191 lines
4.4 KiB
HTML
191 lines
4.4 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 IO_CANCEL</TITLE>
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</HEAD><BODY>
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<H1>IO_CANCEL</H1>
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Section: Linux Programmer's Manual (2)<BR>Updated: 2017-09-15<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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io_cancel - cancel an outstanding asynchronous I/O operation
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<A NAME="lbAC"> </A>
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<H2>SYNOPSIS</H2>
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<PRE>
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<B>#include <<A HREF="file:///usr/include/linux/aio_abi.h">linux/aio_abi.h</A>></B> /* Defines needed types */
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<B>int io_cancel(aio_context_t </B><I>ctx_id</I><B>, struct iocb *</B><I>iocb</I><B>,</B>
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<B> struct io_event *</B><I>result</I><B>);</B>
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</PRE>
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<P>
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<I>Note</I>:
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There is no glibc wrapper for this system call; see NOTES.
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<A NAME="lbAD"> </A>
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<H2>DESCRIPTION</H2>
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<P>
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The
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<B>io_cancel</B>()
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system call
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attempts to cancel an asynchronous I/O operation previously submitted with
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<B><A HREF="/cgi-bin/man/man2html?2+io_submit">io_submit</A></B>(2).
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The
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<I>iocb</I>
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argument describes the operation to be canceled and the
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<I>ctx_id</I>
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argument is the AIO context to which the operation was submitted.
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If the operation is successfully canceled, the event will be copied into
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the memory pointed to by
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<I>result</I>
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without being placed into the
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completion queue.
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<A NAME="lbAE"> </A>
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<H2>RETURN VALUE</H2>
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On success,
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<B>io_cancel</B>()
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returns 0.
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For the failure return, see NOTES.
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<A NAME="lbAF"> </A>
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<H2>ERRORS</H2>
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<DL COMPACT>
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<DT id="1"><B>EAGAIN</B>
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<DD>
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The <I>iocb</I> specified was not canceled.
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<DT id="2"><B>EFAULT</B>
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<DD>
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One of the data structures points to invalid data.
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<DT id="3"><B>EINVAL</B>
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<DD>
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The AIO context specified by <I>ctx_id</I> is invalid.
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<DT id="4"><B>ENOSYS</B>
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<DD>
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<B>io_cancel</B>()
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is not implemented on this architecture.
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</DL>
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<A NAME="lbAG"> </A>
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<H2>VERSIONS</H2>
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<P>
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The asynchronous I/O system calls first appeared in Linux 2.5.
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<A NAME="lbAH"> </A>
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<H2>CONFORMING TO</H2>
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<P>
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<B>io_cancel</B>()
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is Linux-specific and should not be used
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in programs that are intended to be portable.
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<A NAME="lbAI"> </A>
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<H2>NOTES</H2>
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Glibc does not provide a wrapper function for this system call.
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You could invoke it using
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<B><A HREF="/cgi-bin/man/man2html?2+syscall">syscall</A></B>(2).
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But instead, you probably want to use the
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<B>io_cancel</B>()
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wrapper function provided by
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<I>libaio</I>.
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<P>
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Note that the
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<I>libaio</I>
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wrapper function uses a different type
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(<I>io_context_t</I>)
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for the
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<I>ctx_id</I>
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argument.
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Note also that the
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<I>libaio</I>
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wrapper does not follow the usual C library conventions for indicating errors:
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on error it returns a negated error number
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(the negative of one of the values listed in ERRORS).
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If the system call is invoked via
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<B><A HREF="/cgi-bin/man/man2html?2+syscall">syscall</A></B>(2),
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then the return value follows the usual conventions for
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indicating an error: -1, with
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<I>errno</I>
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set to a (positive) value that indicates the error.
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<A NAME="lbAJ"> </A>
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<H2>SEE ALSO</H2>
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<B><A HREF="/cgi-bin/man/man2html?2+io_destroy">io_destroy</A></B>(2),
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<B><A HREF="/cgi-bin/man/man2html?2+io_getevents">io_getevents</A></B>(2),
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<B><A HREF="/cgi-bin/man/man2html?2+io_setup">io_setup</A></B>(2),
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<B><A HREF="/cgi-bin/man/man2html?2+io_submit">io_submit</A></B>(2),
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<B><A HREF="/cgi-bin/man/man2html?7+aio">aio</A></B>(7)
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<A NAME="lbAK"> </A>
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<H2>COLOPHON</H2>
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This page is part of release 5.05 of the Linux
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<I>man-pages</I>
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project.
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A description of the project,
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information about reporting bugs,
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and the latest version of this page,
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can be found at
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<A HREF="https://www.kernel.org/doc/man-pages/.">https://www.kernel.org/doc/man-pages/.</A>
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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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<DT id="9"><A HREF="#lbAF">ERRORS</A><DD>
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<DT id="10"><A HREF="#lbAG">VERSIONS</A><DD>
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<DT id="11"><A HREF="#lbAH">CONFORMING TO</A><DD>
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<DT id="12"><A HREF="#lbAI">NOTES</A><DD>
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<DT id="13"><A HREF="#lbAJ">SEE ALSO</A><DD>
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<DT id="14"><A HREF="#lbAK">COLOPHON</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: 00:05:33 GMT, March 31, 2021
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