internal static void ValidateHeader(CFHeader header)
{
if (header.Signature != CFHeader.DefaultSignature)
throw new CompoundFileException("Invalid header: signature");
if(header.CLSID != Guid.Empty)
throw new CompoundFileException("Invalid header: CLSID");
if(header.MinorVersion != 0x3E)
throw new CompoundFileException("Invalid header: Minor version");
if (header.MajorVersion != 3 && header.MajorVersion != 4)
throw new CompoundFileException("Invalid header: Major version");
if(header.ByteOrder != 0xFFFE)
throw new CompoundFileException("Invalid header: Byte order");
if(header.MajorVersion == 3 && header.SectorShift != 0x0009)
throw new CompoundFileException("Invalid header: Sector shirt for v3");
if (header.MajorVersion == 4 && header.SectorShift != 0x000c)
throw new CompoundFileException("Invalid header: Sector shirt for v4");
if(header.MiniSectorShift != 0x0006)
throw new CompoundFileException("Invalid header: Mini sector shirt");
if(header.Reserved[0] != 0 || header.Reserved[1] != 0 ||
header.Reserved[2] != 0 || header.Reserved[3] != 0 ||
header.Reserved[4] != 0 || header.Reserved[5] != 0)
throw new CompoundFileException("Invalid header: Reserved");
if(header.MajorVersion == 3 && header.DirectorySectorsCount != 0)
throw new CompoundFileException("Invalid header: Directory sectors for v3");
// TODO numbers and first sector
if(header.MiniStreamCutoffSize != 0x1000)
throw new CompoundFileException("Invalid header: Mini stream cutoff size");
// TODO mini numbers and first sector
// TODO mini DIFAT and number DIFAT
}
private void Initialize()
{
header = ReaderUtils.ReadHeader(BaseStream);
ReaderUtils.ValidateHeader(header);
}
internal static CFHeader ReadHeader(Stream s)
{
s.Position = 0;
byte[] headerBytes = new byte[HeaderSize];
int headerRead = s.Read(headerBytes, 0, HeaderSize);
if (headerRead != HeaderSize)
{
throw new CompoundFileException("Invalid header: eof of file");
}
CFHeader header = new CFHeader();
header.Signature = BitConverter.ToUInt64(headerBytes, 0);
header.CLSID = new Guid(GetByteArrayPortion(headerBytes, 8, 16));
header.MinorVersion = BitConverter.ToUInt16(headerBytes, 24);
header.MajorVersion = BitConverter.ToUInt16(headerBytes, 26);
header.ByteOrder = BitConverter.ToUInt16(headerBytes, 28);
header.SectorShift = BitConverter.ToUInt16(headerBytes, 30);
header.MiniSectorShift = BitConverter.ToUInt16(headerBytes, 32);
header.Reserved = GetByteArrayPortion(headerBytes, 34, 6);
header.DirectorySectorsCount = BitConverter.ToUInt32(headerBytes, 40);
header.FATSectorsCount = BitConverter.ToUInt32(headerBytes, 44);
header.FirstDirectorySectorLocation = BitConverter.ToUInt32(headerBytes, 48);
header.TransactionSignatureNumber = BitConverter.ToUInt32(headerBytes, 52);
header.MiniStreamCutoffSize = BitConverter.ToUInt32(headerBytes, 56);
header.FirstMiniFATSectorLocation = BitConverter.ToUInt32(headerBytes, 60);
header.MiniFATSectorsCount = BitConverter.ToUInt32(headerBytes, 64);
header.FirstDIFATSectorLocation = BitConverter.ToUInt32(headerBytes, 68);
header.DIFATSectorsCount = BitConverter.ToUInt32(headerBytes, 72);
header.DIFAT = new uint[HeaderDIFATSectorsCount];
for (int i = 0; i < HeaderDIFATSectorsCount; i++)
{
header.DIFAT[i] = BitConverter.ToUInt32(headerBytes, 76 + i * 4);
}
// skip checking zeros after the header data
return header;
}