// Copyright 2014 Renato Tegon Forti, Antony Polukhin.
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// Copyright 2015-2019 Antony Polukhin.
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//
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// Distributed under the Boost Software License, Version 1.0.
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// (See accompanying file LICENSE_1_0.txt
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// or copy at http://www.boost.org/LICENSE_1_0.txt)
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#ifndef BOOST_DLL_DETAIL_POSIX_ELF_INFO_HPP
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#define BOOST_DLL_DETAIL_POSIX_ELF_INFO_HPP
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#include <boost/dll/config.hpp>
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#ifdef BOOST_HAS_PRAGMA_ONCE
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# pragma once
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#endif
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#include <cstring>
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#include <fstream>
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#include <limits>
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#include <boost/cstdint.hpp>
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#include <boost/throw_exception.hpp>
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namespace boost { namespace dll { namespace detail {
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template <class AddressOffsetT>
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struct Elf_Ehdr_template {
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unsigned char e_ident[16]; /* Magic number and other info */
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boost::uint16_t e_type; /* Object file type */
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boost::uint16_t e_machine; /* Architecture */
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boost::uint32_t e_version; /* Object file version */
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AddressOffsetT e_entry; /* Entry point virtual address */
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AddressOffsetT e_phoff; /* Program header table file offset */
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AddressOffsetT e_shoff; /* Section header table file offset */
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boost::uint32_t e_flags; /* Processor-specific flags */
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boost::uint16_t e_ehsize; /* ELF header size in bytes */
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boost::uint16_t e_phentsize; /* Program header table entry size */
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boost::uint16_t e_phnum; /* Program header table entry count */
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boost::uint16_t e_shentsize; /* Section header table entry size */
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boost::uint16_t e_shnum; /* Section header table entry count */
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boost::uint16_t e_shstrndx; /* Section header string table index */
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};
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typedef Elf_Ehdr_template<boost::uint32_t> Elf32_Ehdr_;
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typedef Elf_Ehdr_template<boost::uint64_t> Elf64_Ehdr_;
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template <class AddressOffsetT>
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struct Elf_Shdr_template {
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boost::uint32_t sh_name; /* Section name (string tbl index) */
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boost::uint32_t sh_type; /* Section type */
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AddressOffsetT sh_flags; /* Section flags */
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AddressOffsetT sh_addr; /* Section virtual addr at execution */
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AddressOffsetT sh_offset; /* Section file offset */
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AddressOffsetT sh_size; /* Section size in bytes */
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boost::uint32_t sh_link; /* Link to another section */
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boost::uint32_t sh_info; /* Additional section information */
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AddressOffsetT sh_addralign; /* Section alignment */
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AddressOffsetT sh_entsize; /* Entry size if section holds table */
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};
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typedef Elf_Shdr_template<boost::uint32_t> Elf32_Shdr_;
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typedef Elf_Shdr_template<boost::uint64_t> Elf64_Shdr_;
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template <class AddressOffsetT>
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struct Elf_Sym_template;
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template <>
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struct Elf_Sym_template<boost::uint32_t> {
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typedef boost::uint32_t AddressOffsetT;
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boost::uint32_t st_name; /* Symbol name (string tbl index) */
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AddressOffsetT st_value; /* Symbol value */
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AddressOffsetT st_size; /* Symbol size */
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unsigned char st_info; /* Symbol type and binding */
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unsigned char st_other; /* Symbol visibility */
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boost::uint16_t st_shndx; /* Section index */
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};
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template <>
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struct Elf_Sym_template<boost::uint64_t> {
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typedef boost::uint64_t AddressOffsetT;
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boost::uint32_t st_name; /* Symbol name (string tbl index) */
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unsigned char st_info; /* Symbol type and binding */
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unsigned char st_other; /* Symbol visibility */
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boost::uint16_t st_shndx; /* Section index */
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AddressOffsetT st_value; /* Symbol value */
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AddressOffsetT st_size; /* Symbol size */
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};
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typedef Elf_Sym_template<boost::uint32_t> Elf32_Sym_;
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typedef Elf_Sym_template<boost::uint64_t> Elf64_Sym_;
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template <class AddressOffsetT>
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class elf_info {
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typedef boost::dll::detail::Elf_Ehdr_template<AddressOffsetT> header_t;
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typedef boost::dll::detail::Elf_Shdr_template<AddressOffsetT> section_t;
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typedef boost::dll::detail::Elf_Sym_template<AddressOffsetT> symbol_t;
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BOOST_STATIC_CONSTANT(boost::uint32_t, SHT_SYMTAB_ = 2);
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BOOST_STATIC_CONSTANT(boost::uint32_t, SHT_STRTAB_ = 3);
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BOOST_STATIC_CONSTANT(unsigned char, STB_LOCAL_ = 0); /* Local symbol */
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BOOST_STATIC_CONSTANT(unsigned char, STB_GLOBAL_ = 1); /* Global symbol */
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BOOST_STATIC_CONSTANT(unsigned char, STB_WEAK_ = 2); /* Weak symbol */
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/* Symbol visibility specification encoded in the st_other field. */
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BOOST_STATIC_CONSTANT(unsigned char, STV_DEFAULT_ = 0); /* Default symbol visibility rules */
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BOOST_STATIC_CONSTANT(unsigned char, STV_INTERNAL_ = 1); /* Processor specific hidden class */
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BOOST_STATIC_CONSTANT(unsigned char, STV_HIDDEN_ = 2); /* Sym unavailable in other modules */
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BOOST_STATIC_CONSTANT(unsigned char, STV_PROTECTED_ = 3); /* Not preemptible, not exported */
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public:
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static bool parsing_supported(std::ifstream& fs) {
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const unsigned char magic_bytes[5] = {
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0x7f, 'E', 'L', 'F', sizeof(boost::uint32_t) == sizeof(AddressOffsetT) ? 1 : 2
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};
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unsigned char ch;
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fs.seekg(0);
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for (std::size_t i = 0; i < sizeof(magic_bytes); ++i) {
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fs >> ch;
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if (ch != magic_bytes[i]) {
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return false;
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}
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}
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return true;
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}
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static std::vector<std::string> sections(std::ifstream& fs) {
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std::vector<std::string> ret;
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std::vector<char> names;
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sections_names_raw(fs, names);
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const char* name_begin = &names[0];
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const char* const name_end = name_begin + names.size();
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ret.reserve(header(fs).e_shnum);
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do {
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ret.push_back(name_begin);
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name_begin += ret.back().size() + 1;
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} while (name_begin != name_end);
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return ret;
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}
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private:
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template <class Integer>
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static void checked_seekg(std::ifstream& fs, Integer pos) {
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/* TODO: use cmp_less, cmp_greater
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if ((std::numeric_limits<std::streamoff>::max)() < pos) {
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boost::throw_exception(std::runtime_error("Integral overflow while getting info from ELF file"));
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}
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if ((std::numeric_limits<std::streamoff>::min)() > pos){
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boost::throw_exception(std::runtime_error("Integral underflow while getting info from ELF file"));
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}
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*/
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fs.seekg(static_cast<std::streamoff>(pos));
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}
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template <class T>
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static void read_raw(std::ifstream& fs, T& value, std::size_t size = sizeof(T)) {
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fs.read(reinterpret_cast<char*>(&value), size);
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}
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static header_t header(std::ifstream& fs) {
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header_t elf;
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fs.seekg(0);
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read_raw(fs, elf);
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return elf;
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}
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static void sections_names_raw(std::ifstream& fs, std::vector<char>& sections) {
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const header_t elf = header(fs);
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section_t section_names_section;
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checked_seekg(fs, elf.e_shoff + elf.e_shstrndx * sizeof(section_t));
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read_raw(fs, section_names_section);
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sections.resize(static_cast<std::size_t>(section_names_section.sh_size));
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checked_seekg(fs, section_names_section.sh_offset);
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read_raw(fs, sections[0], static_cast<std::size_t>(section_names_section.sh_size));
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}
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static void symbols_text(std::ifstream& fs, std::vector<symbol_t>& symbols, std::vector<char>& text) {
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const header_t elf = header(fs);
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checked_seekg(fs, elf.e_shoff);
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for (std::size_t i = 0; i < elf.e_shnum; ++i) {
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section_t section;
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read_raw(fs, section);
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if (section.sh_type == SHT_SYMTAB_) {
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symbols.resize(static_cast<std::size_t>(section.sh_size / sizeof(symbol_t)));
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const std::ifstream::pos_type pos = fs.tellg();
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checked_seekg(fs, section.sh_offset);
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read_raw(fs, symbols[0], static_cast<std::size_t>(section.sh_size - (section.sh_size % sizeof(symbol_t))) );
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checked_seekg(fs, pos);
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} else if (section.sh_type == SHT_STRTAB_) {
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text.resize(static_cast<std::size_t>(section.sh_size));
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const std::ifstream::pos_type pos = fs.tellg();
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checked_seekg(fs, section.sh_offset);
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read_raw(fs, text[0], static_cast<std::size_t>(section.sh_size));
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checked_seekg(fs, pos);
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}
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}
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}
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static bool is_visible(const symbol_t& sym) BOOST_NOEXCEPT {
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// `(sym.st_info >> 4) != STB_LOCAL_ && !!sym.st_size` check also workarounds the
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// GCC's issue https://sourceware.org/bugzilla/show_bug.cgi?id=13621
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return (sym.st_other & 0x03) == STV_DEFAULT_ && (sym.st_info >> 4) != STB_LOCAL_ && !!sym.st_size;
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}
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public:
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static std::vector<std::string> symbols(std::ifstream& fs) {
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std::vector<std::string> ret;
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std::vector<symbol_t> symbols;
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std::vector<char> text;
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symbols_text(fs, symbols, text);
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ret.reserve(symbols.size());
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for (std::size_t i = 0; i < symbols.size(); ++i) {
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if (is_visible(symbols[i])) {
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ret.push_back(&text[0] + symbols[i].st_name);
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if (ret.back().empty()) {
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ret.pop_back(); // Do not show empty names
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}
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}
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}
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return ret;
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}
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static std::vector<std::string> symbols(std::ifstream& fs, const char* section_name) {
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std::vector<std::string> ret;
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std::size_t index = 0;
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std::size_t ptrs_in_section_count = 0;
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{
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std::vector<char> names;
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sections_names_raw(fs, names);
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const header_t elf = header(fs);
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for (; index < elf.e_shnum; ++index) {
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section_t section;
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checked_seekg(fs, elf.e_shoff + index * sizeof(section_t));
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read_raw(fs, section);
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if (!std::strcmp(&names[0] + section.sh_name, section_name)) {
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if (!section.sh_entsize) {
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section.sh_entsize = 1;
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}
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ptrs_in_section_count = static_cast<std::size_t>(section.sh_size / section.sh_entsize);
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break;
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}
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}
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}
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std::vector<symbol_t> symbols;
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std::vector<char> text;
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symbols_text(fs, symbols, text);
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if (ptrs_in_section_count < symbols.size()) {
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ret.reserve(ptrs_in_section_count);
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} else {
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ret.reserve(symbols.size());
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}
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for (std::size_t i = 0; i < symbols.size(); ++i) {
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if (symbols[i].st_shndx == index && is_visible(symbols[i])) {
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ret.push_back(&text[0] + symbols[i].st_name);
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if (ret.back().empty()) {
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ret.pop_back(); // Do not show empty names
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}
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}
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}
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return ret;
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}
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};
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typedef elf_info<boost::uint32_t> elf_info32;
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typedef elf_info<boost::uint64_t> elf_info64;
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}}} // namespace boost::dll::detail
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#endif // BOOST_DLL_DETAIL_POSIX_ELF_INFO_HPP
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