212 lines
7.2 KiB
HTML
212 lines
7.2 KiB
HTML
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<!-- Copyright (c) 2001 The Open Group, All Rights Reserved -->
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<title>accept</title>
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<basefont size="3"> <a name="accept"></a> <a name="tag_03_09"></a><!-- accept -->
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<!--header start-->
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<center><font size="2">The Open Group Base Specifications Issue 6<br>
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IEEE Std 1003.1-2001<br>
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Copyright © 2001 The IEEE and The Open Group, All Rights reserved.</font></center>
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<!--header end-->
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<hr size="2" noshade>
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<h4><a name="tag_03_09_01"></a>NAME</h4>
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<blockquote>accept - accept a new connection on a socket</blockquote>
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<h4><a name="tag_03_09_02"></a>SYNOPSIS</h4>
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<blockquote class="synopsis">
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<p><code><tt>#include <<a href="../basedefs/sys/socket.h.html">sys/socket.h</a>><br>
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<br>
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int accept(int</tt> <i>socket</i><tt>, struct sockaddr *restrict</tt> <i>address</i><tt>,<br>
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socklen_t *restrict</tt> <i>address_len</i><tt>);<br>
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</tt></code></p>
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</blockquote>
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<h4><a name="tag_03_09_03"></a>DESCRIPTION</h4>
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<blockquote>
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<p>The <i>accept</i>() function shall extract the first connection on the queue of pending connections, create a new socket with
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the same socket type protocol and address family as the specified socket, and allocate a new file descriptor for that socket.</p>
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<p>The <i>accept</i>() function takes the following arguments:</p>
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<dl compact>
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<dt><i>socket</i></dt>
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<dd>Specifies a socket that was created with <a href="../functions/socket.html"><i>socket</i>()</a>, has been bound to an address
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with <a href="../functions/bind.html"><i>bind</i>()</a>, and has issued a successful call to <a href=
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"../functions/listen.html"><i>listen</i>()</a>.</dd>
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<dt><i>address</i></dt>
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<dd>Either a null pointer, or a pointer to a <b>sockaddr</b> structure where the address of the connecting socket shall be
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returned.</dd>
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<dt><i>address_len</i></dt>
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<dd>Points to a <b>socklen_t</b> structure which on input specifies the length of the supplied <b>sockaddr</b> structure, and on
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output specifies the length of the stored address.</dd>
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</dl>
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<p>If <i>address</i> is not a null pointer, the address of the peer for the accepted connection shall be stored in the
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<b>sockaddr</b> structure pointed to by <i>address</i>, and the length of this address shall be stored in the object pointed to by
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<i>address_len</i>.</p>
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<p>If the actual length of the address is greater than the length of the supplied <b>sockaddr</b> structure, the stored address
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shall be truncated.</p>
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<p>If the protocol permits connections by unbound clients, and the peer is not bound, then the value stored in the object pointed
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to by <i>address</i> is unspecified.</p>
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<p>If the listen queue is empty of connection requests and O_NONBLOCK is not set on the file descriptor for the socket,
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<i>accept</i>() shall block until a connection is present. If the <a href="../functions/listen.html"><i>listen</i>()</a> queue is
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empty of connection requests and O_NONBLOCK is set on the file descriptor for the socket, <i>accept</i>() shall fail and set
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<i>errno</i> to [EAGAIN] or [EWOULDBLOCK].</p>
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<p>The accepted socket cannot itself accept more connections. The original socket remains open and can accept more connections.</p>
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</blockquote>
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<h4><a name="tag_03_09_04"></a>RETURN VALUE</h4>
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<blockquote>
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<p>Upon successful completion, <i>accept</i>() shall return the non-negative file descriptor of the accepted socket. Otherwise, -1
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shall be returned and <i>errno</i> set to indicate the error.</p>
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</blockquote>
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<h4><a name="tag_03_09_05"></a>ERRORS</h4>
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<blockquote>
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<p>The <i>accept</i>() function shall fail if:</p>
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<dl compact>
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<dt>[EAGAIN] or [EWOULDBLOCK]</dt>
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<dd><br>
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O_NONBLOCK is set for the socket file descriptor and no connections are present to be accepted.</dd>
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<dt>[EBADF]</dt>
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<dd>The <i>socket</i> argument is not a valid file descriptor.</dd>
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<dt>[ECONNABORTED]</dt>
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<dd><br>
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A connection has been aborted.</dd>
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<dt>[EINTR]</dt>
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<dd>The <i>accept</i>() function was interrupted by a signal that was caught before a valid connection arrived.</dd>
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<dt>[EINVAL]</dt>
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<dd>The <i>socket</i> is not accepting connections.</dd>
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<dt>[EMFILE]</dt>
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<dd>{OPEN_MAX} file descriptors are currently open in the calling process.</dd>
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<dt>[ENFILE]</dt>
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<dd>The maximum number of file descriptors in the system are already open.</dd>
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<dt>[ENOTSOCK]</dt>
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<dd>The <i>socket</i> argument does not refer to a socket.</dd>
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<dt>[EOPNOTSUPP]</dt>
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<dd>The socket type of the specified socket does not support accepting connections.</dd>
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</dl>
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<p>The <i>accept</i>() function may fail if:</p>
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<dl compact>
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<dt>[ENOBUFS]</dt>
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<dd>No buffer space is available.</dd>
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<dt>[ENOMEM]</dt>
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<dd>There was insufficient memory available to complete the operation.</dd>
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<dt>[EPROTO]</dt>
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<dd><sup>[<a href="javascript:open_code('XSR')">XSR</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
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A protocol error has occurred; for example, the STREAMS protocol stack has not been initialized. <img src="../images/opt-end.gif"
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alt="[Option End]" border="0"></dd>
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</dl>
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</blockquote>
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<hr>
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<div class="box"><em>The following sections are informative.</em></div>
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<h4><a name="tag_03_09_06"></a>EXAMPLES</h4>
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<blockquote>
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<p>None.</p>
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</blockquote>
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<h4><a name="tag_03_09_07"></a>APPLICATION USAGE</h4>
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<blockquote>
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<p>When a connection is available, <a href="../functions/select.html"><i>select</i>()</a> indicates that the file descriptor for
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the socket is ready for reading.</p>
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</blockquote>
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<h4><a name="tag_03_09_08"></a>RATIONALE</h4>
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<blockquote>
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<p>None.</p>
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</blockquote>
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<h4><a name="tag_03_09_09"></a>FUTURE DIRECTIONS</h4>
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<blockquote>
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<p>None.</p>
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</blockquote>
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<h4><a name="tag_03_09_10"></a>SEE ALSO</h4>
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<blockquote>
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<p><a href="bind.html"><i>bind</i>()</a> , <a href="connect.html"><i>connect</i>()</a> , <a href="listen.html"><i>listen</i>()</a>
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, <a href="socket.html"><i>socket</i>()</a> , the Base Definitions volume of IEEE Std 1003.1-2001, <a href=
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"../basedefs/sys/socket.h.html"><i><sys/socket.h></i></a></p>
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</blockquote>
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<h4><a name="tag_03_09_11"></a>CHANGE HISTORY</h4>
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<blockquote>
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<p>First released in Issue 6. Derived from the XNS, Issue 5.2 specification.</p>
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<p>The <b>restrict</b> keyword is added to the <i>accept</i>() prototype for alignment with the ISO/IEC 9899:1999
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standard.</p>
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</blockquote>
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<div class="box"><em>End of informative text.</em></div>
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<center><font size="2"><!--footer start-->
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UNIX ® is a registered Trademark of The Open Group.<br>
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POSIX ® is a registered Trademark of The IEEE.<br>
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