Support/FileSystem: Add file_magic and move a vew clients over to it.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@146523 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 114 insertions, 2 deletions

diff --git a/lib/Support/PathV2.cpp b/lib/Support/PathV2.cpp
index 9cf16dab38..7cc434bde7 100644
--- a/lib/Support/PathV2.cpp
+++ b/lib/Support/PathV2.cpp
@@ -13,6 +13,7 @@
 
 #include "llvm/Support/PathV2.h"
 #include "llvm/Support/FileSystem.h"
+#include "llvm/Support/Endian.h"
 #include "llvm/Support/ErrorHandling.h"
 #include <cctype>
 #include <cstdio>
@@ -738,13 +739,124 @@ error_code has_magic(const Twine &path, const Twine &magic, bool &result) {
   return success;
 }
 
-error_code identify_magic(const Twine &path, LLVMFileType &result) {
+/// @brief Identify the magic in magic.
+file_magic identify_magic(StringRef magic) {
+  switch ((unsigned char)magic[0]) {
+    case 0xDE:  // 0x0B17C0DE = BC wraper
+      if (magic[1] == (char)0xC0 && magic[2] == (char)0x17 &&
+          magic[3] == (char)0x0B)
+        return file_magic::bitcode;
+      break;
+    case 'B':
+      if (magic[1] == 'C' && magic[2] == (char)0xC0 && magic[3] == (char)0xDE)
+        return file_magic::bitcode;
+      break;
+    case '!':
+      if (magic.size() >= 8)
+        if (memcmp(magic.data(),"!<arch>\n",8) == 0)
+          return file_magic::archive;
+      break;
+
+    case '\177':
+      if (magic[1] == 'E' && magic[2] == 'L' && magic[3] == 'F') {
+        if (magic.size() >= 18 && magic[17] == 0)
+          switch (magic[16]) {
+            default: break;
+            case 1: return file_magic::elf_relocatable;
+            case 2: return file_magic::elf_executable;
+            case 3: return file_magic::elf_shared_object;
+            case 4: return file_magic::elf_core;
+          }
+      }
+      break;
+
+    case 0xCA:
+      if (magic[1] == char(0xFE) && magic[2] == char(0xBA) &&
+          magic[3] == char(0xBE)) {
+        // This is complicated by an overlap with Java class files.
+        // See the Mach-O section in /usr/share/file/magic for details.
+        if (magic.size() >= 8 && magic[7] < 43)
+          // FIXME: Universal Binary of any type.
+          return file_magic::macho_dynamically_linked_shared_lib;
+      }
+      break;
+
+      // The two magic numbers for mach-o are:
+      // 0xfeedface - 32-bit mach-o
+      // 0xfeedfacf - 64-bit mach-o
+    case 0xFE:
+    case 0xCE:
+    case 0xCF: {
+      uint16_t type = 0;
+      if (magic[0] == char(0xFE) && magic[1] == char(0xED) &&
+          magic[2] == char(0xFA) &&
+          (magic[3] == char(0xCE) || magic[3] == char(0xCF))) {
+        /* Native endian */
+        if (magic.size() >= 16) type = magic[14] << 8 | magic[15];
+      } else if ((magic[0] == char(0xCE) || magic[0] == char(0xCF)) &&
+                 magic[1] == char(0xFA) && magic[2] == char(0xED) &&
+                 magic[3] == char(0xFE)) {
+        /* Reverse endian */
+        if (magic.size() >= 14) type = magic[13] << 8 | magic[12];
+      }
+      switch (type) {
+        default: break;
+        case 1: return file_magic::macho_object;
+        case 2: return file_magic::macho_executable;
+        case 3: return file_magic::macho_fixed_virtual_memory_shared_lib;
+        case 4: return file_magic::macho_core;
+        case 5: return file_magic::macho_preload_executabl;
+        case 6: return file_magic::macho_dynamically_linked_shared_lib;
+        case 7: return file_magic::macho_dynamic_linker;
+        case 8: return file_magic::macho_bundle;
+        case 9: return file_magic::macho_dynamic_linker;
+        case 10: return file_magic::macho_dsym_companion;
+      }
+      break;
+    }
+    case 0xF0: // PowerPC Windows
+    case 0x83: // Alpha 32-bit
+    case 0x84: // Alpha 64-bit
+    case 0x66: // MPS R4000 Windows
+    case 0x50: // mc68K
+    case 0x4c: // 80386 Windows
+      if (magic[1] == 0x01)
+        return file_magic::coff_object;
+
+    case 0x90: // PA-RISC Windows
+    case 0x68: // mc68K Windows
+      if (magic[1] == 0x02)
+        return file_magic::coff_object;
+      break;
+
+    case 0x4d: // Possible MS-DOS stub on Windows PE file
+      if (magic[1] == 0x5a) {
+        uint32_t off =
+          *reinterpret_cast<const support::ulittle32_t*>(magic.data() + 0x3c);
+        // PE/COFF file, either EXE or DLL.
+        if (off < magic.size() && memcmp(magic.data() + off, "PE\0\0",4) == 0)
+          return file_magic::pecoff_executable;
+      }
+      break;
+
+    case 0x64: // x86-64 Windows.
+      if (magic[1] == char(0x86))
+        return file_magic::coff_object;
+      break;
+
+    default:
+      break;
+  }
+  return file_magic::unknown;
+}
+
+error_code identify_magic(const Twine &path, file_magic &result) {
   SmallString<32> Magic;
   error_code ec = get_magic(path, Magic.capacity(), Magic);
   if (ec && ec != errc::value_too_large)
     return ec;
 
-  result = IdentifyFileType(Magic.data(), Magic.size());
+  result = identify_magic(Magic);
   return success;
 }