[163] | 1 | /* |
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| 2 | This file is part of Libelfpp. |
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| 3 | |
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| 4 | Libelfpp is free software: you can redistribute it and/or modify |
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| 5 | it under the terms of the GNU Lesser General Public License as |
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| 6 | published by the Free Software Foundation, either version 3 of the |
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| 7 | License, or (at your option) any later version. |
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| 8 | |
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| 9 | Libelfpp is distributed in the hope that it will be useful, but |
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| 10 | WITHOUT ANY WARRANTY; without even the implied warranty of |
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| 11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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| 12 | General Public License for more details. |
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| 13 | |
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| 14 | You should have received a copy of the GNU Lesser General Public |
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| 15 | License along with Libelfpp. If not, see |
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| 16 | <http://www.gnu.org/licenses/>. |
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| 17 | |
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| 18 | Copyright (c) Alexandre Becoulet <alexandre.becoulet@free.fr> |
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| 19 | */ |
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| 20 | |
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| 21 | |
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| 22 | #include <stdexcept> |
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| 23 | #include <cstring> |
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| 24 | |
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| 25 | #include <dpp/foreach> |
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| 26 | #include <dpp/interval_set> |
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| 27 | |
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| 28 | #include <elfpp/object> |
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| 29 | #include <elfpp/access> |
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| 30 | #include <elfpp/section> |
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| 31 | #include <elfpp/segment> |
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| 32 | #include <elfpp/symbol> |
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| 33 | #include <elfpp/reloc> |
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| 34 | |
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| 35 | namespace elfpp |
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| 36 | { |
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| 37 | |
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| 38 | ei_class_e object::get_word_width(e_machine_e machine) |
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| 39 | { |
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| 40 | switch (machine) |
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| 41 | { |
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| 42 | case EM_386: |
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| 43 | return ELFCLASS32; |
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| 44 | |
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| 45 | case EM_X86_64: |
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| 46 | return ELFCLASS64; |
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| 47 | |
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| 48 | default: |
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| 49 | throw std::runtime_error("unable to guess machine word width"); |
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| 50 | } |
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| 51 | } |
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| 52 | |
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| 53 | ei_data_e object::get_byte_order(e_machine_e machine) |
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| 54 | { |
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| 55 | switch (machine) |
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| 56 | { |
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| 57 | case EM_SPARC: |
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| 58 | return ELFDATA2MSB; |
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| 59 | |
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| 60 | case EM_X86_64: |
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| 61 | case EM_386: |
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| 62 | return ELFDATA2LSB; |
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| 63 | |
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| 64 | default: |
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| 65 | throw std::runtime_error("unable to guess machine byte order"); |
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| 66 | } |
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| 67 | } |
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| 68 | |
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| 69 | object::object(e_machine_e machine, |
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| 70 | ei_class_e word_width, |
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| 71 | ei_data_e byte_order) |
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| 72 | : section_tab_(), |
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| 73 | os_abi_(ELFOSABI_SYSV), |
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| 74 | type_(ET_REL), |
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| 75 | machine_(machine), |
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| 76 | generate_symtab_(true), |
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| 77 | entry_(0), |
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| 78 | flags_(0) |
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| 79 | { |
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| 80 | switch (machine) |
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| 81 | { |
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| 82 | case EM_X86_64: |
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| 83 | case EM_386: |
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| 84 | rel_with_addend_ = false; |
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| 85 | break; |
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| 86 | |
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| 87 | default: |
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| 88 | rel_with_addend_ = true; |
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| 89 | break; |
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| 90 | } |
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| 91 | |
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| 92 | if (byte_order == ELFDATANONE) |
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| 93 | byte_order = get_byte_order(machine); |
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| 94 | |
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| 95 | if (word_width == ELFCLASSNONE) |
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| 96 | word_width = get_word_width(machine); |
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| 97 | |
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| 98 | switch (word_width) |
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| 99 | { |
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| 100 | case ELFCLASS32: { |
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| 101 | static elf32_access a; |
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| 102 | access_ = static_cast<elf_access*>(&a); |
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| 103 | break; |
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| 104 | } |
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| 105 | |
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| 106 | case ELFCLASS64: { |
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| 107 | static elf64_access a; |
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| 108 | access_ = static_cast<elf_access*>(&a); |
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| 109 | break; |
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| 110 | } |
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| 111 | |
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| 112 | default: |
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| 113 | throw std::runtime_error("bad elf class"); |
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| 114 | } |
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| 115 | |
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| 116 | |
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| 117 | } |
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| 118 | |
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| 119 | object::object() |
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| 120 | : section_tab_(), |
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| 121 | os_abi_(ELFOSABI_SYSV), |
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| 122 | type_(ET_REL), |
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| 123 | machine_(EM_NONE), |
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| 124 | generate_symtab_(true), |
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| 125 | entry_(0), |
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| 126 | flags_(0) |
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| 127 | {} |
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| 128 | |
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| 129 | |
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| 130 | |
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| 131 | void object::copy_info(object& obj) |
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| 132 | { |
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| 133 | this->word_width_ = obj.word_width_ ; |
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| 134 | this->byteorder_ = obj.byteorder_ ; |
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| 135 | this->machine_ = obj.machine_ ; |
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| 136 | this->os_abi_ = obj.os_abi_ ; |
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| 137 | this->abi_ver_ = obj.abi_ver_ ; |
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| 138 | this->type_ = obj.type_ ; |
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| 139 | this->flags_ = obj.flags_ ; |
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| 140 | |
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| 141 | switch (this->word_width_) |
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| 142 | { |
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| 143 | case ELFCLASS32: { |
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| 144 | static elf32_access a; |
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| 145 | access_ = static_cast<elf_access*>(&a); |
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| 146 | break; |
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| 147 | } |
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| 148 | |
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| 149 | case ELFCLASS64: { |
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| 150 | static elf64_access a; |
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| 151 | access_ = static_cast<elf_access*>(&a); |
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| 152 | break; |
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| 153 | } |
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| 154 | |
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| 155 | default: |
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| 156 | throw std::runtime_error("bad elf class"); |
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| 157 | } |
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| 158 | |
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| 159 | } |
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| 160 | |
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| 161 | object::object(const std::string &filename) |
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| 162 | : generate_symtab_(false) |
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| 163 | { |
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| 164 | FILE *file = fopen(filename.c_str(), "rb"); |
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| 165 | |
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| 166 | if (!file) |
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| 167 | throw std::runtime_error("unable to open file"); |
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| 168 | |
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| 169 | unsigned char e_ident[EI_NIDENT]; /* Magic number and other info */ |
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| 170 | |
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| 171 | if (fread(e_ident, EI_NIDENT, 1, file) != 1) |
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| 172 | throw std::runtime_error("unable to read file"); |
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| 173 | |
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| 174 | try { |
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| 175 | |
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| 176 | if (std::memcmp(e_ident, ELFMAG, 4)) |
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| 177 | throw std::runtime_error("bad elf file header"); |
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| 178 | |
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| 179 | switch (e_ident[EI_CLASS]) |
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| 180 | { |
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| 181 | case ELFCLASS32: { |
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| 182 | static elf32_access a; |
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| 183 | access_ = static_cast<elf_access*>(&a); |
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| 184 | break; |
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| 185 | } |
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| 186 | |
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| 187 | case ELFCLASS64: { |
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| 188 | static elf64_access a; |
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| 189 | access_ = static_cast<elf_access*>(&a); |
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| 190 | break; |
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| 191 | } |
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| 192 | |
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| 193 | default: |
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| 194 | throw std::runtime_error("bad elf class"); |
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| 195 | } |
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| 196 | |
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| 197 | access_->read(*this, file); |
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| 198 | |
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| 199 | } catch (...) { |
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| 200 | fclose(file); |
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| 201 | throw; |
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| 202 | } |
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| 203 | |
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| 204 | fclose(file); |
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| 205 | } |
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| 206 | |
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| 207 | object::~object() |
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| 208 | { |
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| 209 | FOREACH2(s, section_tab_) |
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| 210 | delete &*s; |
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| 211 | |
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| 212 | FOREACH(s, sym_tab_) |
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| 213 | delete s->second; |
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| 214 | } |
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| 215 | |
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| 216 | e_machine_e object::get_machine() |
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| 217 | { |
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| 218 | return machine_; |
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| 219 | } |
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| 220 | ei_class_e object::get_word_width() |
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| 221 | { |
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| 222 | return word_width_; |
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| 223 | } |
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| 224 | ei_data_e object::get_byteorder() |
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| 225 | { |
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| 226 | return byteorder_; |
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| 227 | } |
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| 228 | |
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| 229 | section & object::get_section(const std::string &name) |
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| 230 | { |
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| 231 | FOREACH(s, section_tab_) |
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| 232 | if (s->get_name() == name) |
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| 233 | return *s; |
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| 234 | |
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| 235 | throw std::runtime_error("no such section"); |
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| 236 | } |
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| 237 | |
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| 238 | void object::parse_symbol_table() |
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| 239 | { |
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| 240 | access_->load_symtab(*this); |
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| 241 | access_->load_reltab(*this); |
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| 242 | } |
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| 243 | |
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| 244 | void object::set_relative_relocs(symbol *sym) |
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| 245 | { |
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| 246 | // find mangled symbol for each relocation and set offset relative |
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| 247 | // to symbol value. |
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| 248 | FOREACH2(k, sym->get_reloc_table()) |
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| 249 | { |
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| 250 | if (k->get_mangled_symbol()) |
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| 251 | continue; |
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| 252 | |
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| 253 | if (sym->get_type() == STT_SECTION) |
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| 254 | { |
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| 255 | section *sS = sym->get_section(); |
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| 256 | int64_t addend = k->get_addend(); |
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| 257 | try { |
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| 258 | symbol &ss = sS->get_symbol(addend); |
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| 259 | k->set_symbol(&ss); |
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| 260 | k->set_addend(addend - ss.get_value()); |
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| 261 | } catch (std::runtime_error &e) { |
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| 262 | #if 0 |
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| 263 | std::cerr << e.what() << " at " << sS->get_name() << ":" << std::hex << addend |
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| 264 | << " while resolving section symbol addend at " |
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| 265 | << k->get_section()->get_name() << ":" << k->get_offset() << " type " << k->get_type() << std::endl; |
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| 266 | #endif |
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| 267 | } |
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| 268 | } |
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| 269 | |
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| 270 | try { |
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| 271 | symbol &msym = k->get_section()->get_symbol(k->get_offset()); |
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| 272 | // std::cerr << *i->second << " " << msym << std::endl; |
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| 273 | k->set_mangled_symbol(&msym); |
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| 274 | k->set_offset(k->get_offset() - msym.get_value()); |
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| 275 | |
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| 276 | } catch (std::runtime_error &e) { |
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| 277 | #if 0 |
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| 278 | if (strncmp(k->get_section()->get_name().c_str(), ".debug", 6)) |
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| 279 | std::cerr << e.what() << " at " << k->get_section()->get_name() << ":" << std::hex << k->get_offset() << std::endl; |
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| 280 | #endif |
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| 281 | } |
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| 282 | |
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| 283 | } |
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| 284 | } |
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| 285 | |
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| 286 | void object::create_orphan_symbols() |
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| 287 | { |
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| 288 | FOREACH(s, get_section_table()) |
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| 289 | { |
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| 290 | if (!(s->get_flags() & SHF_ALLOC)) |
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| 291 | continue; |
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| 292 | |
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| 293 | typedef dpp::interval_set<uint32_t> is_t; |
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| 294 | is_t is; |
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| 295 | |
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| 296 | is |= is_t::interval_type(s->get_size(), (uint32_t)-1); |
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| 297 | |
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| 298 | FOREACH(i, s->get_symbol_table()) |
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| 299 | { |
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| 300 | uint32_t val = i->second->get_value(); |
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| 301 | size_t size = i->second->get_size(); |
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| 302 | |
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| 303 | if (size) |
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| 304 | is |= is_t::interval_type(val, val + size); |
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| 305 | } |
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| 306 | |
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| 307 | is = ~is; |
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| 308 | |
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| 309 | // create symbols for all orphan section areas in this object |
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| 310 | FOREACH(i, is) |
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| 311 | { |
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| 312 | static int nosym_id = 0; |
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| 313 | char name[32]; |
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| 314 | sprintf(name, "nosym_%i", nosym_id++); |
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| 315 | symbol *sym = new symbol(name); |
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| 316 | |
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| 317 | sym->set_value(i->low_bound()); |
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| 318 | sym->set_size(i->high_bound() - i->low_bound()); |
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| 319 | sym->set_section(*s); |
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| 320 | s->add_symbol(*sym); |
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| 321 | } |
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| 322 | } |
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| 323 | } |
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| 324 | |
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| 325 | void object::load_symbol_data() |
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| 326 | { |
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| 327 | FOREACH(s, get_section_table()) |
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| 328 | { |
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| 329 | if (s->get_type() == SHT_NOBITS) |
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| 330 | continue; |
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| 331 | |
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| 332 | FOREACH(i, s->get_symbol_table()) |
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| 333 | { |
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| 334 | symbol *j = i->second; |
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| 335 | |
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| 336 | // copy section data in each symbol content buffer |
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| 337 | size_t size = j->get_size(); |
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| 338 | |
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| 339 | if (size != 0 && j->get_value() + size <= s->get_size()) |
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| 340 | j->set_content(s->get_content() + j->get_value()); |
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| 341 | } |
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| 342 | } |
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| 343 | } |
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| 344 | |
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| 345 | void object::set_relative_relocs() |
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| 346 | { |
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| 347 | FOREACH(s, get_section_table()) |
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| 348 | { |
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| 349 | FOREACH(i, s->get_symbol_table()) |
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| 350 | set_relative_relocs(i->second); |
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| 351 | } |
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| 352 | |
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| 353 | FOREACH(i, get_symbol_table()) |
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| 354 | set_relative_relocs(i->second); |
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| 355 | } |
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| 356 | |
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| 357 | void object::write(const std::string &filename) |
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| 358 | { |
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| 359 | FILE *file = fopen(filename.c_str(), "wb"); |
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| 360 | |
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| 361 | if (!file) |
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| 362 | throw std::runtime_error("unable to open file"); |
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| 363 | |
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| 364 | try { |
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| 365 | access_->write(*this, file); |
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| 366 | } catch (...) { |
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| 367 | fclose(file); |
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| 368 | throw; |
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| 369 | } |
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| 370 | |
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| 371 | fclose(file); |
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| 372 | } |
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| 373 | |
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| 374 | void object::add_section(section &sec) |
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| 375 | { |
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| 376 | section_tab_.push_back(sec); |
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| 377 | } |
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| 378 | |
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| 379 | void object::add_segment(segment &seg) |
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| 380 | { |
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| 381 | segment_tab_.push_back(seg); |
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| 382 | } |
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| 383 | |
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| 384 | void object::remove_section(section &sec) |
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| 385 | { |
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| 386 | sec.remove(); |
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| 387 | } |
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| 388 | |
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| 389 | void object::add_symbol(symbol &sym) |
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| 390 | { |
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| 391 | #if 0 |
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| 392 | if (sym.get_section()) |
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| 393 | sym.get_section()->add_symbol(sym); |
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| 394 | else |
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| 395 | #endif |
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| 396 | sym_tab_.insert(sym_tab_map_t::value_type(sym.get_name(), &sym)); |
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| 397 | } |
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| 398 | |
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| 399 | void object::remove_symbol(symbol &sym) |
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| 400 | { |
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| 401 | sym_tab_.erase(sym.get_name()); |
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| 402 | } |
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| 403 | |
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| 404 | } |
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| 405 | |
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