| <html lang="en"> |
| <head> |
| <title>Socket Option Functions - The GNU C Library</title> |
| <meta http-equiv="Content-Type" content="text/html"> |
| <meta name="description" content="The GNU C Library"> |
| <meta name="generator" content="makeinfo 4.13"> |
| <link title="Top" rel="start" href="index.html#Top"> |
| <link rel="up" href="Socket-Options.html#Socket-Options" title="Socket Options"> |
| <link rel="next" href="Socket_002dLevel-Options.html#Socket_002dLevel-Options" title="Socket-Level Options"> |
| <link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage"> |
| <!-- |
| This file documents the GNU C library. |
| |
| This is Edition 0.12, last updated 2007-10-27, |
| of `The GNU C Library Reference Manual', for version |
| 2.8 (Sourcery G++ Lite 2011.03-41). |
| |
| Copyright (C) 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2001, 2002, |
| 2003, 2007, 2008, 2010 Free Software Foundation, Inc. |
| |
| Permission is granted to copy, distribute and/or modify this document |
| under the terms of the GNU Free Documentation License, Version 1.3 or |
| any later version published by the Free Software Foundation; with the |
| Invariant Sections being ``Free Software Needs Free Documentation'' |
| and ``GNU Lesser General Public License'', the Front-Cover texts being |
| ``A GNU Manual'', and with the Back-Cover Texts as in (a) below. A |
| copy of the license is included in the section entitled "GNU Free |
| Documentation License". |
| |
| (a) The FSF's Back-Cover Text is: ``You have the freedom to |
| copy and modify this GNU manual. Buying copies from the FSF |
| supports it in developing GNU and promoting software freedom.''--> |
| <meta http-equiv="Content-Style-Type" content="text/css"> |
| <style type="text/css"><!-- |
| pre.display { font-family:inherit } |
| pre.format { font-family:inherit } |
| pre.smalldisplay { font-family:inherit; font-size:smaller } |
| pre.smallformat { font-family:inherit; font-size:smaller } |
| pre.smallexample { font-size:smaller } |
| pre.smalllisp { font-size:smaller } |
| span.sc { font-variant:small-caps } |
| span.roman { font-family:serif; font-weight:normal; } |
| span.sansserif { font-family:sans-serif; font-weight:normal; } |
| --></style> |
| <link rel="stylesheet" type="text/css" href="../cs.css"> |
| </head> |
| <body> |
| <div class="node"> |
| <a name="Socket-Option-Functions"></a> |
| <p> |
| Next: <a rel="next" accesskey="n" href="Socket_002dLevel-Options.html#Socket_002dLevel-Options">Socket-Level Options</a>, |
| Up: <a rel="up" accesskey="u" href="Socket-Options.html#Socket-Options">Socket Options</a> |
| <hr> |
| </div> |
| |
| <h4 class="subsection">16.12.1 Socket Option Functions</h4> |
| |
| <p><a name="index-sys_002fsocket_002eh-1828"></a>Here are the functions for examining and modifying socket options. |
| They are declared in <samp><span class="file">sys/socket.h</span></samp>. |
| |
| <!-- sys/socket.h --> |
| <!-- BSD --> |
| <div class="defun"> |
| — Function: int <b>getsockopt</b> (<var>int socket, int level, int optname, void *optval, socklen_t *optlen-ptr</var>)<var><a name="index-getsockopt-1829"></a></var><br> |
| <blockquote><p>The <code>getsockopt</code> function gets information about the value of |
| option <var>optname</var> at level <var>level</var> for socket <var>socket</var>. |
| |
| <p>The option value is stored in a buffer that <var>optval</var> points to. |
| Before the call, you should supply in <code>*</code><var>optlen-ptr</var> the |
| size of this buffer; on return, it contains the number of bytes of |
| information actually stored in the buffer. |
| |
| <p>Most options interpret the <var>optval</var> buffer as a single <code>int</code> |
| value. |
| |
| <p>The actual return value of <code>getsockopt</code> is <code>0</code> on success |
| and <code>-1</code> on failure. The following <code>errno</code> error conditions |
| are defined: |
| |
| <dl> |
| <dt><code>EBADF</code><dd>The <var>socket</var> argument is not a valid file descriptor. |
| |
| <br><dt><code>ENOTSOCK</code><dd>The descriptor <var>socket</var> is not a socket. |
| |
| <br><dt><code>ENOPROTOOPT</code><dd>The <var>optname</var> doesn't make sense for the given <var>level</var>. |
| </dl> |
| </p></blockquote></div> |
| |
| <!-- sys/socket.h --> |
| <!-- BSD --> |
| <div class="defun"> |
| — Function: int <b>setsockopt</b> (<var>int socket, int level, int optname, void *optval, socklen_t optlen</var>)<var><a name="index-setsockopt-1830"></a></var><br> |
| <blockquote><p>This function is used to set the socket option <var>optname</var> at level |
| <var>level</var> for socket <var>socket</var>. The value of the option is passed |
| in the buffer <var>optval</var> of size <var>optlen</var>. |
| |
| <!-- Argh. -zw --> |
| </blockquote></div> |
| |
| </body></html> |
| |
