Magic.cpp revision 360660 
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
24using namespace llvm;
25using namespace llvm::support::endian;
26using namespace llvm::sys::fs;
27
28template <size_t N>
29static bool startswith(StringRef Magic, const char (&S)[N]) {
30  return Magic.startswith(StringRef(S, N - 1));
31}
32
33/// Identify the magic in magic.
34file_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
65  case 0x01:
66    // XCOFF format
67    if (startswith(Magic, "\x01\xDF"))
68      return file_magic::xcoff_object_32;
69    if (startswith(Magic, "\x01\xF7"))
70      return file_magic::xcoff_object_64;
71    break;
72
73  case 0xDE: // 0x0B17C0DE = BC wraper
74    if (startswith(Magic, "\xDE\xC0\x17\x0B"))
75      return file_magic::bitcode;
76    break;
77  case 'B':
78    if (startswith(Magic, "BC\xC0\xDE"))
79      return file_magic::bitcode;
80    break;
81  case '!':
82    if (startswith(Magic, "!<arch>\n") || startswith(Magic, "!<thin>\n"))
83      return file_magic::archive;
84    break;
85
86  case '\177':
87    if (startswith(Magic, "\177ELF") && Magic.size() >= 18) {
88      bool Data2MSB = Magic[5] == 2;
89      unsigned high = Data2MSB ? 16 : 17;
90      unsigned low = Data2MSB ? 17 : 16;
91      if (Magic[high] == 0) {
92        switch (Magic[low]) {
93        default:
94          return file_magic::elf;
95        case 1:
96          return file_magic::elf_relocatable;
97        case 2:
98          return file_magic::elf_executable;
99        case 3:
100          return file_magic::elf_shared_object;
101        case 4:
102          return file_magic::elf_core;
103        }
104      }
105      // It's still some type of ELF file.
106      return file_magic::elf;
107    }
108    break;
109
110  case 0xCA:
111    if (startswith(Magic, "\xCA\xFE\xBA\xBE") ||
112        startswith(Magic, "\xCA\xFE\xBA\xBF")) {
113      // This is complicated by an overlap with Java class files.
114      // See the Mach-O section in /usr/share/file/magic for details.
115      if (Magic.size() >= 8 && Magic[7] < 43)
116        return file_magic::macho_universal_binary;
117    }
118    break;
119
120  // The two magic numbers for mach-o are:
121  // 0xfeedface - 32-bit mach-o
122  // 0xfeedfacf - 64-bit mach-o
123  case 0xFE:
124  case 0xCE:
125  case 0xCF: {
126    uint16_t type = 0;
127    if (startswith(Magic, "\xFE\xED\xFA\xCE") ||
128        startswith(Magic, "\xFE\xED\xFA\xCF")) {
129      /* Native endian */
130      size_t MinSize;
131      if (Magic[3] == char(0xCE))
132        MinSize = sizeof(MachO::mach_header);
133      else
134        MinSize = sizeof(MachO::mach_header_64);
135      if (Magic.size() >= MinSize)
136        type = Magic[12] << 24 | Magic[13] << 12 | Magic[14] << 8 | Magic[15];
137    } else if (startswith(Magic, "\xCE\xFA\xED\xFE") ||
138               startswith(Magic, "\xCF\xFA\xED\xFE")) {
139      /* Reverse endian */
140      size_t MinSize;
141      if (Magic[0] == char(0xCE))
142        MinSize = sizeof(MachO::mach_header);
143      else
144        MinSize = sizeof(MachO::mach_header_64);
145      if (Magic.size() >= MinSize)
146        type = Magic[15] << 24 | Magic[14] << 12 | Magic[13] << 8 | Magic[12];
147    }
148    switch (type) {
149    default:
150      break;
151    case 1:
152      return file_magic::macho_object;
153    case 2:
154      return file_magic::macho_executable;
155    case 3:
156      return file_magic::macho_fixed_virtual_memory_shared_lib;
157    case 4:
158      return file_magic::macho_core;
159    case 5:
160      return file_magic::macho_preload_executable;
161    case 6:
162      return file_magic::macho_dynamically_linked_shared_lib;
163    case 7:
164      return file_magic::macho_dynamic_linker;
165    case 8:
166      return file_magic::macho_bundle;
167    case 9:
168      return file_magic::macho_dynamically_linked_shared_lib_stub;
169    case 10:
170      return file_magic::macho_dsym_companion;
171    case 11:
172      return file_magic::macho_kext_bundle;
173    }
174    break;
175  }
176  case 0xF0: // PowerPC Windows
177  case 0x83: // Alpha 32-bit
178  case 0x84: // Alpha 64-bit
179  case 0x66: // MPS R4000 Windows
180  case 0x50: // mc68K
181  case 0x4c: // 80386 Windows
182  case 0xc4: // ARMNT Windows
183    if (Magic[1] == 0x01)
184      return file_magic::coff_object;
185    LLVM_FALLTHROUGH;
186
187  case 0x90: // PA-RISC Windows
188  case 0x68: // mc68K Windows
189    if (Magic[1] == 0x02)
190      return file_magic::coff_object;
191    break;
192
193  case 'M': // Possible MS-DOS stub on Windows PE file, MSF/PDB file or a
194            // Minidump file.
195    if (startswith(Magic, "MZ") && Magic.size() >= 0x3c + 4) {
196      uint32_t off = read32le(Magic.data() + 0x3c);
197      // PE/COFF file, either EXE or DLL.
198      if (Magic.substr(off).startswith(
199              StringRef(COFF::PEMagic, sizeof(COFF::PEMagic))))
200        return file_magic::pecoff_executable;
201    }
202    if (Magic.startswith("Microsoft C/C++ MSF 7.00\r\n"))
203      return file_magic::pdb;
204    if (startswith(Magic, "MDMP"))
205      return file_magic::minidump;
206    break;
207
208  case 0x64: // x86-64 or ARM64 Windows.
209    if (Magic[1] == char(0x86) || Magic[1] == char(0xaa))
210      return file_magic::coff_object;
211    break;
212
213  default:
214    break;
215  }
216  return file_magic::unknown;
217}
218
219std::error_code llvm::identify_magic(const Twine &Path, file_magic &Result) {
220  auto FileOrError = MemoryBuffer::getFile(Path, -1LL, false);
221  if (!FileOrError)
222    return FileOrError.getError();
223
224  std::unique_ptr<MemoryBuffer> FileBuffer = std::move(*FileOrError);
225  Result = identify_magic(FileBuffer->getBuffer());
226
227  return std::error_code();
228}
229