179 lines
4.6 KiB
HTML
179 lines
4.6 KiB
HTML
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<HTML><HEAD><TITLE>Man page of SD_BUS_PROCESS</TITLE>
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</HEAD><BODY>
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<H1>SD_BUS_PROCESS</H1>
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Section: sd_bus_process (3)<BR>Updated: <BR><A HREF="#index">Index</A>
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<A HREF="/cgi-bin/man/man2html">Return to Main Contents</A><HR>
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<A NAME="lbAB"> </A>
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<H2>NAME</H2>
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sd_bus_process - Drive the connection
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<A NAME="lbAC"> </A>
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<H2>SYNOPSIS</H2>
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<P>
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<B>
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</B><PRE>
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#include <<A HREF="file:///usr/include/systemd/sd-bus.h">systemd/sd-bus.h</A>>
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</PRE>
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<DL COMPACT>
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<DT id="1">
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<B>int sd_bus_process(sd_bus *</B><I>bus</I><B>, sd_bus_message **</B><I>ret</I><B>);</B>
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</DL>
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<A NAME="lbAD"> </A>
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<H2>DESCRIPTION</H2>
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<P>
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<B>sd_bus_process()</B>
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<DD>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
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<B>sd_bus_process()</B>
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again. For that either user the simple, synchronous
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<B><A HREF="/cgi-bin/man/man2html?3+sd_bus_wait">sd_bus_wait</A></B>(3)
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call, or hook up the bus connection object to an external or manual event loop using
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<B><A HREF="/cgi-bin/man/man2html?3+sd_bus_get_fd">sd_bus_get_fd</A></B>(3).
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<P>
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<B>sd_bus_process()</B>
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processes at most one incoming message per call. If the parameter
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<I>ret</I>
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is not
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<B>NULL</B>
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and the call processed a message,
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<I>*ret</I>
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is set to this message. The caller owns a reference to this message and should call
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<B><A HREF="/cgi-bin/man/man2html?3+sd_bus_message_unref">sd_bus_message_unref</A></B>(3)
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when the message is no longer needed. If
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<I>ret</I>
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is not NULL, progress was made, but no message was processed,
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<I>*ret</I>
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is set to
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<B>NULL</B>.
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<P>
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If a the bus object is connected to an
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<B><A HREF="/cgi-bin/man/man2html?3+sd-event">sd-event</A></B>(3)
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event loop (with
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<B><A HREF="/cgi-bin/man/man2html?3+sd_bus_attach_event">sd_bus_attach_event</A></B>(3)), it is not necessary to call
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<B>sd_bus_process()</B>
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directly as it is invoked automatically when necessary.
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<A NAME="lbAE"> </A>
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<H2>RETURN VALUE</H2>
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<P>
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If progress was made, a positive integer is returned. If no progress was made, 0 is returned. If an error occurs, a negative
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<I>errno</I>-style error code is returned.
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<A NAME="lbAF"> </A>
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<H3>Errors</H3>
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<P>
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Returned errors may indicate the following problems:
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<P>
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<B>-EINVAL</B>
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<DL COMPACT><DT id="2"><DD>
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An invalid bus object was passed.
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</DL>
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<P>
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<B>-ECHILD</B>
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<DL COMPACT><DT id="3"><DD>
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The bus connection was allocated in a parent process and is being reused in a child process after
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<B>fork()</B>.
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</DL>
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<P>
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<B>-ENOTCONN</B>
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<DL COMPACT><DT id="4"><DD>
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The bus connection has been terminated already.
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</DL>
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<P>
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<B>-ECONNRESET</B>
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<DL COMPACT><DT id="5"><DD>
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The bus connection has been terminated just now.
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</DL>
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<P>
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<B>-EBUSY</B>
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<DL COMPACT><DT id="6"><DD>
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This function is already being called, i.e.
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<B>sd_bus_process()</B>
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has been called from a callback function that itself was called by
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<B>sd_bus_process()</B>.
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</DL>
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<A NAME="lbAG"> </A>
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<H2>NOTES</H2>
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<P>
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These APIs are implemented as a shared library, which can be compiled and linked to with the
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<B>libsystemd</B> <B><A HREF="/cgi-bin/man/man2html?1+pkg-config">pkg-config</A></B>(1)
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file.
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<A NAME="lbAH"> </A>
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<H2>SEE ALSO</H2>
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<P>
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<B><A HREF="/cgi-bin/man/man2html?1+systemd">systemd</A></B>(1),
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<B><A HREF="/cgi-bin/man/man2html?3+sd-bus">sd-bus</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+sd_bus_wait">sd_bus_wait</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+sd_bus_get_fd">sd_bus_get_fd</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+sd_bus_message_unref">sd_bus_message_unref</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+sd-event">sd-event</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+sd_bus_attach_event">sd_bus_attach_event</A></B>(3)
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<P>
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<HR>
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<A NAME="index"> </A><H2>Index</H2>
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<DL>
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<DT id="7"><A HREF="#lbAB">NAME</A><DD>
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<DT id="8"><A HREF="#lbAC">SYNOPSIS</A><DD>
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<DT id="9"><A HREF="#lbAD">DESCRIPTION</A><DD>
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<DT id="10"><A HREF="#lbAE">RETURN VALUE</A><DD>
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<DL>
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<DT id="11"><A HREF="#lbAF">Errors</A><DD>
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</DL>
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<DT id="12"><A HREF="#lbAG">NOTES</A><DD>
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<DT id="13"><A HREF="#lbAH">SEE ALSO</A><DD>
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</DL>
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<HR>
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This document was created by
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<A HREF="/cgi-bin/man/man2html">man2html</A>,
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using the manual pages.<BR>
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Time: 00:05:55 GMT, March 31, 2021
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</BODY>
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</HTML>
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