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 0x03: 75 if (startswith(Magic, "\x03\xF0\x00")) 76 return file_magic::goff_object; 77 break; 78 79 case 0xDE: // 0x0B17C0DE = BC wraper 80 if (startswith(Magic, "\xDE\xC0\x17\x0B")) 81 return file_magic::bitcode; 82 break; 83 case 'B': 84 if (startswith(Magic, "BC\xC0\xDE")) 85 return file_magic::bitcode; 86 break; 87 case '!': 88 if (startswith(Magic, "!<arch>\n") || startswith(Magic, "!<thin>\n")) 89 return file_magic::archive; 90 break; 91 case '<': 92 if (startswith(Magic, "<bigaf>\n")) 93 return file_magic::archive; 94 break; 95 case '\177': 96 if (startswith(Magic, "\177ELF") && Magic.size() >= 18) { 97 bool Data2MSB = Magic[5] == 2; 98 unsigned high = Data2MSB ? 16 : 17; 99 unsigned low = Data2MSB ? 17 : 16; 100 if (Magic[high] == 0) { 101 switch (Magic[low]) { 102 default: 103 return file_magic::elf; 104 case 1: 105 return file_magic::elf_relocatable; 106 case 2: 107 return file_magic::elf_executable; 108 case 3: 109 return file_magic::elf_shared_object; 110 case 4: 111 return file_magic::elf_core; 112 } 113 } 114 // It's still some type of ELF file. 115 return file_magic::elf; 116 } 117 break; 118 119 case 0xCA: 120 if (startswith(Magic, "\xCA\xFE\xBA\xBE") || 121 startswith(Magic, "\xCA\xFE\xBA\xBF")) { 122 // This is complicated by an overlap with Java class files. 123 // See the Mach-O section in /usr/share/file/magic for details. 124 if (Magic.size() >= 8 && Magic[7] < 43) 125 return file_magic::macho_universal_binary; 126 } 127 break; 128 129 // The two magic numbers for mach-o are: 130 // 0xfeedface - 32-bit mach-o 131 // 0xfeedfacf - 64-bit mach-o 132 case 0xFE: 133 case 0xCE: 134 case 0xCF: { 135 uint16_t type = 0; 136 if (startswith(Magic, "\xFE\xED\xFA\xCE") || 137 startswith(Magic, "\xFE\xED\xFA\xCF")) { 138 /* Native endian */ 139 size_t MinSize; 140 if (Magic[3] == char(0xCE)) 141 MinSize = sizeof(MachO::mach_header); 142 else 143 MinSize = sizeof(MachO::mach_header_64); 144 if (Magic.size() >= MinSize) 145 type = Magic[12] << 24 | Magic[13] << 12 | Magic[14] << 8 | Magic[15]; 146 } else if (startswith(Magic, "\xCE\xFA\xED\xFE") || 147 startswith(Magic, "\xCF\xFA\xED\xFE")) { 148 /* Reverse endian */ 149 size_t MinSize; 150 if (Magic[0] == char(0xCE)) 151 MinSize = sizeof(MachO::mach_header); 152 else 153 MinSize = sizeof(MachO::mach_header_64); 154 if (Magic.size() >= MinSize) 155 type = Magic[15] << 24 | Magic[14] << 12 | Magic[13] << 8 | Magic[12]; 156 } 157 switch (type) { 158 default: 159 break; 160 case 1: 161 return file_magic::macho_object; 162 case 2: 163 return file_magic::macho_executable; 164 case 3: 165 return file_magic::macho_fixed_virtual_memory_shared_lib; 166 case 4: 167 return file_magic::macho_core; 168 case 5: 169 return file_magic::macho_preload_executable; 170 case 6: 171 return file_magic::macho_dynamically_linked_shared_lib; 172 case 7: 173 return file_magic::macho_dynamic_linker; 174 case 8: 175 return file_magic::macho_bundle; 176 case 9: 177 return file_magic::macho_dynamically_linked_shared_lib_stub; 178 case 10: 179 return file_magic::macho_dsym_companion; 180 case 11: 181 return file_magic::macho_kext_bundle; 182 } 183 break; 184 } 185 case 0xF0: // PowerPC Windows 186 case 0x83: // Alpha 32-bit 187 case 0x84: // Alpha 64-bit 188 case 0x66: // MPS R4000 Windows 189 case 0x50: // mc68K 190 case 0x4c: // 80386 Windows 191 case 0xc4: // ARMNT Windows 192 if (Magic[1] == 0x01) 193 return file_magic::coff_object; 194 LLVM_FALLTHROUGH; 195 196 case 0x90: // PA-RISC Windows 197 case 0x68: // mc68K Windows 198 if (Magic[1] == 0x02) 199 return file_magic::coff_object; 200 break; 201 202 case 'M': // Possible MS-DOS stub on Windows PE file, MSF/PDB file or a 203 // Minidump file. 204 if (startswith(Magic, "MZ") && Magic.size() >= 0x3c + 4) { 205 uint32_t off = read32le(Magic.data() + 0x3c); 206 // PE/COFF file, either EXE or DLL. 207 if (Magic.substr(off).startswith( 208 StringRef(COFF::PEMagic, sizeof(COFF::PEMagic)))) 209 return file_magic::pecoff_executable; 210 } 211 if (Magic.startswith("Microsoft C/C++ MSF 7.00\r\n")) 212 return file_magic::pdb; 213 if (startswith(Magic, "MDMP")) 214 return file_magic::minidump; 215 break; 216 217 case 0x64: // x86-64 or ARM64 Windows. 218 if (Magic[1] == char(0x86) || Magic[1] == char(0xaa)) 219 return file_magic::coff_object; 220 break; 221 222 case 0x2d: // YAML '-' 223 if (startswith(Magic, "--- !tapi") || startswith(Magic, "---\narchs:")) 224 return file_magic::tapi_file; 225 break; 226 227 default: 228 break; 229 } 230 return file_magic::unknown; 231 } 232 233 std::error_code llvm::identify_magic(const Twine &Path, file_magic &Result) { 234 auto FileOrError = MemoryBuffer::getFile(Path, /*IsText=*/false, 235 /*RequiresNullTerminator=*/false); 236 if (!FileOrError) 237 return FileOrError.getError(); 238 239 std::unique_ptr<MemoryBuffer> FileBuffer = std::move(*FileOrError); 240 Result = identify_magic(FileBuffer->getBuffer()); 241 242 return std::error_code(); 243 } 244