509 lines
12 KiB
HTML
509 lines
12 KiB
HTML
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<!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>recv()--Receive Data</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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<!-- Unix8 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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<!--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>
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<!-- 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>recv()--Receive Data</h2>
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<div class="box" style="width: 60%;">
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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 recv(int <em>socket_descriptor</em>,
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char *<em>buffer</em>,
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int <em>buffer_length</em>,
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int <em>flags</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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<br>
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<div class="box" style="width: 60%;">
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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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ssize_t recv(int <em>socket_descriptor</em>,
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void *<em>buffer</em>,
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size_t <em>buffer_length</em>,
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int <em>flags</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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<br>
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<p>The <em>recv()</em> function is used to receive data through a socket.</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 structures 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 socket descriptor that is to be read from.<br>
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<br>
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</dd>
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<dt><strong>buffer</strong></dt>
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<dd>(Input) The pointer to the buffer in which the data that is to be read is
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stored.<br>
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<br>
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</dd>
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<dt><strong>buffer_length</strong></dt>
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<dd>(Input) The length of the <em>buffer</em>.<br>
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<br>
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</dd>
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<dt><strong>flags</strong></dt>
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<dd>(Input) A flag value that controls the reception of the data. The
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<em>flags</em> value is either zero, or is obtained by performing an OR
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operation on one or more of the following constants:
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<table cellpadding="5">
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<!-- cols="15 85" -->
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<tr>
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<td align="left" valign="top"><em><samp>MSG_OOB</samp></em></td>
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<td align="left" valign="top">Receive out-of-band data. Valid only for sockets
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with an address family of <samp>AF_INET</samp> or <samp>AF_INET6</samp> and type <samp>SOCK_STREAM</samp>.</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em><samp>MSG_PEEK</samp></em></td>
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<td align="left" valign="top">Obtain a copy of the message without removing the
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message from the socket.</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em><samp>MSG_WAITALL</samp></em></td>
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<td align="left" valign="top">Wait for a full request or an error.</td>
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</tr>
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</table>
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</dd>
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</dl>
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<br>
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<h3>Authorities</h3>
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<p>No authorization is required.</p>
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<br>
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<h3>Return Value</h3>
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<p><em>recv()</em> returns an integer. Possible values are:</p>
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<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 the number of bytes received.</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>recv()</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>The socket pointed to by the <em>socket_descriptor</em> parameter is using a
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connection-oriented transport service, and a <em>connect()</em> was previously
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completed. The process, however, does not have the appropriate privileges to
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the objects that were needed to establish a connection. For example, the
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<em>connect()</em> required the use of an APPC device that the process was not
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authorized to.</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>
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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>[ECONNABORTED]</em></td>
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<td align="left" valign="top">Connection ended abnormally.
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<p>This error code indicates that the transport provider ended the connection
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abnormally because of one of the following:</p>
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<ul>
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<li>The retransmission limit has been reached for data that was being sent on
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the socket.<br>
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<br>
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</li>
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<li>A protocol error was detected.<br>
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</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>[ECONNREFUSED]</em></td>
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<td align="left" valign="top">The destination socket refused an attempted
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connect 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>[ECONNRESET]</em></td>
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<td align="left" valign="top">A connection with a remote socket was reset by
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that 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>[EFAULT]</em></td>
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<td align="left" valign="top">Bad address.
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<p>The system detected an address which was not valid while attempting to
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access the <em>buffer</em> parameter.</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>buffer_length</em> parameter specifies a negative value.<br>
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<br>
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</li>
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<li>The <em>flags</em> parameter specifies a value that includes the
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<samp>MSG_OOB</samp> flag, but no OOB data was available to be received.<br>
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<br>
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</li>
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<li>The <em>flags</em> parameter specifies a value that includes the
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<samp>MSG_OOB</samp> flag, and the socket option <samp>SO_OOBINLINE</samp> has
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been set.<br>
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<br>
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</li>
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<li>The <em>socket_descriptor</em> parameter points to a socket that is using a
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connectionless transport service, is not a socket of type
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<samp>SOCK_RAW</samp>, and is not bound to an address.<br>
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</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>[ENOBUFS]</em></td>
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<td align="left" valign="top">There is not enough buffer space for the
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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>[ENOTCONN]</em></td>
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<td align="left" valign="top">Requested operation requires a connection.
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<p>This error code is returned only on sockets that use a connection-oriented
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transport service.</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>[ENOTSOCK]</em></td>
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<td align="left" valign="top">The specified descriptor does not reference a
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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>This error code indicates one of the following:</p>
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<ul>
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<li>The <em>flags</em> parameter specifies a value that includes the
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<samp>MSG_OOB</samp> flag, but the <em>socket_descriptor</em> parameter points
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to a connectionless socket.<br>
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<br>
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</li>
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<li>The <em>flags</em> parameter specifies a value that includes the
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<samp>MSG_OOB</samp> flag, but the <em>socket_descriptor</em> parameter points
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to a socket that does not have an address family of <samp>AF_INET</samp> or <samp>AF_INET6</samp>.<br>
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</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>[ETIMEDOUT]</em></td>
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<td align="left" valign="top">A remote host did not respond within the timeout
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period.
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<p>A nonblocking <em>connect()</em> call was previously done that resulted in
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the connection establishment timing out. No connection is established. This
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error code is returned only on sockets that use a connection-oriented transport
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service.</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 specified
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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 thread to be
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suspended.</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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||
|
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|
||
|
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<table width="100%" cellpadding="5">
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||
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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 align="left" valign="top">CPE3418 E</td>
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<td align="left" 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>
|
||
|
|
</tr>
|
||
|
|
</table>
|
||
|
|
|
||
|
|
<br>
|
||
|
|
<br>
|
||
|
|
|
||
|
|
|
||
|
|
<h3>Usage Notes</h3>
|
||
|
|
|
||
|
|
<ol>
|
||
|
|
<li>For sockets that use a connection-oriented transport service (for example,
|
||
|
|
sockets with a type of <samp>SOCK_STREAM</samp>), a returned value of zero
|
||
|
|
indicates one of the following:
|
||
|
|
|
||
|
|
<ul>
|
||
|
|
<li>The partner program has issued a <em>close()</em> for the socket.<br>
|
||
|
|
<br>
|
||
|
|
</li>
|
||
|
|
|
||
|
|
<li>The partner program has issued a <em>shutdown()</em> to disable writing to
|
||
|
|
the socket.<br>
|
||
|
|
<br>
|
||
|
|
</li>
|
||
|
|
|
||
|
|
<li>The connection is broken and the error was returned on a previously issued
|
||
|
|
socket function.<br>
|
||
|
|
<br>
|
||
|
|
</li>
|
||
|
|
|
||
|
|
<li>A <em>shutdown()</em> to disable reading was previously done on the
|
||
|
|
socket.</li>
|
||
|
|
</ul>
|
||
|
|
|
||
|
|
<br>
|
||
|
|
<br>
|
||
|
|
</li>
|
||
|
|
|
||
|
|
<li>The following applies to sockets that use a connectionless transport
|
||
|
|
service (for example, a socket with a type of <samp>SOCK_DGRAM</samp>):
|
||
|
|
|
||
|
|
<ul>
|
||
|
|
<li>If a <em>connect()</em> has been issued previously, then data can be
|
||
|
|
received only from the address specified in the previous
|
||
|
|
<em>connect()</em>.<br>
|
||
|
|
<br>
|
||
|
|
</li>
|
||
|
|
|
||
|
|
<li>The address from which data is received is discarded, since the
|
||
|
|
<em>recv()</em> has no address parameter.<br>
|
||
|
|
<br>
|
||
|
|
</li>
|
||
|
|
|
||
|
|
<li>The entire message must be read in a single read operation. If the size of
|
||
|
|
the message is too large to fit in the user supplied buffer, the remaining
|
||
|
|
bytes of the message are discarded.<br>
|
||
|
|
<br>
|
||
|
|
</li>
|
||
|
|
|
||
|
|
<li>A returned value of zero indicates one of the following:
|
||
|
|
|
||
|
|
<ul>
|
||
|
|
<li>The partner program has sent a NULL message (a datagram with no user
|
||
|
|
data),<br>
|
||
|
|
<br>
|
||
|
|
</li>
|
||
|
|
|
||
|
|
<li>A <em>shutdown()</em> to disable reading was previously done on the
|
||
|
|
socket.<br>
|
||
|
|
<br>
|
||
|
|
</li>
|
||
|
|
|
||
|
|
<li>The buffer length specified was zero.</li>
|
||
|
|
</ul>
|
||
|
|
</li>
|
||
|
|
</ul><br>
|
||
|
|
</li>
|
||
|
|
|
||
|
|
<li>When you develop in C-based
|
||
|
|
languages and an application is compiled with the _XOPEN_SOURCE macro defined
|
||
|
|
to the value 520 or greater, the <em>recv()</em> API is mapped to
|
||
|
|
<em>qso_recv98()</em>.</li>
|
||
|
|
</ol>
|
||
|
|
|
||
|
|
<br>
|
||
|
|
|
||
|
|
|
||
|
|
<h3>Related Information</h3>
|
||
|
|
|
||
|
|
<ul>
|
||
|
|
<li><a href=
|
||
|
|
"_xopen_source.htm">_XOPEN_SOURCE</a>--Using _XOPEN_SOURCE for the UNIX 98
|
||
|
|
compatible interface<br>
|
||
|
|
<br>
|
||
|
|
</li>
|
||
|
|
|
||
|
|
<li><a href="fcntl.htm">fcntl()</a>--Perform File Control Command<br>
|
||
|
|
<br>
|
||
|
|
</li>
|
||
|
|
|
||
|
|
<li><a href="ioctl.htm">ioctl()</a>--Perform I/O Control Request<br>
|
||
|
|
<br>
|
||
|
|
</li>
|
||
|
|
|
||
|
|
<li><a href="recvfr.htm">recvfrom()</a>--Receive Data<br>
|
||
|
|
<br>
|
||
|
|
</li>
|
||
|
|
|
||
|
|
<li><a href="recvms.htm">recvmsg()</a>--Receive Data or Descriptors or
|
||
|
|
Both</li>
|
||
|
|
</ul>
|
||
|
|
|
||
|
|
<br>
|
||
|
|
<hr>
|
||
|
|
API introduced: V3R1
|
||
|
|
|
||
|
|
<hr>
|
||
|
|
<center>
|
||
|
|
<table cellpadding="2" cellspacing="2">
|
||
|
|
<tr align="center">
|
||
|
|
<td valign="middle" align="center"><a href="#Top_Of_Page">Top</a> |
|
||
|
|
<a href="unix.htm">UNIX-Type APIs</a> |
|
||
|
|
<a href="aplist.htm">APIs by category</a> </td>
|
||
|
|
</tr>
|
||
|
|
</table>
|
||
|
|
</center>
|
||
|
|
</body>
|
||
|
|
</html>
|
||
|
|
|