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 #include "llvm/ADT/StringRef.h" 11 #include "llvm/ADT/Twine.h" 12 #include "llvm/BinaryFormat/COFF.h" 13 #include "llvm/BinaryFormat/ELF.h" 14 #include "llvm/BinaryFormat/MachO.h" 15 #include "llvm/Support/Endian.h" 16 #include "llvm/Support/FileSystem.h" 17 #include "llvm/Support/MemoryBuffer.h" 18 19 #if !defined(_MSC_VER) && !defined(__MINGW32__) 20 #include <unistd.h> 21 #else 22 #include <io.h> 23 #endif 24 25 using namespace llvm; 26 using namespace llvm::support::endian; 27 using namespace llvm::sys::fs; 28 29 template <size_t N> 30 static bool startswith(StringRef Magic, const char (&S)[N]) { 31 return Magic.startswith(StringRef(S, N - 1)); 32 } 33 34 /// Identify the magic in magic. 35 file_magic llvm::identify_magic(StringRef Magic) { 36 if (Magic.size() < 4) 37 return file_magic::unknown; 38 switch ((unsigned char)Magic[0]) { 39 case 0x00: { 40 // COFF bigobj, CL.exe's LTO object file, or short import library file 41 if (startswith(Magic, "\0\0\xFF\xFF")) { 42 size_t MinSize = 43 offsetof(COFF::BigObjHeader, UUID) + sizeof(COFF::BigObjMagic); 44 if (Magic.size() < MinSize) 45 return file_magic::coff_import_library; 46 47 const char *Start = Magic.data() + offsetof(COFF::BigObjHeader, UUID); 48 if (memcmp(Start, COFF::BigObjMagic, sizeof(COFF::BigObjMagic)) == 0) 49 return file_magic::coff_object; 50 if (memcmp(Start, COFF::ClGlObjMagic, sizeof(COFF::BigObjMagic)) == 0) 51 return file_magic::coff_cl_gl_object; 52 return file_magic::coff_import_library; 53 } 54 // Windows resource file 55 if (Magic.size() >= sizeof(COFF::WinResMagic) && 56 memcmp(Magic.data(), COFF::WinResMagic, sizeof(COFF::WinResMagic)) == 0) 57 return file_magic::windows_resource; 58 // 0x0000 = COFF unknown machine type 59 if (Magic[1] == 0) 60 return file_magic::coff_object; 61 if (startswith(Magic, "\0asm")) 62 return file_magic::wasm_object; 63 break; 64 } 65 66 case 0x01: 67 // XCOFF format 68 if (startswith(Magic, "\x01\xDF")) 69 return file_magic::xcoff_object_32; 70 if (startswith(Magic, "\x01\xF7")) 71 return file_magic::xcoff_object_64; 72 break; 73 74 case 0xDE: // 0x0B17C0DE = BC wraper 75 if (startswith(Magic, "\xDE\xC0\x17\x0B")) 76 return file_magic::bitcode; 77 break; 78 case 'B': 79 if (startswith(Magic, "BC\xC0\xDE")) 80 return file_magic::bitcode; 81 break; 82 case '!': 83 if (startswith(Magic, "!<arch>\n") || startswith(Magic, "!<thin>\n")) 84 return file_magic::archive; 85 break; 86 87 case '\177': 88 if (startswith(Magic, "\177ELF") && Magic.size() >= 18) { 89 bool Data2MSB = Magic[5] == 2; 90 unsigned high = Data2MSB ? 16 : 17; 91 unsigned low = Data2MSB ? 17 : 16; 92 if (Magic[high] == 0) { 93 switch (Magic[low]) { 94 default: 95 return file_magic::elf; 96 case 1: 97 return file_magic::elf_relocatable; 98 case 2: 99 return file_magic::elf_executable; 100 case 3: 101 return file_magic::elf_shared_object; 102 case 4: 103 return file_magic::elf_core; 104 } 105 } 106 // It's still some type of ELF file. 107 return file_magic::elf; 108 } 109 break; 110 111 case 0xCA: 112 if (startswith(Magic, "\xCA\xFE\xBA\xBE") || 113 startswith(Magic, "\xCA\xFE\xBA\xBF")) { 114 // This is complicated by an overlap with Java class files. 115 // See the Mach-O section in /usr/share/file/magic for details. 116 if (Magic.size() >= 8 && Magic[7] < 43) 117 return file_magic::macho_universal_binary; 118 } 119 break; 120 121 // The two magic numbers for mach-o are: 122 // 0xfeedface - 32-bit mach-o 123 // 0xfeedfacf - 64-bit mach-o 124 case 0xFE: 125 case 0xCE: 126 case 0xCF: { 127 uint16_t type = 0; 128 if (startswith(Magic, "\xFE\xED\xFA\xCE") || 129 startswith(Magic, "\xFE\xED\xFA\xCF")) { 130 /* Native endian */ 131 size_t MinSize; 132 if (Magic[3] == 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[12] << 24 | Magic[13] << 12 | Magic[14] << 8 | Magic[15]; 138 } else if (startswith(Magic, "\xCE\xFA\xED\xFE") || 139 startswith(Magic, "\xCF\xFA\xED\xFE")) { 140 /* Reverse endian */ 141 size_t MinSize; 142 if (Magic[0] == char(0xCE)) 143 MinSize = sizeof(MachO::mach_header); 144 else 145 MinSize = sizeof(MachO::mach_header_64); 146 if (Magic.size() >= MinSize) 147 type = Magic[15] << 24 | Magic[14] << 12 | Magic[13] << 8 | Magic[12]; 148 } 149 switch (type) { 150 default: 151 break; 152 case 1: 153 return file_magic::macho_object; 154 case 2: 155 return file_magic::macho_executable; 156 case 3: 157 return file_magic::macho_fixed_virtual_memory_shared_lib; 158 case 4: 159 return file_magic::macho_core; 160 case 5: 161 return file_magic::macho_preload_executable; 162 case 6: 163 return file_magic::macho_dynamically_linked_shared_lib; 164 case 7: 165 return file_magic::macho_dynamic_linker; 166 case 8: 167 return file_magic::macho_bundle; 168 case 9: 169 return file_magic::macho_dynamically_linked_shared_lib_stub; 170 case 10: 171 return file_magic::macho_dsym_companion; 172 case 11: 173 return file_magic::macho_kext_bundle; 174 } 175 break; 176 } 177 case 0xF0: // PowerPC Windows 178 case 0x83: // Alpha 32-bit 179 case 0x84: // Alpha 64-bit 180 case 0x66: // MPS R4000 Windows 181 case 0x50: // mc68K 182 case 0x4c: // 80386 Windows 183 case 0xc4: // ARMNT Windows 184 if (Magic[1] == 0x01) 185 return file_magic::coff_object; 186 LLVM_FALLTHROUGH; 187 188 case 0x90: // PA-RISC Windows 189 case 0x68: // mc68K Windows 190 if (Magic[1] == 0x02) 191 return file_magic::coff_object; 192 break; 193 194 case 'M': // Possible MS-DOS stub on Windows PE file, MSF/PDB file or a 195 // Minidump file. 196 if (startswith(Magic, "MZ") && Magic.size() >= 0x3c + 4) { 197 uint32_t off = read32le(Magic.data() + 0x3c); 198 // PE/COFF file, either EXE or DLL. 199 if (Magic.substr(off).startswith( 200 StringRef(COFF::PEMagic, sizeof(COFF::PEMagic)))) 201 return file_magic::pecoff_executable; 202 } 203 if (Magic.startswith("Microsoft C/C++ MSF 7.00\r\n")) 204 return file_magic::pdb; 205 if (startswith(Magic, "MDMP")) 206 return file_magic::minidump; 207 break; 208 209 case 0x64: // x86-64 or ARM64 Windows. 210 if (Magic[1] == char(0x86) || Magic[1] == char(0xaa)) 211 return file_magic::coff_object; 212 break; 213 214 case 0x2d: // YAML '-' 215 if (startswith(Magic, "--- !tapi") || startswith(Magic, "---\narchs:")) 216 return file_magic::tapi_file; 217 break; 218 219 default: 220 break; 221 } 222 return file_magic::unknown; 223 } 224 225 std::error_code llvm::identify_magic(const Twine &Path, file_magic &Result) { 226 auto FileOrError = MemoryBuffer::getFile(Path, -1LL, false); 227 if (!FileOrError) 228 return FileOrError.getError(); 229 230 std::unique_ptr<MemoryBuffer> FileBuffer = std::move(*FileOrError); 231 Result = identify_magic(FileBuffer->getBuffer()); 232 233 return std::error_code(); 234 } 235