systemd sd_bus_emit_signal 3 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 #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 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_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. On success, these functions return a non-negative integer. On failure, they return a negative errno-style error code. 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_signal3, sd_bus_message_append3 and sd_bus_send3 for more possible errors. sd-bus3, busctl1, sd_bus_message_new_signal3, sd_bus_message_append3, sd_bus_send3, sd_bus_call_method3