sd_bus_emit_signal - Man Page

#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, 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, 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, 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_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_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_manager(3)​.

On success, these functions return a non-negative integer​. On failure, they return a negative errno-style error code​.

Functions described here are available as a shared library, which can be compiled against and linked to with the libsystemd ​pkg-config(1) file​.

All functions listed here are thread-agnostic and only a single thread may operate on a given object at any given time​. Different threads may access the same object at different times​. Multiple independent objects may be used from different threads in parallel​.

The code described here uses getenv(3), which is declared to be not multi-thread-safe​. This means that the code calling the functions described here must not call setenv(3) from a parallel thread​. It is recommended to only do calls to setenv() from an early phase of the program when no other threads have been started​.

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​.

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)

sd-bus(3), sd_bus_add_object(3), sd_bus_add_object_manager(3), sd_bus_call_method(3), sd_bus_message_new_signal(3), systemd.directives(7), systemd.index(7).

The man pages sd_bus_emit_interfaces_added(3), sd_bus_emit_interfaces_added_strv(3), sd_bus_emit_interfaces_removed(3), sd_bus_emit_interfaces_removed_strv(3), sd_bus_emit_object_added(3), sd_bus_emit_object_removed(3), sd_bus_emit_properties_changed(3), sd_bus_emit_properties_changed_strv(3), sd_bus_emit_signal_to(3), sd_bus_emit_signal_tov(3) and sd_bus_emit_signalv(3) are aliases of sd_bus_emit_signal(3).