проверить, открыто ли автобусное соединение или готово (Check whether the bus connection is open or ready)
Имя (Name)
sd_bus_is_open, sd_bus_is_ready - Check whether the bus
connection is open or ready
Синопсис (Synopsis)
#include <systemd/sd-bus.h>
int sd_bus_is_open(sd_bus *bus);
int sd_bus_is_ready(sd_bus *bus);
Описание (Description)
sd_bus_is_open() checks whether the specified bus connection is
open, i.e. in the process of being established, already
established or in the process of being torn down. It returns zero
when the connection has not been started yet (i.e.
sd_bus_start(3) or some equivalent call has not been invoked
yet), or is fully terminated again (for example after
sd_bus_close(3)), it returns positive otherwise.
sd_bus_is_ready() checks whether the specified connection is
fully established, i.e. completed the connection and
authentication phases of the protocol and received the Hello()
method call response, and is not in the process of being torn
down again. It returns zero outside of this state, and positive
otherwise. Effectively, this function returns positive while
regular messages can be sent or received on the connection.
The bus argument may be NULL, zero is also returned in that case.
To be notified when the connection is fully established, use
sd_bus_set_connected_signal(3) and install a match for the
Connected() signal on the "org.freedesktop.DBus.Local" interface.
To be notified when the connection is torn down again, install a
match for the Disconnected() signal on the
"org.freedesktop.DBus.Local" interface.
Возвращаемое значение (Return value)
Those functions return 0 if the bus is not in the given state,
and a positive integer when it is. On failure, a negative
errno-style error code is returned.
Errors
Returned errors may indicate the following problems:
-ECHILD
The bus connection has been created in a different process.
Примечание (Note)
These APIs are implemented as a shared library, which can be
compiled and linked to with the libsystemd pkg-config(1) file.
Смотри также (See also)
systemd(1), sd-bus(3), sd_bus_start(3), sd_bus_close(3),
sd_bus_set_connected_signal(3)
