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Serge Lamikhov-Center 2012-02-19 16:24:34 +02:00
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<preface id="introduction">
<title>Introduction</title>
<para>
ELFIO is a C++ library for reading and generating files in the ELF binary
format. This library is not based on any other product. It is also
platform independent. The library uses standard ANSI C++ constructions
and runs on a wide variety of architectures.
ELFIO is a C++ library for reading and generating files in ELF binary
format. This library is independent and does not require any other product.
It is also cross-platform - the library uses standard ANSI C++ constructions
and runs on wide variety of architectures.
</para>
<para>
While the library's implementation does make your work easier: a basic
While the library's implementation does make your work much easier: basic
knowledge of the ELF binary format is required. Information about ELF
format can be found widely on the web.
</para>
@ -45,7 +45,7 @@
steps are required. To make your application be aware about the
ELFIO classes and types declarations, just include <filename>elfio.hpp</filename> header file.
All ELFIO library declarations reside in ELFIO namespace.
So, our tutorial code starts from this:
So, this tutorial code starts from the following code:
</para>
<programlistingco>
<areaspec>
@ -82,7 +82,7 @@ int main( int argc, char** argv )
This chapter will explain how to work with the reader portion
of the ELFIO library. The first step would be creation of the <classname>elfio</classname>
class instance. The <classname>elfio</classname> constructor does not
recieve any parameters. After that, we initialize the instance by
receive any parameters. After that, we initialize the instance by
loading an ELF file with name passed as a parameter.
<programlistingco>
<areaspec>
@ -256,7 +256,7 @@ int main( int argc, char** argv )
<classname>note_section_accessor</classname>
</para></listitem>
</itemizedlist>
Defenetly, it is possible to extend the library by implementing additional
Definitely, it is possible to extend the library by implementing additional
accessors serving particular purposes.
</para>
<para>

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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.
<code class="classname">IELFO</code> - ELF File Producer Interface
</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>
ELFIO is a C++ library for reading and generating files in ELF binary
format. This library is independent and does not require any other product.
It is also cross-platform - the library uses standard ANSI C++ constructions
and runs on wide variety of architectures.
</p><p>
While the library's implementation does make your work much easier: basic
knowledge of the ELF binary format is required. Information about ELF
format can be found widely on the web.
</p></div><div class="chapter" title="Chapter 1. Getting Started With ELFIO"><div class="titlepage"><div><div><h2 class="title"><a name="get-started"></a>Chapter 1. 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>
The ELFIO library is a header only library. No preparatory compilation
steps are required. To make your application be aware about the
ELFIO classes and types declarations, just include <code class="filename">elfio.hpp</code> header file.
All ELFIO library declarations reside in ELFIO namespace.
So, this tutorial code starts from the following code:
</p><div class="programlistingco"><pre class="programlisting">
#include &lt;iostream&gt;
#include &lt;elfio.hpp&gt;
using namespace ELFIO;
int main( int argc, char** argv )
{
if ( argc != 2 ) {
std::cout &lt;&lt; "Usage: tutorial &lt;elf_file&gt;" &lt;&lt; std::endl;
return 1;
}
</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>
Include <code class="filename">elfio.hpp</code> header file
</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>
The ELFIO namespace usage
</p></td></tr></table></div></div><p>
This chapter will explain how to work with the reader portion
of the ELFIO library. The first step would be creation of the <code class="classname">elfio</code>
class instance. The <code class="classname">elfio</code> constructor does not
receive any parameters. After that, we initialize the instance by
loading an ELF file with name passed as a parameter.
</p><div class="programlistingco"><pre class="programlisting">
// Create an elfio reader
elfio reader;
// Load ELF data
if ( !reader.load( argv[1] ) ) {
std::cout &lt;&lt; "Can't find or process ELF file " &lt;&lt; argv[1] &lt;&lt; std::endl;
return 2;
}
</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>
Create <code class="classname">elfio</code> class instance
</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>
Initialize the instance by loading ELF file. The function
<code class="function">load</code> returns
<span class="returnvalue">true</span>
if the ELF file was found and processed successfully. It returns
<span class="returnvalue">false</span> otherwise.
</p></td></tr></table></div></div><p>
</p><p>
From here, ELF header properties are accessible. This makes it possible
to request file parameters such as encoding, machine type,
entry point, etc. To get the class and the encoding of the file use:
</p><div class="programlistingco"><pre class="programlisting">
// Print ELF file properties
std::cout &lt;&lt; "ELF file class : ";
if ( reader.get_class() == ELFCLASS32 )
std::cout &lt;&lt; "ELF32" &lt;&lt; std::endl;
else
std::cout &lt;&lt; "ELF64" &lt;&lt; std::endl;
std::cout &lt;&lt; "ELF file encoding : ";
if ( reader.get_encoding() == ELFDATA2LSB )
std::cout &lt;&lt; "Little endian" &lt;&lt; std::endl;
else
std::cout &lt;&lt; "Big endian" &lt;&lt; std::endl;
</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>
Member function <code class="function">get_class()</code> returns ELF file
class. Possible values are <code class="constant">ELFCLASS32</code> or
<code class="constant">ELFCLASS64</code>.
</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>
Member function <code class="function">get_encoding()</code> returns ELF file
format encoding. Possible values are <code class="constant">ELFDATA2LSB</code>
and <code class="constant">ELFDATA2MSB</code>.
</p></td></tr></table></div></div><p>
</p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>
Standard ELF types, flags and constants
are defined in the <code class="filename">elf_types.hpp</code> header file.
This file is included automatically into the project.
For example: <code class="constant">ELFCLASS32</code>,
<code class="constant">ELFCLASS64</code> constants define a value for 32/64 bit
architectures. <code class="constant">ELFDATA2LSB</code> and
<code class="constant">ELFDATA2MSB</code> constants define value
for little and big endian encoding.
</p></div><p>
ELF binary files may consist of several sections. Each section has it's own
responsibility: some contain executable code; others describe program
dependencies; others symbol tables and so on. See ELF binary format
documentation for a full description of each section.
</p><p>
The following code demonstrates how to find out the amount of sections
the ELF file contains. The code also presents how to access particular
section properties like names and sizes:
</p><pre class="programlisting">
// Print ELF file sections info
Elf_Half sec_num = reader.sections.size();
std::cout &lt;&lt; "Number of sections: " &lt;&lt; sec_num &lt;&lt; std::endl;
for ( int i = 0; i &lt; sec_num; ++i ) {
const section* psec = reader.sections[i];
std::cout &lt;&lt; " [" &lt;&lt; i &lt;&lt; "] "
&lt;&lt; psec-&gt;get_name()
&lt;&lt; "\t"
&lt;&lt; psec-&gt;get_size()
&lt;&lt; std::endl;
// Access to section's data
// const char* p = reader.sections[i]-&gt;get_data()
}
</pre><p>
</p><p>
<code class="methodname">sections</code> member of <code class="classname">reader</code>
object permits to obtain number of sections the ELF file contains. It
also serves for getting access to individual section by using
<code class="methodname">operator[]</code>, which returns a pointer to
corresponding section's interface.
</p><p>
Similarly, segments of the ELF file can be processed:
</p><pre class="programlisting">
// Print ELF file segments info
Elf_Half seg_num = reader.segments.size();
std::cout &lt;&lt; "Number of segments: " &lt;&lt; seg_num &lt;&lt; std::endl;
for ( int i = 0; i &lt; seg_num; ++i ) {
const segment* pseg = reader.segments[i];
std::cout &lt;&lt; " [" &lt;&lt; i &lt;&lt; "] 0x" &lt;&lt; std::hex
&lt;&lt; pseg-&gt;get_flags()
&lt;&lt; "\t0x"
&lt;&lt; pseg-&gt;get_virtual_address()
&lt;&lt; "\t0x"
&lt;&lt; pseg-&gt;get_file_size()
&lt;&lt; "\t0x"
&lt;&lt; pseg-&gt;get_memory_size()
&lt;&lt; std::endl;
// Access to segments's data
// const char* p = reader.segments[i]-&gt;get_data()
}
</pre><p>
In this case, segments' attributes and data are obtained by using
<code class="methodname">segments</code> member of the <code class="classname">reader</code>.
</p><p>
The full text of this example comes together with ELFIO library
distribution.
</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>
To simplify creation and interpretation of the ELF sections' data,
the ELFIO library comes with auxiliary classes - accessors. To the moment
of this document writing, the following accessors are available:
</p><div class="itemizedlist"><ul class="itemizedlist" type="opencircle"><li class="listitem" style="list-style-type: circle"><p>
<code class="classname">string_section_accessor</code>
</p></li><li class="listitem" style="list-style-type: circle"><p>
<code class="classname">symbol_section_accessor</code>
</p></li><li class="listitem" style="list-style-type: circle"><p>
<code class="classname">relocation_section_accessor</code>
</p></li><li class="listitem" style="list-style-type: circle"><p>
<code class="classname">note_section_accessor</code>
</p></li></ul></div><p>
Definitely, it is possible to extend the library by implementing additional
accessors serving particular purposes.
</p><p>
Let's see how the accessors can be used with the previous ELF file reader
example. For this example purposes, we will print out all symbols in a
symbol section.
</p><pre class="programlisting">
if ( psec-&gt;get_type() == SHT_SYMTAB ) {
const symbol_section_accessor symbols( reader, psec );
for ( unsigned int j = 0; j &lt; symbols.get_symbols_num(); ++j ) {
std::string name;
Elf64_Addr value;
Elf_Xword size;
unsigned char bind;
unsigned char type;
Elf_Half section_index;
unsigned char other;
symbols.get_symbol( j, name, value, size, bind,
type, section_index, other );
std::cout &lt;&lt; j &lt;&lt; " " &lt;&lt; name &lt;&lt; std::endl;
}
}
</pre><p>
We create <code class="classname">symbol_section_accessor</code> instance first.
Usually, accessors receive the <code class="classname">elfio</code> and
<code class="classname">section*</code> parameters for their constructors.
<code class="methodname">get_symbol</code> is used to retrieve a particular entry
in the symbol table.
</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>
The source code for the ELF Dumping Utility can be found in
the "Examples" directory; included there are more examples on how
to use different ELFIO reader interfaces.
</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>
The ELFIO library is a header only library. No preparatory compilation
steps are required. To make your application be aware about the
ELFIO classes and types declarations, just include <code class="filename">elfio.hpp</code> header file.
All ELFIO library declarations reside in ELFIO namespace.
So, our tutorial code starts from this:
</p></div></div><div class="chapter" title="Chapter 2. ELFIO Library Classes"><div class="titlepage"><div><div><h2 class="title"><a name="section-interface"></a>Chapter 2. 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>
The ELFIO library consists of two independent parts: ELF File Reader
</p><p>
</p><div class="table"><a name="id9253246"></a><p class="title"><b>Table 2.1. 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">
sections
</td><td align="left">
A container that stores pointers to ELF file section instances.
implementing operator[] and size() f
</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">bool <b class="fsfunc">load</b>
(</code></td><td><var class="pdparam">file_name</var><code>)</code>;</td><td> </td></tr></table><div class="paramdef-list"><code>const std::string&amp; <var class="pdparam">file_name</var>
</code>;</div><div class="funcprototype-spacer"> </div></div>
</td><td align="left">
Initializes <code class="classname">elfio</code> object by loading data
from ELF binary file. File name provided in <em class="parameter"><code>file_name</code></em>.
Returns <span class="returnvalue">true</span> if the file was processed successfully.
</td></tr></tbody></table></div></div><p><br class="table-break">
</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>
The ELFIO library consists of two independent parts: ELF File Reader
(<code class="classname">IELFI</code>)
and ELF Producer (<code class="classname">IELFO</code>).
Each is represented by its own set of interfaces.
The library does not contain any classes that need to be explicitly
instantiated. ELFIO itself provides the interfaces that
are used to access the library's functionality.
</p><p>
</p><div class="table"><a name="id9240401"></a><p class="title"><b>Table 2.2. 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">
<div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">
<b class="fsfunc">elfio</b>
(</code></td><td><code>)</code>;</td><td> </td></tr></table><div class="funcprototype-spacer"> </div></div>
</td><td align="left">
The constructor.
</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">
<b class="fsfunc">~elfio</b>
(</code></td><td><code>)</code>;</td><td> </td></tr></table><div class="funcprototype-spacer"> </div></div>
</td><td align="left">
The destructor.
</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">create</b>
(</code></td><td><var class="pdparam">file_class</var>, </td><td> </td></tr><tr><td> </td><td><var class="pdparam">encoding</var><code>)</code>;</td><td> </td></tr></table><div class="paramdef-list"><code>unsigned char <var class="pdparam">file_class</var>
</code>;<br><code>unsigned char <var class="pdparam">encoding</var>
</code>;</div><div class="funcprototype-spacer"> </div></div>
</td><td align="left">
Cleans and initializes empty <code class="classname">elfio</code> object.
<em class="parameter"><code>file_class</code></em> is either ELFCLASS32 or ELFCLASS64.
<em class="parameter"><code>file_class</code></em> is either ELFDATA2LSB or 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">bool <b class="fsfunc">load</b>
(</code></td><td><var class="pdparam">file_name</var><code>)</code>;</td><td> </td></tr></table><div class="paramdef-list"><code>const std::string&amp; <var class="pdparam">file_name</var>
</code>;</div><div class="funcprototype-spacer"> </div></div>
</td><td align="left">
Initializes <code class="classname">elfio</code> object by loading data
from ELF binary file. File name provided in <em class="parameter"><code>file_name</code></em>.
Returns <span class="returnvalue">true</span> if the file was processed successfully.
</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">bool <b class="fsfunc">save</b>
(</code></td><td><var class="pdparam">file_name</var><code>)</code>;</td><td> </td></tr></table><div class="paramdef-list"><code>const std::string&amp; <var class="pdparam">file_name</var>
</code>;</div><div class="funcprototype-spacer"> </div></div>
</td><td align="left">
Creates a file in ELF binary format. File name provided in <em class="parameter"><code>file_name</code></em>.
Returns <span class="returnvalue">true</span> if the file was created successfully.
</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_class</b>
(</code></td><td><code>)</code>;</td><td> </td></tr></table><div class="funcprototype-spacer"> </div></div>
</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> </td></tr></table><div class="funcprototype-spacer"> </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> </td></tr></table><div class="funcprototype-spacer"> </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> </td></tr></table><div class="funcprototype-spacer"> </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> </td></tr></table><div class="funcprototype-spacer"> </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> </td></tr></table><div class="funcprototype-spacer"> </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> </td></tr></table><div class="funcprototype-spacer"> </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> </td></tr></table><div class="funcprototype-spacer"> </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> </td></tr></table><div class="paramdef-list"><code>unsigned char <var class="pdparam">value</var>
</code>;</div><div class="funcprototype-spacer"> </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> </td></tr></table><div class="funcprototype-spacer"> </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> </td></tr></table><div class="paramdef-list"><code>unsigned char <var class="pdparam">value</var>
</code>;</div><div class="funcprototype-spacer"> </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> </td></tr></table><div class="funcprototype-spacer"> </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> </td></tr></table><div class="paramdef-list"><code>Elf_Half <var class="pdparam">value</var>
</code>;</div><div class="funcprototype-spacer"> </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> </td></tr></table><div class="funcprototype-spacer"> </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> </td></tr></table><div class="paramdef-list"><code>Elf_Half <var class="pdparam">value</var>
</code>;</div><div class="funcprototype-spacer"> </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> </td></tr></table><div class="funcprototype-spacer"> </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> </td></tr></table><div class="paramdef-list"><code>Elf_Word <var class="pdparam">value</var>
</code>;</div><div class="funcprototype-spacer"> </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 2.3. 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> </td></tr></table><div class="funcprototype-spacer"> </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> </td></tr></table><div class="paramdef-list"><code>Elf64_Addr <var class="pdparam">value</var>
</code>;</div><div class="funcprototype-spacer"> </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> </td></tr></table><div class="funcprototype-spacer"> </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> </td></tr></table><div class="paramdef-list"><code>Elf64_Off <var class="pdparam">value</var>
</code>;</div><div class="funcprototype-spacer"> </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> </td></tr></table><div class="funcprototype-spacer"> </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> </td></tr></table><div class="paramdef-list"><code>Elf64_Off <var class="pdparam">value</var>
</code>;</div><div class="funcprototype-spacer"> </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> </td></tr></table><div class="funcprototype-spacer"> </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> </td></tr></table><div class="paramdef-list"><code>Elf_Half <var class="pdparam">value</var>
</code>;</div><div class="funcprototype-spacer"> </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&amp; <b class="fsfunc">get_convertor</b>
(</code></td><td><code>)</code>;</td><td> </td></tr></table><div class="funcprototype-spacer"> </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 3.  IELFO - ELF File Producer Interface"><div class="titlepage"><div><div><h2 class="title"><a name="ielfo"></a>Chapter 3. 
<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()-&gt;CreateELFO( &amp;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-&gt;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-&gt;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-&gt;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-&gt;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-&gt;AddSection( pTextSec );
pTextSec-&gt;Release();
pSegment-&gt;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-&gt;SetEntry( 0x08040000 );
// Create ELF file
pELFO-&gt;Save( "test.elf" );
pELFO-&gt;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>

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