|
NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | NOTES | SEE ALSO | COLOPHON |
SD_BUS_PROCESS(3) sd_bus_process SD_BUS_PROCESS(3)
sd_bus_process - Drive the connection
#include <systemd/sd-bus.h>
int sd_bus_process(sd_bus *bus, sd_bus_message **ret);
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_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 a 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.
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().
These APIs are implemented as a shared library, which can be compiled
and linked to with the libsystemd pkg-config(1) file.
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)
This page is part of the systemd (systemd system and service manager)
project. Information about the project can be found at
⟨http://www.freedesktop.org/wiki/Software/systemd⟩. If you have a bug
report for this manual page, see
⟨http://www.freedesktop.org/wiki/Software/systemd/#bugreports⟩. This
page was obtained from the project's upstream Git repository
⟨https://github.com/systemd/systemd.git⟩ on 2020-08-13. (At that
time, the date of the most recent commit that was found in the repos‐
itory was 2020-08-11.) If you discover any rendering problems in
this HTML version of the page, or you believe there is a better or
more up-to-date source for the page, or you have corrections or
improvements to the information in this COLOPHON (which is not part
of the original manual page), send a mail to man-pages@man7.org
systemd 246 SD_BUS_PROCESS(3)
Pages that refer to this page: sd-bus(3) , sd_bus_attach_event(3) , sd_bus_detach_event(3) , sd_bus_get_event(3) , sd_bus_get_events(3) , sd_bus_get_fd(3) , sd_bus_get_n_queued_read(3) , sd_bus_get_n_queued_write(3) , sd_bus_get_timeout(3) , sd_bus_set_fd(3) , sd_bus_start(3) , sd_bus_wait(3) , 30-systemd-environment-d-generator(7) , systemd.directives(7) , systemd.index(7)