x SuSE Linux 13.1-RELEASE x
x SuSE Linux 13.1-RELEASEx
SD_BUS_SET_WATCH_BIND(3) sd_bus_set_watch_bind SD_BUS_SET_WATCH_BIND(3)
NAME
sd_bus_set_watch_bind, sd_bus_get_watch_bind - Control socket binding
watching on bus connections
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);
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.
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, library
or module instance.
NOTES
Functions described here are available as a shared library, which can
be compiled against and linked to with the libsystemd pkg-config(1)
file.
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.
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)
systemd 254 SD_BUS_SET_WATCH_BIND(3)
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