for the error, this function will not * block; otherwise it will. See detailed explanation in * docs for dbus_bus_add_match(). * * @param connection connection to the message bus * @param rule textual form of match rule * @param error location to store any errors */ void dbus_bus_remove_match (DBusConnection *connection, const char *rule, DBusError *error) { DBusMessage *msg; _dbus_return_if_fail (rule != NULL); msg = dbus_message_new_method_call (DBUS_SERVICE_DBUS, DBUS_PATH_DBUS, DBUS_INTERFACE_DBUS, "RemoveMatch"); if (!dbus_message_append_args (msg, DBUS_TYPE_STRING, &rule, DBUS_TYPE_INVALID)) { dbus_message_unref (msg); _DBUS_SET_OOM (error); return; } send_no_return_values (connection, msg, error); dbus_message_unref (msg); } /** @} */