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DBusConnection
[D-BUS message system public API]

Connection to another application. More...

Functions

DBusConnection * dbus_connection_open (const char *address, DBusError *error)
 Opens a new connection to a remote address. More...

DBusConnection * dbus_connection_ref (DBusConnection *connection)
 Increments the reference count of a DBusConnection. More...

void dbus_connection_unref (DBusConnection *connection)
 Decrements the reference count of a DBusConnection, and finalizes it if the count reaches zero. More...

void dbus_connection_disconnect (DBusConnection *connection)
 Closes the connection, so no further data can be sent or received. More...

dbus_bool_t dbus_connection_get_is_connected (DBusConnection *connection)
 Gets whether the connection is currently connected. More...

dbus_bool_t dbus_connection_get_is_authenticated (DBusConnection *connection)
 Gets whether the connection was authenticated. More...

void dbus_connection_set_exit_on_disconnect (DBusConnection *connection, dbus_bool_t exit_on_disconnect)
 Set whether _exit() should be called when the connection receives a disconnect signal. More...

DBusPreallocatedSenddbus_connection_preallocate_send (DBusConnection *connection)
 Preallocates resources needed to send a message, allowing the message to be sent without the possibility of memory allocation failure. More...

void dbus_connection_free_preallocated_send (DBusConnection *connection, DBusPreallocatedSend *preallocated)
 Frees preallocated message-sending resources from dbus_connection_preallocate_send(). More...

void dbus_connection_send_preallocated (DBusConnection *connection, DBusPreallocatedSend *preallocated, DBusMessage *message, dbus_uint32_t *client_serial)
 Sends a message using preallocated resources. More...

dbus_bool_t dbus_connection_send (DBusConnection *connection, DBusMessage *message, dbus_uint32_t *client_serial)
 Adds a message to the outgoing message queue. More...

dbus_bool_t dbus_connection_send_with_reply (DBusConnection *connection, DBusMessage *message, DBusPendingCall **pending_return, int timeout_milliseconds)
 Queues a message to send, as with dbus_connection_send_message(), but also returns a DBusPendingCall used to receive a reply to the message. More...

DBusMessage_dbus_connection_block_for_reply (DBusConnection *connection, dbus_uint32_t client_serial, int timeout_milliseconds)
 Blocks a certain time period while waiting for a reply. More...

DBusMessagedbus_connection_send_with_reply_and_block (DBusConnection *connection, DBusMessage *message, int timeout_milliseconds, DBusError *error)
 Sends a message and blocks a certain time period while waiting for a reply. More...

void dbus_connection_flush (DBusConnection *connection)
 Blocks until the outgoing message queue is empty. More...

DBusMessagedbus_connection_borrow_message (DBusConnection *connection)
 Returns the first-received message from the incoming message queue, leaving it in the queue. More...

void dbus_connection_return_message (DBusConnection *connection, DBusMessage *message)
 Used to return a message after peeking at it using dbus_connection_borrow_message(). More...

void dbus_connection_steal_borrowed_message (DBusConnection *connection, DBusMessage *message)
 Used to keep a message after peeking at it using dbus_connection_borrow_message(). More...

DBusMessagedbus_connection_pop_message (DBusConnection *connection)
 Returns the first-received message from the incoming message queue, removing it from the queue. More...

DBusDispatchStatus dbus_connection_get_dispatch_status (DBusConnection *connection)
 Gets the current state (what we would currently return from dbus_connection_dispatch()) but doesn't actually dispatch any messages. More...

DBusDispatchStatus dbus_connection_dispatch (DBusConnection *connection)
 Processes data buffered while handling watches, queueing zero or more incoming messages. More...

dbus_bool_t dbus_connection_set_watch_functions (DBusConnection *connection, DBusAddWatchFunction add_function, DBusRemoveWatchFunction remove_function, DBusWatchToggledFunction toggled_function, void *data, DBusFreeFunction free_data_function)
 Sets the watch functions for the connection. More...

dbus_bool_t dbus_connection_set_timeout_functions (DBusConnection *connection, DBusAddTimeoutFunction add_function, DBusRemoveTimeoutFunction remove_function, DBusTimeoutToggledFunction toggled_function, void *data, DBusFreeFunction free_data_function)
 Sets the timeout functions for the connection. More...

void dbus_connection_set_wakeup_main_function (DBusConnection *connection, DBusWakeupMainFunction wakeup_main_function, void *data, DBusFreeFunction free_data_function)
 Sets the mainloop wakeup function for the connection. More...

void dbus_connection_set_dispatch_status_function (DBusConnection *connection, DBusDispatchStatusFunction function, void *data, DBusFreeFunction free_data_function)
 Set a function to be invoked when the dispatch status changes. More...

dbus_bool_t dbus_connection_get_unix_user (DBusConnection *connection, unsigned long *uid)
 Gets the UNIX user ID of the connection if any. More...

void dbus_connection_set_unix_user_function (DBusConnection *connection, DBusAllowUnixUserFunction function, void *data, DBusFreeFunction free_data_function)
 Sets a predicate function used to determine whether a given user ID is allowed to connect. More...

dbus_bool_t dbus_connection_add_filter (DBusConnection *connection, DBusHandleMessageFunction function, void *user_data, DBusFreeFunction free_data_function)
 Adds a message filter. More...

void dbus_connection_remove_filter (DBusConnection *connection, DBusHandleMessageFunction function, void *user_data)
 Removes a previously-added message filter. More...

dbus_bool_t dbus_connection_register_object_path (DBusConnection *connection, const char *path, const DBusObjectPathVTable *vtable, void *user_data)
 Registers a handler for a given path in the object hierarchy. More...

dbus_bool_t dbus_connection_register_fallback (DBusConnection *connection, const char *path, const DBusObjectPathVTable *vtable, void *user_data)
 Registers a fallback handler for a given subsection of the object hierarchy. More...

dbus_bool_t dbus_connection_unregister_object_path (DBusConnection *connection, const char *path)
 Unregisters the handler registered with exactly the given path. More...

dbus_bool_t dbus_connection_list_registered (DBusConnection *connection, const char *parent_path, char ***child_entries)
 Lists the registered fallback handlers and object path handlers at the given parent_path. More...

dbus_bool_t dbus_connection_allocate_data_slot (dbus_int32_t *slot_p)
 Allocates an integer ID to be used for storing application-specific data on any DBusConnection. More...

void dbus_connection_free_data_slot (dbus_int32_t *slot_p)
 Deallocates a global ID for connection data slots. More...

dbus_bool_t dbus_connection_set_data (DBusConnection *connection, dbus_int32_t slot, void *data, DBusFreeFunction free_data_func)
 Stores a pointer on a DBusConnection, along with an optional function to be used for freeing the data when the data is set again, or when the connection is finalized. More...

void * dbus_connection_get_data (DBusConnection *connection, dbus_int32_t slot)
 Retrieves data previously set with dbus_connection_set_data(). More...

void dbus_connection_set_change_sigpipe (dbus_bool_t will_modify_sigpipe)
 This function sets a global flag for whether dbus_connection_new() will set SIGPIPE behavior to SIG_IGN. More...

void dbus_connection_set_max_message_size (DBusConnection *connection, long size)
 Specifies the maximum size message this connection is allowed to receive. More...

long dbus_connection_get_max_message_size (DBusConnection *connection)
 Gets the value set by dbus_connection_set_max_message_size(). More...

void dbus_connection_set_max_received_size (DBusConnection *connection, long size)
 Sets the maximum total number of bytes that can be used for all messages received on this connection. More...

long dbus_connection_get_max_received_size (DBusConnection *connection)
 Gets the value set by dbus_connection_set_max_received_size(). More...

long dbus_connection_get_outgoing_size (DBusConnection *connection)
 Gets the approximate size in bytes of all messages in the outgoing message queue. More...


Detailed Description

Connection to another application.

A DBusConnection represents a connection to another application. Messages can be sent and received via this connection. The other application may be a message bus; for convenience, the function dbus_bus_get() is provided to automatically open a connection to the well-known message buses.

In brief a DBusConnection is a message queue associated with some message transport mechanism such as a socket. The connection maintains a queue of incoming messages and a queue of outgoing messages.

Incoming messages are normally processed by calling dbus_connection_dispatch(). dbus_connection_dispatch() runs any handlers registered for the topmost message in the message queue, then discards the message, then returns.

dbus_connection_get_dispatch_status() indicates whether messages are currently in the queue that need dispatching. dbus_connection_set_dispatch_status_function() allows you to set a function to be used to monitor the dispatch status.

If you're using GLib or Qt add-on libraries for D-BUS, there are special convenience APIs in those libraries that hide all the details of dispatch and watch/timeout monitoring. For example, dbus_connection_setup_with_g_main().

If you aren't using these add-on libraries, you have to manually call dbus_connection_set_dispatch_status_function(), dbus_connection_set_watch_functions(), dbus_connection_set_timeout_functions() providing appropriate functions to integrate the connection with your application's main loop.

When you use dbus_connection_send() or one of its variants to send a message, the message is added to the outgoing queue. It's actually written to the network later; either in dbus_watch_handle() invoked by your main loop, or in dbus_connection_flush() which blocks until it can write out the entire outgoing queue. The GLib/Qt add-on libraries again handle the details here for you by setting up watch functions.

When a connection is disconnected, you are guaranteed to get a signal "Disconnected" from the interface DBUS_INTERFACE_ORG_FREEDESKTOP_LOCAL, path DBUS_PATH_ORG_FREEDESKTOP_LOCAL.

You may not drop the last reference to a DBusConnection until that connection has been disconnected.

You may dispatch the unprocessed incoming message queue even if the connection is disconnected. However, "Disconnected" will always be the last message in the queue (obviously no messages are received after disconnection).

DBusConnection has thread locks and drops them when invoking user callbacks, so in general is transparently threadsafe. However, DBusMessage does NOT have thread locks; you must not send the same message to multiple DBusConnection that will be used from different threads.


Function Documentation

DBusMessage* _dbus_connection_block_for_reply DBusConnection   connection,
dbus_uint32_t    client_serial,
int    timeout_milliseconds
 

Blocks a certain time period while waiting for a reply.

If no reply arrives, returns NULL.

Todo:
could use performance improvements (it keeps scanning the whole message queue for example) and has thread issues, see comments in source

Does not re-enter the main loop or run filter/path-registered callbacks. The reply to the message will not be seen by filter callbacks.

Parameters:
connection  the connection
client_serial  the reply serial to wait for
timeout_milliseconds  timeout in milliseconds or -1 for default
Returns:
the message that is the reply or NULL if no reply

Definition at line 1839 of file dbus-connection.c.

References disconnect_message_link.

dbus_bool_t dbus_connection_add_filter DBusConnection   connection,
DBusHandleMessageFunction    function,
void *    user_data,
DBusFreeFunction    free_data_function
 

Adds a message filter.

Filters are handlers that are run on all incoming messages, prior to the objects registered with dbus_connection_register_object_path(). Filters are run in the order that they were added. The same handler can be added as a filter more than once, in which case it will be run more than once. Filters added during a filter callback won't be run on the message being processed.

Todo:
we don't run filters on messages while blocking without entering the main loop, since filters are run as part of dbus_connection_dispatch(). This is probably a feature, as filters could create arbitrary reentrancy. But kind of sucks if you're trying to filter METHOD_RETURN for some reason.
Parameters:
connection  the connection
function  function to handle messages
user_data  user data to pass to the function
free_data_function  function to use for freeing user data
Returns:
TRUE on success, FALSE if not enough memory.

Definition at line 3045 of file dbus-connection.c.

References filter_list, DBusMessageFilter::free_user_data_function, DBusMessageFilter::function, DBusMessageFilter::refcount, DBusMessageFilter::user_data, and DBusAtomic::value.

dbus_bool_t dbus_connection_allocate_data_slot dbus_int32_t   slot_p
 

Allocates an integer ID to be used for storing application-specific data on any DBusConnection.

The allocated ID may then be used with dbus_connection_set_data() and dbus_connection_get_data(). The passed-in slot must be initialized to -1, and is filled in with the slot ID. If the passed-in slot is not -1, it's assumed to be already allocated, and its refcount is incremented.

The allocated slot is global, i.e. all DBusConnection objects will have a slot with the given integer ID reserved.

Parameters:
slot_p  address of a global variable storing the slot
Returns:
FALSE on failure (no memory)

Definition at line 3318 of file dbus-connection.c.

DBusMessage* dbus_connection_borrow_message DBusConnection   connection
 

Returns the first-received message from the incoming message queue, leaving it in the queue.

If the queue is empty, returns NULL.

The caller does not own a reference to the returned message, and must either return it using dbus_connection_return_message() or keep it after calling dbus_connection_steal_borrowed_message(). No one can get at the message while its borrowed, so return it as quickly as possible and don't keep a reference to it after returning it. If you need to keep the message, make a copy of it.

Parameters:
connection  the connection.
Returns:
next message in the incoming queue.

Definition at line 2087 of file dbus-connection.c.

References dispatch_acquired, incoming_messages, and message_borrowed.

void dbus_connection_disconnect DBusConnection   connection
 

Closes the connection, so no further data can be sent or received.

Any further attempts to send data will result in errors. This function does not affect the connection's reference count. It's safe to disconnect a connection more than once; all calls after the first do nothing. It's impossible to "reconnect" a connection, a new connection must be created. This function may result in a call to the DBusDispatchStatusFunction set with dbus_connection_set_dispatch_status_function(), as the disconnect message it generates needs to be dispatched.

Parameters:
connection  the connection.

Definition at line 1308 of file dbus-connection.c.

References transport.

DBusDispatchStatus dbus_connection_dispatch DBusConnection   connection
 

Processes data buffered while handling watches, queueing zero or more incoming messages.

Then pops the first-received message from the current incoming message queue, runs any handlers for it, and unrefs the message. Returns a status indicating whether messages/data remain, more memory is needed, or all data has been processed.

Even if the dispatch status is DBUS_DISPATCH_DATA_REMAINS, does not necessarily dispatch a message, as the data may be part of authentication or the like.

Todo:
some FIXME in here about handling DBUS_HANDLER_RESULT_NEED_MEMORY

right now a message filter gets run on replies to a pending call in here, but not in the case where we block without entering the main loop. Simple solution might be to just have the pending call stuff run before the filters.

FIXME what if we call out to application code to handle a message, holding the dispatch lock, and the application code runs the main loop and dispatches again? Probably deadlocks at the moment. Maybe we want a dispatch status of DBUS_DISPATCH_IN_PROGRESS, and then the GSource etc. could handle the situation?

Parameters:
connection  the connection
Returns:
dispatch status

Definition at line 2461 of file dbus-connection.c.

References DBusList::data, exit_on_disconnect, filter_list, DBusMessageFilter::function, objects, pending_replies, DBusPendingCall::timeout_link, and DBusMessageFilter::user_data.

void dbus_connection_flush DBusConnection   connection
 

Blocks until the outgoing message queue is empty.

Parameters:
connection  the connection.

Definition at line 2034 of file dbus-connection.c.

References n_outgoing.

void dbus_connection_free_data_slot dbus_int32_t   slot_p
 

Deallocates a global ID for connection data slots.

dbus_connection_get_data() and dbus_connection_set_data() may no longer be used with this slot. Existing data stored on existing DBusConnection objects will be freed when the connection is finalized, but may not be retrieved (and may only be replaced if someone else reallocates the slot). When the refcount on the passed-in slot reaches 0, it is set to -1.

Parameters:
slot_p  address storing the slot to deallocate

Definition at line 3337 of file dbus-connection.c.

void dbus_connection_free_preallocated_send DBusConnection   connection,
DBusPreallocatedSend   preallocated
 

Frees preallocated message-sending resources from dbus_connection_preallocate_send().

Should only be called if the preallocated resources are not used to send a message.

Parameters:
connection  the connection
preallocated  the resources

Definition at line 1486 of file dbus-connection.c.

References DBusPreallocatedSend::connection, DBusPreallocatedSend::counter_link, DBusList::data, and DBusPreallocatedSend::queue_link.

void* dbus_connection_get_data DBusConnection   connection,
dbus_int32_t    slot
 

Retrieves data previously set with dbus_connection_set_data().

The slot must still be allocated (must not have been freed).

Parameters:
connection  the connection
slot  the slot to get data from
Returns:
the data, or NULL if not found

Definition at line 3398 of file dbus-connection.c.

References slot_list.

DBusDispatchStatus dbus_connection_get_dispatch_status DBusConnection   connection
 

Gets the current state (what we would currently return from dbus_connection_dispatch()) but doesn't actually dispatch any messages.

Parameters:
connection  the connection.
Returns:
current dispatch status

Definition at line 2418 of file dbus-connection.c.

dbus_bool_t dbus_connection_get_is_authenticated DBusConnection   connection
 

Gets whether the connection was authenticated.

(Note that if the connection was authenticated then disconnected, this function still returns TRUE)

Parameters:
connection  the connection
Returns:
TRUE if the connection was ever authenticated

Definition at line 1362 of file dbus-connection.c.

References transport.

dbus_bool_t dbus_connection_get_is_connected DBusConnection   connection
 

Gets whether the connection is currently connected.

All connections are connected when they are opened. A connection may become disconnected when the remote application closes its end, or exits; a connection may also be disconnected with dbus_connection_disconnect().

Parameters:
connection  the connection.
Returns:
TRUE if the connection is still alive.

Definition at line 1340 of file dbus-connection.c.

long dbus_connection_get_max_message_size DBusConnection   connection
 

Gets the value set by dbus_connection_set_max_message_size().

Parameters:
connection  the connection
Returns:
the max size of a single message

Definition at line 3455 of file dbus-connection.c.

References transport.

long dbus_connection_get_max_received_size DBusConnection   connection
 

Gets the value set by dbus_connection_set_max_received_size().

Parameters:
connection  the connection
Returns:
the max size of all live messages

Definition at line 3511 of file dbus-connection.c.

References transport.

long dbus_connection_get_outgoing_size DBusConnection   connection
 

Gets the approximate size in bytes of all messages in the outgoing message queue.

The size is approximate in that you shouldn't use it to decide how many bytes to read off the network or anything of that nature, as optimizations may choose to tell small white lies to avoid performance overhead.

Parameters:
connection  the connection
Returns:
the number of bytes that have been queued up but not sent

Definition at line 3534 of file dbus-connection.c.

References outgoing_counter.

dbus_bool_t dbus_connection_get_unix_user DBusConnection   connection,
unsigned long *    uid
 

Gets the UNIX user ID of the connection if any.

Returns TRUE if the uid is filled in. Always returns FALSE on non-UNIX platforms. Always returns FALSE prior to authenticating the connection.

Parameters:
connection  the connection
uid  return location for the user ID
Returns:
TRUE if uid is filled in with a valid user ID

Definition at line 2966 of file dbus-connection.c.

References transport.

dbus_bool_t dbus_connection_list_registered DBusConnection   connection,
const char *    parent_path,
char ***    child_entries
 

Lists the registered fallback handlers and object path handlers at the given parent_path.

The returned array should be freed with dbus_free_string_array().

Parameters:
connection  the connection
parent_path  the path to list the child handlers of
child_entries  returns NULL-terminated array of children
Returns:
FALSE if no memory to allocate the child entries

Definition at line 3276 of file dbus-connection.c.

References objects.

DBusConnection* dbus_connection_open const char *    address,
DBusError   error
 

Opens a new connection to a remote address.

Todo:
specify what the address parameter is. Right now it's just the name of a UNIX domain socket. It should be something more complex that encodes which transport to use.

If the open fails, the function returns NULL, and provides a reason for the failure in the result parameter. Pass NULL for the result parameter if you aren't interested in the reason for failure.

Parameters:
address  the address.
error  address where an error can be returned.
Returns:
new connection, or NULL on failure.

Definition at line 1093 of file dbus-connection.c.

DBusMessage* dbus_connection_pop_message DBusConnection   connection
 

Returns the first-received message from the incoming message queue, removing it from the queue.

The caller owns a reference to the returned message. If the queue is empty, returns NULL.

This function bypasses any message handlers that are registered, and so using it is usually wrong. Instead, let the main loop invoke dbus_connection_dispatch(). Popping messages manually is only useful in very simple programs that don't share a DBusConnection with any libraries or other modules.

Parameters:
connection  the connection.
Returns:
next message in the incoming queue.

Definition at line 2273 of file dbus-connection.c.

DBusPreallocatedSend* dbus_connection_preallocate_send DBusConnection   connection
 

Preallocates resources needed to send a message, allowing the message to be sent without the possibility of memory allocation failure.

Allows apps to create a future guarantee that they can send a message regardless of memory shortages.

Parameters:
connection  the connection we're preallocating for.
Returns:
the preallocated resources, or NULL

Definition at line 1460 of file dbus-connection.c.

DBusConnection* dbus_connection_ref DBusConnection   connection
 

Increments the reference count of a DBusConnection.

Parameters:
connection  the connection.
Returns:
the connection.

Definition at line 1129 of file dbus-connection.c.

References refcount, and DBusAtomic::value.

dbus_bool_t dbus_connection_register_fallback DBusConnection   connection,
const char *    path,
const DBusObjectPathVTable   vtable,
void *    user_data
 

Registers a fallback handler for a given subsection of the object hierarchy.

The given vtable handles messages at or below the given path. You can use this to establish a default message handling policy for a whole "subdirectory."

Parameters:
connection  the connection
path  a '/' delimited string of path elements
vtable  the virtual table
user_data  data to pass to functions in the vtable
Returns:
FALSE if not enough memory

Definition at line 3204 of file dbus-connection.c.

References objects.

dbus_bool_t dbus_connection_register_object_path DBusConnection   connection,
const char *    path,
const DBusObjectPathVTable   vtable,
void *    user_data
 

Registers a handler for a given path in the object hierarchy.

The given vtable handles messages sent to exactly the given path.

Parameters:
connection  the connection
path  a '/' delimited string of path elements
vtable  the virtual table
user_data  data to pass to functions in the vtable
Returns:
FALSE if not enough memory

Definition at line 3161 of file dbus-connection.c.

References objects.

void dbus_connection_remove_filter DBusConnection   connection,
DBusHandleMessageFunction    function,
void *    user_data
 

Removes a previously-added message filter.

It is a programming error to call this function for a handler that has not been added as a filter. If the given handler was added more than once, only one instance of it will be removed (the most recently-added instance).

Parameters:
connection  the connection
function  the handler to remove
user_data  user data for the handler to remove

Definition at line 3097 of file dbus-connection.c.

References DBusList::data, filter_list, DBusMessageFilter::free_user_data_function, DBusMessageFilter::function, and DBusMessageFilter::user_data.

void dbus_connection_return_message DBusConnection   connection,
DBusMessage   message
 

Used to return a message after peeking at it using dbus_connection_borrow_message().

Parameters:
connection  the connection
message  the message from dbus_connection_borrow_message()

Definition at line 2125 of file dbus-connection.c.

References dispatch_acquired, message_borrowed, and message_returned_cond.

dbus_bool_t dbus_connection_send DBusConnection   connection,
DBusMessage   message,
dbus_uint32_t   client_serial
 

Adds a message to the outgoing message queue.

Does not block to write the message to the network; that happens asynchronously. To force the message to be written, call dbus_connection_flush(). Because this only queues the message, the only reason it can fail is lack of memory. Even if the connection is disconnected, no error will be returned.

If the function fails due to lack of memory, it returns FALSE. The function will never fail for other reasons; even if the connection is disconnected, you can queue an outgoing message, though obviously it won't be sent.

Parameters:
connection  the connection.
message  the message to write.
client_serial  return location for client serial.
Returns:
TRUE on success.

Definition at line 1630 of file dbus-connection.c.

void dbus_connection_send_preallocated DBusConnection   connection,
DBusPreallocatedSend   preallocated,
DBusMessage   message,
dbus_uint32_t   client_serial
 

Sends a message using preallocated resources.

This function cannot fail. It works identically to dbus_connection_send() in other respects. Preallocated resources comes from dbus_connection_preallocate_send(). This function "consumes" the preallocated resources, they need not be freed separately.

Parameters:
connection  the connection
preallocated  the preallocated resources
message  the message to send
client_serial  return location for client serial assigned to the message

Definition at line 1566 of file dbus-connection.c.

References DBusPreallocatedSend::connection.

dbus_bool_t dbus_connection_send_with_reply DBusConnection   connection,
DBusMessage   message,
DBusPendingCall **    pending_return,
int    timeout_milliseconds
 

Queues a message to send, as with dbus_connection_send_message(), but also returns a DBusPendingCall used to receive a reply to the message.

If no reply is received in the given timeout_milliseconds, this function expires the pending reply and generates a synthetic error reply (generated in-process, not by the remote application) indicating that a timeout occurred.

A DBusPendingCall will see a reply message after any filters, but before any object instances or other handlers. A DBusPendingCall will always see exactly one reply message, unless it's cancelled with dbus_pending_call_cancel().

If a filter filters out the reply before the handler sees it, the reply is immediately timed out and a timeout error reply is generated. If a filter removes the timeout error reply then the DBusPendingCall will get confused. Filtering the timeout error is thus considered a bug and will print a warning.

If NULL is passed for the pending_return, the DBusPendingCall will still be generated internally, and used to track the message reply timeout. This means a timeout error will occur if no reply arrives, unlike with dbus_connection_send().

If -1 is passed for the timeout, a sane default timeout is used. -1 is typically the best value for the timeout for this reason, unless you want a very short or very long timeout. There is no way to avoid a timeout entirely, other than passing INT_MAX for the timeout to postpone it indefinitely.

Parameters:
connection  the connection
message  the message to send
pending_return  return location for a DBusPendingCall object, or NULL
timeout_milliseconds  timeout in milliseconds or -1 for default
Returns:
TRUE if the message is successfully queued, FALSE if no memory.

Definition at line 1716 of file dbus-connection.c.

References DBusPendingCall::reply_serial, and DBusPendingCall::timeout_link.

DBusMessage* dbus_connection_send_with_reply_and_block DBusConnection   connection,
DBusMessage   message,
int    timeout_milliseconds,
DBusError   error
 

Sends a message and blocks a certain time period while waiting for a reply.

This function does not reenter the main loop, i.e. messages other than the reply are queued up but not processed. This function is used to do non-reentrant "method calls."

If a normal reply is received, it is returned, and removed from the incoming message queue. If it is not received, NULL is returned and the error is set to DBUS_ERROR_NO_REPLY. If an error reply is received, it is converted to a DBusError and returned as an error, then the reply message is deleted. If something else goes wrong, result is set to whatever is appropriate, such as DBUS_ERROR_NO_MEMORY or DBUS_ERROR_DISCONNECTED.

Parameters:
connection  the connection
message  the message to send
timeout_milliseconds  timeout in milliseconds or -1 for default
error  return location for error message
Returns:
the message that is the reply or NULL with an error code if the function fails.

Definition at line 1987 of file dbus-connection.c.

void dbus_connection_set_change_sigpipe dbus_bool_t    will_modify_sigpipe
 

This function sets a global flag for whether dbus_connection_new() will set SIGPIPE behavior to SIG_IGN.

Parameters:
will_modify_sigpipe  TRUE to allow sigpipe to be set to SIG_IGN

Definition at line 3423 of file dbus-connection.c.

dbus_bool_t dbus_connection_set_data DBusConnection   connection,
dbus_int32_t    slot,
void *    data,
DBusFreeFunction    free_data_func
 

Stores a pointer on a DBusConnection, along with an optional function to be used for freeing the data when the data is set again, or when the connection is finalized.

The slot number must have been allocated with dbus_connection_allocate_data_slot().

Parameters:
connection  the connection
slot  the slot number
data  the data to store
free_data_func  finalizer function for the data
Returns:
TRUE if there was enough memory to store the data

Definition at line 3358 of file dbus-connection.c.

References slot_list.

void dbus_connection_set_dispatch_status_function DBusConnection   connection,
DBusDispatchStatusFunction    function,
void *    data,
DBusFreeFunction    free_data_function
 

Set a function to be invoked when the dispatch status changes.

If the dispatch status is DBUS_DISPATCH_DATA_REMAINS, then dbus_connection_dispatch() needs to be called to process incoming messages. However, dbus_connection_dispatch() MUST NOT BE CALLED from inside the DBusDispatchStatusFunction. Indeed, almost any reentrancy in this function is a bad idea. Instead, the DBusDispatchStatusFunction should simply save an indication that messages should be dispatched later, when the main loop is re-entered.

Parameters:
connection  the connection
function  function to call on dispatch status changes
data  data for function
free_data_function  free the function data

Definition at line 2929 of file dbus-connection.c.

References dispatch_status_data, dispatch_status_function, and free_dispatch_status_data.

void dbus_connection_set_exit_on_disconnect DBusConnection   connection,
dbus_bool_t    exit_on_disconnect
 

Set whether _exit() should be called when the connection receives a disconnect signal.

The call to _exit() comes after any handlers for the disconnect signal run; handlers can cancel the exit by calling this function.

By default, exit_on_disconnect is FALSE; but for message bus connections returned from dbus_bus_get() it will be toggled on by default.

Parameters:
connection  the connection
exit_on_disconnect  TRUE if _exit() should be called after a disconnect signal

Definition at line 1389 of file dbus-connection.c.

References exit_on_disconnect.

void dbus_connection_set_max_message_size DBusConnection   connection,
long    size
 

Specifies the maximum size message this connection is allowed to receive.

Larger messages will result in disconnecting the connection.

Parameters:
connection  a DBusConnection
size  maximum message size the connection can receive, in bytes

Definition at line 3437 of file dbus-connection.c.

References transport.

void dbus_connection_set_max_received_size DBusConnection   connection,
long    size
 

Sets the maximum total number of bytes that can be used for all messages received on this connection.

Messages count toward the maximum until they are finalized. When the maximum is reached, the connection will not read more data until some messages are finalized.

The semantics of the maximum are: if outstanding messages are already above the maximum, additional messages will not be read. The semantics are not: if the next message would cause us to exceed the maximum, we don't read it. The reason is that we don't know the size of a message until after we read it.

Thus, the max live messages size can actually be exceeded by up to the maximum size of a single message.

Also, if we read say 1024 bytes off the wire in a single read(), and that contains a half-dozen small messages, we may exceed the size max by that amount. But this should be inconsequential.

This does imply that we can't call read() with a buffer larger than we're willing to exceed this limit by.

Parameters:
connection  the connection
size  the maximum size in bytes of all outstanding messages

Definition at line 3493 of file dbus-connection.c.

References transport.

dbus_bool_t dbus_connection_set_timeout_functions DBusConnection   connection,
DBusAddTimeoutFunction    add_function,
DBusRemoveTimeoutFunction    remove_function,
DBusTimeoutToggledFunction    toggled_function,
void *    data,
DBusFreeFunction    free_data_function
 

Sets the timeout functions for the connection.

These functions are responsible for making the application's main loop aware of timeouts. When using Qt, typically the DBusAddTimeoutFunction would create a QTimer. When using GLib, the DBusAddTimeoutFunction would call g_timeout_add.

The DBusTimeoutToggledFunction notifies the application that the timeout has been enabled or disabled. Call dbus_timeout_get_enabled() to check this. A disabled timeout should have no effect, and enabled timeout should be added to the main loop. This feature is used instead of simply adding/removing the timeout because enabling/disabling can be done without memory allocation. With Qt, QTimer::start() and QTimer::stop() can be used to enable and disable. The toggled function may be NULL if a main loop re-queries dbus_timeout_get_enabled() every time anyway. Whenever a timeout is toggled, its interval may change.

The DBusTimeout can be queried for the timer interval using dbus_timeout_get_interval(). dbus_timeout_handle() should be called repeatedly, each time the interval elapses, starting after it has elapsed once. The timeout stops firing when it is removed with the given remove_function. The timer interval may change whenever the timeout is added, removed, or toggled.

Parameters:
connection  the connection.
add_function  function to add a timeout.
remove_function  function to remove a timeout.
toggled_function  function to notify of enable/disable
data  data to pass to add_function and remove_function.
free_data_function  function to be called to free the data.
Returns:
FALSE on failure (no memory)

Definition at line 2845 of file dbus-connection.c.

References timeouts.

void dbus_connection_set_unix_user_function DBusConnection   connection,
DBusAllowUnixUserFunction    function,
void *    data,
DBusFreeFunction    free_data_function
 

Sets a predicate function used to determine whether a given user ID is allowed to connect.

When an incoming connection has authenticated with a particular user ID, this function is called; if it returns TRUE, the connection is allowed to proceed, otherwise the connection is disconnected.

If the function is set to NULL (as it is by default), then only the same UID as the server process will be allowed to connect.

Parameters:
connection  the connection
function  the predicate
data  data to pass to the predicate
free_data_function  function to free the data

Definition at line 3003 of file dbus-connection.c.

References transport.

void dbus_connection_set_wakeup_main_function DBusConnection   connection,
DBusWakeupMainFunction    wakeup_main_function,
void *    data,
DBusFreeFunction    free_data_function
 

Sets the mainloop wakeup function for the connection.

Thi function is responsible for waking up the main loop (if its sleeping) when some some change has happened to the connection that the mainloop needs to reconsiders (e.g. a message has been queued for writing). When using Qt, this typically results in a call to QEventLoop::wakeUp(). When using GLib, it would call g_main_context_wakeup().

Parameters:
connection  the connection.
wakeup_main_function  function to wake up the mainloop
data  data to pass wakeup_main_function
free_data_function  function to be called to free the data.

Definition at line 2887 of file dbus-connection.c.

References free_wakeup_main_data, wakeup_main_data, and wakeup_main_function.

dbus_bool_t dbus_connection_set_watch_functions DBusConnection   connection,
DBusAddWatchFunction    add_function,
DBusRemoveWatchFunction    remove_function,
DBusWatchToggledFunction    toggled_function,
void *    data,
DBusFreeFunction    free_data_function
 

Sets the watch functions for the connection.

These functions are responsible for making the application's main loop aware of file descriptors that need to be monitored for events, using select() or poll(). When using Qt, typically the DBusAddWatchFunction would create a QSocketNotifier. When using GLib, the DBusAddWatchFunction could call g_io_add_watch(), or could be used as part of a more elaborate GSource. Note that when a watch is added, it may not be enabled.

The DBusWatchToggledFunction notifies the application that the watch has been enabled or disabled. Call dbus_watch_get_enabled() to check this. A disabled watch should have no effect, and enabled watch should be added to the main loop. This feature is used instead of simply adding/removing the watch because enabling/disabling can be done without memory allocation. The toggled function may be NULL if a main loop re-queries dbus_watch_get_enabled() every time anyway.

The DBusWatch can be queried for the file descriptor to watch using dbus_watch_get_fd(), and for the events to watch for using dbus_watch_get_flags(). The flags returned by dbus_watch_get_flags() will only contain DBUS_WATCH_READABLE and DBUS_WATCH_WRITABLE, never DBUS_WATCH_HANGUP or DBUS_WATCH_ERROR; all watches implicitly include a watch for hangups, errors, and other exceptional conditions.

Once a file descriptor becomes readable or writable, or an exception occurs, dbus_watch_handle() should be called to notify the connection of the file descriptor's condition.

dbus_watch_handle() cannot be called during the DBusAddWatchFunction, as the connection will not be ready to handle that watch yet.

It is not allowed to reference a DBusWatch after it has been passed to remove_function.

If FALSE is returned due to lack of memory, the failure may be due to a FALSE return from the new add_function. If so, the add_function may have been called successfully one or more times, but the remove_function will also have been called to remove any successful adds. i.e. if FALSE is returned the net result should be that dbus_connection_set_watch_functions() has no effect, but the add_function and remove_function may have been called.

Todo:
We need to drop the lock when we call the add/remove/toggled functions which can be a side effect of setting the watch functions.
Parameters:
connection  the connection.
add_function  function to begin monitoring a new descriptor.
remove_function  function to stop monitoring a descriptor.
toggled_function  function to notify of enable/disable
data  data to pass to add_function and remove_function.
free_data_function  function to be called to free the data.
Returns:
FALSE on failure (no memory)

Definition at line 2781 of file dbus-connection.c.

References watches.

void dbus_connection_steal_borrowed_message DBusConnection   connection,
DBusMessage   message
 

Used to keep a message after peeking at it using dbus_connection_borrow_message().

Before using this function, see the caveats/warnings in the documentation for dbus_connection_pop_message().

Parameters:
connection  the connection
message  the message from dbus_connection_borrow_message()

Definition at line 2153 of file dbus-connection.c.

References dispatch_acquired, incoming_messages, message_borrowed, message_returned_cond, and n_incoming.

void dbus_connection_unref DBusConnection   connection
 

Decrements the reference count of a DBusConnection, and finalizes it if the count reaches zero.

It is a bug to drop the last reference to a connection that has not been disconnected.

Todo:
in practice it can be quite tricky to never unref a connection that's still connected; maybe there's some way we could avoid the requirement.
Parameters:
connection  the connection.

Definition at line 1263 of file dbus-connection.c.

References refcount, and DBusAtomic::value.

dbus_bool_t dbus_connection_unregister_object_path DBusConnection   connection,
const char *    path
 

Unregisters the handler registered with exactly the given path.

It's a bug to call this function for a path that isn't registered. Can unregister both fallback paths and object paths.

Parameters:
connection  the connection
path  a '/' delimited string of path elements
Returns:
FALSE if not enough memory

Definition at line 3244 of file dbus-connection.c.

References objects.


Generated on Wed Jun 9 05:01:27 2004 for D-BUS by doxygen1.2.15