sd_bus_process(3) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | NOTES | SEE ALSO | COLOPHON

SD_BUS_PROCESS(3)            sd_bus_process            SD_BUS_PROCESS(3)

NAME         top

       sd_bus_process - Drive the connection

SYNOPSIS         top

       #include <systemd/sd-bus.h>

       int sd_bus_process(sd_bus *bus, sd_bus_message **ret);

DESCRIPTION         top

       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         top

       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         top

       These APIs are implemented as a shared library, which can be
       compiled and linked to with the libsystemd pkg-config(1) file.

SEE ALSO         top

       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)

COLOPHON         top

       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 2021-06-20.  (At that
       time, the date of the most recent commit that was found in the
       repository was 2021-06-19.)  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 249                                            SD_BUS_PROCESS(3)

Pages that refer to this page: sd-bus(3)sd_bus_attach_event(3)sd_bus_get_fd(3)sd_bus_get_n_queued_read(3)sd_bus_send(3)sd_bus_start(3)sd_bus_wait(3)systemd.directives(7)systemd.index(7)