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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | NOTES | SEE ALSO | COLOPHON |
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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 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.
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().
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.
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 2023-06-23. (At that
time, the date of the most recent commit that was found in the
repository was 2023-06-23.) 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 253 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)
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HTML rendering created 2023-06-24 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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