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<center><font size="2">The Open Group Base Specifications Issue 6<br>
IEEE Std 1003.1-2001<br>
Copyright &copy; 2001 The IEEE and The Open Group, All Rights reserved.</font></center>
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<hr size="2" noshade>
<h4><a name="tag_13_02_01"></a>NAME</h4>
<blockquote>aio.h - asynchronous input and output (<b>REALTIME</b>)</blockquote>
<h4><a name="tag_13_02_02"></a>SYNOPSIS</h4>
<blockquote class="synopsis">
<div class="box"><tt><sup>[<a href="javascript:open_code('AIO')">AIO</a>]</sup> <img src="../images/opt-start.gif" alt=
"[Option Start]" border="0"> #include &lt;aio.h&gt; <img src="../images/opt-end.gif" alt="[Option End]" border="0"></tt></div>
</blockquote>
<h4><a name="tag_13_02_03"></a>DESCRIPTION</h4>
<blockquote>
<p>The <i>&lt;aio.h&gt;</i> header shall define the <b>aiocb</b> structure which shall include at least the following members:</p>
<pre>
<tt>int aio_fildes </tt> File descriptor. <tt>
off_t aio_offset </tt> File offset. <tt>
volatile void *aio_buf </tt> Location of buffer. <tt>
size_t aio_nbytes </tt> Length of transfer. <tt>
int aio_reqprio </tt> Request priority offset. <tt>
struct sigevent aio_sigevent </tt> Signal number and value. <tt>
int aio_lio_opcode</tt> Operation to be performed. <tt>
</tt>
</pre>
<p>This header shall also include the following constants:</p>
<dl compact>
<dt>AIO_ALLDONE</dt>
<dd>A return value indicating that none of the requested operations could be canceled since they are already complete.</dd>
<dt>AIO_CANCELED</dt>
<dd>A return value indicating that all requested operations have been canceled.</dd>
<dt>AIO_NOTCANCELED</dt>
<dd><br>
A return value indicating that some of the requested operations could not be canceled since they are in progress.</dd>
<dt>LIO_NOP</dt>
<dd>A <a href="../functions/lio_listio.html"><i>lio_listio</i>()</a> element operation option indicating that no transfer is
requested.</dd>
<dt>LIO_NOWAIT</dt>
<dd>A <a href="../functions/lio_listio.html"><i>lio_listio</i>()</a> synchronization operation indicating that the calling thread
is to continue execution while the <a href="../functions/lio_listio.html"><i>lio_listio</i>()</a> operation is being performed, and
no notification is given when the operation is complete.</dd>
<dt>LIO_READ</dt>
<dd>A <a href="../functions/lio_listio.html"><i>lio_listio</i>()</a> element operation option requesting a read.</dd>
<dt>LIO_WAIT</dt>
<dd>A <a href="../functions/lio_listio.html"><i>lio_listio</i>()</a> synchronization operation indicating that the calling thread
is to suspend until the <a href="../functions/lio_listio.html"><i>lio_listio</i>()</a> operation is complete.</dd>
<dt>LIO_WRITE</dt>
<dd>A <a href="../functions/lio_listio.html"><i>lio_listio</i>()</a> element operation option requesting a write.</dd>
</dl>
<p>The following shall be declared as functions and may also be defined as macros. Function prototypes shall be provided.</p>
<pre>
<tt>int aio_cancel(int, struct aiocb *);
int aio_error(const struct aiocb *);
int aio_fsync(int, struct aiocb *);
int aio_read(struct aiocb *);
ssize_t aio_return(struct aiocb *);
int aio_suspend(const struct aiocb *const[], int,
const struct timespec *);
int aio_write(struct aiocb *);
int lio_listio(int, struct aiocb *restrict const[restrict], int,
struct sigevent *restrict);
</tt>
</pre>
<p>Inclusion of the <i>&lt;aio.h&gt;</i> header may make visible symbols defined in the headers <a href=
"../basedefs/fcntl.h.html"><i>&lt;fcntl.h&gt;</i></a>, <a href="../basedefs/signal.h.html"><i>&lt;signal.h&gt;</i></a>, <a href=
"../basedefs/sys/types.h.html"><i>&lt;sys/types.h&gt;</i></a>, and <a href="../basedefs/time.h.html"><i>&lt;time.h&gt;</i></a>.</p>
</blockquote>
<hr>
<div class="box"><em>The following sections are informative.</em></div>
<h4><a name="tag_13_02_04"></a>APPLICATION USAGE</h4>
<blockquote>
<p>None.</p>
</blockquote>
<h4><a name="tag_13_02_05"></a>RATIONALE</h4>
<blockquote>
<p>None.</p>
</blockquote>
<h4><a name="tag_13_02_06"></a>FUTURE DIRECTIONS</h4>
<blockquote>
<p>None.</p>
</blockquote>
<h4><a name="tag_13_02_07"></a>SEE ALSO</h4>
<blockquote>
<p><a href="fcntl.h.html"><i>&lt;fcntl.h&gt;</i></a> , <a href="signal.h.html"><i>&lt;signal.h&gt;</i></a> , <a href=
"sys/types.h.html"><i>&lt;sys/types.h&gt;</i></a> , <a href="time.h.html"><i>&lt;time.h&gt;</i></a> , the System Interfaces volume
of IEEE&nbsp;Std&nbsp;1003.1-2001, <a href="../functions/fsync.html"><i>fsync</i>()</a>, <a href=
"../functions/lseek.html"><i>lseek</i>()</a>, <a href="../functions/read.html"><i>read</i>()</a>, <a href=
"../functions/write.html"><i>write</i>()</a></p>
</blockquote>
<h4><a name="tag_13_02_08"></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_13_02_09"></a>Issue 6</h4>
<blockquote>
<p>The <i>&lt;aio.h&gt;</i> header is marked as part of the Asynchronous Input and Output option.</p>
<p>The description of the constants is expanded.</p>
<p>The <b>restrict</b> keyword is added to the prototype for <a href="../functions/lio_listio.html"><i>lio_listio</i>()</a>.</p>
</blockquote>
<div class="box"><em>End of informative text.</em></div>
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