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 message processing. 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 synchronously poll for I/O events before calling into
sd_bus_process() again. For that either user the simple, synchronous
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
These APIs are implemented as a shared
library, which can be compiled and linked to with the