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127 lines
5.1 KiB
HTML
127 lines
5.1 KiB
HTML
4 years ago
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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<html>
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<!-- This file documents the BFD library.
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Copyright (C) 1991-2019 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 1.3 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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<!-- Created by GNU Texinfo 6.4, http://www.gnu.org/software/texinfo/ -->
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<head>
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<title>How It Works (Untitled Document)</title>
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<meta name="description" content="How It Works (Untitled Document)">
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<meta name="keywords" content="How It Works (Untitled Document)">
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<meta name="resource-type" content="document">
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<meta name="distribution" content="global">
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<meta name="Generator" content="makeinfo">
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<link href="index.html#Top" rel="start" title="Top">
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<link href="BFD-Index.html#BFD-Index" rel="index" title="BFD Index">
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<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
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<link href="Overview.html#Overview" rel="up" title="Overview">
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<link href="What-BFD-Version-2-Can-Do.html#What-BFD-Version-2-Can-Do" rel="next" title="What BFD Version 2 Can Do">
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<link href="History.html#History" rel="prev" title="History">
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<style type="text/css">
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ul.no-bullet {list-style: none}
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-->
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</style>
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</head>
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<body lang="en">
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<a name="How-It-Works"></a>
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<div class="header">
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<p>
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Next: <a href="What-BFD-Version-2-Can-Do.html#What-BFD-Version-2-Can-Do" accesskey="n" rel="next">What BFD Version 2 Can Do</a>, Previous: <a href="History.html#History" accesskey="p" rel="prev">History</a>, Up: <a href="Overview.html#Overview" accesskey="u" rel="up">Overview</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="BFD-Index.html#BFD-Index" title="Index" rel="index">Index</a>]</p>
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</div>
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<hr>
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<a name="How-To-Use-BFD"></a>
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<h3 class="section">1.2 How To Use BFD</h3>
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<p>To use the library, include <samp>bfd.h</samp> and link with <samp>libbfd.a</samp>.
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</p>
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<p>BFD provides a common interface to the parts of an object file
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for a calling application.
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</p>
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<p>When an application successfully opens a target file (object, archive, or
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whatever), a pointer to an internal structure is returned. This pointer
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points to a structure called <code>bfd</code>, described in
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<samp>bfd.h</samp>. Our convention is to call this pointer a BFD, and
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instances of it within code <code>abfd</code>. All operations on
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the target object file are applied as methods to the BFD. The mapping is
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defined within <code>bfd.h</code> in a set of macros, all beginning
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with ‘<samp>bfd_</samp>’ to reduce namespace pollution.
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</p>
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<p>For example, this sequence does what you would probably expect:
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return the number of sections in an object file attached to a BFD
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<code>abfd</code>.
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</p>
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<div class="example">
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<pre class="example">#include "bfd.h"
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unsigned int number_of_sections (abfd)
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bfd *abfd;
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{
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return bfd_count_sections (abfd);
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}
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</pre></div>
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<p>The abstraction used within BFD is that an object file has:
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</p>
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<ul>
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<li> a header,
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</li><li> a number of sections containing raw data (see <a href="Sections.html#Sections">Sections</a>),
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</li><li> a set of relocations (see <a href="Relocations.html#Relocations">Relocations</a>), and
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</li><li> some symbol information (see <a href="Symbols.html#Symbols">Symbols</a>).
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</li></ul>
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<p>Also, BFDs opened for archives have the additional attribute of an index
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and contain subordinate BFDs. This approach is fine for a.out and coff,
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but loses efficiency when applied to formats such as S-records and
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IEEE-695.
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</p>
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</body>
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</html>
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