x SuSE Linux 13.1-RELEASE x
x SuSE Linux 13.1-RELEASEx
SD_BUS_EMIT_SIGNAL(3) sd_bus_emit_signal SD_BUS_EMIT_SIGNAL(3)
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.
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 254 SD_BUS_EMIT_SIGNAL(3)
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