Fix identify_magic() to check that a file that starts with MH_MAGIC is
at least as big as the mach header to be identified as a Mach-O file and
make sure smaller files are not identified as a Mach-O files but as
unknown files. Also fix identify_magic() so it looks at all 4 bytes of
the filetype field when determining the type of the Mach-O file.
Then fix the macho-invalid-header test case to check that it is an
unknown file and make sure it does not get the error for
object_error::parse_failed.  And also update the unit tests.

llvm-svn: 258883
diff --git a/llvm/unittests/Support/Path.cpp b/llvm/unittests/Support/Path.cpp
index 3f626f8..7bbac7a 100644
--- a/llvm/unittests/Support/Path.cpp
+++ b/llvm/unittests/Support/Path.cpp
@@ -726,21 +726,29 @@
 const char elf_relocatable[] = { 0x7f, 'E', 'L', 'F', 1, 2, 1, 0, 0,
                                  0,    0,   0,   0,   0, 0, 0, 0, 1 };
 const char macho_universal_binary[] = "\xca\xfe\xba\xbe...\0x00";
-const char macho_object[] = "\xfe\xed\xfa\xce..........\x00\x01";
-const char macho_executable[] = "\xfe\xed\xfa\xce..........\x00\x02";
+const char macho_object[] =
+    "\xfe\xed\xfa\xce........\x00\x00\x00\x01............";
+const char macho_executable[] =
+    "\xfe\xed\xfa\xce........\x00\x00\x00\x02............";
 const char macho_fixed_virtual_memory_shared_lib[] =
-    "\xfe\xed\xfa\xce..........\x00\x03";
-const char macho_core[] = "\xfe\xed\xfa\xce..........\x00\x04";
-const char macho_preload_executable[] = "\xfe\xed\xfa\xce..........\x00\x05";
+    "\xfe\xed\xfa\xce........\x00\x00\x00\x03............";
+const char macho_core[] =
+    "\xfe\xed\xfa\xce........\x00\x00\x00\x04............";
+const char macho_preload_executable[] =
+    "\xfe\xed\xfa\xce........\x00\x00\x00\x05............";
 const char macho_dynamically_linked_shared_lib[] =
-    "\xfe\xed\xfa\xce..........\x00\x06";
-const char macho_dynamic_linker[] = "\xfe\xed\xfa\xce..........\x00\x07";
-const char macho_bundle[] = "\xfe\xed\xfa\xce..........\x00\x08";
-const char macho_dsym_companion[] = "\xfe\xed\xfa\xce..........\x00\x0a";
-const char macho_kext_bundle[] = "\xfe\xed\xfa\xce..........\x00\x0b";
+    "\xfe\xed\xfa\xce........\x00\x00\x00\x06............";
+const char macho_dynamic_linker[] =
+    "\xfe\xed\xfa\xce........\x00\x00\x00\x07............";
+const char macho_bundle[] =
+    "\xfe\xed\xfa\xce........\x00\x00\x00\x08............";
+const char macho_dsym_companion[] =
+    "\xfe\xed\xfa\xce........\x00\x00\x00\x0a............";
+const char macho_kext_bundle[] =
+    "\xfe\xed\xfa\xce........\x00\x00\x00\x0b............";
 const char windows_resource[] = "\x00\x00\x00\x00\x020\x00\x00\x00\xff";
 const char macho_dynamically_linked_shared_lib_stub[] =
-    "\xfe\xed\xfa\xce..........\x00\x09";
+    "\xfe\xed\xfa\xce........\x00\x00\x00\x09............";
 
 TEST_F(FileSystemTest, Magic) {
   struct type {