/// <summary>
/// Implements the Extract method which extracts a backup archive. A DataWriter must be already assigned and configured or an
/// exception will be raised.
/// </summary>
public override void Extract(CancellationToken token)
{
// Initialize
Close();
Progress.FilePosition = 0;
Progress.RunningCompressed = 0;
Progress.RunningUncompressed = 0;
Progress.Status = ExtractionStatus.Running;
Progress.LastException = null;
ProgressEventArgs args;
try
{
// Read the file header
JpaArchiveHeader archiveHeader = ReadArchiveHeader();
// Invoke event at start of extraction
args = new ProgressEventArgs(Progress);
OnProgressEvent(args);
while ((CurrentPartNumber != null) && (Progress.FilePosition < archiveHeader.TotalLength))
{
JpaFileHeader fileHeader = ReadFileHeader();
// See https://www.codeproject.com/articles/742774/cancel-a-loop-in-a-task-with-cancellationtokens
if (token.IsCancellationRequested)
{
token.ThrowIfCancellationRequested();
}
ProcessDataBlock(fileHeader.CompressedSize, fileHeader.UncompressedSize, fileHeader.CompressionType, fileHeader.EntityType, fileHeader.EntityPath, token);
args = new ProgressEventArgs(Progress);
OnProgressEvent(args);
}
}
catch (OperationCanceledException cancelledException)
{
// The operation was cancelled. Set the state to Idle and reset the extraction.
Close();
Progress.FilePosition = 0;
Progress.RunningCompressed = 0;
Progress.RunningUncompressed = 0;
Progress.Status = ExtractionStatus.Idle;
Progress.LastException = cancelledException;
// Invoke an event notifying susbcribers about the cancelation.
args = new ProgressEventArgs(Progress);
OnProgressEvent(args);
return;
}
catch (Exception errorException)
{
// Any other exception. Close the option file and set the status to error.
Close();
Progress.Status = ExtractionStatus.Error;
Progress.LastException = errorException;
// Invoke an event notifying of the error state
args = new ProgressEventArgs(Progress);
OnProgressEvent(args);
return;
}
// Invoke an event signaling the end of extraction
Progress.Status = ExtractionStatus.Finished;
args = new ProgressEventArgs(Progress);
OnProgressEvent(args);
}
/// <summary>
/// Reads the Entity Description Block in the current position of the JPA archive
/// </summary>
/// <returns>The entity description block (file header)</returns>
public JpaFileHeader ReadFileHeader()
{
JpaFileHeader fileHeader = new JpaFileHeader();
fileHeader.Signature = ReadAsciiString(3);
if (fileHeader.Signature != "JPF")
{
throw new InvalidArchiveException(String.Format(Language.ResourceManager.GetString("ERR_FORMAT_INVALID_HEADER_AT_POSITION"), CurrentPartNumber, InputStream.Position - 3));
}
fileHeader.BlockLength = ReadUShort();
fileHeader.LengthOfEntityPath = ReadUShort();
fileHeader.EntityPath = ReadUtf8String(fileHeader.LengthOfEntityPath);
fileHeader.EntityType = (TEntityType)Enum.ToObject(typeof(TEntityType), ReadSByte());
fileHeader.CompressionType = (TCompressionType)Enum.ToObject(typeof(TCompressionType), ReadSByte());
fileHeader.CompressedSize = ReadULong();
fileHeader.UncompressedSize = ReadULong();
fileHeader.EntityPermissions = ReadULong();
ushort standardEntityBlockLength = (ushort)(21 + fileHeader.LengthOfEntityPath);
if (fileHeader.BlockLength > standardEntityBlockLength)
{
// We need to loop while we have remaining header bytes
ushort remainingBytes = (ushort)(fileHeader.BlockLength - standardEntityBlockLength);
while (remainingBytes > 0)
{
// Get the extra header signature
byte[] headerSignature = ReadBytes(2);
// The next two bytes tell us how long this header is, including the signature
ushort extraHeaderLength = ReadUShort();
remainingBytes -= extraHeaderLength;
if ((headerSignature[0] == 0x00) && (headerSignature[1] == 0x01))
{
// Timestamp extra field
fileHeader.TimeStamp = ReadLong();
}
else
{
throw new InvalidArchiveException(String.Format(Language.ResourceManager.GetString("ERR_FORMAT_INVALID_EXTRA_HEADER_AT_POSITION"), CurrentPartNumber, InputStream.Position - 3));
}
}
}
// Invoke the OnEntityEvent event. We need to do some work to get there, through...
// -- Create a new archive information record
EntityInformation info = new EntityInformation();
// -- Incorporate bits from the file header
info.CompressedSize = fileHeader.CompressedSize;
info.UncompressedSize = fileHeader.UncompressedSize;
info.StoredName = fileHeader.EntityPath;
// -- Get the absolute path of the file
info.AbsoluteName = "";
if (DataWriter != null)
{
info.AbsoluteName = DataWriter.GetAbsoluteFilePath(fileHeader.EntityPath);
}
// -- Get some bits from the currently open archive file
info.PartNumber = CurrentPartNumber ?? 1;
info.PartOffset = InputStream.Position;
// -- Create the event arguments object
EntityEventArgs args = new EntityEventArgs(info);
// -- Finally, invoke the event
OnEntityEvent(args);
// Lastly, return the read file header
return(fileHeader);
}
