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Diffstat (limited to 'dbus/dbus-connection.c')
| -rw-r--r-- | dbus/dbus-connection.c | 623 |
1 files changed, 623 insertions, 0 deletions
diff --git a/dbus/dbus-connection.c b/dbus/dbus-connection.c new file mode 100644 index 00000000..f60e53a9 --- /dev/null +++ b/dbus/dbus-connection.c @@ -0,0 +1,623 @@ +/* -*- mode: C; c-file-style: "gnu" -*- */ +/* dbus-connection.c DBusConnection object + * + * Copyright (C) 2002 Red Hat Inc. + * + * Licensed under the Academic Free License version 1.2 + * + * 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + * + */ + +#include "dbus-connection.h" +#include "dbus-list.h" +#include "dbus-transport.h" +#include "dbus-watch.h" +#include "dbus-connection-internal.h" +#include "dbus-list.h" + +/** + * @defgroup DBusConnection DBusConnection + * @ingroup DBus + * @brief Connection to another application + * + * A DBusConnection represents a connection to another + * application. Messages can be sent and received via this connection. + * + * The connection maintains a queue of incoming messages and a queue + * of outgoing messages. dbus_connection_pop_message() and friends + * can be used to read incoming messages from the queue. + * Outgoing messages are automatically discarded as they are + * written to the network. + * + * In brief a DBusConnection is a message queue associated with some + * message transport mechanism such as a socket. + * + */ + +/** + * @defgroup DBusConnectionInternals DBusConnection implementation details + * @ingroup DBusInternals + * @brief Implementation details of DBusConnection + * + * @{ + */ + +/** + * Implementation details of DBusConnection. All fields are private. + */ +struct DBusConnection +{ + int refcount; /**< Reference count. */ + + DBusList *outgoing_messages; /**< Queue of messages we need to send, send the end of the list first. */ + DBusList *incoming_messages; /**< Queue of messages we have received, end of the list received most recently. */ + + int n_outgoing; /**< Length of outgoing queue. */ + int n_incoming; /**< Length of incoming queue. */ + + DBusTransport *transport; /**< Object that sends/receives messages over network. */ + DBusWatchList *watches; /**< Stores active watches. */ + + DBusConnectionErrorFunction error_function; /**< Callback for errors. */ + void *error_data; /**< Data for error callback. */ + DBusFreeFunction error_free_data_function; /**< Free function for error callback data. */ +}; + +/** + * Adds a message to the incoming message queue, returning #FALSE + * if there's insufficient memory to queue the message. + * + * @param connection the connection. + * @param message the message to queue. + * @returns #TRUE on success. + */ +dbus_bool_t +_dbus_connection_queue_received_message (DBusConnection *connection, + DBusMessage *message) +{ + if (!_dbus_list_append (&connection->incoming_messages, + message)) + return FALSE; + + dbus_message_ref (message); + connection->n_incoming += 1; + + return TRUE; +} + +/** + * Checks whether there are messages in the outgoing message queue. + * + * @param connection the connection. + * @returns #TRUE if the outgoing queue is non-empty. + */ +dbus_bool_t +_dbus_connection_have_messages_to_send (DBusConnection *connection) +{ + return connection->outgoing_messages != NULL; +} + +/** + * Gets the next outgoing message. The message remanins in the + * queue, and the caller does not own a reference to it. + * + * @param connection the connection. + * @returns the message to be sent. + */ +DBusMessage* +_dbus_connection_get_message_to_send (DBusConnection *connection) +{ + return _dbus_list_get_last (&connection->outgoing_messages); +} + +/** + * Notifies the connection that a message has been sent, so the + * message can be removed from the outgoing queue. + * + * @param connection the connection. + * @param message the message that was sent. + */ +void +_dbus_connection_message_sent (DBusConnection *connection, + DBusMessage *message) +{ + _dbus_assert (message == _dbus_list_get_last (&connection->outgoing_messages)); + _dbus_list_pop_last (&connection->outgoing_messages); + dbus_message_unref (message); + + connection->n_outgoing -= 1; + if (connection->n_outgoing == 0) + _dbus_transport_messages_pending (connection->transport, + connection->n_outgoing); +} + +/** + * 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. + * + * @param connection the connection. + * @param watch the watch to add. + * @returns #TRUE on success. + */ +dbus_bool_t +_dbus_connection_add_watch (DBusConnection *connection, + DBusWatch *watch) +{ + return _dbus_watch_list_add_watch (connection->watches, + watch); + + return TRUE; +} + +/** + * 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. + * + * @param connection the connection. + * @param watch the watch to remove. + */ +void +_dbus_connection_remove_watch (DBusConnection *connection, + DBusWatch *watch) +{ + _dbus_watch_list_remove_watch (connection->watches, + watch); +} + +static void +handle_error (DBusConnection *connection, + DBusResultCode result) +{ + if (result != DBUS_RESULT_SUCCESS && + connection->error_function != NULL) + { + dbus_connection_ref (connection); + (* connection->error_function) (connection, result, + connection->error_data); + dbus_connection_unref (connection); + } +} + +static void +set_result_handled (DBusConnection *connection, + DBusResultCode *result_address, + DBusResultCode result) +{ + dbus_set_result (result_address, result); + handle_error (connection, result); +} + +/** + * Reports a transport error to the connection. Typically + * results in an application error callback being invoked. + * + * @param connection the connection. + * @param result_code the error code. + */ +void +_dbus_connection_transport_error (DBusConnection *connection, + DBusResultCode result_code) +{ + handle_error (connection, result_code); +} + +/** + * Queues incoming messages and sends outgoing messages for this + * connection, optionally blocking in the process. Each call to + * _dbus_connection_do_iteration() 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. + * + * @param connection the connection. + * @param flags iteration flags. + * @param timeout_milliseconds maximum blocking time, or -1 for no limit. + */ +void +_dbus_connection_do_iteration (DBusConnection *connection, + unsigned int flags, + int timeout_milliseconds) +{ + if (connection->n_outgoing == 0) + flags &= ~DBUS_ITERATION_DO_WRITING; + + _dbus_transport_do_iteration (connection->transport, + flags, timeout_milliseconds); +} + +/** + * 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. + * + * @param transport the transport. + * @returns the new connection, or #NULL on failure. + */ +DBusConnection* +_dbus_connection_new_for_transport (DBusTransport *transport) +{ + DBusConnection *connection; + DBusWatchList *watch_list; + + watch_list = NULL; + connection = NULL; + + watch_list = _dbus_watch_list_new (); + if (watch_list == NULL) + goto error; + + connection = dbus_new0 (DBusConnection, 1); + if (connection == NULL) + goto error; + + connection->refcount = 1; + connection->transport = transport; + connection->watches = watch_list; + + _dbus_transport_ref (transport); + _dbus_transport_set_connection (transport, connection); + + return connection; + + error: + + _dbus_assert (connection == NULL); + + if (watch_list) + _dbus_watch_list_free (watch_list); + + return NULL; +} + +/** @} */ + +/** + * @addtogroup DBusConnection + * + * @{ + */ + +/** + * 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. + * + * @param address the address. + * @param result address where a result code can be returned. + * @returns new connection, or #NULL on failure. + */ +DBusConnection* +dbus_connection_open (const char *address, + DBusResultCode *result) +{ + DBusConnection *connection; + DBusTransport *transport; + + transport = _dbus_transport_open (address, result); + if (transport == NULL) + return NULL; + + connection = _dbus_connection_new_for_transport (transport); + + _dbus_transport_unref (transport); + + if (connection == NULL) + { + dbus_set_result (result, DBUS_RESULT_NO_MEMORY); + return NULL; + } + + return connection; +} + +/** + * Increments the reference count of a DBusConnection. + * + * @param connection the connection. + */ +void +dbus_connection_ref (DBusConnection *connection) +{ + connection->refcount += 1; +} + +/** + * Decrements the reference count of a DBusConnection, and finalizes + * it if the count reaches zero. If a connection is still connected + * when it's finalized, it will be disconnected (that is, associated + * file handles will be closed). + * + * @param connection the connection. + */ +void +dbus_connection_unref (DBusConnection *connection) +{ + _dbus_assert (connection != NULL); + _dbus_assert (connection->refcount > 0); + + connection->refcount -= 1; + if (connection->refcount == 0) + { + /* free error data as a side effect */ + dbus_connection_set_error_function (connection, + NULL, NULL, NULL); + + _dbus_watch_list_free (connection->watches); + + _dbus_list_foreach (&connection->outgoing_messages, + (DBusForeachFunction) dbus_message_unref, + NULL); + _dbus_list_clear (&connection->outgoing_messages); + + _dbus_list_foreach (&connection->incoming_messages, + (DBusForeachFunction) dbus_message_unref, + NULL); + _dbus_list_clear (&connection->incoming_messages); + + _dbus_transport_unref (connection->transport); + + dbus_free (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. + * + * @param connection the connection. + */ +void +dbus_connection_disconnect (DBusConnection *connection) +{ + _dbus_transport_disconnect (connection->transport); +} + +/** + * 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(). + * + * @param connection the connection. + * @returns #TRUE if the connection is still alive. + */ +dbus_bool_t +dbus_connection_get_is_connected (DBusConnection *connection) +{ + return _dbus_transport_get_is_connected (connection->transport); +} + +/** + * 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(). + * + * If the function fails, it returns #FALSE and returns the + * reason for failure via the result parameter. + * The result parameter can be #NULL if you aren't interested + * in the reason for the failure. + * + * @param connection the connection. + * @param message the message to write. + * @param result address where result code can be placed. + * @returns #TRUE on success. + */ +dbus_bool_t +dbus_connection_send_message (DBusConnection *connection, + DBusMessage *message, + DBusResultCode *result) +{ + if (!_dbus_list_prepend (&connection->outgoing_messages, + message)) + { + set_result_handled (connection, result, DBUS_RESULT_NO_MEMORY); + return FALSE; + } + + dbus_message_ref (message); + connection->n_outgoing += 1; + + _dbus_message_lock (message); + + if (connection->n_outgoing == 1) + _dbus_transport_messages_pending (connection->transport, + connection->n_outgoing); +} + +/** + * Blocks until the outgoing message queue is empty. + * + * @param connection the connection. + */ +void +dbus_connection_flush (DBusConnection *connection) +{ + while (connection->n_outgoing > 0) + _dbus_connection_do_iteration (connection, + DBUS_ITERATION_DO_WRITING | + DBUS_ITERATION_BLOCK, + -1); +} + +/** + * Gets the number of messages in the incoming message queue. + * + * @param connection the connection. + * @returns the number of messages in the queue. + */ +int +dbus_connection_get_n_messages (DBusConnection *connection) +{ + return connection->n_incoming; +} + +/** + * Returns the first-received message from the incoming message queue, + * leaving it in the queue. The caller does not own a reference to the + * returned message. If the queue is empty, returns #NULL. + * + * @param connection the connection. + * @returns next message in the incoming queue. + */ +DBusMessage* +dbus_connection_peek_message (DBusConnection *connection) +{ + return _dbus_list_get_first (&connection->incoming_messages); +} + +/** + * 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. + * + * @param connection the connection. + * @returns next message in the incoming queue. + */ +DBusMessage* +dbus_connection_pop_message (DBusConnection *connection) +{ + if (connection->n_incoming > 0) + { + connection->n_incoming -= 1; + return _dbus_list_pop_first (&connection->incoming_messages); + } + else + return NULL; +} + +/** + * Sets the error handler function for the connection. + * + * @param connection the connection. + * @param error_function the error handler. + * @param data data to pass to the error handler. + * @param free_data_function function to be called to free the data. + */ +void +dbus_connection_set_error_function (DBusConnection *connection, + DBusConnectionErrorFunction error_function, + void *data, + DBusFreeFunction free_data_function) +{ + if (connection->error_free_data_function != NULL) + (* connection->error_free_data_function) (connection->error_data); + + connection->error_function = error_function; + connection->error_data = data; + connection->error_free_data_function = 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. + * + * 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_connection_handle_watch() should be called to + * notify the connection of the file descriptor's condition. + * + * dbus_connection_handle_watch() 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. + * + * @param connection the connection. + * @param add_function function to begin monitoring a new descriptor. + * @param remove_function function to stop monitoring a descriptor. + * @param data data to pass to add_function and remove_function. + * @param free_data_function function to be called to free the data. + */ +void +dbus_connection_set_watch_functions (DBusConnection *connection, + DBusAddWatchFunction add_function, + DBusRemoveWatchFunction remove_function, + void *data, + DBusFreeFunction free_data_function) +{ + /* ref connection for slightly better reentrancy */ + dbus_connection_ref (connection); + + _dbus_watch_list_set_functions (connection->watches, + add_function, remove_function, + data, free_data_function); + + /* drop our paranoid refcount */ + dbus_connection_unref (connection); +} + +/** + * Called to notify the connection when a previously-added watch + * is ready for reading or writing, or has an exception such + * as a hangup. + * + * @param connection the connection. + * @param watch the watch. + * @param condition the current condition of the file descriptors being watched. + */ +void +dbus_connection_handle_watch (DBusConnection *connection, + DBusWatch *watch, + unsigned int condition) +{ + _dbus_transport_handle_watch (connection->transport, + watch, condition); +} + +/** @} */ |