Fix the Endianness bug by adding the little endian UTF marker.

[ecbeckmann]

Summary

Quick fix

[uweigand]

This doesn't look correct either:

EndianCorrectedNameString[0] = 0xFEFF;

On a big-endian host system, this will set the endian marker to FE FF, i.e. to indicate BE instead of LE.

Probably needs a ulittle16 somewhere to work on both big- and little-endian hosts.

[zturner]

llvm/tools/llvm-readobj/COFFDumper.cpp

1565–1572

How about this:

ArrayRef<UTF16> RawEntryNameString = unwrapOrError(RSF.getEntryNameString(Entry));
std::vector<UTF16> EndianCorrectedString;
if (llvm::sys::IsBigEndianHost) {
  EndianCorrectedString.resize(RawEntryNameString.size() + 1);
  std::copy(RawEntryNameString.begin(), RawEntryNameString.end(), EndianCorrectedString.begin() + 1);
  EndianCorrectedString[0] = UNI_UTF16_BYTE_ORDER_MARK_SWAPPED;
  RawEntryNameString = makeArrayRef(EndianCorrectedString);
}

[ruiu]

Adding a byte order mark doesn't seems like a good way to fix the issue. Why don't you add a flag indicating whether it is BE or LE to convertUTF16ToUTF8String?

[ecbeckmann]

Check endianness of system before adding marker.

[uweigand]

llvm/tools/llvm-readobj/COFFDumper.cpp

1565–1572

This does fix the problem for me.

[ruiu]

Do you mean the bot is still red? If I broke something I'd first try to roll it back if the error is not just a simple mistake but needs another round of code review.

llvm/lib/Object/COFFObjectFile.cpp

if (auto EC = errorToErrorCode(X))                                           \
     return EC;
 
 ErrorOr<ArrayRef<UTF16>> ResourceSectionRef::getDirStringAtOffset(uint32_t Offset) {
   BinaryStreamReader Reader = BinaryStreamReader(BBS);
   Reader.setOffset(Offset);
   uint16_t Length;
   RETURN_IF_ERROR(Reader.readInteger(Length));
   ArrayRef<UTF16> RawDirString;
-  // Strings are stored as 2-byte aligned unicode characters but readFixedString
-  // assumes byte string, so we double length.
   RETURN_IF_ERROR(Reader.readArray(RawDirString, Length));
   return RawDirString;
 }
 
 ErrorOr<ArrayRef<UTF16>>
 ResourceSectionRef::getEntryNameString(const coff_resource_dir_entry &Entry) {
   return getDirStringAtOffset(Entry.Identifier.getNameOffset());
 }

llvm/tools/llvm-readobj/COFFDumper.cpp

void COFFDumper::printResourceDirectoryTable(
   for (int i = 0; i < Table.NumberOfNameEntries + Table.NumberOfIDEntries;
        i++) {
     auto Entry = unwrapOrError(getResourceDirectoryTableEntry(Table, i));
     StringRef Name;
     SmallString<20> IDStr;
     raw_svector_ostream OS(IDStr);
     if (i < Table.NumberOfNameEntries) {
       ArrayRef<UTF16> RawEntryNameString = unwrapOrError(RSF.getEntryNameString(Entry));
+      std::vector<UTF16> EndianCorrectedNameString(RawEntryNameString.size() +
+                                                   1);
+      std::copy(RawEntryNameString.begin(), RawEntryNameString.end(),
+                EndianCorrectedNameString.begin() + 1);
+      EndianCorrectedNameString[0] = 0xFEFF;
       std::string EntryNameString;
-      if (!llvm::convertUTF16ToUTF8String(RawEntryNameString, EntryNameString))
+      if (!llvm::convertUTF16ToUTF8String(EndianCorrectedNameString,
+                                          EntryNameString))
         error(object_error::parse_failed);
       OS << ": ";
       OS << EntryNameString;
     } else {
       if (Level == "Type") {
         ScopedPrinter Printer(OS);
         Printer.printEnum("", Entry.Identifier.ID,
                           makeArrayRef(ResourceTypeNames));