наблюдение за привязкой управляющего разъема при подключении к шине (Control socket binding watching on bus connections)
Имя (Name)
sd_bus_set_watch_bind, sd_bus_get_watch_bind - Control socket
binding watching on bus connections
Синопсис (Synopsis)
#include <systemd/sd-bus.h>
int sd_bus_set_watch_bind(sd_bus *bus, int b);
int sd_bus_get_watch_bind(sd_bus *bus);
Описание (Description)
sd_bus_set_watch_bind() may be used to enable or disable
client-side watching of server socket binding for a bus
connection object. If the b is true, the feature is enabled,
otherwise disabled (which is the default). When enabled, and the
selected bus address refers to an AF_UNIX socket in the file
system which does not exist while the connection attempt is made
an inotify(7) watch is installed on it, waiting for the socket to
appear. As soon as the socket appears the connection is made.
This functionality is useful in particular in early-boot programs
that need to run before the system bus is available, but want to
connect to it the instant it may be connected to.
sd_bus_get_watch_bind() may be used to query the current setting
of this feature. It returns zero when the feature is disabled,
and positive if enabled.
Note that no timeout is applied while we wait for the socket to
appear. This means that any synchronous remote operation (such as
sd_bus_call(3), sd_bus_add_match(3) or sd_bus_request_name(3)),
that is used on a connection with this feature enabled that
hasn't been established yet, might block forever if the socket is
never created. However, asynchronous remote operations (such as
sd_bus_send(3), sd_bus_call_async(3), sd_bus_add_match_async(3))
do not block in this case, and safely enqueue the requested
operations to be dispatched the instant the connection is set up.
Use sd_bus_is_ready(3) to determine whether the connection is
fully established, i.e. whether the peer socket has been bound,
connected to and authenticated. Use
sd_bus_set_connected_signal(3) to be notified when the connection
is fully established.
Возвращаемое значение (Return value)
On success, these functions return 0 or a positive integer. On
failure, they return a negative errno-style error code.
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), inotify(7), sd_bus_call(3),
sd_bus_add_match(3), sd_bus_request_name(3), sd_bus_is_ready(3),
sd_bus_set_connected_signal(3)
