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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html><head><meta name="generator" content="HTML Tidy, see www.w3.org"><meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"><link type="text/css" rel="stylesheet" href="style.css"><!-- Generated by The Open Group's rhtm tool v1.2.1 --><!-- Copyright (c) 2001-2004 IEEE and The Open Group, All Rights Reserved --><title>aio_cancel</title></head><body bgcolor="white"><script type="text/javascript" language="JavaScript" src="../jscript/codes.js"></script><basefont size="3"> <a name="aio_cancel"></a> <a name="tag_03_14"></a><!-- aio_cancel --> <!--header start--><center><font size="2">The Open Group Base Specifications Issue 6<br>IEEE Std 1003.1, 2004 Edition<br>Copyright © 2001-2004 The IEEE and The Open Group, All Rights reserved.</font></center><!--header end--><hr size="2" noshade><h4><a name="tag_03_14_01"></a>NAME</h4><blockquote>aio_cancel - cancel an asynchronous I/O request (<b>REALTIME</b>)</blockquote><h4><a name="tag_03_14_02"></a>SYNOPSIS</h4><blockquote class="synopsis"><div class="box"><code><tt><sup>[<a href="javascript:open_code('AIO')">AIO</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0"> #include <<a href="../basedefs/aio.h.html">aio.h</a>><br><br> int aio_cancel(int</tt> <i>fildes</i><tt>, struct aiocb *</tt><i>aiocbp</i><tt>); <img src="../images/opt-end.gif" alt="[Option End]" border="0"></tt></code></div><tt><br></tt></blockquote><h4><a name="tag_03_14_03"></a>DESCRIPTION</h4><blockquote><p>The <i>aio_cancel</i>() function shall attempt to cancel one or more asynchronous I/O requests currently outstanding againstfile descriptor <i>fildes</i>. The <i>aiocbp</i> argument points to the asynchronous I/O control block for a particular request tobe canceled. If <i>aiocbp</i> is NULL, then all outstanding cancelable asynchronous I/O requests against <i>fildes</i> shall becanceled.</p><p>Normal asynchronous notification shall occur for asynchronous I/O operations that are successfully canceled. If there arerequests that cannot be canceled, then the normal asynchronous completion process shall take place for those requests when they arecompleted.</p><p>For requested operations that are successfully canceled, the associated error status shall be set to [ECANCELED] and the returnstatus shall be -1. For requested operations that are not successfully canceled, the <i>aiocbp</i> shall not be modified by<i>aio_cancel</i>().</p><p>If <i>aiocbp</i> is not NULL, then if <i>fildes</i> does not have the same value as the file descriptor with which theasynchronous operation was initiated, unspecified results occur.</p><p>Which operations are cancelable is implementation-defined.</p></blockquote><h4><a name="tag_03_14_04"></a>RETURN VALUE</h4><blockquote><p>The <i>aio_cancel</i>() function shall return the value AIO_CANCELED if the requested operation(s) were canceled. The valueAIO_NOTCANCELED shall be returned if at least one of the requested operation(s) cannot be canceled because it is in progress. Inthis case, the state of the other operations, if any, referenced in the call to <i>aio_cancel</i>() is not indicated by the returnvalue of <i>aio_cancel</i>(). The application may determine the state of affairs for these operations by using <a href="../functions/aio_error.html"><i>aio_error</i>()</a>. The value AIO_ALLDONE is returned if all of the operations have alreadycompleted. Otherwise, the function shall return -1 and set <i>errno</i> to indicate the error.</p></blockquote><h4><a name="tag_03_14_05"></a>ERRORS</h4><blockquote><p>The <i>aio_cancel</i>() function shall fail if:</p><dl compact><dt>[EBADF]</dt><dd>The <i>fildes</i> argument is not a valid file descriptor.</dd></dl></blockquote><hr><div class="box"><em>The following sections are informative.</em></div><h4><a name="tag_03_14_06"></a>EXAMPLES</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_03_14_07"></a>APPLICATION USAGE</h4><blockquote><p>The <i>aio_cancel</i>() function is part of the Asynchronous Input and Output option and need not be available on allimplementations.</p></blockquote><h4><a name="tag_03_14_08"></a>RATIONALE</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_03_14_09"></a>FUTURE DIRECTIONS</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_03_14_10"></a>SEE ALSO</h4><blockquote><p><a href="aio_read.html"><i>aio_read</i>()</a>, <a href="aio_write.html"><i>aio_write</i>()</a>, the Base Definitions volume ofIEEE Std 1003.1-2001, <a href="../basedefs/aio.h.html"><i><aio.h></i></a></p></blockquote><h4><a name="tag_03_14_11"></a>CHANGE HISTORY</h4><blockquote><p>First released in Issue 5. Included for alignment with the POSIX Realtime Extension.</p></blockquote><h4><a name="tag_03_14_12"></a>Issue 6</h4><blockquote><p>The [ENOSYS] error condition has been removed as stubs need not be provided if an implementation does not support theAsynchronous Input and Output option.</p><p>The APPLICATION USAGE section is added.</p><p>IEEE Std 1003.1-2001/Cor 2-2004, item XSH/TC2/D6/10 is applied, removing the words ``to the calling process'' inthe RETURN VALUE section. The term was unnecessary and precluded threads.</p></blockquote><div class="box"><em>End of informative text.</em></div><hr size="2" noshade><center><font size="2"><!--footer start-->UNIX ® is a registered Trademark of The Open Group.<br>POSIX ® is a registered Trademark of The IEEE.<br>[ <a href="../mindex.html">Main Index</a> | <a href="../basedefs/contents.html">XBD</a> | <a href="../utilities/contents.html">XCU</a> | <a href="../functions/contents.html">XSH</a> | <a href="../xrat/contents.html">XRAT</a>]</font></center><!--footer end--><hr size="2" noshade></body></html>⌨️ 快捷键说明
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