sd_bus_process — Drive the connection
sd_bus_process() drives the connection between the client and the message bus.
That is, it handles connecting, authentication, and processing of messages. When invoked, pending I/O
work is executed, and queued incoming messages are dispatched to registered callbacks. Each time it is
invoked a single operation is executed. It returns zero when no operations were pending and positive if a
message was processed. When zero is returned the caller should poll for I/O events before calling into
sd_bus_process() again. For that either use the simple, blocking
sd_bus_wait(3) call, or
hook up the bus connection object to an external or manual event loop using
sd_bus_process() processes at most one incoming message per call. If the parameter
ret is not
NULL and the call processed a message,
*ret is set to this message. The caller owns a reference to this message and should call
sd_bus_message_unref(3) when the
message is no longer needed. If
ret is not
NULL, progress was made, but no message was
*ret is set to
If progress was made, a positive integer is returned. If no progress was made, 0 is returned. If an
error occurs, a negative
errno-style error code is returned.
Returned errors may indicate the following problems:
An invalid bus object was passed.
The bus connection was allocated in a parent process and is being reused in a child
The bus connection has been terminated already.
The bus connection has been terminated just now.
This function is already being called, i.e.
has been called from a callback function that itself was called by
Functions described here are available as a shared
library, which can be compiled against and linked to with the
The code described here uses
which is declared to be not multi-thread-safe. This means that the code calling the functions described
here must not call
from a parallel thread. It is recommended to only do calls to
from an early phase of the program when no other threads have been started.
sd_bus_process() was added in version 231.