Error reporting
[D-Bus low-level public API]

Error reporting. More...

Data Structures
struct	DBusError
	Object representing an exception. More...
Typedefs
typedef DBusError	DBusError
	Mostly-opaque type representing an error that occurred.
Functions
void	dbus_error_init (DBusError *error)
	Initializes a DBusError structure.
void	dbus_error_free (DBusError *error)
	Frees an error that's been set (or just initialized), then reinitializes the error as in dbus_error_init().
void	dbus_set_error_const (DBusError *error, const char *name, const char *message)
	Assigns an error name and message to a DBusError.
void	dbus_move_error (DBusError *src, DBusError *dest)
	Moves an error src into dest, freeing src and overwriting dest.
dbus_bool_t	dbus_error_has_name (const DBusError *error, const char *name)
	Checks whether the error is set and has the given name.
dbus_bool_t	dbus_error_is_set (const DBusError *error)
	Checks whether an error occurred (the error is set).
void	dbus_set_error (DBusError *error, const char *name, const char *format,...)
	Assigns an error name and message to a DBusError.

---

Detailed Description

Error reporting.

Types and functions related to reporting errors.

In essence D-Bus error reporting works as follows:

 DBusError error;
 dbus_error_init (&error);
 dbus_some_function (arg1, arg2, &error);
 if (dbus_error_is_set (&error))
   {
     fprintf (stderr, "an error occurred: %s\n", error.message);
     dbus_error_free (&error);
   }

By convention, all functions allow NULL instead of a DBusError*, so callers who don't care about the error can ignore it.

There are some rules. An error passed to a D-Bus function must always be unset; you can't pass in an error that's already set. If a function has a return code indicating whether an error occurred, and also a DBusError parameter, then the error will always be set if and only if the return code indicates an error occurred. i.e. the return code and the error are never going to disagree.

An error only needs to be freed if it's been set, not if it's merely been initialized.

You can check the specific error that occurred using dbus_error_has_name().

Errors will not be set for programming errors, such as passing invalid arguments to the libdbus API. Instead, libdbus will print warnings, exit on a failed assertion, or even crash in those cases (in other words, incorrect use of the API results in undefined behavior, possibly accompanied by helpful debugging output if you're lucky).

---

Function Documentation

void dbus_error_free

(

DBusError *

error

)

Frees an error that's been set (or just initialized), then reinitializes the error as in dbus_error_init().

Parameters:

error

memory where the error is stored.

Definition at line 207 of file dbus-errors.c.

References DBusRealError::const_message, dbus_error_init(), dbus_free(), DBusRealError::message, DBusRealError::name, and NULL.

Referenced by _dbus_get_local_machine_uuid_encoded(), _dbus_keyring_new_for_credentials(), _dbus_read_uuid_file(), dbus_connection_register_fallback(), dbus_connection_register_object_path(), dbus_move_error(), and dbus_server_listen().

dbus_bool_t dbus_error_has_name	(	const DBusError *	error,
		const char *	name
	)

Checks whether the error is set and has the given name.

Parameters:

	error	the error
	name	the name

Returns:

TRUE if the given named error occurred

Definition at line 298 of file dbus-errors.c.

References _dbus_assert, _dbus_string_equal(), _dbus_string_init_const(), FALSE, DBusError::message, DBusError::name, and NULL.

Referenced by _dbus_read_uuid_file(), dbus_connection_register_fallback(), and dbus_connection_register_object_path().

void dbus_error_init

(

DBusError *

error

)

Initializes a DBusError structure.

Does not allocate any memory; the error only needs to be freed if it is set at some point.

Parameters:

error

the DBusError.

Definition at line 184 of file dbus-errors.c.

References _dbus_assert, DBusRealError::const_message, DBusRealError::message, DBusRealError::name, NULL, and TRUE.

Referenced by _dbus_keyring_new_for_credentials(), dbus_error_free(), and dbus_move_error().

dbus_bool_t dbus_error_is_set

(

const DBusError *

error

)

Checks whether an error occurred (the error is set).

Parameters:

error

the error object

Returns:

TRUE if an error occurred

Definition at line 325 of file dbus-errors.c.

References _dbus_assert, FALSE, DBusError::message, DBusError::name, and NULL.

Referenced by _dbus_transport_open(), _dbus_write_pid_to_file_and_pipe(), dbus_address_unescape_value(), dbus_parse_address(), and dbus_server_listen().

void dbus_move_error	(	DBusError *	src,
		DBusError *	dest
	)

Moves an error src into dest, freeing src and overwriting dest.

Both src and dest must be initialized. src is reinitialized to an empty error. dest may not contain an existing error. If the destination is NULL, just frees and reinits the source error.

Parameters:

	src	the source error
	dest	the destination error or NULL

Definition at line 275 of file dbus-errors.c.

References dbus_error_free(), and dbus_error_init().

Referenced by _dbus_read_uuid_file(), _dbus_transport_open(), and dbus_server_listen().

void dbus_set_error	(	DBusError *	error,
		const char *	name,
		const char *	format,
			...
	)

Assigns an error name and message to a DBusError.

Does nothing if error is NULL.

The format may be NULL, which means a (pretty much useless) default message will be deduced from the name. This is not a good idea, just go ahead and provide a useful error message. It won't hurt you.

If no memory can be allocated for the error message, an out-of-memory error message will be set instead.

Parameters:

	error	the error.or NULL
	name	the error name
	format	printf-style format string.

Definition at line 350 of file dbus-errors.c.

References _dbus_assert, _dbus_strdup(), _dbus_string_append(), _dbus_string_append_printf_valist(), _dbus_string_free(), _dbus_string_init(), _dbus_string_steal_data(), DBusRealError::const_message, dbus_free(), FALSE, DBusRealError::message, DBusError::message, DBusRealError::name, DBusError::name, and NULL.

Referenced by _dbus_babysitter_set_child_exit_error(), _dbus_become_daemon(), _dbus_change_to_daemon_user(), _dbus_check_dir_is_private_to_user(), _dbus_close(), _dbus_connect_tcp_socket(), _dbus_connect_unix_socket(), _dbus_create_directory(), _dbus_create_file_exclusively(), _dbus_delete_directory(), _dbus_delete_file(), _dbus_directory_get_next_file(), _dbus_directory_open(), _dbus_file_get_contents(), _dbus_full_duplex_pipe(), _dbus_get_autolaunch_address(), _dbus_is_console_user(), _dbus_keyring_new_for_credentials(), _dbus_listen_tcp_socket(), _dbus_listen_unix_socket(), _dbus_make_file_world_readable(), _dbus_message_iter_get_args_valist(), _dbus_object_tree_register(), _dbus_pipe_write(), _dbus_read_credentials_socket(), _dbus_server_listen_platform_specific(), _dbus_server_new_for_domain_socket(), _dbus_server_new_for_tcp_socket(), _dbus_set_bad_address(), _dbus_spawn_async_with_babysitter(), _dbus_stat(), _dbus_string_save_to_file(), _dbus_transport_new_for_domain_socket(), _dbus_transport_new_for_tcp_socket(), _dbus_user_database_lookup(), _dbus_user_database_lookup_group(), _dbus_write_pid_to_file_and_pipe(), dbus_connection_send_with_reply_and_block(), dbus_message_demarshal(), dbus_parse_address(), dbus_server_listen(), dbus_set_error_from_message(), dbus_signature_validate(), and dbus_signature_validate_single().

void dbus_set_error_const	(	DBusError *	error,
		const char *	name,
		const char *	message
	)

Assigns an error name and message to a DBusError.

Does nothing if error is NULL. The message may be NULL, which means a default message will be deduced from the name. The default message will be totally useless, though, so using a NULL message is not recommended.

Because this function does not copy the error name or message, you must ensure the name and message are global data that won't be freed. You probably want dbus_set_error() instead, in most cases.

Parameters:

	error	the error.or NULL
	name	the error name (not copied!!!)
	message	the error message (not copied!!!)

Definition at line 239 of file dbus-errors.c.

References _dbus_assert, DBusRealError::const_message, DBusRealError::message, DBusError::message, DBusRealError::name, DBusError::name, NULL, and TRUE.

Referenced by _dbus_keyring_get_best_key(), and _dbus_keyring_new_for_credentials().

---