sd_bus_get_watch_bind(3) — Linux manual page


SD_BUS_SET_WATCH_BIND(3)    sd_bus_set_watch_bind   SD_BUS_SET_WATCH_BIND(3)

NAME         top

       sd_bus_set_watch_bind, sd_bus_get_watch_bind - Control socket binding
       watching on bus connections

SYNOPSIS         top

       #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         top

       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

       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         top

       On success, these functions return 0 or a positive integer. On
       failure, they return a negative errno-style error code.

       Returned errors may indicate the following problems:

           The bus connection has been created in a different process.

NOTES         top

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

SEE ALSO         top

       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),

COLOPHON         top

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systemd 246                                         SD_BUS_SET_WATCH_BIND(3)

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