Method ProcessExtra50

Libraries/unrar/arcread.cpp:950–1196

void Archive::ProcessExtra50(RawRead *Raw,size_t ExtraSize,BaseBlock *bb)
{
  // Read extra data from the end of block skipping any fields before it.
  size_t ExtraStart=Raw->Size()-ExtraSize;
  if (ExtraStart<Raw->GetPos())
    return;
  Raw->SetPos(ExtraStart);
  while (Raw->DataLeft()>=2)
  {
    int64 FieldSize=Raw->GetV(); // Needs to be signed for check below and can be negative.
    if (FieldSize<=0 || Raw->DataLeft()==0 || FieldSize>(int64)Raw->DataLeft())
      break;
    size_t NextPos=size_t(Raw->GetPos()+FieldSize);
    uint64 FieldType=Raw->GetV();

    FieldSize=int64(NextPos-Raw->GetPos()); // Field size without size and type fields.

    if (FieldSize<0) // FieldType is longer than expected extra field size.
      break;

    if (bb->HeaderType==HEAD_MAIN)
    {
      MainHeader *hd=(MainHeader *)bb;
      if (FieldType==MHEXTRA_LOCATOR)
      {
        hd->Locator=true;
        uint Flags=(uint)Raw->GetV();
        if ((Flags & MHEXTRA_LOCATOR_QLIST)!=0)
        {
          uint64 Offset=Raw->GetV();
          if (Offset!=0) // 0 means that reserved space was not enough to write the offset.
            hd->QOpenOffset=Offset+CurBlockPos;
        }
        if ((Flags & MHEXTRA_LOCATOR_RR)!=0)
        {
          uint64 Offset=Raw->GetV();
          if (Offset!=0) // 0 means that reserved space was not enough to write the offset.
            hd->RROffset=Offset+CurBlockPos;
        }
      }
    }

    if (bb->HeaderType==HEAD_FILE || bb->HeaderType==HEAD_SERVICE)
    {
      FileHeader *hd=(FileHeader *)bb;
      switch(FieldType)
      {
        case FHEXTRA_CRYPT:
          {
            FileHeader *hd=(FileHeader *)bb;
            uint EncVersion=(uint)Raw->GetV();
            if (EncVersion>CRYPT_VERSION)
            {
              wchar Info[20];
              swprintf(Info,ASIZE(Info),L"x%u",EncVersion);
              UnkEncVerMsg(hd->FileName,Info);
            }
            else