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fa29711731
(Elf_file::large_shndx_offset): New function. (Elf_file::construct): Initialize large_shndx_offset_. (Elf_File::initialize_shnum): If necessary, adjust shstrndx_ and set large_shndx_offset_.
485 lines
14 KiB
C++
485 lines
14 KiB
C++
// elfcpp_file.h -- file access for elfcpp -*- C++ -*-
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// Copyright 2006, 2007, Free Software Foundation, Inc.
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// Written by Ian Lance Taylor <iant@google.com>.
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// This file is part of elfcpp.
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// This program is free software; you can redistribute it and/or
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// modify it under the terms of the GNU Library General Public License
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// as published by the Free Software Foundation; either version 2, or
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// (at your option) any later version.
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// In addition to the permissions in the GNU Library General Public
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// License, the Free Software Foundation gives you unlimited
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// permission to link the compiled version of this file into
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// combinations with other programs, and to distribute those
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// combinations without any restriction coming from the use of this
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// file. (The Library Public License restrictions do apply in other
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// respects; for example, they cover modification of the file, and
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/// distribution when not linked into a combined executable.)
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// This program is distributed in the hope that it will be useful, but
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// WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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// Library General Public License for more details.
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// You should have received a copy of the GNU Library General Public
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// License along with this program; if not, write to the Free Software
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// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA
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// 02110-1301, USA.
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// This header file defines the class Elf_file which can be used to
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// read useful data from an ELF file. The functions here are all
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// templates which take a file interface object as a parameter. This
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// type must have a subtype View. This type must support two methods:
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// View view(off_t file_offset, off_t data_size)
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// returns a View for the specified part of the file.
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// void error(const char* printf_format, ...)
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// prints an error message and does not return. The subtype View must
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// support a method
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// const unsigned char* data()
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// which returns a pointer to a buffer containing the requested data.
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// This general interface is used to read data from the file. Objects
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// of type View will never survive longer than the elfcpp function.
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// Some of these functions must return a reference to part of the
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// file. To use these, the file interface must support a subtype
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// Location:
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// Location(off_t file_offset, off_t data_size)
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// To use this in conjunction with the accessors types Shdr, etc., the
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// file interface should support an overload of view:
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// View view(Location)
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// This permits writing
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// elfcpp::Shdr shdr(file, ef.section_header(n));
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#ifndef ELFPCP_FILE_H
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#define ELFCPP_FILE_H
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#include <string>
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#include <cstring>
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namespace elfcpp
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{
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// This object is used to read an ELF file.
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// SIZE: The size of file, 32 or 64.
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// BIG_ENDIAN: Whether the file is in big-endian format.
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// FILE: A file reading type as described above.
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template<int size, bool big_endian, typename File>
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class Elf_file
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{
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private:
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typedef Elf_file<size, big_endian, File> This;
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public:
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static const int ehdr_size = Elf_sizes<size>::ehdr_size;
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static const int phdr_size = Elf_sizes<size>::phdr_size;
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static const int shdr_size = Elf_sizes<size>::shdr_size;
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static const int sym_size = Elf_sizes<size>::sym_size;
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static const int rel_size = Elf_sizes<size>::rel_size;
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static const int rela_size = Elf_sizes<size>::rela_size;
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typedef Ehdr<size, big_endian> Ef_ehdr;
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typedef Phdr<size, big_endian> Ef_phdr;
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typedef Shdr<size, big_endian> Ef_shdr;
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typedef Sym<size, big_endian> Ef_sym;
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// Construct an Elf_file given an ELF file header.
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Elf_file(File* file, const Ef_ehdr& ehdr)
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{ this->construct(file, ehdr); }
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// Construct an ELF file.
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inline
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Elf_file(File* file);
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// Return the file offset to the section headers.
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off_t
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shoff() const
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{ return this->shoff_; }
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// Return the number of sections.
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unsigned int
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shnum()
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{
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this->initialize_shnum();
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return this->shnum_;
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}
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// Return the section index of the section name string table.
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unsigned int
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shstrndx()
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{
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this->initialize_shnum();
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return this->shstrndx_;
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}
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// Return the value to subtract from section indexes >=
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// SHN_LORESERVE. See the comment in initialize_shnum.
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int
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large_shndx_offset()
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{
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this->initialize_shnum();
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return this->large_shndx_offset_;
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}
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// Return the location of the header of section SHNDX.
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typename File::Location
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section_header(unsigned int shndx)
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{
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return typename File::Location(this->section_header_offset(shndx),
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shdr_size);
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}
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// Return the name of section SHNDX.
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std::string
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section_name(unsigned int shndx);
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// Return the location of the contents of section SHNDX.
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typename File::Location
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section_contents(unsigned int shndx);
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// Return the size of section SHNDX.
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typename Elf_types<size>::Elf_WXword
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section_size(unsigned int shndx);
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// Return the flags of section SHNDX.
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typename Elf_types<size>::Elf_WXword
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section_flags(unsigned int shndx);
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// Return the address of section SHNDX.
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typename Elf_types<size>::Elf_Addr
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section_addr(unsigned int shndx);
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// Return the type of section SHNDX.
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Elf_Word
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section_type(unsigned int shndx);
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// Return the link field of section SHNDX.
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Elf_Word
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section_link(unsigned int shndx);
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// Return the info field of section SHNDX.
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Elf_Word
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section_info(unsigned int shndx);
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// Return the addralign field of section SHNDX.
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typename Elf_types<size>::Elf_WXword
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section_addralign(unsigned int shndx);
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private:
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// Shared constructor code.
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void
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construct(File* file, const Ef_ehdr& ehdr);
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// Initialize shnum_ and shstrndx_.
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void
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initialize_shnum();
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// Return the file offset of the header of section SHNDX.
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off_t
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section_header_offset(unsigned int shndx);
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// The file we are reading.
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File* file_;
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// The file offset to the section headers.
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off_t shoff_;
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// The number of sections.
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unsigned int shnum_;
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// The section index of the section name string table.
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unsigned int shstrndx_;
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// Offset to add to sections larger than SHN_LORESERVE.
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int large_shndx_offset_;
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};
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// Template function definitions.
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// Construct an Elf_file given an ELF file header.
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template<int size, bool big_endian, typename File>
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void
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Elf_file<size, big_endian, File>::construct(File* file, const Ef_ehdr& ehdr)
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{
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this->file_ = file;
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this->shoff_ = ehdr.get_e_shoff();
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this->shnum_ = ehdr.get_e_shnum();
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this->shstrndx_ = ehdr.get_e_shstrndx();
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this->large_shndx_offset_ = 0;
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if (ehdr.get_e_ehsize() != This::ehdr_size)
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file->error(_("bad e_ehsize (%d != %d)"),
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ehdr.get_e_ehsize(), This::ehdr_size);
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if (ehdr.get_e_shentsize() != This::shdr_size)
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file->error(_("bad e_shentsize (%d != %d)"),
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ehdr.get_e_shentsize(), This::shdr_size);
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}
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// Construct an ELF file.
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template<int size, bool big_endian, typename File>
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inline
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Elf_file<size, big_endian, File>::Elf_file(File* file)
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{
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typename File::View v(file->view(file_header_offset, This::ehdr_size));
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this->construct(file, Ef_ehdr(v.data()));
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}
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// Initialize the shnum_ and shstrndx_ fields, handling overflow.
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template<int size, bool big_endian, typename File>
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void
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Elf_file<size, big_endian, File>::initialize_shnum()
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{
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if ((this->shnum_ == 0 || this->shstrndx_ == SHN_XINDEX)
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&& this->shoff_ != 0)
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{
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typename File::View v(this->file_->view(this->shoff_, This::shdr_size));
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Ef_shdr shdr(v.data());
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if (this->shnum_ == 0)
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this->shnum_ = shdr.get_sh_size();
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if (this->shstrndx_ == SHN_XINDEX)
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{
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this->shstrndx_ = shdr.get_sh_link();
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// Versions of the GNU binutils between 2.12 and 2.18 did
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// not handle objects with more than SHN_LORESERVE sections
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// correctly. All large section indexes were offset by
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// 0x100. Some information can be found here:
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// http://sourceware.org/bugzilla/show_bug.cgi?id=5900 .
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// Fortunately these object files are easy to detect, as the
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// GNU binutils always put the section header string table
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// near the end of the list of sections. Thus if the
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// section header string table index is larger than the
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// number of sections, then we know we have to subtract
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// 0x100 to get the real section index.
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if (this->shstrndx_ >= this->shnum_)
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{
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if (this->shstrndx_ >= elfcpp::SHN_LORESERVE + 0x100)
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{
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this->large_shndx_offset_ = - 0x100;
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this->shstrndx_ -= 0x100;
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}
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if (this->shstrndx_ >= this->shnum_)
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this->file_->error(_("bad shstrndx: %u >= %u"),
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this->shstrndx_, this->shnum_);
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}
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}
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}
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}
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// Return the file offset of the section header of section SHNDX.
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template<int size, bool big_endian, typename File>
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off_t
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Elf_file<size, big_endian, File>::section_header_offset(unsigned int shndx)
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{
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if (shndx >= this->shnum())
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this->file_->error(_("section_header_offset: bad shndx %u >= %u"),
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shndx, this->shnum());
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return this->shoff_ + This::shdr_size * shndx;
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}
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// Return the name of section SHNDX.
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template<int size, bool big_endian, typename File>
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std::string
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Elf_file<size, big_endian, File>::section_name(unsigned int shndx)
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{
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File* const file = this->file_;
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// Get the section name offset.
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unsigned int sh_name;
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{
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typename File::View v(file->view(this->section_header_offset(shndx),
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This::shdr_size));
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Ef_shdr shdr(v.data());
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sh_name = shdr.get_sh_name();
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}
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// Get the file offset for the section name string table data.
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off_t shstr_off;
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off_t shstr_size;
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{
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const unsigned int shstrndx = this->shstrndx_;
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typename File::View v(file->view(this->section_header_offset(shstrndx),
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This::shdr_size));
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Ef_shdr shstr_shdr(v.data());
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shstr_off = shstr_shdr.get_sh_offset();
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shstr_size = shstr_shdr.get_sh_size();
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}
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if (sh_name >= shstr_size)
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file->error(_("bad section name offset for section %u: %u"),
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shndx, sh_name);
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typename File::View v(file->view(shstr_off, shstr_size));
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const unsigned char* datau = v.data();
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const char* data = reinterpret_cast<const char*>(datau);
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const void* p = ::memchr(data + sh_name, '\0', shstr_size - sh_name);
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if (p == NULL)
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file->error(_("missing null terminator for name of section %u"),
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shndx);
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size_t len = static_cast<const char*>(p) - (data + sh_name);
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return std::string(data + sh_name, len);
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}
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// Return the contents of section SHNDX.
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template<int size, bool big_endian, typename File>
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typename File::Location
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Elf_file<size, big_endian, File>::section_contents(unsigned int shndx)
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{
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File* const file = this->file_;
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if (shndx >= this->shnum())
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file->error(_("section_contents: bad shndx %u >= %u"),
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shndx, this->shnum());
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typename File::View v(file->view(this->section_header_offset(shndx),
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This::shdr_size));
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Ef_shdr shdr(v.data());
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return typename File::Location(shdr.get_sh_offset(), shdr.get_sh_size());
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}
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// Get the size of section SHNDX.
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template<int size, bool big_endian, typename File>
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typename Elf_types<size>::Elf_WXword
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Elf_file<size, big_endian, File>::section_size(unsigned int shndx)
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{
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File* const file = this->file_;
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if (shndx >= this->shnum())
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file->error(_("section_size: bad shndx %u >= %u"),
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shndx, this->shnum());
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typename File::View v(file->view(this->section_header_offset(shndx),
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This::shdr_size));
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Ef_shdr shdr(v.data());
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return shdr.get_sh_size();
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}
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// Return the section flags of section SHNDX.
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template<int size, bool big_endian, typename File>
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typename Elf_types<size>::Elf_WXword
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Elf_file<size, big_endian, File>::section_flags(unsigned int shndx)
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{
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File* const file = this->file_;
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if (shndx >= this->shnum())
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file->error(_("section_flags: bad shndx %u >= %u"),
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shndx, this->shnum());
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typename File::View v(file->view(this->section_header_offset(shndx),
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This::shdr_size));
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Ef_shdr shdr(v.data());
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return shdr.get_sh_flags();
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}
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// Return the address of section SHNDX.
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template<int size, bool big_endian, typename File>
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typename Elf_types<size>::Elf_Addr
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Elf_file<size, big_endian, File>::section_addr(unsigned int shndx)
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{
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File* const file = this->file_;
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if (shndx >= this->shnum())
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file->error(_("section_flags: bad shndx %u >= %u"),
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shndx, this->shnum());
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typename File::View v(file->view(this->section_header_offset(shndx),
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This::shdr_size));
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Ef_shdr shdr(v.data());
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return shdr.get_sh_addr();
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}
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// Return the type of section SHNDX.
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template<int size, bool big_endian, typename File>
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Elf_Word
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Elf_file<size, big_endian, File>::section_type(unsigned int shndx)
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{
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File* const file = this->file_;
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if (shndx >= this->shnum())
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file->error(_("section_type: bad shndx %u >= %u"),
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shndx, this->shnum());
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typename File::View v(file->view(this->section_header_offset(shndx),
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This::shdr_size));
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Ef_shdr shdr(v.data());
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return shdr.get_sh_type();
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}
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// Return the sh_link field of section SHNDX.
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template<int size, bool big_endian, typename File>
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Elf_Word
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Elf_file<size, big_endian, File>::section_link(unsigned int shndx)
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{
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File* const file = this->file_;
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if (shndx >= this->shnum())
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file->error(_("section_link: bad shndx %u >= %u"),
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shndx, this->shnum());
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typename File::View v(file->view(this->section_header_offset(shndx),
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This::shdr_size));
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Ef_shdr shdr(v.data());
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return shdr.get_sh_link();
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}
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// Return the sh_info field of section SHNDX.
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template<int size, bool big_endian, typename File>
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Elf_Word
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Elf_file<size, big_endian, File>::section_info(unsigned int shndx)
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{
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File* const file = this->file_;
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if (shndx >= this->shnum())
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file->error(_("section_info: bad shndx %u >= %u"),
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shndx, this->shnum());
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typename File::View v(file->view(this->section_header_offset(shndx),
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This::shdr_size));
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Ef_shdr shdr(v.data());
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return shdr.get_sh_info();
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}
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// Return the sh_addralign field of section SHNDX.
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template<int size, bool big_endian, typename File>
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typename Elf_types<size>::Elf_WXword
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Elf_file<size, big_endian, File>::section_addralign(unsigned int shndx)
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{
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File* const file = this->file_;
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if (shndx >= this->shnum())
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file->error(_("section_addralign: bad shndx %u >= %u"),
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shndx, this->shnum());
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typename File::View v(file->view(this->section_header_offset(shndx),
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This::shdr_size));
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Ef_shdr shdr(v.data());
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return shdr.get_sh_addralign();
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}
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} // End namespace elfcpp.
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#endif // !defined(ELFCPP_FILE_H)
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