x SuSE Linux 13.1-RELEASE x
x SuSE Linux 13.1-RELEASEx
SD_BUS_PROCESS(3) sd_bus_process SD_BUS_PROCESS(3)
NAME
sd_bus_process - Drive the connection
SYNOPSIS
#include <systemd/sd-bus.h>
int sd_bus_process(sd_bus *bus, sd_bus_message **ret);
DESCRIPTION
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 use
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_get_fd(3).
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
processed, *ret is set to NULL.
If the bus object is connected to an sd-event(3) event loop (with
sd_bus_attach_event(3)), it is not necessary to call sd_bus_process()
directly as it is invoked automatically when necessary.
RETURN VALUE
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.
Errors
Returned errors may indicate the following problems:
-EINVAL
An invalid bus object was passed.
-ECHILD
The bus connection was allocated in a parent process and is being
reused in a child process after fork().
-ENOTCONN
The bus connection has been terminated already.
-ECONNRESET
The bus connection has been terminated just now.
-EBUSY
This function is already being called, i.e. sd_bus_process() has
been called from a callback function that itself was called by
sd_bus_process().
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), sd_bus_wait(3), sd_bus_get_fd(3),
sd_bus_message_unref(3), sd-event(3), sd_bus_attach_event(3)
systemd 254 SD_BUS_PROCESS(3)
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