DBusConnection implementation details
[D-Bus secret internal implementation details]

Implementation details of DBusConnection. More...

Data Structures

struct  DBusMessageFilter
 Internal struct representing a message filter function. More...
struct  DBusPreallocatedSend
 Internals of DBusPreallocatedSend. More...
struct  DBusConnection
 Implementation details of DBusConnection. More...

Typedefs

typedef DBusMessageFilter DBusMessageFilter
 Internal struct representing a message filter function.
typedef dbus_bool_t(*) DBusWatchAddFunction (DBusWatchList *list, DBusWatch *watch)
 Function to be called in protected_change_watch() with refcount held.
typedef void(*) DBusWatchRemoveFunction (DBusWatchList *list, DBusWatch *watch)
 Function to be called in protected_change_watch() with refcount held.
typedef void(*) DBusWatchToggleFunction (DBusWatchList *list, DBusWatch *watch, dbus_bool_t enabled)
 Function to be called in protected_change_watch() with refcount held.
typedef dbus_bool_t(*) DBusTimeoutAddFunction (DBusTimeoutList *list, DBusTimeout *timeout)
 Function to be called in protected_change_timeout() with refcount held.
typedef void(*) DBusTimeoutRemoveFunction (DBusTimeoutList *list, DBusTimeout *timeout)
 Function to be called in protected_change_timeout() with refcount held.
typedef void(*) DBusTimeoutToggleFunction (DBusTimeoutList *list, DBusTimeout *timeout, dbus_bool_t enabled)
 Function to be called in protected_change_timeout() with refcount held.

Functions

void _dbus_connection_lock (DBusConnection *connection)
 Acquires the connection lock.
void _dbus_connection_unlock (DBusConnection *connection)
 Releases the connection lock.
void _dbus_connection_queue_received_message_link (DBusConnection *connection, DBusList *link)
 Adds a message-containing list link to the incoming message queue, taking ownership of the link and the message's current refcount.
void _dbus_connection_queue_synthesized_message_link (DBusConnection *connection, DBusList *link)
 Adds a link + message to the incoming message queue.
dbus_bool_t _dbus_connection_has_messages_to_send_unlocked (DBusConnection *connection)
 Checks whether there are messages in the outgoing message queue.
dbus_bool_t dbus_connection_has_messages_to_send (DBusConnection *connection)
 Checks whether there are messages in the outgoing message queue.
DBusMessage * _dbus_connection_get_message_to_send (DBusConnection *connection)
 Gets the next outgoing message.
void _dbus_connection_message_sent (DBusConnection *connection, DBusMessage *message)
 Notifies the connection that a message has been sent, so the message can be removed from the outgoing queue.
dbus_bool_t _dbus_connection_add_watch_unlocked (DBusConnection *connection, DBusWatch *watch)
 Adds a watch using the connection's DBusAddWatchFunction if available.
void _dbus_connection_remove_watch_unlocked (DBusConnection *connection, DBusWatch *watch)
 Removes a watch using the connection's DBusRemoveWatchFunction if available.
void _dbus_connection_toggle_watch_unlocked (DBusConnection *connection, DBusWatch *watch, dbus_bool_t enabled)
 Toggles a watch and notifies app via connection's DBusWatchToggledFunction if available.
dbus_bool_t _dbus_connection_add_timeout_unlocked (DBusConnection *connection, DBusTimeout *timeout)
 Adds a timeout using the connection's DBusAddTimeoutFunction if available.
void _dbus_connection_remove_timeout_unlocked (DBusConnection *connection, DBusTimeout *timeout)
 Removes a timeout using the connection's DBusRemoveTimeoutFunction if available.
void _dbus_connection_toggle_timeout_unlocked (DBusConnection *connection, DBusTimeout *timeout, dbus_bool_t enabled)
 Toggles a timeout and notifies app via connection's DBusTimeoutToggledFunction if available.
void _dbus_connection_remove_pending_call (DBusConnection *connection, DBusPendingCall *pending)
 Removes a pending call from the connection, such that the pending reply will be ignored.
void _dbus_connection_do_iteration_unlocked (DBusConnection *connection, unsigned int flags, int timeout_milliseconds)
 Queues incoming messages and sends outgoing messages for this connection, optionally blocking in the process.
DBusConnection * _dbus_connection_new_for_transport (DBusTransport *transport)
 Creates a new connection for the given transport.
DBusConnection * _dbus_connection_ref_unlocked (DBusConnection *connection)
 Increments the reference count of a DBusConnection.
void _dbus_connection_unref_unlocked (DBusConnection *connection)
 Decrements the reference count of a DBusConnection.
dbus_bool_t _dbus_connection_handle_watch (DBusWatch *watch, unsigned int condition, void *data)
 A callback for use with dbus_watch_new() to create a DBusWatch.
void _dbus_connection_close_possibly_shared (DBusConnection *connection)
 Closes a shared OR private connection, while dbus_connection_close() can only be used on private connections.
dbus_bool_t _dbus_connection_send_and_unlock (DBusConnection *connection, DBusMessage *message, dbus_uint32_t *client_serial)
 Like dbus_connection_send(), but assumes the connection is already locked on function entry, and unlocks before returning.
void _dbus_connection_close_if_only_one_ref (DBusConnection *connection)
 Used internally to handle the semantics of dbus_server_set_new_connection_function().
void _dbus_connection_block_pending_call (DBusPendingCall *pending)
 Blocks until a pending call times out or gets a reply.

Detailed Description

Implementation details of DBusConnection.

Function Documentation

dbus_bool_t _dbus_connection_add_timeout_unlocked ( DBusConnection *  connection,
DBusTimeout *  timeout 
)

Adds a timeout using the connection's DBusAddTimeoutFunction if available.

Otherwise records the timeout to be added when said function is available. Also re-adds the timeout if the DBusAddTimeoutFunction changes. May fail due to lack of memory. The timeout will fire repeatedly until removed. Connection lock should be held when calling this.

Parameters:
connection the connection.
timeout the timeout to add.
Returns:
TRUE on success.

Definition at line 823 of file dbus-connection.c.

References _dbus_timeout_list_add_timeout(), FALSE, and NULL.

dbus_bool_t _dbus_connection_add_watch_unlocked ( DBusConnection *  connection,
DBusWatch *  watch 
)

Adds a watch using the connection's DBusAddWatchFunction if available.

Otherwise records the watch to be added when said function is available. Also re-adds the watch if the DBusAddWatchFunction changes. May fail due to lack of memory. Connection lock should be held when calling this.

Parameters:
connection the connection.
watch the watch to add.
Returns:
TRUE on success.

Definition at line 702 of file dbus-connection.c.

References _dbus_watch_list_add_watch(), FALSE, and NULL.

void _dbus_connection_block_pending_call ( DBusPendingCall *  pending  ) 

Blocks until a pending call times out or gets a reply.

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.

Returns immediately if pending call already got a reply.

Todo:
could use performance improvements (it keeps scanning the whole message queue for example)
Parameters:
pending the pending call we block for a reply on

Definition at line 2260 of file dbus-connection.c.

References _dbus_assert, _dbus_connection_do_iteration_unlocked(), _dbus_get_current_time(), _dbus_pending_call_get_completed_unlocked(), _dbus_pending_call_get_connection_and_lock(), _dbus_pending_call_get_reply_serial_unlocked(), _dbus_pending_call_get_timeout_unlocked(), CONNECTION_LOCK, DBUS_DISPATCH_DATA_REMAINS, DBUS_DISPATCH_NEED_MEMORY, DBUS_ERROR_DISCONNECTED, dbus_pending_call_get_completed(), dbus_pending_call_ref(), dbus_pending_call_unref(), dbus_timeout_get_interval(), and NULL.

Referenced by dbus_pending_call_block().

void _dbus_connection_close_if_only_one_ref ( DBusConnection *  connection  ) 

Used internally to handle the semantics of dbus_server_set_new_connection_function().

If the new connection function does not ref the connection, we want to close it.

A bit of a hack, probably the new connection function should have returned a value for whether to close, or should have had to close the connection itself if it didn't want it.

But, this works OK as long as the new connection function doesn't do anything crazy like keep the connection around without ref'ing it.

We have to lock the connection across refcount check and close in case the new connection function spawns a thread that closes and unrefs. In that case, if the app thread closes and unrefs first, we'll harmlessly close again; if the app thread still has the ref, we'll close and then the app will close harmlessly. If the app unrefs without closing, the app is broken since if the app refs from the new connection function it is supposed to also close.

If we didn't atomically check the refcount and close with the lock held though, we could screw this up.

Parameters:
connection the connection

Definition at line 2059 of file dbus-connection.c.

References _dbus_assert, CONNECTION_LOCK, CONNECTION_UNLOCK, DBusConnection::refcount, and DBusAtomic::value.

void _dbus_connection_close_possibly_shared ( DBusConnection *  connection  ) 

Closes a shared OR private connection, while dbus_connection_close() can only be used on private connections.

Should only be called by the dbus code that owns the connection - an owner must be known, the open/close state is like malloc/free, not like ref/unref.

Parameters:
connection the connection

Definition at line 1843 of file dbus-connection.c.

References _dbus_assert, _dbus_current_generation, CONNECTION_LOCK, DBusConnection::generation, and NULL.

void _dbus_connection_do_iteration_unlocked ( DBusConnection *  connection,
unsigned int  flags,
int  timeout_milliseconds 
)

Queues incoming messages and sends outgoing messages for this connection, optionally blocking in the process.

Each call to _dbus_connection_do_iteration_unlocked() will call select() or poll() one time and then read or write data if possible.

The purpose of this function is to be able to flush outgoing messages or queue up incoming messages without returning control to the application and causing reentrancy weirdness.

The flags parameter allows you to specify whether to read incoming messages, write outgoing messages, or both, and whether to block if no immediate action is possible.

The timeout_milliseconds parameter does nothing unless the iteration is blocking.

If there are no outgoing messages and DBUS_ITERATION_DO_READING wasn't specified, then it's impossible to block, even if you specify DBUS_ITERATION_BLOCK; in that case the function returns immediately.

Called with connection lock held.

Parameters:
connection the connection.
flags iteration flags.
timeout_milliseconds maximum blocking time, or -1 for no limit.

Definition at line 1134 of file dbus-connection.c.

References _dbus_transport_do_iteration(), and DBusConnection::n_outgoing.

Referenced by _dbus_connection_block_pending_call().

DBusMessage* _dbus_connection_get_message_to_send ( DBusConnection *  connection  ) 

Gets the next outgoing message.

The message remains in the queue, and the caller does not own a reference to it.

Parameters:
connection the connection.
Returns:
the message to be sent.

Definition at line 569 of file dbus-connection.c.

References _dbus_list_get_last(), and DBusConnection::outgoing_messages.

dbus_bool_t _dbus_connection_handle_watch ( DBusWatch *  watch,
unsigned int  condition,
void *  data 
)

A callback for use with dbus_watch_new() to create a DBusWatch.

Todo:
This is basically a hack - we could delete _dbus_transport_handle_watch() and the virtual handle_watch in DBusTransport if we got rid of it. The reason this is some work is threading, see the _dbus_connection_handle_watch() implementation.
Parameters:
watch the watch.
condition the current condition of the file descriptors being watched.
data must be a pointer to a DBusConnection
Returns:
FALSE if the IO condition may not have been fully handled due to lack of memory

Definition at line 1412 of file dbus-connection.c.

References _dbus_transport_handle_watch(), CONNECTION_LOCK, and DBusConnection::transport.

dbus_bool_t _dbus_connection_has_messages_to_send_unlocked ( DBusConnection *  connection  ) 

Checks whether there are messages in the outgoing message queue.

Called with connection lock held.

Parameters:
connection the connection.
Returns:
TRUE if the outgoing queue is non-empty.

Definition at line 532 of file dbus-connection.c.

References NULL, and DBusConnection::outgoing_messages.

Referenced by dbus_connection_has_messages_to_send().

void _dbus_connection_lock ( DBusConnection *  connection  ) 

Acquires the connection lock.

Parameters:
connection the connection.

Definition at line 353 of file dbus-connection.c.

References CONNECTION_LOCK.

Referenced by _dbus_object_tree_dispatch_and_unlock().

void _dbus_connection_message_sent ( DBusConnection *  connection,
DBusMessage *  message 
)

Notifies the connection that a message has been sent, so the message can be removed from the outgoing queue.

Called with the connection lock held.

Parameters:
connection the connection.
message the message that was sent.

Definition at line 585 of file dbus-connection.c.

References _dbus_assert, _dbus_list_get_last_link(), _dbus_list_prepend_link(), _dbus_list_unlink(), _dbus_message_remove_size_counter(), DBusList::data, dbus_message_get_interface(), dbus_message_get_member(), dbus_message_get_path(), dbus_message_get_signature(), dbus_message_get_type(), dbus_message_unref(), DBusConnection::link_cache, DBusConnection::n_outgoing, NULL, DBusConnection::outgoing_counter, and DBusConnection::outgoing_messages.

DBusConnection* _dbus_connection_new_for_transport ( DBusTransport *  transport  ) 

Creates a new connection for the given transport.

A transport represents a message stream that uses some concrete mechanism, such as UNIX domain sockets. May return NULL if insufficient memory exists to create the connection.

Parameters:
transport the transport.
Returns:
the new connection, or NULL on failure.

Definition at line 1170 of file dbus-connection.c.

References _dbus_condvar_free_at_location(), _dbus_condvar_new_at_location(), _dbus_counter_new(), _dbus_counter_unref(), _dbus_current_generation, _dbus_data_slot_list_init(), _dbus_disable_sigpipe(), _dbus_hash_table_new(), _dbus_hash_table_unref(), _dbus_list_alloc_link(), _dbus_list_free_link(), _dbus_mutex_free_at_location(), _dbus_mutex_new_at_location(), _dbus_object_tree_new(), _dbus_object_tree_unref(), _dbus_timeout_list_free(), _dbus_timeout_list_new(), _dbus_transport_ref(), _dbus_transport_set_connection(), _dbus_watch_list_free(), _dbus_watch_list_new(), DBusConnection::client_serial, CONNECTION_LOCK, CONNECTION_UNLOCK, DBUS_DISPATCH_COMPLETE, dbus_free(), DBUS_HASH_INT, DBUS_INTERFACE_LOCAL, dbus_message_new_signal(), dbus_message_unref(), dbus_new0, DBUS_PATH_LOCAL, DBusConnection::disconnect_message_link, DBusConnection::disconnected_message_arrived, DBusConnection::disconnected_message_processed, DBusConnection::dispatch_cond, DBusConnection::dispatch_mutex, DBusConnection::exit_on_disconnect, FALSE, DBusConnection::filter_list, DBusConnection::generation, DBusConnection::io_path_cond, DBusConnection::io_path_mutex, DBusConnection::last_dispatch_status, DBusConnection::mutex, NULL, DBusConnection::objects, DBusConnection::outgoing_counter, DBusConnection::pending_replies, DBusConnection::refcount, DBusConnection::route_peer_messages, DBusConnection::shareable, DBusConnection::slot_list, DBusConnection::timeouts, DBusConnection::transport, DBusAtomic::value, and DBusConnection::watches.

void _dbus_connection_queue_received_message_link ( DBusConnection *  connection,
DBusList *  link 
)

Adds a message-containing list link to the incoming message queue, taking ownership of the link and the message's current refcount.

Cannot fail due to lack of memory.

Parameters:
connection the connection.
link the message link to queue.

Definition at line 447 of file dbus-connection.c.

References _dbus_assert, _dbus_connection_remove_timeout_unlocked(), _dbus_hash_table_lookup_int(), _dbus_list_append_link(), _dbus_pending_call_get_timeout_unlocked(), _dbus_pending_call_is_timeout_added_unlocked(), _dbus_pending_call_set_timeout_added_unlocked(), _dbus_transport_get_is_authenticated(), DBusList::data, dbus_message_get_interface(), dbus_message_get_member(), dbus_message_get_path(), dbus_message_get_reply_serial(), dbus_message_get_signature(), dbus_message_get_type(), FALSE, DBusConnection::incoming_messages, DBusConnection::n_incoming, NULL, DBusConnection::pending_replies, and DBusConnection::transport.

Referenced by _dbus_transport_queue_messages().

void _dbus_connection_queue_synthesized_message_link ( DBusConnection *  connection,
DBusList *  link 
)

Adds a link + message to the incoming message queue.

Can't fail. Takes ownership of both link and message.

Parameters:
connection the connection.
link the list node and message to queue.

Definition at line 508 of file dbus-connection.c.

References _dbus_list_append_link(), DBusList::data, DBusConnection::incoming_messages, and DBusConnection::n_incoming.

Referenced by _dbus_pending_call_queue_timeout_error_unlocked().

DBusConnection* _dbus_connection_ref_unlocked ( DBusConnection *  connection  ) 

Increments the reference count of a DBusConnection.

Requires that the caller already holds the connection lock.

Parameters:
connection the connection.
Returns:
the connection.

Definition at line 1333 of file dbus-connection.c.

References _dbus_assert, _dbus_atomic_inc(), _dbus_current_generation, DBusConnection::generation, NULL, DBusConnection::refcount, and DBusAtomic::value.

Referenced by _dbus_object_tree_unregister_and_unlock(), _dbus_pending_call_new_unlocked(), _dbus_transport_get_is_authenticated(), dbus_connection_dispatch(), dbus_connection_set_timeout_functions(), and dbus_connection_set_watch_functions().

void _dbus_connection_remove_pending_call ( DBusConnection *  connection,
DBusPendingCall *  pending 
)

Removes a pending call from the connection, such that the pending reply will be ignored.

May drop the last reference to the pending call.

Parameters:
connection the connection
pending the pending call

Definition at line 987 of file dbus-connection.c.

References CONNECTION_LOCK.

Referenced by dbus_pending_call_cancel().

void _dbus_connection_remove_timeout_unlocked ( DBusConnection *  connection,
DBusTimeout *  timeout 
)

Removes a timeout using the connection's DBusRemoveTimeoutFunction if available.

It's an error to call this function on a timeout that was not previously added. Connection lock should be held when calling this.

Parameters:
connection the connection.
timeout the timeout to remove.

Definition at line 841 of file dbus-connection.c.

References _dbus_timeout_list_remove_timeout(), FALSE, and NULL.

Referenced by _dbus_connection_queue_received_message_link().

void _dbus_connection_remove_watch_unlocked ( DBusConnection *  connection,
DBusWatch *  watch 
)

Removes a watch using the connection's DBusRemoveWatchFunction if available.

It's an error to call this function on a watch that was not previously added. Connection lock should be held when calling this.

Parameters:
connection the connection.
watch the watch to remove.

Definition at line 720 of file dbus-connection.c.

References _dbus_watch_list_remove_watch(), FALSE, and NULL.

dbus_bool_t _dbus_connection_send_and_unlock ( DBusConnection *  connection,
DBusMessage *  message,
dbus_uint32_t *  client_serial 
)

Like dbus_connection_send(), but assumes the connection is already locked on function entry, and unlocks before returning.

Parameters:
connection the connection
message the message to send
client_serial return location for client serial of sent message
Returns:
FALSE on out-of-memory

Definition at line 2011 of file dbus-connection.c.

References _dbus_assert, CONNECTION_UNLOCK, FALSE, NULL, and TRUE.

Referenced by dbus_connection_send().

void _dbus_connection_toggle_timeout_unlocked ( DBusConnection *  connection,
DBusTimeout *  timeout,
dbus_bool_t  enabled 
)

Toggles a timeout and notifies app via connection's DBusTimeoutToggledFunction if available.

It's an error to call this function on a timeout that was not previously added. Connection lock should be held when calling this.

Parameters:
connection the connection.
timeout the timeout to toggle.
enabled whether to enable or disable

Definition at line 861 of file dbus-connection.c.

References _dbus_timeout_list_toggle_timeout(), and NULL.

void _dbus_connection_toggle_watch_unlocked ( DBusConnection *  connection,
DBusWatch *  watch,
dbus_bool_t  enabled 
)

Toggles a watch and notifies app via connection's DBusWatchToggledFunction if available.

It's an error to call this function on a watch that was not previously added. Connection lock should be held when calling this.

Parameters:
connection the connection.
watch the watch to toggle.
enabled whether to enable or disable

Definition at line 740 of file dbus-connection.c.

References _dbus_assert, _dbus_watch_list_toggle_watch(), and NULL.

void _dbus_connection_unlock ( DBusConnection *  connection  ) 

Releases the connection lock.

Parameters:
connection the connection.

Definition at line 364 of file dbus-connection.c.

References CONNECTION_UNLOCK.

Referenced by _dbus_object_tree_dispatch_and_unlock(), _dbus_object_tree_list_registered_and_unlock(), and _dbus_object_tree_unregister_and_unlock().

void _dbus_connection_unref_unlocked ( DBusConnection *  connection  ) 

Decrements the reference count of a DBusConnection.

Requires that the caller already holds the connection lock.

Parameters:
connection the connection.

Definition at line 1357 of file dbus-connection.c.

References _dbus_assert, _dbus_atomic_dec(), NULL, DBusConnection::refcount, and DBusAtomic::value.

Referenced by _dbus_transport_get_is_authenticated().

dbus_bool_t dbus_connection_has_messages_to_send ( DBusConnection *  connection  ) 

Checks whether there are messages in the outgoing message queue.

Use dbus_connection_flush() to block until all outgoing messages have been written to the underlying transport (such as a socket).

Parameters:
connection the connection.
Returns:
TRUE if the outgoing queue is non-empty.

Definition at line 548 of file dbus-connection.c.

References _dbus_connection_has_messages_to_send_unlocked(), CONNECTION_LOCK, CONNECTION_UNLOCK, FALSE, and NULL.

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