sd_bus_start — Initiate a bus connection to the D-bus broker daemon
#include <systemd/sd-bus.h>
int sd_bus_start( | sd_bus *bus); |
sd_bus_start() connects an existing bus connection object to the D-Bus
broker daemon, usually
dbus-daemon(1)
or
dbus-broker(1).
The mechanism to use for the connection must be configured before the call to
sd_bus_start(), using one of
sd_bus_set_address(3),
sd_bus_set_fd(3), or
sd_bus_set_exec(3).
sd_bus_start() will open the connection socket or spawn the executable as
needed, and asynchronously start a org.freedesktop.DBus.Hello() call. The
answer to the Hello call will be processed later from
sd_bus_process(3). If
opening of the connection or queuing of the asynchronous call fail, the connection will be closed with
sd_bus_close(3).
In most cases, it is better to use
sd_bus_default_user(3),
sd_bus_default_system(3)
or related calls instead of the more low-level sd_bus_new() and
sd_bus_start(). The higher-level functions not only allocate a bus object but also
start the connection to a well-known bus in a single function call.
On success, this function returns a non-negative integer. On failure, it returns a negative errno-style error code.
In addition, other connection-related errors may be returned. See sd_bus_send(3).
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.