1 //===- llvm/BinaryFormat/Magic.cpp - File magic identification --*- C++ -*-===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 #include "llvm/BinaryFormat/Magic.h" 10 11 #include "llvm/BinaryFormat/COFF.h" 12 #include "llvm/BinaryFormat/ELF.h" 13 #include "llvm/BinaryFormat/MachO.h" 14 #include "llvm/Support/Endian.h" 15 #include "llvm/Support/FileSystem.h" 16 #include "llvm/Support/MemoryBuffer.h" 17 18 #if !defined(_MSC_VER) && !defined(__MINGW32__) 19 #include <unistd.h> 20 #else 21 #include <io.h> 22 #endif 23 24 using namespace llvm; 25 using namespace llvm::support::endian; 26 using namespace llvm::sys::fs; 27 28 template <size_t N> 29 static bool startswith(StringRef Magic, const char (&S)[N]) { 30 return Magic.startswith(StringRef(S, N - 1)); 31 } 32 33 /// Identify the magic in magic. 34 file_magic llvm::identify_magic(StringRef Magic) { 35 if (Magic.size() < 4) 36 return file_magic::unknown; 37 switch ((unsigned char)Magic[0]) { 38 case 0x00: { 39 // COFF bigobj, CL.exe's LTO object file, or short import library file 40 if (startswith(Magic, "\0\0\xFF\xFF")) { 41 size_t MinSize = 42 offsetof(COFF::BigObjHeader, UUID) + sizeof(COFF::BigObjMagic); 43 if (Magic.size() < MinSize) 44 return file_magic::coff_import_library; 45 46 const char *Start = Magic.data() + offsetof(COFF::BigObjHeader, UUID); 47 if (memcmp(Start, COFF::BigObjMagic, sizeof(COFF::BigObjMagic)) == 0) 48 return file_magic::coff_object; 49 if (memcmp(Start, COFF::ClGlObjMagic, sizeof(COFF::BigObjMagic)) == 0) 50 return file_magic::coff_cl_gl_object; 51 return file_magic::coff_import_library; 52 } 53 // Windows resource file 54 if (Magic.size() >= sizeof(COFF::WinResMagic) && 55 memcmp(Magic.data(), COFF::WinResMagic, sizeof(COFF::WinResMagic)) == 0) 56 return file_magic::windows_resource; 57 // 0x0000 = COFF unknown machine type 58 if (Magic[1] == 0) 59 return file_magic::coff_object; 60 if (startswith(Magic, "\0asm")) 61 return file_magic::wasm_object; 62 break; 63 } 64 case 0xDE: // 0x0B17C0DE = BC wraper 65 if (startswith(Magic, "\xDE\xC0\x17\x0B")) 66 return file_magic::bitcode; 67 break; 68 case 'B': 69 if (startswith(Magic, "BC\xC0\xDE")) 70 return file_magic::bitcode; 71 break; 72 case '!': 73 if (startswith(Magic, "!<arch>\n") || startswith(Magic, "!<thin>\n")) 74 return file_magic::archive; 75 break; 76 77 case '\177': 78 if (startswith(Magic, "\177ELF") && Magic.size() >= 18) { 79 bool Data2MSB = Magic[5] == 2; 80 unsigned high = Data2MSB ? 16 : 17; 81 unsigned low = Data2MSB ? 17 : 16; 82 if (Magic[high] == 0) { 83 switch (Magic[low]) { 84 default: 85 return file_magic::elf; 86 case 1: 87 return file_magic::elf_relocatable; 88 case 2: 89 return file_magic::elf_executable; 90 case 3: 91 return file_magic::elf_shared_object; 92 case 4: 93 return file_magic::elf_core; 94 } 95 } 96 // It's still some type of ELF file. 97 return file_magic::elf; 98 } 99 break; 100 101 case 0xCA: 102 if (startswith(Magic, "\xCA\xFE\xBA\xBE") || 103 startswith(Magic, "\xCA\xFE\xBA\xBF")) { 104 // This is complicated by an overlap with Java class files. 105 // See the Mach-O section in /usr/share/file/magic for details. 106 if (Magic.size() >= 8 && Magic[7] < 43) 107 return file_magic::macho_universal_binary; 108 } 109 break; 110 111 // The two magic numbers for mach-o are: 112 // 0xfeedface - 32-bit mach-o 113 // 0xfeedfacf - 64-bit mach-o 114 case 0xFE: 115 case 0xCE: 116 case 0xCF: { 117 uint16_t type = 0; 118 if (startswith(Magic, "\xFE\xED\xFA\xCE") || 119 startswith(Magic, "\xFE\xED\xFA\xCF")) { 120 /* Native endian */ 121 size_t MinSize; 122 if (Magic[3] == char(0xCE)) 123 MinSize = sizeof(MachO::mach_header); 124 else 125 MinSize = sizeof(MachO::mach_header_64); 126 if (Magic.size() >= MinSize) 127 type = Magic[12] << 24 | Magic[13] << 12 | Magic[14] << 8 | Magic[15]; 128 } else if (startswith(Magic, "\xCE\xFA\xED\xFE") || 129 startswith(Magic, "\xCF\xFA\xED\xFE")) { 130 /* Reverse endian */ 131 size_t MinSize; 132 if (Magic[0] == char(0xCE)) 133 MinSize = sizeof(MachO::mach_header); 134 else 135 MinSize = sizeof(MachO::mach_header_64); 136 if (Magic.size() >= MinSize) 137 type = Magic[15] << 24 | Magic[14] << 12 | Magic[13] << 8 | Magic[12]; 138 } 139 switch (type) { 140 default: 141 break; 142 case 1: 143 return file_magic::macho_object; 144 case 2: 145 return file_magic::macho_executable; 146 case 3: 147 return file_magic::macho_fixed_virtual_memory_shared_lib; 148 case 4: 149 return file_magic::macho_core; 150 case 5: 151 return file_magic::macho_preload_executable; 152 case 6: 153 return file_magic::macho_dynamically_linked_shared_lib; 154 case 7: 155 return file_magic::macho_dynamic_linker; 156 case 8: 157 return file_magic::macho_bundle; 158 case 9: 159 return file_magic::macho_dynamically_linked_shared_lib_stub; 160 case 10: 161 return file_magic::macho_dsym_companion; 162 case 11: 163 return file_magic::macho_kext_bundle; 164 } 165 break; 166 } 167 case 0xF0: // PowerPC Windows 168 case 0x83: // Alpha 32-bit 169 case 0x84: // Alpha 64-bit 170 case 0x66: // MPS R4000 Windows 171 case 0x50: // mc68K 172 case 0x4c: // 80386 Windows 173 case 0xc4: // ARMNT Windows 174 if (Magic[1] == 0x01) 175 return file_magic::coff_object; 176 LLVM_FALLTHROUGH; 177 178 case 0x90: // PA-RISC Windows 179 case 0x68: // mc68K Windows 180 if (Magic[1] == 0x02) 181 return file_magic::coff_object; 182 break; 183 184 case 'M': // Possible MS-DOS stub on Windows PE file, MSF/PDB file or a 185 // Minidump file. 186 if (startswith(Magic, "MZ") && Magic.size() >= 0x3c + 4) { 187 uint32_t off = read32le(Magic.data() + 0x3c); 188 // PE/COFF file, either EXE or DLL. 189 if (Magic.substr(off).startswith( 190 StringRef(COFF::PEMagic, sizeof(COFF::PEMagic)))) 191 return file_magic::pecoff_executable; 192 } 193 if (Magic.startswith("Microsoft C/C++ MSF 7.00\r\n")) 194 return file_magic::pdb; 195 if (startswith(Magic, "MDMP")) 196 return file_magic::minidump; 197 break; 198 199 case 0x64: // x86-64 or ARM64 Windows. 200 if (Magic[1] == char(0x86) || Magic[1] == char(0xaa)) 201 return file_magic::coff_object; 202 break; 203 204 default: 205 break; 206 } 207 return file_magic::unknown; 208 } 209 210 std::error_code llvm::identify_magic(const Twine &Path, file_magic &Result) { 211 auto FileOrError = MemoryBuffer::getFile(Path, -1LL, false); 212 if (!FileOrError) 213 return FileOrError.getError(); 214 215 std::unique_ptr<MemoryBuffer> FileBuffer = std::move(*FileOrError); 216 Result = identify_magic(FileBuffer->getBuffer()); 217 218 return std::error_code(); 219 } 220