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Diffstat (limited to 'binutils-2.25/elfcpp/elfcpp_file.h')
| -rw-r--r-- | binutils-2.25/elfcpp/elfcpp_file.h | 688 |
1 files changed, 688 insertions, 0 deletions
diff --git a/binutils-2.25/elfcpp/elfcpp_file.h b/binutils-2.25/elfcpp/elfcpp_file.h new file mode 100644 index 00000000..8dd7ad5c --- /dev/null +++ b/binutils-2.25/elfcpp/elfcpp_file.h @@ -0,0 +1,688 @@ +// elfcpp_file.h -- file access for elfcpp -*- C++ -*- + +// Copyright 2006, 2007, Free Software Foundation, Inc. +// Written by Ian Lance Taylor <iant@google.com>. + +// This file is part of elfcpp. + +// This program is free software; you can redistribute it and/or +// modify it under the terms of the GNU Library General Public License +// as published by the Free Software Foundation; either version 2, or +// (at your option) any later version. + +// In addition to the permissions in the GNU Library General Public +// License, the Free Software Foundation gives you unlimited +// permission to link the compiled version of this file into +// combinations with other programs, and to distribute those +// combinations without any restriction coming from the use of this +// file. (The Library Public License restrictions do apply in other +// respects; for example, they cover modification of the file, and +/// distribution when not linked into a combined executable.) + +// This program is distributed in the hope that it will be useful, but +// WITHOUT ANY WARRANTY; without even the implied warranty of +// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +// Library General Public License for more details. + +// You should have received a copy of the GNU Library General Public +// License along with this program; if not, write to the Free Software +// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA +// 02110-1301, USA. + +// This header file defines the class Elf_file which can be used to +// read useful data from an ELF file. The functions here are all +// templates which take a file interface object as a parameter. This +// type must have a subtype View. This type must support two methods: +// View view(off_t file_offset, off_t data_size) +// returns a View for the specified part of the file. +// void error(const char* printf_format, ...) +// prints an error message and does not return. The subtype View must +// support a method +// const unsigned char* data() +// which returns a pointer to a buffer containing the requested data. +// This general interface is used to read data from the file. Objects +// of type View will never survive longer than the elfcpp function. + +// Some of these functions must return a reference to part of the +// file. To use these, the file interface must support a subtype +// Location: +// Location(off_t file_offset, off_t data_size) +// To use this in conjunction with the accessors types Shdr, etc., the +// file interface should support an overload of view: +// View view(Location) +// This permits writing +// elfcpp::Shdr shdr(file, ef.section_header(n)); + +#ifndef ELFCPP_FILE_H +#define ELFCPP_FILE_H + +#include <string> +#include <cstdio> +#include <cstring> + +#include "elfcpp.h" + +namespace elfcpp +{ + +// A simple helper class to recognize if a file has an ELF header. + +class Elf_recognizer +{ + public: + // Maximum header size. The user should try to read this much of + // the file when using this class. + + static const int max_header_size = Elf_sizes<64>::ehdr_size; + + // Checks if the file contains the ELF magic. Other header fields + // are not checked. + + static bool + is_elf_file(const unsigned char* ehdr_buf, int size); + + // Check if EHDR_BUF/BUFSIZE is a valid header of a 32-bit or + // 64-bit, little-endian or big-endian ELF file. Assumes + // is_elf_file() has been checked to be true. If the header is not + // valid, *ERROR contains a human-readable error message. If is is, + // *SIZE is set to either 32 or 64, *BIG_ENDIAN is set to indicate + // whether the file is big-endian. + + static bool + is_valid_header(const unsigned char* ehdr_buf, off_t bufsize, + int* size, bool* big_endian, + std::string* error); +}; + +// This object is used to read an ELF file. +// SIZE: The size of file, 32 or 64. +// BIG_ENDIAN: Whether the file is in big-endian format. +// FILE: A file reading type as described above. + +template<int size, bool big_endian, typename File> +class Elf_file +{ + private: + typedef Elf_file<size, big_endian, File> This; + + public: + static const int ehdr_size = Elf_sizes<size>::ehdr_size; + static const int phdr_size = Elf_sizes<size>::phdr_size; + static const int shdr_size = Elf_sizes<size>::shdr_size; + static const int sym_size = Elf_sizes<size>::sym_size; + static const int rel_size = Elf_sizes<size>::rel_size; + static const int rela_size = Elf_sizes<size>::rela_size; + + typedef Ehdr<size, big_endian> Ef_ehdr; + typedef Phdr<size, big_endian> Ef_phdr; + typedef Shdr<size, big_endian> Ef_shdr; + typedef Sym<size, big_endian> Ef_sym; + + // Construct an Elf_file given an ELF file header. + Elf_file(File* file, const Ef_ehdr& ehdr) + { this->construct(file, ehdr); } + + // Construct an ELF file. + inline + Elf_file(File* file); + + // Return the file offset to the section headers. + off_t + shoff() const + { return this->shoff_; } + + // Find the first section with an sh_type field equal to TYPE and + // return its index. Returns SHN_UNDEF if there is no such section. + unsigned int + find_section_by_type(unsigned int type); + + // Return the number of sections. + unsigned int + shnum() + { + this->initialize_shnum(); + return this->shnum_; + } + + // Return the section index of the section name string table. + unsigned int + shstrndx() + { + this->initialize_shnum(); + return this->shstrndx_; + } + + // Return the value to subtract from section indexes >= + // SHN_LORESERVE. See the comment in initialize_shnum. + int + large_shndx_offset() + { + this->initialize_shnum(); + return this->large_shndx_offset_; + } + + // Return the location of the header of section SHNDX. + typename File::Location + section_header(unsigned int shndx) + { + return typename File::Location(this->section_header_offset(shndx), + shdr_size); + } + + // Return the name of section SHNDX. + std::string + section_name(unsigned int shndx); + + // Return the location of the contents of section SHNDX. + typename File::Location + section_contents(unsigned int shndx); + + // Return the size of section SHNDX. + typename Elf_types<size>::Elf_WXword + section_size(unsigned int shndx); + + // Return the flags of section SHNDX. + typename Elf_types<size>::Elf_WXword + section_flags(unsigned int shndx); + + // Return the address of section SHNDX. + typename Elf_types<size>::Elf_Addr + section_addr(unsigned int shndx); + + // Return the type of section SHNDX. + Elf_Word + section_type(unsigned int shndx); + + // Return the link field of section SHNDX. + Elf_Word + section_link(unsigned int shndx); + + // Return the info field of section SHNDX. + Elf_Word + section_info(unsigned int shndx); + + // Return the addralign field of section SHNDX. + typename Elf_types<size>::Elf_WXword + section_addralign(unsigned int shndx); + + private: + // Shared constructor code. + void + construct(File* file, const Ef_ehdr& ehdr); + + // Initialize shnum_ and shstrndx_. + void + initialize_shnum(); + + // Return the file offset of the header of section SHNDX. + off_t + section_header_offset(unsigned int shndx); + + // The file we are reading. + File* file_; + // The file offset to the section headers. + off_t shoff_; + // The number of sections. + unsigned int shnum_; + // The section index of the section name string table. + unsigned int shstrndx_; + // Offset to add to sections larger than SHN_LORESERVE. + int large_shndx_offset_; +}; + +// A small wrapper around SHT_STRTAB data mapped to memory. It checks that the +// index is not out of bounds and the string is NULL-terminated. + +class Elf_strtab +{ + public: + // Construct an Elf_strtab for a section with contents *P and size SIZE. + Elf_strtab(const unsigned char* p, size_t size); + + // Return the file offset to the section headers. + bool + get_c_string(size_t offset, const char** cstring) const + { + if (offset >= this->usable_size_) + return false; + *cstring = this->base_ + offset; + return true; + } + + private: + // Contents of the section mapped to memory. + const char* base_; + // One larger that the position of the last NULL character in the section. + // For valid SHT_STRTAB sections, this is the size of the section. + size_t usable_size_; +}; + +// Inline function definitions. + +// Check for presence of the ELF magic number. + +inline bool +Elf_recognizer::is_elf_file(const unsigned char* ehdr_buf, int size) +{ + if (size < 4) + return false; + + static unsigned char elfmagic[4] = + { + elfcpp::ELFMAG0, elfcpp::ELFMAG1, + elfcpp::ELFMAG2, elfcpp::ELFMAG3 + }; + return memcmp(ehdr_buf, elfmagic, 4) == 0; +} + +namespace +{ + +// Print a number to a string. + +inline std::string +internal_printf_int(const char* format, int arg) +{ + char buf[256]; + snprintf(buf, sizeof(buf), format, arg); + return std::string(buf); +} + +} // End anonymous namespace. + +// Check the validity of the ELF header. + +inline bool +Elf_recognizer::is_valid_header( + const unsigned char* ehdr_buf, + off_t bufsize, + int* size, + bool* big_endian, + std::string* error) +{ + if (bufsize < elfcpp::EI_NIDENT) + { + *error = _("ELF file too short"); + return false; + } + + int v = ehdr_buf[elfcpp::EI_VERSION]; + if (v != elfcpp::EV_CURRENT) + { + if (v == elfcpp::EV_NONE) + *error = _("invalid ELF version 0"); + else + *error = internal_printf_int(_("unsupported ELF version %d"), v); + return false; + } + + int c = ehdr_buf[elfcpp::EI_CLASS]; + if (c == elfcpp::ELFCLASSNONE) + { + *error = _("invalid ELF class 0"); + return false; + } + else if (c != elfcpp::ELFCLASS32 + && c != elfcpp::ELFCLASS64) + { + *error = internal_printf_int(_("unsupported ELF class %d"), c); + return false; + } + + int d = ehdr_buf[elfcpp::EI_DATA]; + if (d == elfcpp::ELFDATANONE) + { + *error = _("invalid ELF data encoding"); + return false; + } + else if (d != elfcpp::ELFDATA2LSB + && d != elfcpp::ELFDATA2MSB) + { + *error = internal_printf_int(_("unsupported ELF data encoding %d"), d); + return false; + } + + *big_endian = (d == elfcpp::ELFDATA2MSB); + + if (c == elfcpp::ELFCLASS32) + { + if (bufsize < elfcpp::Elf_sizes<32>::ehdr_size) + { + *error = _("ELF file too short"); + return false; + } + *size = 32; + } + else + { + if (bufsize < elfcpp::Elf_sizes<64>::ehdr_size) + { + *error = _("ELF file too short"); + return false; + } + *size = 64; + } + + return true; +} + +// Template function definitions. + +// Construct an Elf_file given an ELF file header. + +template<int size, bool big_endian, typename File> +void +Elf_file<size, big_endian, File>::construct(File* file, const Ef_ehdr& ehdr) +{ + this->file_ = file; + this->shoff_ = ehdr.get_e_shoff(); + this->shnum_ = ehdr.get_e_shnum(); + this->shstrndx_ = ehdr.get_e_shstrndx(); + this->large_shndx_offset_ = 0; + if (ehdr.get_e_ehsize() != This::ehdr_size) + file->error(_("bad e_ehsize (%d != %d)"), + ehdr.get_e_ehsize(), This::ehdr_size); + if (ehdr.get_e_shentsize() != This::shdr_size) + file->error(_("bad e_shentsize (%d != %d)"), + ehdr.get_e_shentsize(), This::shdr_size); +} + +// Construct an ELF file. + +template<int size, bool big_endian, typename File> +inline +Elf_file<size, big_endian, File>::Elf_file(File* file) +{ + typename File::View v(file->view(file_header_offset, This::ehdr_size)); + this->construct(file, Ef_ehdr(v.data())); +} + +// Initialize the shnum_ and shstrndx_ fields, handling overflow. + +template<int size, bool big_endian, typename File> +void +Elf_file<size, big_endian, File>::initialize_shnum() +{ + if ((this->shnum_ == 0 || this->shstrndx_ == SHN_XINDEX) + && this->shoff_ != 0) + { + typename File::View v(this->file_->view(this->shoff_, This::shdr_size)); + Ef_shdr shdr(v.data()); + + if (this->shnum_ == 0) + this->shnum_ = shdr.get_sh_size(); + + if (this->shstrndx_ == SHN_XINDEX) + { + this->shstrndx_ = shdr.get_sh_link(); + + // Versions of the GNU binutils between 2.12 and 2.18 did + // not handle objects with more than SHN_LORESERVE sections + // correctly. All large section indexes were offset by + // 0x100. Some information can be found here: + // http://sourceware.org/bugzilla/show_bug.cgi?id=5900 . + // Fortunately these object files are easy to detect, as the + // GNU binutils always put the section header string table + // near the end of the list of sections. Thus if the + // section header string table index is larger than the + // number of sections, then we know we have to subtract + // 0x100 to get the real section index. + if (this->shstrndx_ >= this->shnum_) + { + if (this->shstrndx_ >= elfcpp::SHN_LORESERVE + 0x100) + { + this->large_shndx_offset_ = - 0x100; + this->shstrndx_ -= 0x100; + } + if (this->shstrndx_ >= this->shnum_) + this->file_->error(_("bad shstrndx: %u >= %u"), + this->shstrndx_, this->shnum_); + } + } + } +} + +// Find section with sh_type equal to TYPE and return its index. +// Returns SHN_UNDEF if not found. + +template<int size, bool big_endian, typename File> +unsigned int +Elf_file<size, big_endian, File>::find_section_by_type(unsigned int type) +{ + unsigned int shnum = this->shnum(); + typename File::View v(this->file_->view(this->shoff_, + This::shdr_size * shnum)); + for (unsigned int i = 0; i < shnum; i++) + { + Ef_shdr shdr(v.data() + This::shdr_size * i); + if (shdr.get_sh_type() == type) + return i; + } + return SHN_UNDEF; +} + +// Return the file offset of the section header of section SHNDX. + +template<int size, bool big_endian, typename File> +off_t +Elf_file<size, big_endian, File>::section_header_offset(unsigned int shndx) +{ + if (shndx >= this->shnum()) + this->file_->error(_("section_header_offset: bad shndx %u >= %u"), + shndx, this->shnum()); + return this->shoff_ + This::shdr_size * shndx; +} + +// Return the name of section SHNDX. + +template<int size, bool big_endian, typename File> +std::string +Elf_file<size, big_endian, File>::section_name(unsigned int shndx) +{ + File* const file = this->file_; + + // Get the section name offset. + unsigned int sh_name; + { + typename File::View v(file->view(this->section_header_offset(shndx), + This::shdr_size)); + Ef_shdr shdr(v.data()); + sh_name = shdr.get_sh_name(); + } + + // Get the file offset for the section name string table data. + off_t shstr_off; + typename Elf_types<size>::Elf_WXword shstr_size; + { + const unsigned int shstrndx = this->shstrndx_; + typename File::View v(file->view(this->section_header_offset(shstrndx), + This::shdr_size)); + Ef_shdr shstr_shdr(v.data()); + shstr_off = shstr_shdr.get_sh_offset(); + shstr_size = shstr_shdr.get_sh_size(); + } + + if (sh_name >= shstr_size) + file->error(_("bad section name offset for section %u: %u"), + shndx, sh_name); + + typename File::View v(file->view(shstr_off, shstr_size)); + + const unsigned char* datau = v.data(); + const char* data = reinterpret_cast<const char*>(datau); + const void* p = ::memchr(data + sh_name, '\0', shstr_size - sh_name); + if (p == NULL) + file->error(_("missing null terminator for name of section %u"), + shndx); + + size_t len = static_cast<const char*>(p) - (data + sh_name); + + return std::string(data + sh_name, len); +} + +// Return the contents of section SHNDX. + +template<int size, bool big_endian, typename File> +typename File::Location +Elf_file<size, big_endian, File>::section_contents(unsigned int shndx) +{ + File* const file = this->file_; + + if (shndx >= this->shnum()) + file->error(_("section_contents: bad shndx %u >= %u"), + shndx, this->shnum()); + + typename File::View v(file->view(this->section_header_offset(shndx), + This::shdr_size)); + Ef_shdr shdr(v.data()); + return typename File::Location(shdr.get_sh_offset(), shdr.get_sh_size()); +} + +// Get the size of section SHNDX. + +template<int size, bool big_endian, typename File> +typename Elf_types<size>::Elf_WXword +Elf_file<size, big_endian, File>::section_size(unsigned int shndx) +{ + File* const file = this->file_; + + if (shndx >= this->shnum()) + file->error(_("section_size: bad shndx %u >= %u"), + shndx, this->shnum()); + + typename File::View v(file->view(this->section_header_offset(shndx), + This::shdr_size)); + + Ef_shdr shdr(v.data()); + return shdr.get_sh_size(); +} + +// Return the section flags of section SHNDX. + +template<int size, bool big_endian, typename File> +typename Elf_types<size>::Elf_WXword +Elf_file<size, big_endian, File>::section_flags(unsigned int shndx) +{ + File* const file = this->file_; + + if (shndx >= this->shnum()) + file->error(_("section_flags: bad shndx %u >= %u"), + shndx, this->shnum()); + + typename File::View v(file->view(this->section_header_offset(shndx), + This::shdr_size)); + + Ef_shdr shdr(v.data()); + return shdr.get_sh_flags(); +} + +// Return the address of section SHNDX. + +template<int size, bool big_endian, typename File> +typename Elf_types<size>::Elf_Addr +Elf_file<size, big_endian, File>::section_addr(unsigned int shndx) +{ + File* const file = this->file_; + + if (shndx >= this->shnum()) + file->error(_("section_flags: bad shndx %u >= %u"), + shndx, this->shnum()); + + typename File::View v(file->view(this->section_header_offset(shndx), + This::shdr_size)); + + Ef_shdr shdr(v.data()); + return shdr.get_sh_addr(); +} + +// Return the type of section SHNDX. + +template<int size, bool big_endian, typename File> +Elf_Word +Elf_file<size, big_endian, File>::section_type(unsigned int shndx) +{ + File* const file = this->file_; + + if (shndx >= this->shnum()) + file->error(_("section_type: bad shndx %u >= %u"), + shndx, this->shnum()); + + typename File::View v(file->view(this->section_header_offset(shndx), + This::shdr_size)); + + Ef_shdr shdr(v.data()); + return shdr.get_sh_type(); +} + +// Return the sh_link field of section SHNDX. + +template<int size, bool big_endian, typename File> +Elf_Word +Elf_file<size, big_endian, File>::section_link(unsigned int shndx) +{ + File* const file = this->file_; + + if (shndx >= this->shnum()) + file->error(_("section_link: bad shndx %u >= %u"), + shndx, this->shnum()); + + typename File::View v(file->view(this->section_header_offset(shndx), + This::shdr_size)); + + Ef_shdr shdr(v.data()); + return shdr.get_sh_link(); +} + +// Return the sh_info field of section SHNDX. + +template<int size, bool big_endian, typename File> +Elf_Word +Elf_file<size, big_endian, File>::section_info(unsigned int shndx) +{ + File* const file = this->file_; + + if (shndx >= this->shnum()) + file->error(_("section_info: bad shndx %u >= %u"), + shndx, this->shnum()); + + typename File::View v(file->view(this->section_header_offset(shndx), + This::shdr_size)); + + Ef_shdr shdr(v.data()); + return shdr.get_sh_info(); +} + +// Return the sh_addralign field of section SHNDX. + +template<int size, bool big_endian, typename File> +typename Elf_types<size>::Elf_WXword +Elf_file<size, big_endian, File>::section_addralign(unsigned int shndx) +{ + File* const file = this->file_; + + if (shndx >= this->shnum()) + file->error(_("section_addralign: bad shndx %u >= %u"), + shndx, this->shnum()); + + typename File::View v(file->view(this->section_header_offset(shndx), + This::shdr_size)); + + Ef_shdr shdr(v.data()); + return shdr.get_sh_addralign(); +} + +inline +Elf_strtab::Elf_strtab(const unsigned char* p, size_t size) +{ + // Check if the section is NUL-terminated. If it isn't, we ignore + // the last part to make sure we don't return non-NUL-terminated + // strings. + while (size > 0 && p[size - 1] != 0) + size--; + this->base_ = reinterpret_cast<const char*>(p); + this->usable_size_ = size; +} + +} // End namespace elfcpp. + +#endif // !defined(ELFCPP_FILE_H) |