sd_bus_emit_signal
systemd
sd_bus_emit_signal
3
sd_bus_emit_signal
sd_bus_emit_signalv
sd_bus_emit_signal_to
sd_bus_emit_signal_tov
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
#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_signal_to
sd_bus *bus
const char *destination
const char *path
const char *interface
const char *member
const char *types
...
int sd_bus_emit_signal_tov
sd_bus *bus
const char *destination
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
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_signal3,
sd_bus_message_append3 and
sd_bus_send3
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_signal_to() and sd_bus_emit_signal_tov() are
identical to sd_bus_emit_signal() and sd_bus_emit_signalv(), except
that they can emit the signal to a single destination. Give destination as
NULL to broadcast the signal.
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_manager3.
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, library or module instance.
-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_signal3,
sd_bus_message_append3 and
sd_bus_send3
for more possible errors.
History
sd_bus_emit_signal(),
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(), were added in version 221.
sd_bus_emit_object_added(), and
sd_bus_emit_object_removed() were added in version 222.
sd_bus_emit_signalv() was added in version 246.
sd_bus_emit_signal_to() and
sd_bus_emit_signal_tov() were added in version 253.
See Also
sd-bus3
busctl1
sd_bus_message_new_signal3
sd_bus_message_append3
sd_bus_send3
sd_bus_call_method3