154 lines
4.2 KiB
HTML
154 lines
4.2 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_EVENT_SOURCE_SET_DESTROY_CALLBACK</TITLE>
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</HEAD><BODY>
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<H1>SD_EVENT_SOURCE_SET_DESTROY_CALLBACK</H1>
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Section: sd_event_source_set_destroy_callback (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_event_source_set_destroy_callback, sd_event_source_get_destroy_callback, sd_event_destroy_t - Define the callback function for resource cleanup.
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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-event.h">systemd/sd-event.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>typedef int (*sd_event_destroy_t)(void *</B><I>userdata</I><B>);</B>
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<DT id="2">
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<B>int sd_event_source_set_destroy_callback(sd_event_source *</B><I>source</I><B>, sd_event_destroy_t </B><I>callback</I><B>);</B>
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<DT id="3">
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<B>int sd_event_source_get_destroy_callback(sd_event_source *</B><I>source</I><B>, sd_event_destroy_t *</B><I>callback</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_event_source_set_destroy_callback()</B>
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<DD>sets
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<I>callback</I>
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as the callback function to be called right before the event source object
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<I>source</I>
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is deallocated. The
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<I>userdata</I>
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pointer from the event source object will be passed as the
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<I>userdata</I>
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parameter. This pointer can be set by an argument to the constructor functions, see
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<B><A HREF="/cgi-bin/man/man2html?3+sd_event_add_io">sd_event_add_io</A></B>(3), or directly, see
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<B><A HREF="/cgi-bin/man/man2html?3+sd_event_source_set_userdata">sd_event_source_set_userdata</A></B>(3). This callback function is called even if
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<I>userdata</I>
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is
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<B>NULL</B>. Note that this callback is invoked at a time where the event source object itself is already invalidated, and executing operations or taking new references to the event source object is not permissible.
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<P>
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<B>sd_event_source_get_destroy_callback()</B>
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returns the current callback for
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<I>source</I>
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in the
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<I>callback</I>
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parameter.
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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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On success,
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<B>sd_event_source_set_destroy_callback()</B>
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returns 0 or a positive integer. On failure, it returns a negative errno-style error code.
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<P>
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<B>sd_event_source_get_destroy_callback()</B>
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returns positive if the destroy callback function is set, 0 if not. On failure, returns a negative errno-style error code.
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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="4"><DD>
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The
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<I>source</I>
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parameter is
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<B>NULL</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-event">sd-event</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+sd_event_add_io">sd_event_add_io</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+sd_event_add_time">sd_event_add_time</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+sd_event_add_signal">sd_event_add_signal</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+sd_event_add_child">sd_event_add_child</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+sd_event_add_inotify">sd_event_add_inotify</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+sd_event_add_defer">sd_event_add_defer</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+sd_event_source_set_userdata">sd_event_source_set_userdata</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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</HTML>
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