lib/BinaryFormat/Magic.cpp

   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 or MSF/PDB file.
 185     if (startswith(Magic, "MZ") && Magic.size() >= 0x3c + 4) {
 186       uint32_t off = read32le(Magic.data() + 0x3c);
 187       // PE/COFF file, either EXE or DLL.
 188       if (Magic.substr(off).startswith(
 189               StringRef(COFF::PEMagic, sizeof(COFF::PEMagic))))
 190         return file_magic::pecoff_executable;
 191     }
 192     if (Magic.startswith("Microsoft C/C++ MSF 7.00\r\n"))
 193       return file_magic::pdb;
 194     break;
 195
 196   case 0x64: // x86-64 or ARM64 Windows.
 197     if (Magic[1] == char(0x86) || Magic[1] == char(0xaa))
 198       return file_magic::coff_object;
 199     break;
 200
 201   default:
 202     break;
 203   }
 204   return file_magic::unknown;
 205 }
 206
 207 std::error_code llvm::identify_magic(const Twine &Path, file_magic &Result) {
 208   auto FileOrError = MemoryBuffer::getFile(Path, -1LL, false);
 209   if (!FileOrError)
 210     return FileOrError.getError();
 211
 212   std::unique_ptr<MemoryBuffer> FileBuffer = std::move(*FileOrError);
 213   Result = identify_magic(FileBuffer->getBuffer());
 214
 215   return std::error_code();
 216 }