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1 //===- llvm/BinaryFormat/Magic.cpp - File magic identification --*- C++ -*-===//
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2 //
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3 // The LLVM Compiler Infrastructure
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4 //
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5 // This file is distributed under the University of Illinois Open Source
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6 // License. See LICENSE.TXT for details.
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7 //
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8 //===----------------------------------------------------------------------===//
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9
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10 #include "llvm/BinaryFormat/Magic.h"
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11
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12 #include "llvm/BinaryFormat/COFF.h"
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13 #include "llvm/BinaryFormat/ELF.h"
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14 #include "llvm/BinaryFormat/MachO.h"
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15 #include "llvm/Support/Endian.h"
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16 #include "llvm/Support/FileSystem.h"
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17
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18 #if !defined(_MSC_VER) && !defined(__MINGW32__)
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19 #include <unistd.h>
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20 #else
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21 #include <io.h>
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22 #endif
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23
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24 using namespace llvm;
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25 using namespace llvm::support::endian;
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26 using namespace llvm::sys::fs;
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27
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28 template <size_t N>
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29 static bool startswith(StringRef Magic, const char (&S)[N]) {
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30 return Magic.startswith(StringRef(S, N - 1));
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31 }
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32
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33 /// @brief Identify the magic in magic.
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34 file_magic llvm::identify_magic(StringRef Magic) {
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35 if (Magic.size() < 4)
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36 return file_magic::unknown;
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37 switch ((unsigned char)Magic[0]) {
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38 case 0x00: {
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39 // COFF bigobj, CL.exe's LTO object file, or short import library file
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40 if (startswith(Magic, "\0\0\xFF\xFF")) {
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41 size_t MinSize =
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42 offsetof(COFF::BigObjHeader, UUID) + sizeof(COFF::BigObjMagic);
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43 if (Magic.size() < MinSize)
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44 return file_magic::coff_import_library;
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45
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46 const char *Start = Magic.data() + offsetof(COFF::BigObjHeader, UUID);
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47 if (memcmp(Start, COFF::BigObjMagic, sizeof(COFF::BigObjMagic)) == 0)
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48 return file_magic::coff_object;
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49 if (memcmp(Start, COFF::ClGlObjMagic, sizeof(COFF::BigObjMagic)) == 0)
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50 return file_magic::coff_cl_gl_object;
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51 return file_magic::coff_import_library;
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52 }
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53 // Windows resource file
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54 if (Magic.size() >= sizeof(COFF::WinResMagic) &&
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55 memcmp(Magic.data(), COFF::WinResMagic, sizeof(COFF::WinResMagic)) == 0)
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56 return file_magic::windows_resource;
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57 // 0x0000 = COFF unknown machine type
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58 if (Magic[1] == 0)
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59 return file_magic::coff_object;
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60 if (startswith(Magic, "\0asm"))
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61 return file_magic::wasm_object;
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62 break;
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63 }
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64 case 0xDE: // 0x0B17C0DE = BC wraper
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65 if (startswith(Magic, "\xDE\xC0\x17\x0B"))
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66 return file_magic::bitcode;
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67 break;
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68 case 'B':
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69 if (startswith(Magic, "BC\xC0\xDE"))
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70 return file_magic::bitcode;
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71 break;
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72 case '!':
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73 if (startswith(Magic, "!<arch>\n") || startswith(Magic, "!<thin>\n"))
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74 return file_magic::archive;
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75 break;
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76
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77 case '\177':
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78 if (startswith(Magic, "\177ELF") && Magic.size() >= 18) {
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79 bool Data2MSB = Magic[5] == 2;
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80 unsigned high = Data2MSB ? 16 : 17;
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81 unsigned low = Data2MSB ? 17 : 16;
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82 if (Magic[high] == 0) {
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83 switch (Magic[low]) {
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84 default:
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85 return file_magic::elf;
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86 case 1:
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87 return file_magic::elf_relocatable;
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88 case 2:
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89 return file_magic::elf_executable;
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90 case 3:
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91 return file_magic::elf_shared_object;
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92 case 4:
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93 return file_magic::elf_core;
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94 }
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95 }
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96 // It's still some type of ELF file.
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97 return file_magic::elf;
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98 }
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99 break;
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100
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101 case 0xCA:
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102 if (startswith(Magic, "\xCA\xFE\xBA\xBE") ||
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103 startswith(Magic, "\xCA\xFE\xBA\xBF")) {
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104 // This is complicated by an overlap with Java class files.
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105 // See the Mach-O section in /usr/share/file/magic for details.
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106 if (Magic.size() >= 8 && Magic[7] < 43)
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107 return file_magic::macho_universal_binary;
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108 }
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109 break;
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110
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111 // The two magic numbers for mach-o are:
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112 // 0xfeedface - 32-bit mach-o
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113 // 0xfeedfacf - 64-bit mach-o
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114 case 0xFE:
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115 case 0xCE:
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116 case 0xCF: {
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117 uint16_t type = 0;
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118 if (startswith(Magic, "\xFE\xED\xFA\xCE") ||
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119 startswith(Magic, "\xFE\xED\xFA\xCF")) {
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120 /* Native endian */
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121 size_t MinSize;
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122 if (Magic[3] == char(0xCE))
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123 MinSize = sizeof(MachO::mach_header);
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124 else
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125 MinSize = sizeof(MachO::mach_header_64);
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126 if (Magic.size() >= MinSize)
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127 type = Magic[12] << 24 | Magic[13] << 12 | Magic[14] << 8 | Magic[15];
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128 } else if (startswith(Magic, "\xCE\xFA\xED\xFE") ||
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129 startswith(Magic, "\xCF\xFA\xED\xFE")) {
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130 /* Reverse endian */
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131 size_t MinSize;
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132 if (Magic[0] == char(0xCE))
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133 MinSize = sizeof(MachO::mach_header);
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134 else
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135 MinSize = sizeof(MachO::mach_header_64);
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136 if (Magic.size() >= MinSize)
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137 type = Magic[15] << 24 | Magic[14] << 12 | Magic[13] << 8 | Magic[12];
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138 }
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139 switch (type) {
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140 default:
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141 break;
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142 case 1:
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143 return file_magic::macho_object;
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144 case 2:
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145 return file_magic::macho_executable;
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146 case 3:
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147 return file_magic::macho_fixed_virtual_memory_shared_lib;
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148 case 4:
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149 return file_magic::macho_core;
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150 case 5:
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151 return file_magic::macho_preload_executable;
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152 case 6:
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153 return file_magic::macho_dynamically_linked_shared_lib;
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154 case 7:
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155 return file_magic::macho_dynamic_linker;
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156 case 8:
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157 return file_magic::macho_bundle;
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158 case 9:
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159 return file_magic::macho_dynamically_linked_shared_lib_stub;
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160 case 10:
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161 return file_magic::macho_dsym_companion;
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162 case 11:
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163 return file_magic::macho_kext_bundle;
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164 }
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165 break;
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166 }
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167 case 0xF0: // PowerPC Windows
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168 case 0x83: // Alpha 32-bit
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169 case 0x84: // Alpha 64-bit
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170 case 0x66: // MPS R4000 Windows
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171 case 0x50: // mc68K
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172 case 0x4c: // 80386 Windows
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173 case 0xc4: // ARMNT Windows
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174 if (Magic[1] == 0x01)
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175 return file_magic::coff_object;
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176 LLVM_FALLTHROUGH;
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177
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178 case 0x90: // PA-RISC Windows
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179 case 0x68: // mc68K Windows
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180 if (Magic[1] == 0x02)
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181 return file_magic::coff_object;
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182 break;
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183
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184 case 'M': // Possible MS-DOS stub on Windows PE file
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185 if (startswith(Magic, "MZ") && Magic.size() >= 0x3c + 4) {
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186 uint32_t off = read32le(Magic.data() + 0x3c);
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187 // PE/COFF file, either EXE or DLL.
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188 if (Magic.substr(off).startswith(
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189 StringRef(COFF::PEMagic, sizeof(COFF::PEMagic))))
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190 return file_magic::pecoff_executable;
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191 }
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192 break;
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193
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194 case 0x64: // x86-64 or ARM64 Windows.
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195 if (Magic[1] == char(0x86) || Magic[1] == char(0xaa))
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196 return file_magic::coff_object;
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197 break;
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198
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199 default:
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200 break;
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201 }
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202 return file_magic::unknown;
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203 }
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204
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205 std::error_code llvm::identify_magic(const Twine &Path, file_magic &Result) {
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206 int FD;
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207 if (std::error_code EC = openFileForRead(Path, FD))
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208 return EC;
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209
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210 char Buffer[32];
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211 int Length = read(FD, Buffer, sizeof(Buffer));
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212 if (close(FD) != 0 || Length < 0)
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213 return std::error_code(errno, std::generic_category());
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214
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215 Result = identify_magic(StringRef(Buffer, Length));
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216 return std::error_code();
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217 }
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