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[/] [open8_urisc/] [trunk/] [gnu/] [binutils/] [elfcpp/] [elfcpp_file.h] - Rev 178
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// 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)
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