private void ReadHeaders()
{
_freeSpace.Reserve(0, Sizes.OneMiB);
_activeHeader = 0;
_fileStream.Position = 64 * Sizes.OneKiB;
VhdxHeader vhdxHeader1 = StreamUtilities.ReadStruct <VhdxHeader>(_fileStream);
if (vhdxHeader1.IsValid)
{
_header = vhdxHeader1;
_activeHeader = 1;
}
_fileStream.Position = 128 * Sizes.OneKiB;
VhdxHeader vhdxHeader2 = StreamUtilities.ReadStruct <VhdxHeader>(_fileStream);
if (vhdxHeader2.IsValid && (_activeHeader == 0 || _header.SequenceNumber < vhdxHeader2.SequenceNumber))
{
_header = vhdxHeader2;
_activeHeader = 2;
}
if (_activeHeader == 0)
{
throw new IOException("Invalid VHDX file - no valid VHDX headers found");
}
}
private void Initialize()
{
_fileStream.Position = 0;
FileHeader fileHeader = StreamUtilities.ReadStruct <FileHeader>(_fileStream);
if (!fileHeader.IsValid)
{
throw new IOException("Invalid VHDX file - file signature mismatch");
}
_freeSpace = new FreeSpaceTable(_fileStream.Length);
ReadHeaders();
ReplayLog();
ReadRegionTable();
ReadMetadata();
_batStream = OpenRegion(RegionTable.BatGuid);
_freeSpace.Reserve(BatControlledFileExtents());
// Indicate the file is open for modification
if (_fileStream.CanWrite)
{
_header.FileWriteGuid = Guid.NewGuid();
WriteHeader();
}
}
private T ReadStruct <T>(Guid itemId, bool isUser)
where T : IByteArraySerializable, new()
{
MetadataEntryKey key = new MetadataEntryKey(itemId, isUser);
MetadataEntry entry;
if (Table.Entries.TryGetValue(key, out entry))
{
_regionStream.Position = entry.Offset;
return(StreamUtilities.ReadStruct <T>(_regionStream, (int)entry.Length));
}
return(default(T));
}
public Metadata(Stream regionStream)
{
_regionStream = regionStream;
_regionStream.Position = 0;
Table = StreamUtilities.ReadStruct <MetadataTable>(_regionStream);
FileParameters = ReadStruct <FileParameters>(MetadataTable.FileParametersGuid, false);
DiskSize = ReadValue(MetadataTable.VirtualDiskSizeGuid, false, EndianUtilities.ToUInt64LittleEndian);
_page83Data = ReadValue(MetadataTable.Page83DataGuid, false, EndianUtilities.ToGuidLittleEndian);
LogicalSectorSize = ReadValue(MetadataTable.LogicalSectorSizeGuid, false,
EndianUtilities.ToUInt32LittleEndian);
PhysicalSectorSize = ReadValue(MetadataTable.PhysicalSectorSizeGuid, false,
EndianUtilities.ToUInt32LittleEndian);
ParentLocator = ReadStruct <ParentLocator>(MetadataTable.ParentLocatorGuid, false);
}
private void ReadRegionTable()
{
_fileStream.Position = 192 * Sizes.OneKiB;
_regionTable = StreamUtilities.ReadStruct <RegionTable>(_fileStream);
foreach (RegionEntry entry in _regionTable.Regions.Values)
{
if ((entry.Flags & RegionFlags.Required) != 0)
{
if (entry.Guid != RegionTable.BatGuid && entry.Guid != RegionTable.MetadataRegionGuid)
{
throw new IOException("Invalid VHDX file - unrecognised required region");
}
}
_freeSpace.Reserve(entry.FileOffset, entry.Length);
}
}
