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
#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) ; |
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.
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.
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.
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.