NAME

       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

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_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_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).

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.

           Added in version 246.

       -ENOPKG
           The bus cannot be resolved.

           Added in version 246.

       -ECHILD
           The bus was created in a different process, library or module instance.

           Added in version 246.

       -ENOMEM
           Memory allocation failed.

           Added in version 246.

       -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.

           Added in version 246.

       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.

NOTES

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

       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.

HISTORY

       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(), and sd_bus_emit_object_removed() were
       added in version 246.

       sd_bus_emit_signal_to() and sd_bus_emit_signal_tov() were added in version 253.

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)

systemd 255                                                                                SD_BUS_EMIT_SIGNAL(3)