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<html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>ELFIO</title><meta name="generator" content="DocBook XSL Stylesheets V1.76.1"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="book" title="ELFIO"><div class="titlepage"><div><div><h1 class="title"><a name="id9258113"></a>ELFIO</h1></div><div><h2 class="subtitle">User's Guide</h2></div><div><div class="authorgroup"><div class="author"><h3 class="author"><span class="firstname">Serge</span> <span class="surname">Lamikhov-Center</span></h3></div></div></div></div><hr></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="preface"><a href="#introduction">Introduction</a></span></dt><dt><span class="chapter"><a href="#get-started">1. Getting Started With ELFIO</a></span></dt><dd><dl><dt><span class="sect1"><a href="#id9241244">ELF File Reader</a></span></dt><dt><span class="sect1"><a href="#id9259841">ELF Section Data Accessors</a></span></dt><dt><span class="sect1"><a href="#id9263124">ELFDump Utility</a></span></dt><dt><span class="sect1"><a href="#id9239788">ELF File Writer</a></span></dt></dl></dd><dt><span class="chapter"><a href="#section-interface">2. ELFIO Library Classes</a></span></dt><dd><dl><dt><span class="sect1"><a href="#id9267190">Class <code class="classname">elfio</code></a></span></dt><dd><dl><dt><span class="sect2"><a href="#id9249215">Data members</a></span></dt><dt><span class="sect2"><a href="#id9248262">Member functions</a></span></dt></dl></dd></dl></dd><dt><span class="chapter"><a href="#ielfo">3.
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<code class="classname">IELFO</code> - ELF File Producer Interface
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</a></span></dt></dl></div><div class="list-of-tables"><p><b>List of Tables</b></p><dl><dt>2.1. <a href="#id9253246">Class <code class="classname">elfio</code> member functions</a></dt><dt>2.2. <a href="#id9240401">Class <code class="classname">elfio</code> member functions</a></dt><dt>2.3. <a href="#id9251712">Class <code class="classname">elfio</code> member functions (continue)</a></dt></dl></div><div class="preface" title="Introduction"><div class="titlepage"><div><div><h2 class="title"><a name="introduction"></a>Introduction</h2></div></div></div><p>
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ELFIO is a C++ library for reading and generating files in ELF binary
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format. This library is independent and does not require any other product.
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It is also cross-platform - the library uses standard ANSI C++ constructions
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and runs on wide variety of architectures.
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</p><p>
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While the library's implementation does make your work much easier: basic
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knowledge of the ELF binary format is required. Information about ELF
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format can be found widely on the web.
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</p></div><div class="chapter" title="Chapter<65>1.<2E>Getting Started With ELFIO"><div class="titlepage"><div><div><h2 class="title"><a name="get-started"></a>Chapter<EFBFBD>1.<2E>Getting Started With ELFIO</h2></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="sect1"><a href="#id9241244">ELF File Reader</a></span></dt><dt><span class="sect1"><a href="#id9259841">ELF Section Data Accessors</a></span></dt><dt><span class="sect1"><a href="#id9263124">ELFDump Utility</a></span></dt><dt><span class="sect1"><a href="#id9239788">ELF File Writer</a></span></dt></dl></div><div class="sect1" title="ELF File Reader"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id9241244"></a>ELF File Reader</h2></div></div></div><p>
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The ELFIO library is a header only library. No preparatory compilation
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steps are required. To make your application be aware about the
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ELFIO classes and types declarations, just include <code class="filename">elfio.hpp</code> header file.
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All ELFIO library declarations reside in ELFIO namespace.
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So, this tutorial code starts from the following code:
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</p><div class="programlistingco"><pre class="programlisting">
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#include <iostream>
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#include <elfio.hpp>
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using namespace ELFIO;
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int main( int argc, char** argv )
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{
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if ( argc != 2 ) {
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std::cout << "Usage: tutorial <elf_file>" << std::endl;
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return 1;
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}
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</pre><div class="calloutlist"><table border="0" summary="Callout list"><tr><td width="5%" valign="top" align="left"><p><img src="images/callouts/1.png" alt="1" border="0"></p></td><td valign="top" align="left"><p>
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Include <code class="filename">elfio.hpp</code> header file
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</p></td></tr><tr><td width="5%" valign="top" align="left"><p><img src="images/callouts/2.png" alt="2" border="0"></p></td><td valign="top" align="left"><p>
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The ELFIO namespace usage
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</p></td></tr></table></div></div><p>
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This chapter will explain how to work with the reader portion
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of the ELFIO library. The first step would be creation of the <code class="classname">elfio</code>
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class instance. The <code class="classname">elfio</code> constructor does not
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receive any parameters. After that, we initialize the instance by
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loading an ELF file with name passed as a parameter.
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</p><div class="programlistingco"><pre class="programlisting">
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// Create an elfio reader
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elfio reader;
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// Load ELF data
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if ( !reader.load( argv[1] ) ) {
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std::cout << "Can't find or process ELF file " << argv[1] << std::endl;
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return 2;
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}
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</pre><div class="calloutlist"><table border="0" summary="Callout list"><tr><td width="5%" valign="top" align="left"><p><img src="images/callouts/1.png" alt="1" border="0"></p></td><td valign="top" align="left"><p>
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Create <code class="classname">elfio</code> class instance
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</p></td></tr><tr><td width="5%" valign="top" align="left"><p><img src="images/callouts/2.png" alt="2" border="0"></p></td><td valign="top" align="left"><p>
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Initialize the instance by loading ELF file. The function
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<code class="function">load</code> returns
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<span class="returnvalue">true</span>
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if the ELF file was found and processed successfully. It returns
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<span class="returnvalue">false</span> otherwise.
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</p></td></tr></table></div></div><p>
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</p><p>
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From here, ELF header properties are accessible. This makes it possible
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to request file parameters such as encoding, machine type,
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entry point, etc. To get the class and the encoding of the file use:
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</p><div class="programlistingco"><pre class="programlisting">
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// Print ELF file properties
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std::cout << "ELF file class : ";
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if ( reader.get_class() == ELFCLASS32 )
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std::cout << "ELF32" << std::endl;
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else
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std::cout << "ELF64" << std::endl;
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std::cout << "ELF file encoding : ";
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if ( reader.get_encoding() == ELFDATA2LSB )
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std::cout << "Little endian" << std::endl;
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else
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std::cout << "Big endian" << std::endl;
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</pre><div class="calloutlist"><table border="0" summary="Callout list"><tr><td width="5%" valign="top" align="left"><p><img src="images/callouts/1.png" alt="1" border="0"></p></td><td valign="top" align="left"><p>
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Member function <code class="function">get_class()</code> returns ELF file
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class. Possible values are <code class="constant">ELFCLASS32</code> or
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<code class="constant">ELFCLASS64</code>.
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</p></td></tr><tr><td width="5%" valign="top" align="left"><p><img src="images/callouts/2.png" alt="2" border="0"></p></td><td valign="top" align="left"><p>
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Member function <code class="function">get_encoding()</code> returns ELF file
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format encoding. Possible values are <code class="constant">ELFDATA2LSB</code>
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and <code class="constant">ELFDATA2MSB</code>.
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</p></td></tr></table></div></div><p>
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</p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>
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Standard ELF types, flags and constants
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are defined in the <code class="filename">elf_types.hpp</code> header file.
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This file is included automatically into the project.
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For example: <code class="constant">ELFCLASS32</code>,
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<code class="constant">ELFCLASS64</code> constants define a value for 32/64 bit
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architectures. <code class="constant">ELFDATA2LSB</code> and
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<code class="constant">ELFDATA2MSB</code> constants define value
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for little and big endian encoding.
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</p></div><p>
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ELF binary files may consist of several sections. Each section has it's own
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responsibility: some contain executable code; others describe program
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dependencies; others symbol tables and so on. See ELF binary format
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documentation for a full description of each section.
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</p><p>
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The following code demonstrates how to find out the amount of sections
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the ELF file contains. The code also presents how to access particular
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section properties like names and sizes:
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</p><pre class="programlisting">
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// Print ELF file sections info
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Elf_Half sec_num = reader.sections.size();
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std::cout << "Number of sections: " << sec_num << std::endl;
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for ( int i = 0; i < sec_num; ++i ) {
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const section* psec = reader.sections[i];
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std::cout << " [" << i << "] "
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<< psec->get_name()
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<< "\t"
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<< psec->get_size()
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<< std::endl;
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// Access to section's data
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// const char* p = reader.sections[i]->get_data()
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}
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</pre><p>
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</p><p>
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<code class="methodname">sections</code> member of <code class="classname">reader</code>
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object permits to obtain number of sections the ELF file contains. It
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also serves for getting access to individual section by using
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<code class="methodname">operator[]</code>, which returns a pointer to
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corresponding section's interface.
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</p><p>
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Similarly, segments of the ELF file can be processed:
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</p><pre class="programlisting">
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// Print ELF file segments info
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Elf_Half seg_num = reader.segments.size();
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std::cout << "Number of segments: " << seg_num << std::endl;
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for ( int i = 0; i < seg_num; ++i ) {
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const segment* pseg = reader.segments[i];
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std::cout << " [" << i << "] 0x" << std::hex
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<< pseg->get_flags()
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<< "\t0x"
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<< pseg->get_virtual_address()
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<< "\t0x"
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<< pseg->get_file_size()
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<< "\t0x"
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<< pseg->get_memory_size()
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<< std::endl;
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// Access to segments's data
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// const char* p = reader.segments[i]->get_data()
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}
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</pre><p>
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In this case, segments' attributes and data are obtained by using
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<code class="methodname">segments</code> member of the <code class="classname">reader</code>.
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</p><p>
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The full text of this example comes together with ELFIO library
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distribution.
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</p></div><div class="sect1" title="ELF Section Data Accessors"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id9259841"></a>ELF Section Data Accessors</h2></div></div></div><p>
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To simplify creation and interpretation of the ELF sections' data,
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the ELFIO library comes with auxiliary classes - accessors. To the moment
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of this document writing, the following accessors are available:
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</p><div class="itemizedlist"><ul class="itemizedlist" type="opencircle"><li class="listitem" style="list-style-type: circle"><p>
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<code class="classname">string_section_accessor</code>
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</p></li><li class="listitem" style="list-style-type: circle"><p>
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<code class="classname">symbol_section_accessor</code>
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</p></li><li class="listitem" style="list-style-type: circle"><p>
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<code class="classname">relocation_section_accessor</code>
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</p></li><li class="listitem" style="list-style-type: circle"><p>
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<code class="classname">note_section_accessor</code>
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</p></li></ul></div><p>
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Definitely, it is possible to extend the library by implementing additional
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accessors serving particular purposes.
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</p><p>
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Let's see how the accessors can be used with the previous ELF file reader
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example. For this example purposes, we will print out all symbols in a
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symbol section.
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</p><pre class="programlisting">
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if ( psec->get_type() == SHT_SYMTAB ) {
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const symbol_section_accessor symbols( reader, psec );
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for ( unsigned int j = 0; j < symbols.get_symbols_num(); ++j ) {
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std::string name;
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Elf64_Addr value;
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Elf_Xword size;
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unsigned char bind;
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unsigned char type;
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Elf_Half section_index;
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unsigned char other;
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symbols.get_symbol( j, name, value, size, bind,
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type, section_index, other );
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std::cout << j << " " << name << std::endl;
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}
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}
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</pre><p>
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We create <code class="classname">symbol_section_accessor</code> instance first.
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Usually, accessors receive the <code class="classname">elfio</code> and
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<code class="classname">section*</code> parameters for their constructors.
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<code class="methodname">get_symbol</code> is used to retrieve a particular entry
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in the symbol table.
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</p></div><div class="sect1" title="ELFDump Utility"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id9263124"></a>ELFDump Utility</h2></div></div></div><p>
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The source code for the ELF Dumping Utility can be found in
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the "Examples" directory; included there are more examples on how
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to use different ELFIO reader interfaces.
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</p></div><div class="sect1" title="ELF File Writer"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id9239788"></a>ELF File Writer</h2></div></div></div><p>
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The ELFIO library is a header only library. No preparatory compilation
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steps are required. To make your application be aware about the
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ELFIO classes and types declarations, just include <code class="filename">elfio.hpp</code> header file.
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All ELFIO library declarations reside in ELFIO namespace.
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So, our tutorial code starts from this:
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</p></div></div><div class="chapter" title="Chapter<65>2.<2E>ELFIO Library Classes"><div class="titlepage"><div><div><h2 class="title"><a name="section-interface"></a>Chapter<EFBFBD>2.<2E>ELFIO Library Classes</h2></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="sect1"><a href="#id9267190">Class <code class="classname">elfio</code></a></span></dt><dd><dl><dt><span class="sect2"><a href="#id9249215">Data members</a></span></dt><dt><span class="sect2"><a href="#id9248262">Member functions</a></span></dt></dl></dd></dl></div><div class="sect1" title="Class elfio"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id9267190"></a>Class <code class="classname">elfio</code></h2></div></div></div><div class="sect2" title="Data members"><div class="titlepage"><div><div><h3 class="title"><a name="id9249215"></a>Data members</h3></div></div></div><p>
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The ELFIO library consists of two independent parts: ELF File Reader
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</p><p>
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</p><div class="table"><a name="id9253246"></a><p class="title"><b>Table<EFBFBD>2.1.<2E>Class <code class="classname">elfio</code> member functions</b></p><div class="table-contents"><table summary="Class elfio member functions" border="1"><colgroup><col align="left" class="c1"><col align="left" class="c2"></colgroup><thead><tr><th align="center">Function</th><th align="center">Description</th></tr></thead><tbody><tr><td align="left">
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sections
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</td><td align="left">
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A container that stores pointers to ELF file section instances.
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implementing operator[] and size() f
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</td></tr><tr><td align="left">
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<div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">bool <b class="fsfunc">load</b>
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(</code></td><td><var class="pdparam">file_name</var><code>)</code>;</td><td><EFBFBD></td></tr></table><div class="paramdef-list"><code>const std::string& <var class="pdparam">file_name</var>
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</code>;</div><div class="funcprototype-spacer"><EFBFBD></div></div>
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</td><td align="left">
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Initializes <code class="classname">elfio</code> object by loading data
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from ELF binary file. File name provided in <em class="parameter"><code>file_name</code></em>.
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Returns <span class="returnvalue">true</span> if the file was processed successfully.
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</td></tr></tbody></table></div></div><p><br class="table-break">
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</p></div><div class="sect2" title="Member functions"><div class="titlepage"><div><div><h3 class="title"><a name="id9248262"></a>Member functions</h3></div></div></div><p>
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The ELFIO library consists of two independent parts: ELF File Reader
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(<code class="classname">IELFI</code>)
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and ELF Producer (<code class="classname">IELFO</code>).
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Each is represented by its own set of interfaces.
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The library does not contain any classes that need to be explicitly
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instantiated. ELFIO itself provides the interfaces that
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are used to access the library's functionality.
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</p><p>
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</p><div class="table"><a name="id9240401"></a><p class="title"><b>Table<EFBFBD>2.2.<2E>Class <code class="classname">elfio</code> member functions</b></p><div class="table-contents"><table summary="Class elfio member functions" border="1"><colgroup><col align="left" class="c1"><col align="left" class="c2"></colgroup><thead><tr><th align="center">Function</th><th align="center">Description</th></tr></thead><tbody><tr><td align="left">
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<div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">
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<b class="fsfunc">elfio</b>
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(</code></td><td><code>)</code>;</td><td><EFBFBD></td></tr></table><div class="funcprototype-spacer"><EFBFBD></div></div>
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</td><td align="left">
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The constructor.
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</td></tr><tr><td align="left">
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<div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">
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<b class="fsfunc">~elfio</b>
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(</code></td><td><code>)</code>;</td><td><EFBFBD></td></tr></table><div class="funcprototype-spacer"><EFBFBD></div></div>
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</td><td align="left">
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The destructor.
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</td></tr><tr><td align="left">
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<div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">void <b class="fsfunc">create</b>
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(</code></td><td><var class="pdparam">file_class</var>, </td><td><EFBFBD></td></tr><tr><td><EFBFBD></td><td><var class="pdparam">encoding</var><code>)</code>;</td><td><EFBFBD></td></tr></table><div class="paramdef-list"><code>unsigned char <var class="pdparam">file_class</var>
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</code>;<br><code>unsigned char <var class="pdparam">encoding</var>
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</code>;</div><div class="funcprototype-spacer"><EFBFBD></div></div>
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</td><td align="left">
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Cleans and initializes empty <code class="classname">elfio</code> object.
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<em class="parameter"><code>file_class</code></em> is either ELFCLASS32 or ELFCLASS64.
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<em class="parameter"><code>file_class</code></em> is either ELFDATA2LSB or ELFDATA2MSB.
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</td></tr><tr><td align="left">
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<div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">bool <b class="fsfunc">load</b>
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(</code></td><td><var class="pdparam">file_name</var><code>)</code>;</td><td><EFBFBD></td></tr></table><div class="paramdef-list"><code>const std::string& <var class="pdparam">file_name</var>
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</code>;</div><div class="funcprototype-spacer"><EFBFBD></div></div>
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</td><td align="left">
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Initializes <code class="classname">elfio</code> object by loading data
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from ELF binary file. File name provided in <em class="parameter"><code>file_name</code></em>.
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Returns <span class="returnvalue">true</span> if the file was processed successfully.
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</td></tr><tr><td align="left">
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<div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">bool <b class="fsfunc">save</b>
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(</code></td><td><var class="pdparam">file_name</var><code>)</code>;</td><td><EFBFBD></td></tr></table><div class="paramdef-list"><code>const std::string& <var class="pdparam">file_name</var>
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</code>;</div><div class="funcprototype-spacer"><EFBFBD></div></div>
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</td><td align="left">
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Creates a file in ELF binary format. File name provided in <em class="parameter"><code>file_name</code></em>.
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Returns <span class="returnvalue">true</span> if the file was created successfully.
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</td></tr><tr><td align="left">
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<div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">unsigned char <b class="fsfunc">get_class</b>
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(</code></td><td><code>)</code>;</td><td><EFBFBD></td></tr></table><div class="funcprototype-spacer"><EFBFBD></div></div>
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</td><td align="left">
|
||
Returns ELF file class. Possible values are ELFCLASS32 or ELFCLASS64.
|
||
</td></tr><tr><td align="left">
|
||
<div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">unsigned char <b class="fsfunc">get_elf_version</b>
|
||
(</code></td><td><code>)</code>;</td><td><EFBFBD></td></tr></table><div class="funcprototype-spacer"><EFBFBD></div></div>
|
||
</td><td align="left">
|
||
Returns ELF file format version.
|
||
</td></tr><tr><td align="left">
|
||
<div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">unsigned char <b class="fsfunc">get_encoding</b>
|
||
(</code></td><td><code>)</code>;</td><td><EFBFBD></td></tr></table><div class="funcprototype-spacer"><EFBFBD></div></div>
|
||
</td><td align="left">
|
||
Returns ELF file format encoding. Possible values are ELFDATA2LSB and
|
||
ELFDATA2MSB.
|
||
</td></tr><tr><td align="left">
|
||
<div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">Elf_Word <b class="fsfunc">get_version</b>
|
||
(</code></td><td><code>)</code>;</td><td><EFBFBD></td></tr></table><div class="funcprototype-spacer"><EFBFBD></div></div>
|
||
</td><td align="left">
|
||
Identifies the object file version.
|
||
</td></tr><tr><td align="left">
|
||
<div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">Elf_Half <b class="fsfunc">get_header_size</b>
|
||
(</code></td><td><code>)</code>;</td><td><EFBFBD></td></tr></table><div class="funcprototype-spacer"><EFBFBD></div></div>
|
||
</td><td align="left">
|
||
Returns the ELF header's size in bytes.
|
||
</td></tr><tr><td align="left">
|
||
<div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">Elf_Half <b class="fsfunc">get_section_entry_size</b>
|
||
(</code></td><td><code>)</code>;</td><td><EFBFBD></td></tr></table><div class="funcprototype-spacer"><EFBFBD></div></div>
|
||
</td><td align="left">
|
||
Returns a section's entry size in ELF file header section table.
|
||
</td></tr><tr><td align="left">
|
||
<div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">Elf_Half <b class="fsfunc">get_segment_entry_size</b>
|
||
(</code></td><td><code>)</code>;</td><td><EFBFBD></td></tr></table><div class="funcprototype-spacer"><EFBFBD></div></div>
|
||
</td><td align="left">
|
||
Returns a segment's entry size in ELF file header program table.
|
||
</td></tr><tr><td align="left">
|
||
<div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">unsigned char <b class="fsfunc">get_os_abi</b>
|
||
(</code></td><td><code>)</code>;</td><td><EFBFBD></td></tr></table><div class="funcprototype-spacer"><EFBFBD></div></div>
|
||
</td><td align="left">
|
||
Returns operating system ABI identification.
|
||
</td></tr><tr><td align="left">
|
||
<div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">void <b class="fsfunc">set_os_abi</b>
|
||
(</code></td><td><var class="pdparam">value</var><code>)</code>;</td><td><EFBFBD></td></tr></table><div class="paramdef-list"><code>unsigned char <var class="pdparam">value</var>
|
||
</code>;</div><div class="funcprototype-spacer"><EFBFBD></div></div>
|
||
</td><td align="left">
|
||
Sets operating system ABI identification.
|
||
</td></tr><tr><td align="left">
|
||
<div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">unsigned char <b class="fsfunc">get_abi_version</b>
|
||
(</code></td><td><code>)</code>;</td><td><EFBFBD></td></tr></table><div class="funcprototype-spacer"><EFBFBD></div></div>
|
||
</td><td align="left">
|
||
Returns ABI version.
|
||
</td></tr><tr><td align="left">
|
||
<div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">void <b class="fsfunc">set_abi_version</b>
|
||
(</code></td><td><var class="pdparam">value</var><code>)</code>;</td><td><EFBFBD></td></tr></table><div class="paramdef-list"><code>unsigned char <var class="pdparam">value</var>
|
||
</code>;</div><div class="funcprototype-spacer"><EFBFBD></div></div>
|
||
</td><td align="left">
|
||
Sets ABI version.
|
||
</td></tr><tr><td align="left">
|
||
<div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">Elf_Half <b class="fsfunc">get_type</b>
|
||
(</code></td><td><code>)</code>;</td><td><EFBFBD></td></tr></table><div class="funcprototype-spacer"><EFBFBD></div></div>
|
||
</td><td align="left">
|
||
Returns the object file type.
|
||
</td></tr><tr><td align="left">
|
||
<div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">void <b class="fsfunc">set_type</b>
|
||
(</code></td><td><var class="pdparam">value</var><code>)</code>;</td><td><EFBFBD></td></tr></table><div class="paramdef-list"><code>Elf_Half <var class="pdparam">value</var>
|
||
</code>;</div><div class="funcprototype-spacer"><EFBFBD></div></div>
|
||
</td><td align="left">
|
||
Sets the object file type.
|
||
</td></tr><tr><td align="left">
|
||
<div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">Elf_Half <b class="fsfunc">get_machine</b>
|
||
(</code></td><td><code>)</code>;</td><td><EFBFBD></td></tr></table><div class="funcprototype-spacer"><EFBFBD></div></div>
|
||
</td><td align="left">
|
||
Returns the object file's architecture.
|
||
</td></tr><tr><td align="left">
|
||
<div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">void <b class="fsfunc">set_machine</b>
|
||
(</code></td><td><var class="pdparam">value</var><code>)</code>;</td><td><EFBFBD></td></tr></table><div class="paramdef-list"><code>Elf_Half <var class="pdparam">value</var>
|
||
</code>;</div><div class="funcprototype-spacer"><EFBFBD></div></div>
|
||
</td><td align="left">
|
||
Sets the object file's architecture.
|
||
</td></tr><tr><td align="left">
|
||
<div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">Elf_Word <b class="fsfunc">get_flags</b>
|
||
(</code></td><td><code>)</code>;</td><td><EFBFBD></td></tr></table><div class="funcprototype-spacer"><EFBFBD></div></div>
|
||
</td><td align="left">
|
||
Returns processor-specific flags associated with the file.
|
||
</td></tr><tr><td align="left">
|
||
<div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">void <b class="fsfunc">set_flags</b>
|
||
(</code></td><td><var class="pdparam">value</var><code>)</code>;</td><td><EFBFBD></td></tr></table><div class="paramdef-list"><code>Elf_Word <var class="pdparam">value</var>
|
||
</code>;</div><div class="funcprototype-spacer"><EFBFBD></div></div>
|
||
</td><td align="left">
|
||
Sets processor-specific flags associated with the file.
|
||
</td></tr></tbody></table></div></div><p><br class="table-break">
|
||
|
||
|
||
</p><div class="table"><a name="id9251712"></a><p class="title"><b>Table<EFBFBD>2.3.<2E>Class <code class="classname">elfio</code> member functions (continue)</b></p><div class="table-contents"><table summary="Class elfio member functions (continue)" border="1"><colgroup><col align="left" class="c1"><col align="left" class="c2"></colgroup><thead><tr><th align="center">Function</th><th align="center">Description</th></tr></thead><tbody><tr><td align="left">
|
||
<div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">Elf64_Addr <b class="fsfunc">get_entry</b>
|
||
(</code></td><td><code>)</code>;</td><td><EFBFBD></td></tr></table><div class="funcprototype-spacer"><EFBFBD></div></div>
|
||
</td><td align="left">
|
||
Returns the virtual address to which the system first transfers control.
|
||
</td></tr><tr><td align="left">
|
||
<div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">void <b class="fsfunc">set_entry</b>
|
||
(</code></td><td><var class="pdparam">value</var><code>)</code>;</td><td><EFBFBD></td></tr></table><div class="paramdef-list"><code>Elf64_Addr <var class="pdparam">value</var>
|
||
</code>;</div><div class="funcprototype-spacer"><EFBFBD></div></div>
|
||
</td><td align="left">
|
||
Sets the virtual address to which the system first transfers control.
|
||
</td></tr><tr><td align="left">
|
||
<div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">Elf64_Off <b class="fsfunc">get_sections_offset</b>
|
||
(</code></td><td><code>)</code>;</td><td><EFBFBD></td></tr></table><div class="funcprototype-spacer"><EFBFBD></div></div>
|
||
</td><td align="left">
|
||
Returns the section header table's file offset in bytes.
|
||
</td></tr><tr><td align="left">
|
||
<div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">void <b class="fsfunc">set_sections_offset</b>
|
||
(</code></td><td><var class="pdparam">value</var><code>)</code>;</td><td><EFBFBD></td></tr></table><div class="paramdef-list"><code>Elf64_Off <var class="pdparam">value</var>
|
||
</code>;</div><div class="funcprototype-spacer"><EFBFBD></div></div>
|
||
</td><td align="left">
|
||
Returns default entry size for .
|
||
</td></tr><tr><td align="left">
|
||
<div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">Elf64_Off <b class="fsfunc">get_segments_offset</b>
|
||
(</code></td><td><code>)</code>;</td><td><EFBFBD></td></tr></table><div class="funcprototype-spacer"><EFBFBD></div></div>
|
||
</td><td align="left">
|
||
Returns the program header table's file offset in bytes.
|
||
</td></tr><tr><td align="left">
|
||
<div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">void <b class="fsfunc">set_segments_offset</b>
|
||
(</code></td><td><var class="pdparam">value</var><code>)</code>;</td><td><EFBFBD></td></tr></table><div class="paramdef-list"><code>Elf64_Off <var class="pdparam">value</var>
|
||
</code>;</div><div class="funcprototype-spacer"><EFBFBD></div></div>
|
||
</td><td align="left">
|
||
Sets the program header table's file offset in bytes.
|
||
</td></tr><tr><td align="left">
|
||
<div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">Elf_Half <b class="fsfunc">get_section_name_str_index</b>
|
||
(</code></td><td><code>)</code>;</td><td><EFBFBD></td></tr></table><div class="funcprototype-spacer"><EFBFBD></div></div>
|
||
</td><td align="left">
|
||
Returns the section header table index of the entry associated with
|
||
the section name string table.
|
||
</td></tr><tr><td align="left">
|
||
<div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">void <b class="fsfunc">set_section_name_str_index</b>
|
||
(</code></td><td><var class="pdparam">value</var><code>)</code>;</td><td><EFBFBD></td></tr></table><div class="paramdef-list"><code>Elf_Half <var class="pdparam">value</var>
|
||
</code>;</div><div class="funcprototype-spacer"><EFBFBD></div></div>
|
||
</td><td align="left">
|
||
Sets the section header table index of the entry associated with
|
||
the section name string table.
|
||
</td></tr><tr><td align="left">
|
||
<div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">endianess_convertor& <b class="fsfunc">get_convertor</b>
|
||
(</code></td><td><code>)</code>;</td><td><EFBFBD></td></tr></table><div class="funcprototype-spacer"><EFBFBD></div></div>
|
||
</td><td align="left">
|
||
Returns endianess convertor reference for the specific
|
||
<code class="classname">elfio</code> object instance.
|
||
</td></tr></tbody></table></div></div><p><br class="table-break">
|
||
|
||
</p></div></div></div><div class="chapter" title="Chapter<65>3.<2E> IELFO - ELF File Producer Interface"><div class="titlepage"><div><div><h2 class="title"><a name="ielfo"></a>Chapter<EFBFBD>3.<2E>
|
||
<code class="classname">IELFO</code> - ELF File Producer Interface
|
||
</h2></div></div></div><p>
|
||
The ELFIO library can help you build a very short ELF executable file.
|
||
This chapter shows how to build an executable file that will run on
|
||
x86 Linux machines and print "Hello World!" on your console.
|
||
</p><p>
|
||
Just as with the reader, the first step is to get
|
||
a pointer onto the ELF File Writer (Producer):
|
||
</p><pre class="programlisting">
|
||
|
||
IELFO* pELFO;
|
||
ELFIO::GetInstance()->CreateELFO( &pELFO );
|
||
</pre><p>
|
||
</p><p>
|
||
Before continuing, the library must be informed about the main
|
||
attributes of the executable file to be built. To do this, declare
|
||
that the executable ELF file will run on a 32 bit x86 machine; has little
|
||
endian encoding and uses the current version of the ELF file format:
|
||
</p><pre class="programlisting">
|
||
|
||
// You can't proceed without this function call!
|
||
pELFO->SetAttr( ELFCLASS32, ELFDATA2LSB, EV_CURRENT,
|
||
ET_EXEC, EM_386, EV_CURRENT, 0 );
|
||
</pre><p>
|
||
</p><p>
|
||
Some sections of an ELF executable file should reside in the program
|
||
segments. To create this loadable segment call the
|
||
<code class="methodname">AddSegment()</code> function.
|
||
</p><pre class="programlisting">
|
||
|
||
// Create a loadable segment
|
||
IELFOSegment* pSegment = pELFO->AddSegment( PT_LOAD,
|
||
0x08040000,
|
||
0x08040000,
|
||
PF_X | PF_R,
|
||
0x1000 );
|
||
</pre><p>
|
||
</p><p>
|
||
The following segment serves as a placeholder for our code section.
|
||
To create this code section call the AddSection() function:
|
||
</p><pre class="programlisting">
|
||
|
||
// Create code section
|
||
IELFOSection* pTextSec = pELFO->AddSection( ".text",
|
||
SHT_PROGBITS,
|
||
SHF_ALLOC | SHF_EXECINSTR,
|
||
0,
|
||
0x10,
|
||
0 );
|
||
</pre><p>
|
||
</p><p>
|
||
Then, add the executable code for the section:
|
||
</p><pre class="programlisting">
|
||
|
||
char text[] =
|
||
{ '\xB8', '\x04', '\x00', '\x00', '\x00', // mov eax, 4
|
||
'\xBB', '\x01', '\x00', '\x00', '\x00', // mov ebx, 1
|
||
'\xB9', '\xFD', '\x00', '\x04', '\x08', // mov ecx, msg
|
||
'\xBA', '\x0E', '\x00', '\x00', '\x00', // mov edx, 14
|
||
'\xCD', '\x80', // int 0x80
|
||
'\xB8', '\x01', '\x00', '\x00', '\x00', // mov eax, 1
|
||
'\xCD', '\x80', // int 0x80
|
||
'\x48', '\x65', '\x6C', '\x6C', '\x6F', // db 'Hello'
|
||
'\x2C', '\x20', '\x57', '\x6F', '\x72', // db ', Wor'
|
||
'\x6C', '\x64', '\x21', '\x0A' // db 'ld!', 10
|
||
};
|
||
pTextSec->SetData( text, sizeof( text ) );
|
||
</pre><p>
|
||
</p><p>
|
||
Next, this code section is put into the loadable segment:
|
||
</p><pre class="programlisting">
|
||
|
||
// Add code section into program segment
|
||
pSegment->AddSection( pTextSec );
|
||
pTextSec->Release();
|
||
pSegment->Release();
|
||
</pre><p>
|
||
</p><p>
|
||
Finally, define the start address of the program
|
||
and create the result file:
|
||
</p><pre class="programlisting">
|
||
|
||
// Set program entry point
|
||
pELFO->SetEntry( 0x08040000 );
|
||
// Create ELF file
|
||
pELFO->Save( "test.elf" );
|
||
pELFO->Release();
|
||
</pre><p>
|
||
</p><p>
|
||
Please note: Call the <code class="methodname">Release()</code> functions
|
||
for each interface you have used.
|
||
This will free all resources the ELFIO library has created.
|
||
</p><p>
|
||
Now compile the program and run it. The result is a new ELF file
|
||
called "test.elf". The size of this working executable file is only
|
||
267 bytes! Run it on your Linux machine with the following commands:
|
||
</p><pre class="programlisting">
|
||
|
||
[Writer]$ ./Writer
|
||
[Writer]$ chmod +x test.elf
|
||
[Writer]$ ./test.elf
|
||
Hello, World!
|
||
|
||
</pre><p>
|
||
</p><p>
|
||
The full text for this program can be found in the "Writer" directory.
|
||
Also, in the "Examples" directory, two other programs "WriteObj"
|
||
and "WriteObj2" demonstrate the creation of ELF object files.
|
||
</p></div></div></body></html>
|