public int ReadFrom(byte[] buffer, int offset)
{
_data = new byte[FixedSize];
Array.Copy(buffer, offset, _data, 0, FixedSize);
Signature = Utilities.ToUInt32LittleEndian(_data, 0);
Checksum = Utilities.ToUInt32LittleEndian(_data, 4);
EntryCount = Utilities.ToUInt32LittleEndian(_data, 8);
Reserved = Utilities.ToUInt32LittleEndian(_data, 12);
Regions = new Dictionary <Guid, RegionEntry>();
if (IsValid)
{
for (int i = 0; i < EntryCount; ++i)
{
RegionEntry entry = Utilities.ToStruct <RegionEntry>(_data, 16 + (32 * i));
Regions.Add(entry.Guid, entry);
}
}
return(Size);
}
/// <summary>
/// Opens an existing region within the VHDX file.
/// </summary>
/// <param name="region">Identifier for the region to open.</param>
/// <returns>A stream containing the region data.</returns>
/// <remarks>Regions are an extension mechanism in VHDX - with some regions defined by
/// the VHDX specification to hold metadata and the block allocation data.</remarks>
public Stream OpenRegion(Guid region)
{
RegionEntry metadataRegion = _regionTable.Regions[region];
return(new SubStream(_fileStream, metadataRegion.FileOffset, metadataRegion.Length));
}