155 lines
3.8 KiB
HTML
155 lines
3.8 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_WAIT</TITLE>
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</HEAD><BODY>
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<H1>SD_BUS_WAIT</H1>
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Section: sd_bus_wait (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_wait - Wait for I/O on a bus 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_wait(sd_bus *</B><I>bus</I><B>, uint64_t </B><I>timeout_usec</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_wait()</B>
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<DD>synchronously waits for I/O on the specified bus connection object. This function is supposed to be called whenever
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<B><A HREF="/cgi-bin/man/man2html?3+sd_bus_process">sd_bus_process</A></B>(3)
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returns zero, indicating that no work is pending on the connection. Internally, this call invokes
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<B><A HREF="/cgi-bin/man/man2html?3+ppoll">ppoll</A></B>(3), to wait for I/O on the bus connection. If the
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<I>timeout_sec</I>
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parameter is specified, the call will block at most for the specified amount of time in µs. Pass
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<B>UINT64_MAX</B>
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to permit it to sleep indefinitely.
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<P>
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After each invocation of
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<B>sd_bus_wait()</B>
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the
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<B>sd_bus_process()</B>
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call should be invoked in order to process any now pending I/O work.
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<P>
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Note that
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<B>sd_bus_wait()</B>
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is suitable only for simple programs as it does not permit waiting for other I/O events. For more complex programs either connect the bus connection object to an external 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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or 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 using
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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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<A NAME="lbAE"> </A>
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<H2>RETURN VALUE</H2>
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<P>
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If any I/O was seen, a positive value is returned, zero otherwise. 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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<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_process">sd_bus_process</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-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="5"><A HREF="#lbAB">NAME</A><DD>
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<DT id="6"><A HREF="#lbAC">SYNOPSIS</A><DD>
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<DT id="7"><A HREF="#lbAD">DESCRIPTION</A><DD>
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<DT id="8"><A HREF="#lbAE">RETURN VALUE</A><DD>
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<DL>
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<DT id="9"><A HREF="#lbAF">Errors</A><DD>
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</DL>
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<DT id="10"><A HREF="#lbAG">NOTES</A><DD>
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<DT id="11"><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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