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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"><html><head><!-- Copyright 1997 The Open Group, All Rights Reserved --><title>socketpair</title></head><body bgcolor=white><center><font size=2>The Single UNIX ® Specification, Version 2<br>Copyright © 1997 The Open Group</font></center><hr size=2 noshade><h4>NAME</h4><blockquote>socketpair - create a pair of connected sockets</blockquote><h4>SYNOPSIS</h4><blockquote><pre><code>#include <<a href="syssocket.h.html">sys/socket.h</a>>int socketpair(int <I>domain</I>, int <I>type</I>, int <I>protocol</I>, int <I>socket_vector</I>[2]);</code></pre></blockquote><h4>DESCRIPTION</h4><blockquote>The<i>socketpair()</i>function creates an unbound pair of connectedsockets in a specified <I>domain</I>, of a specified <I>type</I>, underthe protocol optionally specified by the <I>protocol</I> argument. The twosockets are identical. The file descriptors used in referencing the createdsockets are returned in <I>socket_vector</I>[0] and<I>socket_vector</I>[1].<p><dl compact><dt><I>domain</I><dd>Specifies the communications domain in which the sockets are to be created.<dt><I>type</I><dd>Specifies the type of sockets to be created.<dt><I>protocol</I><dd>Specifies a particular protocol to be used with the sockets.Specifying a <I>protocol</I> of 0 causes<i>socketpair()</i>to use an unspecified default protocol appropriate for therequested socket type.<dt><I>socket_vector</I><dd>Specifies a 2-integer array to hold the file descriptors ofthe created socket pair.</dl><p>The <I>type</I> argument specifies the socket type, which determinesthe semantics of communications over the socket. The socket typessupported by the system are implementation-dependent. Possiblesocket types include:<dl compact><dt>SOCK_STREAM<dd>Provides sequenced, reliable, bidirectional, connection-mode byte streams,and may provide a transmission mechanism for out-of-band data.<dt>SOCK_DGRAM<dd>Provides datagrams, which are connectionless-mode, unreliable messages of fixedmaximum length.<dt>SOCK_SEQPACKET<dd>Provides sequenced, reliable, bidirectional, connection-mode transmissionpath for records. A record can be sent using one or more output operationsand received using one or more input operations, but a single operation nevertransfers part of more than one record. Record boundaries are visible tothe receiver via the MSG_EOR flag.</dl><p>If the <I>protocol</I> argument is non-zero, it must specify aprotocol that is supported by the address family. The protocolssupported by the system are implementation-dependent.<p>The process may need to have appropriate privileges to use the<i>socketpair()</i>function or to create some sockets.</blockquote><h4>RETURN VALUE</h4><blockquote>Upon successful completion, this function returns 0. Otherwise, -1 isreturned and <I>errno</I> is set to indicate the error.</blockquote><h4>ERRORS</h4><blockquote>The<i>socketpair()</i>function will fail if:<dl compact><dt>[EAFNOSUPPORT]<dd>The implementation does not support the specified address family.<dt>[EMFILE]<dd>No more file descriptors are available for this process.<dt>[ENFILE]<dd>No more file descriptors are available for the system.<dt>[EOPNOTSUPP]<dd>The specified protocol does not permit creation of socket pairs.<dt>[EPROTONOSUPPORT]<dd><br>The protocol is not supported by the addressfamily, or the protocol is not supported by theimplementation.<dt>[EPROTOTYPE]<dd>The socket type is not supported by the protocol.</dl><p>The<i>socketpair()</i>function may fail if:<dl compact><dt>[EACCES]<dd>The process does not have appropriate privileges.<dt>[ENOBUFS]<dd>Insufficient resources were available in the system to perform the operation.<dt>[ENOMEM]<dd>Insufficient memory was available to fulfill the request.<dt>[ENOSR]<dd>There were insufficient STREAMS resources available for the operation tocomplete.</dl></blockquote><h4>APPLICATION USAGE</h4><blockquote>The documentation for specific address families specifies which protocols eachaddress family supports. The documentation for specific protocols specifieswhich socket types each protocol supports.<p>The<i>socketpair()</i>function is used primarily with UNIX domain sockets and need not be supportedfor other domains.</blockquote><h4>SEE ALSO</h4><blockquote><i><a href="socket.html">socket()</a></i>,<i><a href="syssocket.h.html"><sys/socket.h></a></i>.</blockquote><hr size=2 noshade><center><font size=2>UNIX ® is a registered Trademark of The Open Group.<br>Copyright © 1997 The Open Group<br> [ <a href="../index.html">Main Index</a> | <a href="../xshix.html">XSH</a> | <a href="../xcuix.html">XCU</a> | <a href="../xbdix.html">XBD</a> | <a href="../cursesix.html">XCURSES</a> | <a href="../xnsix.html">XNS</a> ]</font></center><hr size=2 noshade></body></html>⌨️ 快捷键说明
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