/* -*- 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 <config.h>
#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);
}
/** @} */