комфортные функции для передачи стандартных сигналов D-Bus (convenience functions for emitting (standard) D-Bus signals)
Имя (Name)
sd_bus_emit_signal, sd_bus_emit_signalv,
sd_bus_emit_interfaces_added, sd_bus_emit_interfaces_added_strv,
sd_bus_emit_interfaces_removed,
sd_bus_emit_interfaces_removed_strv,
sd_bus_emit_properties_changed,
sd_bus_emit_properties_changed_strv, sd_bus_emit_object_added,
sd_bus_emit_object_removed - Convenience functions for emitting
(standard) D-Bus signals
Синопсис (Synopsis)
#include <systemd/sd-bus-vtable.h>
int sd_bus_emit_signal(sd_bus *bus, const char *path,
const char *interface, const char *member,
const char *types, ...);
int sd_bus_emit_signalv(sd_bus *bus, const char *path,
const char *interface,
const char *member, const char *types,
va_list ap);
int sd_bus_emit_interfaces_added(sd_bus *bus, const char *path,
const char *interface, ...);
int sd_bus_emit_interfaces_added_strv(sd_bus *bus,
const char *path,
const char **interfaces);
int sd_bus_emit_interfaces_removed(sd_bus *bus, const char *path,
const char *interface, ...);
int sd_bus_emit_interfaces_removed_strv(sd_bus *bus,
const char *path,
const char **interfaces);
int sd_bus_emit_properties_changed(sd_bus *bus, const char *path,
const char *interface,
const char *name, ...);
int sd_bus_emit_properties_changed_strv(sd_bus *bus,
const char *path,
const char *interface,
const char **names);
int sd_bus_emit_object_added(sd_bus *bus, const char *path);
int sd_bus_emit_object_removed(sd_bus *bus, const char *path);
Описание (Description)
sd_bus_emit_signal() is a convenience function for initializing a
bus message object and emitting the corresponding D-Bus signal.
It combines the sd_bus_message_new_signal(3),
sd_bus_message_append(3) and sd_bus_send(3) functions into a
single function call. sd_bus_emit_signalv() is equivalent to
sd_bus_message_append(), except that it is called with a
"va_list" instead of a variable number of arguments.
sd_bus_emit_interfaces_added() and
sd_bus_emit_interfaces_removed() are used to implement the
InterfacesAdded and InterfacesRemoved signals of the
org.freedesktop.DBus.ObjectManager interface. They take a path
whose interfaces have been modified as an argument and a variable
list of interfaces that have been added or removed, respectively.
The final argument passed to sd_bus_emit_interfaces_added() and
sd_bus_emit_interfaces_removed() must be NULL. This allows both
functions to safely determine the number of passed interface
arguments. sd_bus_emit_interfaces_added_strv() and
sd_bus_emit_interfaces_removed_strv() are identical to their
respective counterparts but both take the list of interfaces as a
single argument instead of a variable number of arguments.
sd_bus_emit_properties_changed() is used to implement the
PropertiesChanged signal of the org.freedesktop.DBus.Properties
interface. It takes an object path, interface and a variable list
of property names as its arguments. The final argument passed to
sd_bus_emit_properties_changed() must be NULL. This allows it to
safely determine the number of passed property names.
sd_bus_emit_properties_changed_strv() is identical to
sd_bus_emit_properties_changed() but takes the list of property
names as a single argument instead of a variable number of
arguments.
sd_bus_emit_object_added() and sd_bus_emit_object_removed() are
convenience functions for emitting the InterfacesAdded or
InterfacesRemoved signals for all interfaces registered on a
specific object path, respectively. This includes any parent
fallback vtables if they are not overridden by a more applicable
child vtable. It also includes all the standard D-Bus interfaces
implemented by sd-bus itself on any registered object.
Note that sd_bus_emit_interfaces_added(),
sd_bus_emit_interfaces_removed(), sd_bus_emit_object_added() and
sd_bus_emit_object_removed() require an object manager to have
been registered on the given object path or one of its parent
object paths using sd_bus_add_object_manager(3).
Возвращаемое значение (Return value)
On success, these functions return a non-negative integer. On
failure, they return a negative errno-style error code.
Errors
Returned errors may indicate the following problems:
-EINVAL
One of the required parameters is NULL or invalid. A reserved
D-Bus interface was passed as the interface parameter.
-ENOPKG
The bus cannot be resolved.
-ECHILD
The bus was created in a different process.
-ENOMEM
Memory allocation failed.
-ESRCH
One of sd_bus_emit_interfaces_added(),
sd_bus_emit_interfaces_removed(), sd_bus_emit_object_added()
or sd_bus_emit_object_removed() was called on an object
without an object manager registered on its own object path
or one of its parent object paths.
See the man pages of sd_bus_message_new_signal(3),
sd_bus_message_append(3) and sd_bus_send(3) for more possible
errors.
Примечание (Note)
These APIs are implemented as a shared library, which can be
compiled and linked to with the libsystemd pkg-config(1) file.
Смотри также (See also)
sd-bus(3), busctl(1), sd_bus_message_new_signal(3),
sd_bus_message_append(3), sd_bus_send(3), sd_bus_call_method(3)
