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126 lines
4.8 KiB
HTML
126 lines
4.8 KiB
HTML
15 years ago
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<html lang="en">
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<head>
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<title>File Caching - Untitled</title>
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<meta http-equiv="Content-Type" content="text/html">
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<meta name="description" content="Untitled">
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<meta name="generator" content="makeinfo 4.7">
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<link title="Top" rel="start" href="index.html#Top">
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<link rel="up" href="BFD-front-end.html#BFD-front-end" title="BFD front end">
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<link rel="prev" href="Internal.html#Internal" title="Internal">
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<link rel="next" href="Linker-Functions.html#Linker-Functions" title="Linker Functions">
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<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage">
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<!--
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This file documents the BFD library.
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Copyright (C) 1991, 2000, 2001, 2003, 2006, 2007 Free Software Foundation, Inc.
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Permission is granted to copy, distribute and/or modify this document
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under the terms of the GNU Free Documentation License, Version 1.1 or
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any later version published by the Free Software Foundation; with the
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Invariant Sections being ``GNU General Public License'' and ``Funding
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Free Software'', the Front-Cover texts being (a) (see below), and with
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the Back-Cover Texts being (b) (see below). A copy of the license is
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included in the section entitled ``GNU Free Documentation License''.
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(a) The FSF's Front-Cover Text is:
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A GNU Manual
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(b) The FSF's Back-Cover Text is:
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You have freedom to copy and modify this GNU Manual, like GNU
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software. Copies published by the Free Software Foundation raise
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funds for GNU development.-->
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<meta http-equiv="Content-Style-Type" content="text/css">
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<style type="text/css"><!--
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pre.display { font-family:inherit }
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span.roman { font-family: serif; font-weight: normal; }
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--></style>
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</head>
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<body>
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<div class="node">
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<p>
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<a name="File-Caching"></a>Next: <a rel="next" accesskey="n" href="Linker-Functions.html#Linker-Functions">Linker Functions</a>,
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Previous: <a rel="previous" accesskey="p" href="Internal.html#Internal">Internal</a>,
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Up: <a rel="up" accesskey="u" href="BFD-front-end.html#BFD-front-end">BFD front end</a>
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<hr><br>
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</div>
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<h3 class="section">2.16 File caching</h3>
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<p>The file caching mechanism is embedded within BFD and allows
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the application to open as many BFDs as it wants without
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regard to the underlying operating system's file descriptor
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limit (often as low as 20 open files). The module in
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<code>cache.c</code> maintains a least recently used list of
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<code>BFD_CACHE_MAX_OPEN</code> files, and exports the name
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<code>bfd_cache_lookup</code>, which runs around and makes sure that
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the required BFD is open. If not, then it chooses a file to
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close, closes it and opens the one wanted, returning its file
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handle.
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<h4 class="subsection">2.16.1 Caching functions</h4>
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<p><a name="index-bfd_005fcache_005finit-1364"></a>
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<h5 class="subsubsection">2.16.1.1 <code>bfd_cache_init</code></h5>
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<p><strong>Synopsis</strong>
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<pre class="example"> bfd_boolean bfd_cache_init (bfd *abfd);
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</pre>
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<p><strong>Description</strong><br>
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Add a newly opened BFD to the cache.
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<p><a name="index-bfd_005fcache_005fclose-1365"></a>
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<h5 class="subsubsection">2.16.1.2 <code>bfd_cache_close</code></h5>
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<p><strong>Synopsis</strong>
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<pre class="example"> bfd_boolean bfd_cache_close (bfd *abfd);
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</pre>
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<p><strong>Description</strong><br>
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Remove the BFD <var>abfd</var> from the cache. If the attached file is open,
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then close it too.
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<p><strong>Returns</strong><br>
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<code>FALSE</code> is returned if closing the file fails, <code>TRUE</code> is
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returned if all is well.
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<p><a name="index-bfd_005fcache_005fclose_005fall-1366"></a>
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<h5 class="subsubsection">2.16.1.3 <code>bfd_cache_close_all</code></h5>
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<p><strong>Synopsis</strong>
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<pre class="example"> bfd_boolean bfd_cache_close_all (void);
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</pre>
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<p><strong>Description</strong><br>
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Remove all BFDs from the cache. If the attached file is open,
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then close it too.
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<p><strong>Returns</strong><br>
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<code>FALSE</code> is returned if closing one of the file fails, <code>TRUE</code> is
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returned if all is well.
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<p><a name="index-bfd_005fopen_005ffile-1367"></a>
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<h5 class="subsubsection">2.16.1.4 <code>bfd_open_file</code></h5>
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<p><strong>Synopsis</strong>
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<pre class="example"> FILE* bfd_open_file (bfd *abfd);
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</pre>
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<p><strong>Description</strong><br>
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Call the OS to open a file for <var>abfd</var>. Return the <code>FILE *</code>
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(possibly <code>NULL</code>) that results from this operation. Set up the
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BFD so that future accesses know the file is open. If the <code>FILE *</code>
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returned is <code>NULL</code>, then it won't have been put in the
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cache, so it won't have to be removed from it.
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</body></html>
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