1097 lines
41 KiB
C++
1097 lines
41 KiB
C++
/*
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Copyright (C) 2001-present by Serge Lamikhov-Center
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in
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all copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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THE SOFTWARE.
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*/
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#ifndef ELFIO_HPP
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#define ELFIO_HPP
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#include <string>
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#include <iostream>
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#include <fstream>
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#include <functional>
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#include <algorithm>
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#include <array>
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#include <vector>
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#include <deque>
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#include <memory>
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#include <elfio/elf_types.hpp>
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#include <elfio/elfio_version.hpp>
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#include <elfio/elfio_utils.hpp>
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#include <elfio/elfio_header.hpp>
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#include <elfio/elfio_section.hpp>
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#include <elfio/elfio_segment.hpp>
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#include <elfio/elfio_strings.hpp>
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#define ELFIO_HEADER_ACCESS_GET( TYPE, FNAME ) \
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TYPE get_##FNAME() const { return header ? ( header->get_##FNAME() ) : 0; }
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#define ELFIO_HEADER_ACCESS_GET_SET( TYPE, FNAME ) \
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TYPE get_##FNAME() const \
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{ \
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return header ? ( header->get_##FNAME() ) : 0; \
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} \
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void set_##FNAME( TYPE val ) \
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{ \
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if ( header ) { \
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header->set_##FNAME( val ); \
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} \
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}
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namespace ELFIO {
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//------------------------------------------------------------------------------
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class elfio
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{
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public:
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//------------------------------------------------------------------------------
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elfio() noexcept : sections( this ), segments( this )
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{
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create( ELFCLASS32, ELFDATA2LSB );
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}
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explicit elfio( compression_interface* compression ) noexcept
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: sections( this ), segments( this ),
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compression( std::shared_ptr<compression_interface>( compression ) )
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{
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elfio();
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}
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elfio( elfio&& other ) noexcept
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: sections( this ), segments( this ),
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current_file_pos( other.current_file_pos )
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{
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header = std::move( other.header );
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sections_ = std::move( other.sections_ );
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segments_ = std::move( other.segments_ );
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convertor = std::move( other.convertor );
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addr_translator = std::move( other.addr_translator );
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compression = std::move( other.compression );
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other.header = nullptr;
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other.sections_.clear();
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other.segments_.clear();
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other.compression = nullptr;
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}
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elfio& operator=( elfio&& other ) noexcept
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{
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if ( this != &other ) {
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header = std::move( other.header );
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sections_ = std::move( other.sections_ );
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segments_ = std::move( other.segments_ );
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convertor = std::move( other.convertor );
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addr_translator = std::move( other.addr_translator );
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current_file_pos = other.current_file_pos;
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compression = std::move( other.compression );
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other.current_file_pos = 0;
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other.header = nullptr;
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other.compression = nullptr;
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other.sections_.clear();
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other.segments_.clear();
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}
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return *this;
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}
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//------------------------------------------------------------------------------
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// clang-format off
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elfio( const elfio& ) = delete;
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elfio& operator=( const elfio& ) = delete;
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~elfio() = default;
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// clang-format on
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//------------------------------------------------------------------------------
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void create( unsigned char file_class, unsigned char encoding )
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{
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sections_.clear();
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segments_.clear();
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convertor.setup( encoding );
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header = create_header( file_class, encoding );
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create_mandatory_sections();
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}
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void set_address_translation( std::vector<address_translation>& addr_trans )
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{
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addr_translator.set_address_translation( addr_trans );
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}
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//------------------------------------------------------------------------------
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bool load( const std::string& file_name, bool is_lazy = false )
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{
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pstream = std::make_unique<std::ifstream>();
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pstream->open( file_name.c_str(), std::ios::in | std::ios::binary );
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if ( pstream == nullptr || !*pstream ) {
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return false;
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}
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bool ret = load( *pstream, is_lazy );
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if ( !is_lazy ) {
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pstream.reset();
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}
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return ret;
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}
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//------------------------------------------------------------------------------
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bool load( std::istream& stream, bool is_lazy = false )
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{
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sections_.clear();
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segments_.clear();
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std::array<char, EI_NIDENT> e_ident = { 0 };
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// Read ELF file signature
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stream.seekg( addr_translator[0] );
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stream.read( e_ident.data(), sizeof( e_ident ) );
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// Is it ELF file?
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if ( stream.gcount() != sizeof( e_ident ) ||
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e_ident[EI_MAG0] != ELFMAG0 || e_ident[EI_MAG1] != ELFMAG1 ||
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e_ident[EI_MAG2] != ELFMAG2 || e_ident[EI_MAG3] != ELFMAG3 ) {
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return false;
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}
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if ( ( e_ident[EI_CLASS] != ELFCLASS64 ) &&
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( e_ident[EI_CLASS] != ELFCLASS32 ) ) {
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return false;
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}
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if ( ( e_ident[EI_DATA] != ELFDATA2LSB ) &&
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( e_ident[EI_DATA] != ELFDATA2MSB ) ) {
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return false;
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}
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convertor.setup( e_ident[EI_DATA] );
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header = create_header( e_ident[EI_CLASS], e_ident[EI_DATA] );
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if ( nullptr == header ) {
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return false;
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}
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if ( !header->load( stream ) ) {
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return false;
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}
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load_sections( stream, is_lazy );
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bool is_still_good = load_segments( stream, is_lazy );
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return is_still_good;
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}
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//------------------------------------------------------------------------------
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bool save( const std::string& file_name )
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{
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std::ofstream stream;
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stream.open( file_name.c_str(), std::ios::out | std::ios::binary );
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if ( !stream ) {
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return false;
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}
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return save( stream );
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}
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//------------------------------------------------------------------------------
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bool save( std::ostream& stream )
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{
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if ( !stream || header == nullptr ) {
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return false;
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}
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// Define layout specific header fields
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// The position of the segment table is fixed after the header.
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// The position of the section table is variable and needs to be fixed
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// before saving.
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header->set_segments_num( segments.size() );
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header->set_segments_offset(
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segments.size() > 0 ? header->get_header_size() : 0 );
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header->set_sections_num( sections.size() );
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header->set_sections_offset( 0 );
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// Layout the first section right after the segment table
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current_file_pos =
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header->get_header_size() +
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header->get_segment_entry_size() *
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static_cast<Elf_Xword>( header->get_segments_num() );
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calc_segment_alignment();
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bool is_still_good = layout_segments_and_their_sections();
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is_still_good = is_still_good && layout_sections_without_segments();
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is_still_good = is_still_good && layout_section_table();
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is_still_good = is_still_good && save_header( stream );
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is_still_good = is_still_good && save_sections( stream );
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is_still_good = is_still_good && save_segments( stream );
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return is_still_good;
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}
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//------------------------------------------------------------------------------
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// ELF header access functions
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ELFIO_HEADER_ACCESS_GET( unsigned char, class );
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ELFIO_HEADER_ACCESS_GET( unsigned char, elf_version );
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ELFIO_HEADER_ACCESS_GET( unsigned char, encoding );
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ELFIO_HEADER_ACCESS_GET( Elf_Word, version );
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ELFIO_HEADER_ACCESS_GET( Elf_Half, header_size );
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ELFIO_HEADER_ACCESS_GET( Elf_Half, section_entry_size );
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ELFIO_HEADER_ACCESS_GET( Elf_Half, segment_entry_size );
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ELFIO_HEADER_ACCESS_GET_SET( unsigned char, os_abi );
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ELFIO_HEADER_ACCESS_GET_SET( unsigned char, abi_version );
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ELFIO_HEADER_ACCESS_GET_SET( Elf_Half, type );
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ELFIO_HEADER_ACCESS_GET_SET( Elf_Half, machine );
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ELFIO_HEADER_ACCESS_GET_SET( Elf_Word, flags );
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ELFIO_HEADER_ACCESS_GET_SET( Elf64_Addr, entry );
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ELFIO_HEADER_ACCESS_GET_SET( Elf64_Off, sections_offset );
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ELFIO_HEADER_ACCESS_GET_SET( Elf64_Off, segments_offset );
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ELFIO_HEADER_ACCESS_GET_SET( Elf_Half, section_name_str_index );
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//------------------------------------------------------------------------------
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const endianess_convertor& get_convertor() const { return convertor; }
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//------------------------------------------------------------------------------
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Elf_Xword get_default_entry_size( Elf_Word section_type ) const
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{
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switch ( section_type ) {
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case SHT_RELA:
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if ( header->get_class() == ELFCLASS64 ) {
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return sizeof( Elf64_Rela );
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}
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else {
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return sizeof( Elf32_Rela );
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}
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case SHT_REL:
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if ( header->get_class() == ELFCLASS64 ) {
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return sizeof( Elf64_Rel );
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}
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else {
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return sizeof( Elf32_Rel );
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}
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case SHT_SYMTAB:
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if ( header->get_class() == ELFCLASS64 ) {
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return sizeof( Elf64_Sym );
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}
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else {
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return sizeof( Elf32_Sym );
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}
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case SHT_DYNAMIC:
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if ( header->get_class() == ELFCLASS64 ) {
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return sizeof( Elf64_Dyn );
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}
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else {
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return sizeof( Elf32_Dyn );
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}
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default:
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return 0;
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}
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}
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//------------------------------------------------------------------------------
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//! returns an empty string if no problems are detected,
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//! or a string containing an error message if problems are found,
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//! with one error per line.
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std::string validate() const
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{
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// clang-format off
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std::string errors;
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// Check for overlapping sections in the file
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// This is explicitly forbidden by ELF specification
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for ( int i = 0; i < sections.size(); ++i) {
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for ( int j = i+1; j < sections.size(); ++j ) {
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const section* a = sections[i];
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const section* b = sections[j];
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if ( ( ( a->get_type() & SHT_NOBITS) == 0 )
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&& ( ( b->get_type() & SHT_NOBITS) == 0 )
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&& ( a->get_size() > 0 )
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&& ( b->get_size() > 0 )
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&& ( a->get_offset() > 0 )
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&& ( b->get_offset() > 0 )
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&& ( is_offset_in_section( a->get_offset(), b )
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|| is_offset_in_section( a->get_offset()+a->get_size()-1, b )
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|| is_offset_in_section( b->get_offset(), a )
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|| is_offset_in_section( b->get_offset()+b->get_size()-1, a ) ) ) {
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errors += "Sections " + a->get_name() + " and " + b->get_name() + " overlap in file\n";
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}
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}
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}
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// clang-format on
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// Check for conflicting section / program header tables, where
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// the same offset has different vaddresses in section table and
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// program header table.
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// This doesn't seem to be explicitly forbidden by ELF specification,
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// but:
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// - it doesn't make any sense
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// - ELFIO relies on this being consistent when writing ELF files,
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// since offsets are re-calculated from vaddress
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for ( int h = 0; h < segments.size(); ++h ) {
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const segment* seg = segments[h];
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const section* sec =
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find_prog_section_for_offset( seg->get_offset() );
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if ( seg->get_type() == PT_LOAD && seg->get_file_size() > 0 &&
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sec != nullptr ) {
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Elf64_Addr sec_addr =
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get_virtual_addr( seg->get_offset(), sec );
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if ( sec_addr != seg->get_virtual_address() ) {
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errors += "Virtual address of segment " +
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std::to_string( h ) + " (" +
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to_hex_string( seg->get_virtual_address() ) +
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")" + " conflicts with address of section " +
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sec->get_name() + " (" +
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to_hex_string( sec_addr ) + ")" + " at offset " +
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to_hex_string( seg->get_offset() ) + "\n";
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}
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}
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}
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// more checks to be added here...
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return errors;
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}
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private:
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//------------------------------------------------------------------------------
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static bool is_offset_in_section( Elf64_Off offset, const section* sec )
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{
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return ( offset >= sec->get_offset() ) &&
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( offset < ( sec->get_offset() + sec->get_size() ) );
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}
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//------------------------------------------------------------------------------
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static Elf64_Addr get_virtual_addr( Elf64_Off offset, const section* sec )
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{
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return sec->get_address() + offset - sec->get_offset();
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}
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//------------------------------------------------------------------------------
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const section* find_prog_section_for_offset( Elf64_Off offset ) const
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{
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for ( const auto& sec : sections ) {
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if ( sec->get_type() == SHT_PROGBITS &&
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is_offset_in_section( offset, sec.get() ) ) {
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return sec.get();
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}
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}
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return nullptr;
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}
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//------------------------------------------------------------------------------
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std::unique_ptr<elf_header> create_header( unsigned char file_class,
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unsigned char encoding )
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{
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std::unique_ptr<elf_header> new_header;
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if ( file_class == ELFCLASS64 ) {
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new_header = std::unique_ptr<elf_header>(
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new ( std::nothrow ) elf_header_impl<Elf64_Ehdr>(
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&convertor, encoding, &addr_translator ) );
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}
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else if ( file_class == ELFCLASS32 ) {
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new_header = std::unique_ptr<elf_header>(
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new ( std::nothrow ) elf_header_impl<Elf32_Ehdr>(
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&convertor, encoding, &addr_translator ) );
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}
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else {
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return nullptr;
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}
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return new_header;
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}
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//------------------------------------------------------------------------------
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section* create_section()
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{
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if ( auto file_class = get_class(); file_class == ELFCLASS64 ) {
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sections_.emplace_back(
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new ( std::nothrow ) section_impl<Elf64_Shdr>(
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&convertor, &addr_translator, compression ) );
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}
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else if ( file_class == ELFCLASS32 ) {
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sections_.emplace_back(
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new ( std::nothrow ) section_impl<Elf32_Shdr>(
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&convertor, &addr_translator, compression ) );
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}
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else {
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sections_.pop_back();
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return nullptr;
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}
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section* new_section = sections_.back().get();
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new_section->set_index( static_cast<Elf_Half>( sections_.size() - 1 ) );
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return new_section;
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}
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//------------------------------------------------------------------------------
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segment* create_segment()
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{
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if ( auto file_class = header->get_class(); file_class == ELFCLASS64 ) {
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segments_.emplace_back(
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new ( std::nothrow )
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segment_impl<Elf64_Phdr>( &convertor, &addr_translator ) );
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}
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else if ( file_class == ELFCLASS32 ) {
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segments_.emplace_back(
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new ( std::nothrow )
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segment_impl<Elf32_Phdr>( &convertor, &addr_translator ) );
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}
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else {
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segments_.pop_back();
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return nullptr;
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}
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segment* new_segment = segments_.back().get();
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new_segment->set_index( static_cast<Elf_Half>( segments_.size() - 1 ) );
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return new_segment;
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}
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//------------------------------------------------------------------------------
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void create_mandatory_sections()
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{
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// Create null section without calling to 'add_section' as no string
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// section containing section names exists yet
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section* sec0 = create_section();
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sec0->set_index( 0 );
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sec0->set_name( "" );
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sec0->set_name_string_offset( 0 );
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set_section_name_str_index( 1 );
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section* shstrtab = sections.add( ".shstrtab" );
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shstrtab->set_type( SHT_STRTAB );
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shstrtab->set_addr_align( 1 );
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}
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|
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//------------------------------------------------------------------------------
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bool load_sections( std::istream& stream, bool is_lazy )
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{
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unsigned char file_class = header->get_class();
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Elf_Half entry_size = header->get_section_entry_size();
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Elf_Half num = header->get_sections_num();
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Elf64_Off offset = header->get_sections_offset();
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if ( ( num != 0 && file_class == ELFCLASS64 &&
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entry_size < sizeof( Elf64_Shdr ) ) ||
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( num != 0 && file_class == ELFCLASS32 &&
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entry_size < sizeof( Elf32_Shdr ) ) ) {
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return false;
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}
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for ( Elf_Half i = 0; i < num; ++i ) {
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section* sec = create_section();
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sec->load( stream,
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static_cast<std::streamoff>( offset ) +
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static_cast<std::streampos>( i ) * entry_size,
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is_lazy );
|
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// To mark that the section is not permitted to reassign address
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// during layout calculation
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sec->set_address( sec->get_address() );
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}
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|
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if ( Elf_Half shstrndx = get_section_name_str_index();
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SHN_UNDEF != shstrndx ) {
|
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string_section_accessor str_reader( sections[shstrndx] );
|
|
for ( Elf_Half i = 0; i < num; ++i ) {
|
|
Elf_Word section_offset = sections[i]->get_name_string_offset();
|
|
const char* p = str_reader.get_string( section_offset );
|
|
if ( p != nullptr ) {
|
|
sections[i]->set_name( p );
|
|
}
|
|
}
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
//------------------------------------------------------------------------------
|
|
//! Checks whether the addresses of the section entirely fall within the given segment.
|
|
//! It doesn't matter if the addresses are memory addresses, or file offsets,
|
|
//! they just need to be in the same address space
|
|
static bool is_sect_in_seg( Elf64_Off sect_begin,
|
|
Elf_Xword sect_size,
|
|
Elf64_Off seg_begin,
|
|
Elf64_Off seg_end )
|
|
{
|
|
return ( seg_begin <= sect_begin ) &&
|
|
( sect_begin + sect_size <= seg_end ) &&
|
|
( sect_begin <
|
|
seg_end ); // this is important criteria when sect_size == 0
|
|
// Example: seg_begin=10, seg_end=12 (-> covering the bytes 10 and 11)
|
|
// sect_begin=12, sect_size=0 -> shall return false!
|
|
}
|
|
|
|
//------------------------------------------------------------------------------
|
|
bool load_segments( std::istream& stream, bool is_lazy )
|
|
{
|
|
unsigned char file_class = header->get_class();
|
|
Elf_Half entry_size = header->get_segment_entry_size();
|
|
Elf_Half num = header->get_segments_num();
|
|
Elf64_Off offset = header->get_segments_offset();
|
|
|
|
if ( ( num != 0 && file_class == ELFCLASS64 &&
|
|
entry_size < sizeof( Elf64_Phdr ) ) ||
|
|
( num != 0 && file_class == ELFCLASS32 &&
|
|
entry_size < sizeof( Elf32_Phdr ) ) ) {
|
|
return false;
|
|
}
|
|
|
|
for ( Elf_Half i = 0; i < num; ++i ) {
|
|
if ( file_class == ELFCLASS64 ) {
|
|
segments_.emplace_back(
|
|
new ( std::nothrow ) segment_impl<Elf64_Phdr>(
|
|
&convertor, &addr_translator ) );
|
|
}
|
|
else if ( file_class == ELFCLASS32 ) {
|
|
segments_.emplace_back(
|
|
new ( std::nothrow ) segment_impl<Elf32_Phdr>(
|
|
&convertor, &addr_translator ) );
|
|
}
|
|
else {
|
|
segments_.pop_back();
|
|
return false;
|
|
}
|
|
|
|
segment* seg = segments_.back().get();
|
|
|
|
if ( !seg->load( stream,
|
|
static_cast<std::streamoff>( offset ) +
|
|
static_cast<std::streampos>( i ) * entry_size,
|
|
is_lazy ) ||
|
|
stream.fail() ) {
|
|
segments_.pop_back();
|
|
return false;
|
|
}
|
|
|
|
seg->set_index( i );
|
|
|
|
// Add sections to the segments (similar to readelfs algorithm)
|
|
Elf64_Off segBaseOffset = seg->get_offset();
|
|
Elf64_Off segEndOffset = segBaseOffset + seg->get_file_size();
|
|
Elf64_Off segVBaseAddr = seg->get_virtual_address();
|
|
Elf64_Off segVEndAddr = segVBaseAddr + seg->get_memory_size();
|
|
for ( const auto& psec : sections ) {
|
|
// SHF_ALLOC sections are matched based on the virtual address
|
|
// otherwise the file offset is matched
|
|
if ( ( ( psec->get_flags() & SHF_ALLOC ) == SHF_ALLOC )
|
|
? is_sect_in_seg( psec->get_address(),
|
|
psec->get_size(), segVBaseAddr,
|
|
segVEndAddr )
|
|
: is_sect_in_seg( psec->get_offset(), psec->get_size(),
|
|
segBaseOffset, segEndOffset ) ) {
|
|
// Alignment of segment shall not be updated, to preserve original value
|
|
// It will be re-calculated on saving.
|
|
seg->add_section_index( psec->get_index(), 0 );
|
|
}
|
|
}
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
//------------------------------------------------------------------------------
|
|
bool save_header( std::ostream& stream ) const
|
|
{
|
|
return header->save( stream );
|
|
}
|
|
|
|
//------------------------------------------------------------------------------
|
|
bool save_sections( std::ostream& stream ) const
|
|
{
|
|
for ( const auto& sec : sections_ ) {
|
|
std::streampos headerPosition =
|
|
static_cast<std::streamoff>( header->get_sections_offset() ) +
|
|
static_cast<std::streampos>(
|
|
header->get_section_entry_size() ) *
|
|
sec->get_index();
|
|
|
|
sec->save( stream, headerPosition, sec->get_offset() );
|
|
}
|
|
return true;
|
|
}
|
|
|
|
//------------------------------------------------------------------------------
|
|
bool save_segments( std::ostream& stream ) const
|
|
{
|
|
for ( const auto& seg : segments_ ) {
|
|
std::streampos headerPosition =
|
|
static_cast<std::streamoff>( header->get_segments_offset() ) +
|
|
static_cast<std::streampos>(
|
|
header->get_segment_entry_size() ) *
|
|
seg->get_index();
|
|
|
|
seg->save( stream, headerPosition, seg->get_offset() );
|
|
}
|
|
return true;
|
|
}
|
|
|
|
//------------------------------------------------------------------------------
|
|
bool is_section_without_segment( unsigned int section_index ) const
|
|
{
|
|
bool found = false;
|
|
|
|
for ( unsigned int j = 0; !found && ( j < segments.size() ); ++j ) {
|
|
for ( Elf_Half k = 0;
|
|
!found && ( k < segments[j]->get_sections_num() ); ++k ) {
|
|
found = segments[j]->get_section_index_at( k ) == section_index;
|
|
}
|
|
}
|
|
|
|
return !found;
|
|
}
|
|
|
|
//------------------------------------------------------------------------------
|
|
static bool is_subsequence_of( const segment* seg1, const segment* seg2 )
|
|
{
|
|
// Return 'true' if sections of seg1 are a subset of sections in seg2
|
|
const std::vector<Elf_Half>& sections1 = seg1->get_sections();
|
|
const std::vector<Elf_Half>& sections2 = seg2->get_sections();
|
|
|
|
bool found = false;
|
|
if ( sections1.size() < sections2.size() ) {
|
|
found = std::includes( sections2.begin(), sections2.end(),
|
|
sections1.begin(), sections1.end() );
|
|
}
|
|
|
|
return found;
|
|
}
|
|
|
|
//------------------------------------------------------------------------------
|
|
std::vector<segment*> get_ordered_segments() const
|
|
{
|
|
std::vector<segment*> res;
|
|
std::deque<segment*> worklist;
|
|
|
|
res.reserve( segments.size() );
|
|
for ( const auto& seg : segments ) {
|
|
worklist.emplace_back( seg.get() );
|
|
}
|
|
|
|
// Bring the segments which start at address 0 to the front
|
|
size_t nextSlot = 0;
|
|
for ( size_t i = 0; i < worklist.size(); ++i ) {
|
|
if ( i != nextSlot && worklist[i]->is_offset_initialized() &&
|
|
worklist[i]->get_offset() == 0 ) {
|
|
if ( worklist[nextSlot]->get_offset() == 0 ) {
|
|
++nextSlot;
|
|
}
|
|
std::swap( worklist[i], worklist[nextSlot] );
|
|
++nextSlot;
|
|
}
|
|
}
|
|
|
|
while ( !worklist.empty() ) {
|
|
segment* seg = worklist.front();
|
|
worklist.pop_front();
|
|
|
|
size_t i = 0;
|
|
for ( ; i < worklist.size(); ++i ) {
|
|
if ( is_subsequence_of( seg, worklist[i] ) ) {
|
|
break;
|
|
}
|
|
}
|
|
|
|
if ( i < worklist.size() ) {
|
|
worklist.emplace_back( seg );
|
|
}
|
|
else {
|
|
res.emplace_back( seg );
|
|
}
|
|
}
|
|
|
|
return res;
|
|
}
|
|
|
|
//------------------------------------------------------------------------------
|
|
bool layout_sections_without_segments()
|
|
{
|
|
for ( unsigned int i = 0; i < sections_.size(); ++i ) {
|
|
if ( is_section_without_segment( i ) ) {
|
|
const auto& sec = sections_[i];
|
|
|
|
if ( Elf_Xword section_align = sec->get_addr_align();
|
|
section_align > 1 &&
|
|
current_file_pos % section_align != 0 ) {
|
|
current_file_pos +=
|
|
section_align - current_file_pos % section_align;
|
|
}
|
|
|
|
if ( 0 != sec->get_index() ) {
|
|
sec->set_offset( current_file_pos );
|
|
}
|
|
|
|
if ( SHT_NOBITS != sec->get_type() &&
|
|
SHT_NULL != sec->get_type() ) {
|
|
current_file_pos += sec->get_size();
|
|
}
|
|
}
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
//------------------------------------------------------------------------------
|
|
void calc_segment_alignment() const
|
|
{
|
|
for ( const auto& seg : segments_ ) {
|
|
for ( Elf_Half i = 0; i < seg->get_sections_num(); ++i ) {
|
|
const auto& sect = sections_[seg->get_section_index_at( i )];
|
|
if ( sect->get_addr_align() > seg->get_align() ) {
|
|
seg->set_align( sect->get_addr_align() );
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
//------------------------------------------------------------------------------
|
|
bool layout_segments_and_their_sections()
|
|
{
|
|
std::vector<segment*> worklist;
|
|
std::vector<bool> section_generated( sections.size(), false );
|
|
|
|
// Get segments in a order in where segments which contain a
|
|
// sub sequence of other segments are located at the end
|
|
worklist = get_ordered_segments();
|
|
|
|
for ( auto* seg : worklist ) {
|
|
Elf_Xword segment_memory = 0;
|
|
Elf_Xword segment_filesize = 0;
|
|
Elf_Xword seg_start_pos = current_file_pos;
|
|
// Special case: PHDR segment
|
|
// This segment contains the program headers but no sections
|
|
if ( seg->get_type() == PT_PHDR && seg->get_sections_num() == 0 ) {
|
|
seg_start_pos = header->get_segments_offset();
|
|
segment_memory = segment_filesize =
|
|
header->get_segment_entry_size() *
|
|
static_cast<Elf_Xword>( header->get_segments_num() );
|
|
}
|
|
// Special case:
|
|
else if ( seg->is_offset_initialized() && seg->get_offset() == 0 ) {
|
|
seg_start_pos = 0;
|
|
if ( seg->get_sections_num() > 0 ) {
|
|
segment_memory = segment_filesize = current_file_pos;
|
|
}
|
|
}
|
|
// New segments with not generated sections
|
|
// have to be aligned
|
|
else if ( seg->get_sections_num() > 0 &&
|
|
!section_generated[seg->get_section_index_at( 0 )] ) {
|
|
Elf_Xword align = seg->get_align() > 0 ? seg->get_align() : 1;
|
|
Elf64_Off cur_page_alignment = current_file_pos % align;
|
|
Elf64_Off req_page_alignment =
|
|
seg->get_virtual_address() % align;
|
|
Elf64_Off error = req_page_alignment - cur_page_alignment;
|
|
|
|
current_file_pos += ( seg->get_align() + error ) % align;
|
|
seg_start_pos = current_file_pos;
|
|
}
|
|
else if ( seg->get_sections_num() > 0 ) {
|
|
seg_start_pos =
|
|
sections[seg->get_section_index_at( 0 )]->get_offset();
|
|
}
|
|
|
|
// Write segment's data
|
|
if ( !write_segment_data( seg, section_generated, segment_memory,
|
|
segment_filesize, seg_start_pos ) ) {
|
|
return false;
|
|
}
|
|
|
|
seg->set_file_size( segment_filesize );
|
|
|
|
// If we already have a memory size from loading an elf file (value > 0),
|
|
// it must not shrink!
|
|
// Memory size may be bigger than file size and it is the loader's job to do something
|
|
// with the surplus bytes in memory, like initializing them with a defined value.
|
|
if ( seg->get_memory_size() < segment_memory ) {
|
|
seg->set_memory_size( segment_memory );
|
|
}
|
|
|
|
seg->set_offset( seg_start_pos );
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
//------------------------------------------------------------------------------
|
|
bool layout_section_table()
|
|
{
|
|
// Simply place the section table at the end for now
|
|
Elf64_Off alignmentError = current_file_pos % 4;
|
|
current_file_pos += ( 4 - alignmentError ) % 4;
|
|
header->set_sections_offset( current_file_pos );
|
|
return true;
|
|
}
|
|
|
|
//------------------------------------------------------------------------------
|
|
bool write_segment_data( const segment* seg,
|
|
std::vector<bool>& section_generated,
|
|
Elf_Xword& segment_memory,
|
|
Elf_Xword& segment_filesize,
|
|
const Elf_Xword& seg_start_pos )
|
|
{
|
|
for ( Elf_Half j = 0; j < seg->get_sections_num(); ++j ) {
|
|
Elf_Half index = seg->get_section_index_at( j );
|
|
|
|
section* sec = sections[index];
|
|
|
|
// The NULL section is always generated
|
|
if ( SHT_NULL == sec->get_type() ) {
|
|
section_generated[index] = true;
|
|
continue;
|
|
}
|
|
|
|
Elf_Xword section_align = 0;
|
|
// Fix up the alignment
|
|
if ( !section_generated[index] && sec->is_address_initialized() &&
|
|
SHT_NOBITS != sec->get_type() && SHT_NULL != sec->get_type() &&
|
|
0 != sec->get_size() ) {
|
|
// Align the sections based on the virtual addresses
|
|
// when possible (this is what matters for execution)
|
|
Elf64_Off req_offset =
|
|
sec->get_address() - seg->get_virtual_address();
|
|
Elf64_Off cur_offset = current_file_pos - seg_start_pos;
|
|
if ( req_offset < cur_offset ) {
|
|
// something has gone awfully wrong, abort!
|
|
// section_align would turn out negative, seeking backwards and overwriting previous data
|
|
return false;
|
|
}
|
|
section_align = req_offset - cur_offset;
|
|
}
|
|
else if ( !section_generated[index] &&
|
|
!sec->is_address_initialized() ) {
|
|
// If no address has been specified then only the section
|
|
// alignment constraint has to be matched
|
|
Elf_Xword align = sec->get_addr_align();
|
|
if ( align == 0 ) {
|
|
align = 1;
|
|
}
|
|
Elf64_Off error = current_file_pos % align;
|
|
section_align = ( align - error ) % align;
|
|
}
|
|
else if ( section_generated[index] ) {
|
|
// Alignment for already generated sections
|
|
section_align =
|
|
sec->get_offset() - seg_start_pos - segment_filesize;
|
|
}
|
|
|
|
// Determine the segment file and memory sizes
|
|
// Special case .tbss section (NOBITS) in non TLS segment
|
|
if ( ( ( sec->get_flags() & SHF_ALLOC ) == SHF_ALLOC ) &&
|
|
!( ( ( sec->get_flags() & SHF_TLS ) == SHF_TLS ) &&
|
|
( seg->get_type() != PT_TLS ) &&
|
|
( SHT_NOBITS == sec->get_type() ) ) ) {
|
|
segment_memory += sec->get_size() + section_align;
|
|
}
|
|
|
|
if ( SHT_NOBITS != sec->get_type() ) {
|
|
segment_filesize += sec->get_size() + section_align;
|
|
}
|
|
|
|
// Nothing to be done when generating nested segments
|
|
if ( section_generated[index] ) {
|
|
continue;
|
|
}
|
|
|
|
current_file_pos += section_align;
|
|
|
|
// Set the section addresses when missing
|
|
if ( !sec->is_address_initialized() ) {
|
|
sec->set_address( seg->get_virtual_address() +
|
|
current_file_pos - seg_start_pos );
|
|
}
|
|
|
|
if ( 0 != sec->get_index() ) {
|
|
sec->set_offset( current_file_pos );
|
|
}
|
|
|
|
if ( SHT_NOBITS != sec->get_type() ) {
|
|
current_file_pos += sec->get_size();
|
|
}
|
|
|
|
section_generated[index] = true;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
//------------------------------------------------------------------------------
|
|
public:
|
|
friend class Sections;
|
|
class Sections
|
|
{
|
|
public:
|
|
//------------------------------------------------------------------------------
|
|
explicit Sections( elfio* parent ) : parent( parent ) {}
|
|
|
|
//------------------------------------------------------------------------------
|
|
Elf_Half size() const
|
|
{
|
|
return static_cast<Elf_Half>( parent->sections_.size() );
|
|
}
|
|
|
|
//------------------------------------------------------------------------------
|
|
section* operator[]( unsigned int index ) const
|
|
{
|
|
section* sec = nullptr;
|
|
|
|
if ( index < parent->sections_.size() ) {
|
|
sec = parent->sections_[index].get();
|
|
}
|
|
|
|
return sec;
|
|
}
|
|
|
|
//------------------------------------------------------------------------------
|
|
section* operator[]( const std::string_view& name ) const
|
|
{
|
|
section* sec = nullptr;
|
|
|
|
for ( const auto& it : parent->sections_ ) {
|
|
if ( it->get_name() == name ) {
|
|
sec = it.get();
|
|
break;
|
|
}
|
|
}
|
|
|
|
return sec;
|
|
}
|
|
|
|
//------------------------------------------------------------------------------
|
|
section* add( const std::string& name ) const
|
|
{
|
|
section* new_section = parent->create_section();
|
|
new_section->set_name( name );
|
|
|
|
Elf_Half str_index = parent->get_section_name_str_index();
|
|
section* string_table( parent->sections_[str_index].get() );
|
|
string_section_accessor str_writer( string_table );
|
|
Elf_Word pos = str_writer.add_string( name );
|
|
new_section->set_name_string_offset( pos );
|
|
|
|
return new_section;
|
|
}
|
|
|
|
//------------------------------------------------------------------------------
|
|
std::vector<std::unique_ptr<section>>::iterator begin()
|
|
{
|
|
return parent->sections_.begin();
|
|
}
|
|
|
|
//------------------------------------------------------------------------------
|
|
std::vector<std::unique_ptr<section>>::iterator end()
|
|
{
|
|
return parent->sections_.end();
|
|
}
|
|
|
|
//------------------------------------------------------------------------------
|
|
std::vector<std::unique_ptr<section>>::const_iterator begin() const
|
|
{
|
|
return parent->sections_.cbegin();
|
|
}
|
|
|
|
//------------------------------------------------------------------------------
|
|
std::vector<std::unique_ptr<section>>::const_iterator end() const
|
|
{
|
|
return parent->sections_.cend();
|
|
}
|
|
|
|
//------------------------------------------------------------------------------
|
|
private:
|
|
elfio* parent;
|
|
};
|
|
Sections sections;
|
|
|
|
//------------------------------------------------------------------------------
|
|
friend class Segments;
|
|
class Segments
|
|
{
|
|
public:
|
|
//------------------------------------------------------------------------------
|
|
explicit Segments( elfio* parent ) : parent( parent ) {}
|
|
|
|
//------------------------------------------------------------------------------
|
|
Elf_Half size() const
|
|
{
|
|
return static_cast<Elf_Half>( parent->segments_.size() );
|
|
}
|
|
|
|
//------------------------------------------------------------------------------
|
|
segment* operator[]( unsigned int index ) const
|
|
{
|
|
return parent->segments_[index].get();
|
|
}
|
|
|
|
//------------------------------------------------------------------------------
|
|
segment* add() { return parent->create_segment(); }
|
|
|
|
//------------------------------------------------------------------------------
|
|
std::vector<std::unique_ptr<segment>>::iterator begin()
|
|
{
|
|
return parent->segments_.begin();
|
|
}
|
|
|
|
//------------------------------------------------------------------------------
|
|
std::vector<std::unique_ptr<segment>>::iterator end()
|
|
{
|
|
return parent->segments_.end();
|
|
}
|
|
|
|
//------------------------------------------------------------------------------
|
|
std::vector<std::unique_ptr<segment>>::const_iterator begin() const
|
|
{
|
|
return parent->segments_.cbegin();
|
|
}
|
|
|
|
//------------------------------------------------------------------------------
|
|
std::vector<std::unique_ptr<segment>>::const_iterator end() const
|
|
{
|
|
return parent->segments_.cend();
|
|
}
|
|
|
|
//------------------------------------------------------------------------------
|
|
private:
|
|
elfio* parent;
|
|
};
|
|
Segments segments;
|
|
|
|
//------------------------------------------------------------------------------
|
|
private:
|
|
std::unique_ptr<std::ifstream> pstream = nullptr;
|
|
std::unique_ptr<elf_header> header = nullptr;
|
|
std::vector<std::unique_ptr<section>> sections_;
|
|
std::vector<std::unique_ptr<segment>> segments_;
|
|
endianess_convertor convertor;
|
|
address_translator addr_translator;
|
|
std::shared_ptr<compression_interface> compression = nullptr;
|
|
|
|
Elf_Xword current_file_pos = 0;
|
|
};
|
|
|
|
} // namespace ELFIO
|
|
|
|
#include <elfio/elfio_symbols.hpp>
|
|
#include <elfio/elfio_note.hpp>
|
|
#include <elfio/elfio_relocation.hpp>
|
|
#include <elfio/elfio_dynamic.hpp>
|
|
#include <elfio/elfio_array.hpp>
|
|
#include <elfio/elfio_modinfo.hpp>
|
|
#include <elfio/elfio_versym.hpp>
|
|
|
|
#endif // ELFIO_HPP
|