529 lines
14 KiB
HTML
529 lines
14 KiB
HTML
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<html>
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<meta name="Copyright" content="Copyright (c) 2006 by IBM Corporation">
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<title>accept()--Wait for Connection Request and Make Connection</title>
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<!-- Begin Header Records -->
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<!-- All rights reserved. Licensed Materials Property of IBM -->
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<!-- US Government Users Restricted Rights -->
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<!-- Use, duplication or disclosure restricted by -->
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<!-- GSA ADP Schedule Contract with IBM Corp. -->
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<!-- Change History: -->
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<!-- YYMMDD USERID Change description -->
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<!-- Direct1 SCRIPT J converted by B2H R4.1 (346) (CMS) by V2KEA304 -->
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<!-- at RCHVMW2 on 17 Feb 1999 at 11:05:09 -->
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<!-- Edited by Kersten Feb 02 -->
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<!-- 041207 MULLENBA Added SO_ACCEPTECONNABORTED -->
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<!-- End Header Records -->
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<link rel="stylesheet" type="text/css" href="../rzahg/ic.css">
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</head>
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<body>
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<a name="Top_Of_Page"></a> <!--Java sync-link-->
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<script type="text/javascript" language="Javascript" src="../rzahg/synch.js">
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</script>
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<h2>accept()--Wait for Connection Request and Make Connection</h2>
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<div class="box" style="width: 70%;">
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<br>
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BSD 4.3 Syntax<br>
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<pre>
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#include <sys/types.h>
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#include <sys/socket.h>
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int accept(int <em>socket_descriptor</em>,
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struct sockaddr *<em>address</em>,
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int *<em>address_length</em>)
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</pre>
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Service Program Name: QSOSRV1<br>
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<!-- iddvc RMBR -->
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<br>
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Default Public Authority: *USE<br>
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<!-- iddvc RMBR -->
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<br>
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Threadsafe: Yes<br>
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<!-- iddvc RMBR -->
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<br>
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</div>
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<br>
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<div class="box" style="width: 70%;">
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<br>
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<a href="_xopen_source.htm">UNIX 98 Compatible Syntax</a><br>
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<pre>
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#define _XOPEN_SOURCE 520
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#include <sys/socket.h>
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int accept(int <em>socket_descriptor</em>,
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struct sockaddr *<em>address</em>,
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socklen_t *<em>address_length</em>)
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</pre>
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<br>
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Service Program Name: QSOSRV1<br>
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<!-- iddvc RMBR -->
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<br>
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Default Public Authority: *USE<br>
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<!-- iddvc RMBR -->
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<br>
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Threadsafe: Yes<br>
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<!-- iddvc RMBR -->
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<br>
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</div>
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<p>The <em>accept()</em> function is used to wait for connection requests.
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<em>accept()</em> takes the first connection request on the queue of pending
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connection requests and creates a new socket to service the connection
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request.</p>
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<p><em>accept()</em> is used with connection-oriented socket types, such as
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<samp>SOCK_STREAM</samp>.</p>
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<p>There are two versions of
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the API, as shown above. The base i5/OS API uses BSD 4.3 structures and
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syntax. The other uses syntax and struc<SUP>(TM)</SUP>tures compatible with the UNIX 98
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programming interface specifications. You can select the UNIX 98 compatible
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interface with the <a href="_xopen_source.htm">_XOPEN_SOURCE</a> macro.</p>
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<br>
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<h3>Parameters</h3>
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<dl>
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<dt><strong>socket_descriptor</strong></dt>
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<dd>(Input) The descriptor of the socket on which to wait.<br>
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<br>
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</dd>
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<dt><strong>address</strong></dt>
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<dd>(Output) A pointer to a buffer of type <strong>struct sockaddr</strong> in
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which the address from which the connection request was received is stored. The
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structure <strong>sockaddr</strong> is defined in
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<strong><sys/socket.h></strong>.
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<p> The BSD 4.3 structure is:</p>
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<pre>
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struct sockaddr {
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u_short sa_family;
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char sa_data[14];
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};
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</pre>
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<p>The BSD 4.4/UNIX 98 compatible structure is:</p>
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<pre>
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typedef uchar sa_family_t;
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struct sockaddr {
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uint8_t sa_len;
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sa_family_t sa_family;
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char sa_data[14];
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};
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</pre>
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<p>The BSD 4.4 <em>sa_len</em> field is the length of the address. The
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<em>sa_family</em> field identifies the address family to which the address
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belongs, and <em>sa_data</em> is the address whose format is dependent on the
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address family.</p>
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<p><strong>Note:</strong> See the usage notes about using different address
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families with <strong>sockaddr_storage</strong>.</p>
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</dd>
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<dt><strong>address_length</strong></dt>
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<dd>(Input/output) This parameter is a value-result field. The caller passes a
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pointer to the length of the <em>address</em> parameter. On return from the
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call, <em>address_length</em> contains the actual length of the address from
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which the connection request was received.</dd>
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</dl>
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<br>
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<h3>Authorities</h3>
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<p>When the socket identified by the <strong>socket_descriptor</strong> is of
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type AF_INET and a connection indication request is received over an APPC
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device, the thread must have adequate authority. The thread must have retrieve,
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insert, delete, and update authority to the APPC device. When the thread does
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not have this level of authority, an <em>errno</em> of EACCES is returned.</p>
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<br>
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<h3>Return Value</h3>
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<p><em>accept()</em> returns an integer. Possible values are:</p><ul>
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<li>-1 (unsuccessful)<br>
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<br>
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</li>
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<li>n (successful), where n is a socket descriptor.</li>
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</ul>
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<br>
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<h3>Error Conditions</h3>
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<p>When <em>accept()</em> fails, <em>errno</em> can be set to one of the
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following:</p>
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<table cellpadding="5">
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<!-- cols="20 80" -->
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<tr>
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<td align="left" valign="top"><em>[EACCES]</em></td>
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<td align="left" valign="top">Permission denied.
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<p>A connection indication request was received on the socket referenced by the
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<em>socket_descriptor</em> parameter, but the process that issued the
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<em>accept()</em> did not have the appropriate privileges required to handle
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the request. The connection indication request is reset by the system.</p>
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</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>[EBADF]</em></td>
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<td align="left" valign="top">Descriptor not valid.<br><br>
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</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>[ECONNABORTED]</em></td>
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<td align="left" valign="top">Connection ended abnormally.
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<p>An <em>accept()</em> was issued on a socket for which receives have been
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disallowed (due to a <em>shutdown()</em> call).</p>
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<p>This also could be encountered if time elapsed since a successful
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<em>Rbind()</em> is greater than the margin allowed by the associated <em>SOCKS
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server</em>.</p>
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<p><img src="delta.gif" alt="Start of change">An <em>accept()</em> was
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issued on a socket in blocking mode and
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one or more connections have been reset and there are no acceptable connections
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in the queue. This is only valid if socket option <samp>SO_ACCEPTECONNABORTED</samp>
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was enabled for the listening socket.<img src="deltaend.gif" alt="End of change"></p>
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</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>[EFAULT]</em></td>
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<td align="left" valign="top">Bad address.
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<p>System detected an address which was not valid while attempting to access
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the <em>address</em> or <em>address_length</em> parameters.</p>
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</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>[EINTR]</em></td>
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<td align="left" valign="top">Interrupted function call.<br>
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<br>
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</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>[EINVAL]</em></td>
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<td align="left" valign="top">Parameter not valid.
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<p>This error code indicates one of the following:</p>
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<ul>
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<li>The <em>address_length</em> parameter is set to a value that is less than
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zero, and the <em>address</em> parameter is set to a value other than a NULL
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pointer.<br>
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<br>
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</li>
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<li>A <em>listen()</em> has not been issued against the socket referenced by
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the <em>socket_descriptor</em> parameter.<br><br></li>
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</ul>
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</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>[EIO]</em></td>
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<td align="left" valign="top">Input/output error.<br>
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<br>
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</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>[EMFILE]</em></td>
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<td align="left" valign="top">Too many descriptions for this
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process.<br>
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<br>
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</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>[ENFILE]</em></td>
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<td align="left" valign="top">Too many descriptions in system.<br>
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<br>
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</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>[ENOBUFS]</em></td>
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<td align="left" valign="top">There is not enough buffer space for
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the requested operation.<br>
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<br>
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</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>[ENOTSOCK]</em></td>
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<td align="left" valign="top">The specified descriptor does not
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reference a socket.<br>
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<br>
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</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>[EOPNOTSUPP]</em></td>
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<td align="left" valign="top">Operation not supported.
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<p>The <em>socket_descriptor</em> parameter references a socket that does not
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support the <em>accept()</em>. The <em>accept()</em> is only valid on sockets
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that are connection-oriented (for example, type of
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<samp>SOCK_STREAM</samp>).</p>
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</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>[EUNATCH]</em></td>
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<td align="left" valign="top">The protocol required to support the
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specified address family is not available at this time.<br>
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<br>
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</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>[EUNKNOWN]</em></td>
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<td align="left" valign="top">Unknown system state.<br>
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<br>
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</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>[EWOULDBLOCK]</em></td>
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<td align="left" valign="top">Operation would have caused the
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thread to be suspended.<br>
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<br>
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</td>
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</tr>
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</table>
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<br>
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<br>
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<h3>Error Messages</h3>
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<table width="100%" cellpadding="5">
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<!-- cols="15 85" -->
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<tr>
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<th align="left" valign="top">Message ID</th>
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<th align="left" valign="top">Error Message Text</th>
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</tr>
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<tr>
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<td width="15%" valign="top">CPE3418 E</td>
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<td width="85%" valign="top">Possible APAR condition or hardware failure.</td>
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</tr>
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<tr>
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<td align="left" valign="top">CPF9872 E</td>
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<td align="left" valign="top">Program or service program &1 in library
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&2 ended. Reason code &3.</td>
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</tr>
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<tr>
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<td align="left" valign="top">CPFA081 E</td>
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<td align="left" valign="top">Unable to set return value or error code.</td>
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</tr>
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</table>
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<br>
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<br>
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<h3>Usage Notes</h3>
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<ol>
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<li>If the <em>address</em> parameter is set to a NULL pointer or the
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<em>address_length</em> parameter points to an integer which has a value that
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is equal to zero, the address from which the connection request was received is
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not returned.<br>
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<br>
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</li>
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<li>If the length of the address to be returned exceeds the length of the
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<em>address</em> parameter, the returned address is truncated.<br>
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<br>
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</li>
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<li>The following are inherited by the descriptor returned by the accept()
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call:<br>
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<br>
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<ul>
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<li>All socket options with a level of SOL_SOCKET.<br>
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<br>
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</li>
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<li>The status flags:<br>
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<br>
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<ul>
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<li>Blocking flag (set/reset either by the <em>ioctl()</em> call with the
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FIONBIO request or by the <em>fcntl()</em> call with the F_SETFL command and
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the status flag set to O_NONBLOCK).<br>
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<br>
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</li>
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<li>Asynchronous flag (set/reset either by the <em>ioctl()</em> call with the
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FIOASYNC request or by the <em>fcntl()</em> call with the F_SETFL command and
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the status flag set to FASYNC).<br>
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<br>
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</li>
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</ul>
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</li>
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<li>The process ID or process group ID that is to receive SIGIO or SIGURG
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signals (set/reset by either the <em>ioctl()</em> call with the FIOSETOWN or
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the SIOCSPGRP request, or by the <em>fcntl()</em> call with the F_SETOWN
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command).<br>
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<br>
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</li>
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</ul>
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</li>
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<li>Closing a socket causes any queued but unaccepted connection requests to be
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reset.<br>
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<br>
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</li>
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<li>The structure
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<strong>sockaddr</strong> is a generic structure used for any address family
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but it is only 16 bytes long. The actual address returned for some address
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families may be much larger. You should declare storage for the address with
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the structure <strong>sockaddr_storage</strong>. This structure is large enough
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and aligned for any protocol-specific structure. It may then be cast as
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<strong>sockaddr</strong> structure for use on the APIs. The <em>ss_family</em>
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field of the <strong>sockaddr_storage</strong> will always align with the
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family field of any protocol-specific structure. The BSD 4.3 structure is:<br>
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<br>
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<pre>
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#define _SS_MAXSIZE 304
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#define _SS_ALIGNSIZE (sizeof (char*))
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#define _SS_PAD1SIZE (_SS_ALIGNSIZE - sizeof(sa_family_t))
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#define _SS_PAD2SIZE (_SS_MAXSIZE - (sizeof(sa_family_t)+
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_SS_PAD1SIZE + _SS_ALIGNSIZE))
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struct sockaddr_storage {
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sa_family_t ss_family;
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char _ss_pad1[_SS_PAD1SIZE];
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char* _ss_align;
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char _ss_pad2[_SS_PAD2SIZE];
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};
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</pre>
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The BSD 4.4/UNIX 98 compatible structure is:<br>
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<br>
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<pre>
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#define _SS_MAXSIZE 304
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#define _SS_ALIGNSIZE (sizeof (char*))
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#define _SS_PAD1SIZE (_SS_ALIGNSIZE - (sizeof(uint8_t) + sizeof(sa_family_t)))
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#define _SS_PAD2SIZE (_SS_MAXSIZE - (sizeof(uint8_t) + sizeof(sa_family_t)+
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_SS_PAD1SIZE + _SS_ALIGNSIZE))
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struct sockaddr_storage {
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uint8_t ss_len;
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sa_family_t ss_family;
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char _ss_pad1[_SS_PAD1SIZE];
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char* _ss_align;
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char _ss_pad2[_SS_PAD2SIZE];
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};
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</pre>
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</li>
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<li>If the socket is using an address family of <samp>AF_UNIX</samp>, the
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address (which is a path name) is returned in the default coded character set
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identifier (CCSID) currently in effect for the job.<br>
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<br>
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</li>
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<li>If the socket is using an address family of <samp>AF_UNIX_CCSID</samp>, the
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output structure sockaddr_unc defines the format and coded character set
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identifier (CCSID) of the address (which is a path name).<br>
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<br>
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</li>
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<li>If a successful <em>Rbind()</em> has been performed on the listening
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socket, then a new connection is not returned, but rather an inbound connection
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occurs on the same listening socket. The descriptor number returned is
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different, but it actually refers to the same connection referred to by the
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listening socket.<br>
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<br>
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</li>
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<li>When you develop in C-based
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languages and an application is compiled with the _XOPEN_SOURCE macro defined
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to the value 520 or greater, the <em>accept()</em> API is mapped to
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<em>qso_accept98()</em>.</li>
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</ol>
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<br>
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<h3>Related Information</h3>
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|
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<ul>
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<li><a href=
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"_xopen_source.htm">_XOPEN_SOURCE</a>--Using _XOPEN_SOURCE for the UNIX 98
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compatible interface<br>
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<br>
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</li>
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<li><a href="bind.htm">bind()</a>--Set Local Address for Socket<br>
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<br>
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</li>
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<li><a href="fcntl.htm">fcntl()</a>--Perform File Control Command<br>
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<br>
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</li>
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<li><a href="ioctl.htm">ioctl()</a>--Perform I/O Control Request<br>
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<br>
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</li>
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<li><a href="listen.htm">listen()</a>--Invite Incoming Connections
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Requests</li>
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</ul>
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<br>
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<hr>
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API introduced: V3R1
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