NAME
sd_bus_message_new_signal - Create a signal messageSYNOPSIS
#include <systemd/sd-bus.h>
int
sd_bus_message_new_signal(sd_bus *bus,
sd_bus_message **m,
const char *path,
const char *interface,
const char *member);
DESCRIPTION
The sd_bus_message_new_signal() function creates a new bus message object that encapsulates a D-Bus signal, and returns it in the m output parameter. The signal will be sent to path path, on the interface interface, member member. When this message is sent, no reply is expected. See sd_bus_message_new_method_call(1) for a short description of the meaning of the path, interface, and member parameters.RETURN VALUE
This function returns 0 if the message object was successfully created, and a negative errno-style error code otherwise.Errors
Returned errors may indicate the following problems: -EINVALThe output parameter m is NULL.
The path parameter is not a valid D-Bus path
("/an/object/path"), the interface parameter is not a valid
D-Bus interface name ("an.interface.name"), or the member
parameter is not a valid D-Bus member ("Name").
-ENOTCONN
The bus parameter bus is NULL or
the bus is not connected.
-ENOMEM
Memory allocation failed.
NOTES
These APIs are implemented as a shared library, which can be compiled and linked to with the libsystemd pkg-config(1) file.EXAMPLES
Example 1. Send a simple signal
/* SPDX-License-Identifier: MIT-0 */
#include <systemd/sd-bus.h>
#define _cleanup_(f) __attribute__((cleanup(f)))
int send_unit_files_changed(sd_bus *bus) {
_cleanup_(sd_bus_message_unrefp) sd_bus_message *message = NULL;
int r;
r = sd_bus_message_new_signal(bus, &message,
"/org/freedesktop/systemd1",
"org.freedesktop.systemd1.Manager",
"UnitFilesChanged");
if (r < 0)
return r;
return sd_bus_send(bus, message, NULL);
}
SEE ALSO
systemd(1), sd-bus(3), sd_bus_emit_signal(3)| systemd 252 |