1<?xml version="1.0" encoding="UTF-8" standalone="no"?> 2<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 3<html xmlns="http://www.w3.org/1999/xhtml"> 4 <head> 5 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> 6 <title>DB->fd()</title> 7 <link rel="stylesheet" href="apiReference.css" type="text/css" /> 8 <meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /> 9 <link rel="start" href="index.html" title="Berkeley DB C API Reference" /> 10 <link rel="up" href="db.html" title="Chapter��2.�� The DB Handle" /> 11 <link rel="prev" href="dbexists.html" title="DB->exists()" /> 12 <link rel="next" href="dbget.html" title="DB->get()" /> 13 </head> 14 <body> 15 <div class="navheader"> 16 <table width="100%" summary="Navigation header"> 17 <tr> 18 <th colspan="3" align="center">DB->fd()</th> 19 </tr> 20 <tr> 21 <td width="20%" align="left"><a accesskey="p" href="dbexists.html">Prev</a>��</td> 22 <th width="60%" align="center">Chapter��2.�� 23 The DB Handle 24 </th> 25 <td width="20%" align="right">��<a accesskey="n" href="dbget.html">Next</a></td> 26 </tr> 27 </table> 28 <hr /> 29 </div> 30 <div class="sect1" lang="en" xml:lang="en"> 31 <div class="titlepage"> 32 <div> 33 <div> 34 <h2 class="title" style="clear: both"><a id="dbfd"></a>DB->fd()</h2> 35 </div> 36 </div> 37 </div> 38 <pre class="programlisting">#include <db.h> 39 40int 41DB->fd(DB *db, int *fdp); </pre> 42 <p> 43 The <code class="methodname">DB->fd()</code> method provides access to a file descriptor 44 representative of the underlying database. A file descriptor 45 referring to the same file will be returned to all processes that call 46 <a class="xref" href="dbopen.html" title="DB->open()">DB->open()</a> with the same 47 <span class="bold"><strong>file</strong></span> parameter. 48 </p> 49 <p> 50 This file descriptor may be safely used as a parameter to the 51 <span class="bold"><strong>fcntl</strong></span>(2) and <span class="bold"><strong>flock</strong></span>(2) locking functions. 52 </p> 53 <p> 54 The <code class="methodname">DB->fd()</code> method only supports a coarse-grained form of locking. 55 Applications should instead use the Berkeley DB lock manager where 56 possible. 57 </p> 58 <p> 59 The <code class="methodname">DB->fd()</code> <span> 60 <span> 61 method returns a non-zero error value on failure and 0 on success. 62 </span> 63 64 </span> 65 </p> 66 <div class="sect2" lang="en" xml:lang="en"> 67 <div class="titlepage"> 68 <div> 69 <div> 70 <h3 class="title"><a id="id1634196"></a>Parameters</h3> 71 </div> 72 </div> 73 </div> 74 <div class="sect3" lang="en" xml:lang="en"> 75 <div class="titlepage"> 76 <div> 77 <div> 78 <h4 class="title"><a id="id1634359"></a>fdp</h4> 79 </div> 80 </div> 81 </div> 82 <p> 83 The <span class="bold"><strong>fdp</strong></span> parameter references memory 84 into which the current file descriptor is copied. 85 </p> 86 </div> 87 </div> 88 <div class="sect2" lang="en" xml:lang="en"> 89 <div class="titlepage"> 90 <div> 91 <div> 92 <h3 class="title"><a id="id1634518"></a>Class</h3> 93 </div> 94 </div> 95 </div> 96 <p> 97 <a class="link" href="db.html" title="Chapter��2.�� The DB Handle">DB</a> 98 </p> 99 </div> 100 <div class="sect2" lang="en" xml:lang="en"> 101 <div class="titlepage"> 102 <div> 103 <div> 104 <h3 class="title"><a id="id1634525"></a>See Also</h3> 105 </div> 106 </div> 107 </div> 108 <p> 109 <a class="xref" href="db.html#dblist" title="Database and Related Methods">Database and Related Methods</a> 110 </p> 111 </div> 112 </div> 113 <div class="navfooter"> 114 <hr /> 115 <table width="100%" summary="Navigation footer"> 116 <tr> 117 <td width="40%" align="left"><a accesskey="p" href="dbexists.html">Prev</a>��</td> 118 <td width="20%" align="center"> 119 <a accesskey="u" href="db.html">Up</a> 120 </td> 121 <td width="40%" align="right">��<a accesskey="n" href="dbget.html">Next</a></td> 122 </tr> 123 <tr> 124 <td width="40%" align="left" valign="top">DB->exists()��</td> 125 <td width="20%" align="center"> 126 <a accesskey="h" href="index.html">Home</a> 127 </td> 128 <td width="40%" align="right" valign="top">��DB->get()</td> 129 </tr> 130 </table> 131 </div> 132 </body> 133</html> 134