[Support][FileSystem] Fix identify_magic for big endian ELF.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@178905 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 15 insertions, 4 deletions

diff --git a/lib/Support/PathV2.cpp b/lib/Support/PathV2.cpp
index 58a6ea720e..ac53a9e9e6 100644
--- a/lib/Support/PathV2.cpp
+++ b/lib/Support/PathV2.cpp
@@ -789,8 +789,11 @@ file_magic identify_magic(StringRef magic) {
 
     case '\177':
       if (magic[1] == 'E' && magic[2] == 'L' && magic[3] == 'F') {
-        if (magic.size() >= 18 && magic[17] == 0)
-          switch (magic[16]) {
+        bool Data2MSB = magic[5] == 2;
+        unsigned high = Data2MSB ? 16 : 17;
+        unsigned low  = Data2MSB ? 17 : 16;
+        if (magic.size() >= 18 && magic[high] == 0)
+          switch (magic[low]) {
             default: break;
             case 1: return file_magic::elf_relocatable;
             case 2: return file_magic::elf_executable;
diff --git a/unittests/Support/Path.cpp b/unittests/Support/Path.cpp
index 4511259797..eec8c62d8c 100644
--- a/unittests/Support/Path.cpp
+++ b/unittests/Support/Path.cpp
@@ -298,12 +298,19 @@ TEST_F(FileSystemTest, DirectoryIteration) {
   ASSERT_LT(z0, za1);
 }
 
+const char elf[] = {0x7f, 'E', 'L', 'F', 1, 2, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1};
+
 TEST_F(FileSystemTest, Magic) {
   struct type {
     const char *filename;
     const char *magic_str;
-    size_t      magic_str_len;
-  } types [] = {{"magic.archive", "!<arch>\x0A", 8}};
+    size_t magic_str_len;
+    fs::file_magic magic;
+  } types [] = {
+    {"magic.archive", "!<arch>\x0A", 8, fs::file_magic::archive},
+    {"magic.elf", elf, sizeof(elf),
+     fs::file_magic::elf_relocatable}
+  };
 
   // Create some files filled with magic.
   for (type *i = types, *e = types + (sizeof(types) / sizeof(type)); i != e;
@@ -320,6 +327,7 @@ TEST_F(FileSystemTest, Magic) {
     bool res = false;
     ASSERT_NO_ERROR(fs::has_magic(file_pathname.c_str(), magic, res));
     EXPECT_TRUE(res);
+    EXPECT_EQ(i->magic, fs::identify_magic(magic));
   }
 }