private void Initialize()
{
_fileStream.Position = 0;
FileHeader fileHeader = Utilities.ReadStruct <FileHeader>(_fileStream);
if (!fileHeader.IsValid)
{
throw new IOException("Invalid VHDX file - file signature mismatch");
}
_freeSpace = new FreeSpaceTable(_fileStream.Length);
ReadHeaders();
if (_header.LogGuid != Guid.Empty)
{
throw new NotSupportedException("Detected VHDX file with replay log - not yet supported");
}
_freeSpace.Reserve((long)_header.LogOffset, _header.LogLength);
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 void ReplayLog()
{
_freeSpace.Reserve((long)_header.LogOffset, _header.LogLength);
_logicalStream = _fileStream;
// If log is empty, skip.
if (_header.LogGuid == Guid.Empty)
{
return;
}
LogSequence activeLogSequence = FindActiveLogSequence();
if (activeLogSequence == null || activeLogSequence.Count == 0)
{
throw new IOException("Unable to replay VHDX log, suspected corrupt VHDX file");
}
if (activeLogSequence.Head.FlushedFileOffset > (ulong)_logicalStream.Length)
{
throw new IOException("truncated VHDX file found while replaying log");
}
if (activeLogSequence.Count > 1 || !activeLogSequence.Head.IsEmpty)
{
// However, have seen VHDX with a non-empty log with no data to replay. These are
// 'safe' to open.
if (!_fileStream.CanWrite)
{
SnapshotStream replayStream = new SnapshotStream(_fileStream, Ownership.None);
replayStream.Snapshot();
_logicalStream = replayStream;
}
foreach (LogEntry logEntry in activeLogSequence)
{
if (logEntry.LogGuid != _header.LogGuid)
{
throw new IOException("Invalid log entry in VHDX log, suspected currupt VHDX file");
}
if (logEntry.IsEmpty)
{
continue;
}
logEntry.Replay(_logicalStream);
}
_logicalStream.Seek((long)activeLogSequence.Head.LastFileOffset, SeekOrigin.Begin);
}
}
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 void ReadRegionTable()
{
_fileStream.Position = 192 * Sizes.OneKiB;
_regionTable = Utilities.ReadStruct <RegionTable>(_fileStream);
foreach (var 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);
}
}
private void ReplayLog()
{
_freeSpace.Reserve((long)_header.LogOffset, _header.LogLength);
_logicalStream = _fileStream;
// If log is empty, skip.
if (_header.LogGuid == Guid.Empty)
{
return;
}
LogSequence activeLogSequence = FindActiveLogSequence();
if (activeLogSequence == null || activeLogSequence.Count == 0)
{
throw new IOException("Unable to replay VHDX log, suspected corrupt VHDX file");
}
if (activeLogSequence.Count > 1 || !activeLogSequence.Head.IsEmpty)
{
// TODO - perform actual replay (needs VHDX with real log to replay)
// However, have seen VHDX with a non-empty log with no data to replay. These are
// 'safe' to open.
throw new NotImplementedException("Actual replay of VHDX logs not implemented yet");
//// Have a log to replay, and the base stream is read-only. Use a snapshot stream to
//// replay in RAM.
////if (!_fileStream.CanWrite)
////{
//// SnapshotStream replayStream = new SnapshotStream(_fileStream, Ownership.None);
//// replayStream.Snapshot();
//// _logicalStream = replayStream;
////}
}
}
private void Initialize()
{
_fileStream.Position = 0;
FileHeader fileHeader = Utilities.ReadStruct<FileHeader>(_fileStream);
if (!fileHeader.IsValid)
{
throw new IOException("Invalid VHDX file - file signature mismatch");
}
_freeSpace = new FreeSpaceTable(_fileStream.Length);
ReadHeaders();
if (_header.LogGuid != Guid.Empty)
{
throw new NotSupportedException("Detected VHDX file with replay log - not yet supported");
}
_freeSpace.Reserve((long)_header.LogOffset, _header.LogLength);
ReadRegionTable();
ReadMetadata();
_batStream = OpenRegion(RegionTable.BatGuid);
_freeSpace.Reserve(BatControlledFileExtents());
// Indicate the file is open for modification
if (_fileStream.CanWrite)
{
_header.FileWriteGuid = Guid.NewGuid();
WriteHeader();
}
}
