1<!--$Id: db_fd.so,v 10.31 2005/06/14 14:06:57 bostic Exp $--> 2<!--Copyright (c) 1997,2008 Oracle. All rights reserved.--> 3<!--See the file LICENSE for redistribution information.--> 4<html> 5<head> 6<title>Berkeley DB: Db::fd</title> 7<meta name="description" content="Berkeley DB: An embedded database programmatic toolkit."> 8<meta name="keywords" content="embedded,database,programmatic,toolkit,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,Java,C,C++"> 9</head> 10<body bgcolor=white> 11<table width="100%"><tr valign=top> 12<td> 13<b>Db::fd</b> 14</td> 15<td align=right> 16<a href="/api_cxx/api_core.html"><img src="/images/api.gif" alt="API"></a> 17<a href="/ref/toc.html"><img src="/images/ref.gif" alt="Ref"></a></td> 18</tr></table> 19<hr size=1 noshade> 20<tt> 21<b><pre> 22#include <db_cxx.h> 23<p> 24int 25Db::fd(int *fdp); 26</pre></b> 27<hr size=1 noshade> 28<b>Description: Db::fd</b> 29<p>The Db::fd method provides access to a file descriptor representative 30of the underlying database. A file descriptor referring to the same 31file will be returned to all processes that call <a href="/api_cxx/db_open.html">Db::open</a> with 32the same <b>file</b> parameter.</p> 33<p>This file descriptor may be safely used as a parameter to the 34<b>fcntl</b>(2) and <b>flock</b>(2) locking functions.</p> 35<p>The Db::fd method only supports a coarse-grained form of locking. 36Applications should instead use the Berkeley DB lock manager where possible.</p> 37<p>The Db::fd method 38either returns a non-zero error value 39or throws an exception that encapsulates a non-zero error value on 40failure, and returns 0 on success. 41</p> 42<b>Parameters</b> <br> 43 <b>fdp</b><ul compact><li>The <b>fdp</b> parameter references memory into which 44 the current file descriptor is copied.</ul> 45<br> 46<hr size=1 noshade> 47<br><b>Class</b> 48<a href="/api_cxx/db_class.html">Db</a> 49<br><b>See Also</b> 50<a href="/api_cxx/db_list.html">Databases and Related Methods</a> 51</tt> 52<table width="100%"><tr><td><br></td><td align=right> 53<a href="/api_cxx/api_core.html"><img src="/images/api.gif" alt="API"></a><a href="/ref/toc.html"><img src="/images/ref.gif" alt="Ref"></a> 54</td></tr></table> 55<p><font size=1>Copyright (c) 1996,2008 Oracle. All rights reserved.</font> 56</body> 57</html> 58