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.

       -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_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_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-bus(3), busctl(1), sd_bus_message_new_signal(3), sd_bus_message_append(3),
       sd_bus_send(3), sd_bus_call_method(3)