| SD_BUS_EMIT_SIGNAL(3) | sd_bus_emit_signal | SD_BUS_EMIT_SIGNAL(3) |
.SH "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
.SH "SYNOPSIS"
#include <systemd/sd-bus-vtable.h>
.HP 552u int sd_bus_emit_signal(sd_bus *bus,
const char *path,
const char *interface,
const char *member,
const char *types, ...);
.HP 576u int sd_bus_emit_signalv(sd_bus *bus,
const char *path,
const char *interface,
const char *member,
const char *types,
va_list ap);
.HP 624u int sd_bus_emit_signal_to(sd_bus *bus,
const char *destination,
const char *path,
const char *interface,
const char *member,
const char *types, ...);
.HP 648u 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);
.HP 792u int
sd_bus_emit_interfaces_added(sd_bus *bus,
const char *path,
const char *interface, ...);
.HP 912u int
sd_bus_emit_interfaces_added_strv(sd_bus *bus,
const char *path,
char **interfaces);
.HP 840u int
sd_bus_emit_interfaces_removed(sd_bus *bus,
const char *path,
const char *interface, ...);
.HP 960u int
sd_bus_emit_interfaces_removed_strv(sd_bus *bus,
const char *path,
char **interfaces);
.HP 840u int
sd_bus_emit_properties_changed(sd_bus *bus,
const char *path,
const char *interface,
const char *name, ...);
.HP 960u int
sd_bus_emit_properties_changed_strv(sd_bus *bus,
const char *path,
const char *interface,
char **names);
.HP 696u int sd_bus_emit_object_added(sd_bus *bus,
const char *path);
.HP 744u int sd_bus_emit_object_removed(sd_bus *bus,
const char *path);
.SH "DESCRIPTION"
.PP 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.
.PP 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.
.PP 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.
.PP 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.
.PP 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.
.PP 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).
.SH "RETURN VALUE"
.PP On success, these functions return a non-negative integer. On failure,
they return a negative errno-style error code.
.SS "Errors"
.PP Returned errors may indicate the following problems:
.PP -EINVAL
One of the required parameters is NULL or invalid. A reserved D-Bus
interface was passed as the interface parameter.
.RE
.PP -ENOPKG
The bus cannot be resolved.
.RE
.PP -ECHILD
The bus was created in a different process, library or module instance.
.RE
.PP -ENOMEM
Memory allocation failed.
.RE
.PP -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.
.RE
.PP 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.
.SH "NOTES"
.PP Functions described here are available as a shared library, which can be
compiled against and linked to with the
libsystemd pkg-config(1) file.
.PP 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.
.PP 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.
.SH "HISTORY"
.PP 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.
.PP sd_bus_emit_object_added(), and
sd_bus_emit_object_removed() were added in version 222.
.PP sd_bus_emit_signalv() was added in version 246.
.PP sd_bus_emit_signal_to() and sd_bus_emit_signal_tov() were
added in version 253.
.SH "SEE ALSO"
.PP 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 262.2 |