`sd_bus_message_new_signal` ( 3 )

создать сигнальное сообщение (Create a signal message)

Имя (Name)

sd_bus_message_new_signal - Create a signal message

Синопсис (Synopsis)

#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);

Описание (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.

Возвращаемое значение (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:

-EINVAL The 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.

Примечание (Note)

These APIs are implemented as a shared library, which can be compiled and linked to with the libsystemd pkg-config(1) file.

Примеры (Examples)

Example 1. Send a simple signal

           #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);
           }

       This function in systemd sources is used to emit the
       "UnitFilesChanged" signal when the unit files have been changed.

Смотри также (See also)

systemd(1), sd-bus(3), sd_bus_emit_signal(3)

Исходный текст на man7.org

sd_bus_message_new_signal ( 3 )