/// <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>
/// Read the main header of the archive.
/// </summary>
/// <returns>
/// The main header of the archive
/// </returns>
public JpaArchiveHeader ReadArchiveHeader()
{
JpaArchiveHeader archiveHeader = new JpaArchiveHeader();
// Initialize parts counter
archiveHeader.TotalParts = 1;
// Open the first part
Open(1);
archiveHeader.Signature = ReadAsciiString(3);
if (archiveHeader.Signature != "JPA")
{
throw new InvalidArchiveException(String.Format(Language.ResourceManager.GetString("ERR_FORMAT_INVALID_FILE_TYPE_SIGNATURE"), "JPA"));
}
archiveHeader.HeaderLength = ReadUShort();
archiveHeader.MajorVersion = ReadByte();
archiveHeader.MinorVersion = ReadByte();
archiveHeader.FileCount = ReadULong();
archiveHeader.UncompressedSize = ReadULong();
archiveHeader.CompressedSize = ReadULong();
if (archiveHeader.HeaderLength > 19)
{
// We need to loop while we have remaining header bytes
ushort remainingBytes = (ushort)(archiveHeader.HeaderLength - 19);
while (remainingBytes > 0)
{
// Do we have an extra header? The next three bytes must be JP followed by 0x01 and the header type
byte[] headerSignature = ReadBytes(4);
if ((headerSignature[0] != 0x4a) || (headerSignature[1] != 0x50) || (headerSignature[2] != 0x01))
{
throw new InvalidArchiveException(Language.ResourceManager.GetString("ERR_FORMAT_INVALID_JPA_EXTRA_HEADER"));
}
// The next two bytes tell us how long this header is, without the 4 byte signature and type but WITH the header length field
ushort extraHeaderLength = ReadUShort();
// Subtract the read bytes from the remaining bytes in the header.
remainingBytes -= (ushort)(4 + extraHeaderLength);
// Read the extra header
switch (headerSignature[3])
{
case 0x01:
// Spanned Archive Marker header
archiveHeader.TotalParts = ReadUShort();
break;
default:
// I have no idea what this is!
throw new InvalidArchiveException(Language.ResourceManager.GetString("ERR_FORMAT_INVALID_JPA_EXTRA_HEADER"));
}
}
}
// Invoke the archiveInformation event. We need to do some work to get there, through...
// -- Create a new archive information record
ArchiveInformation info = new ArchiveInformation();
// -- Get the total archive size by looping all of its parts
info.ArchiveSize = 0;
for (int i = 1; i <= Parts; i++)
{
FileInfo fi = new FileInfo(ArchivePath);
info.ArchiveSize += (ulong)fi.Length;
}
archiveHeader.TotalLength = info.ArchiveSize;
// -- Incorporate bits from the file header
info.FileCount = archiveHeader.FileCount;
info.UncompressedSize = archiveHeader.UncompressedSize;
info.CompressedSize = archiveHeader.CompressedSize;
// -- Create the event arguments object
ArchiveInformationEventArgs args = new ArchiveInformationEventArgs(info);
// -- Finally, invoke the event
OnArchiveInformationEvent(args);
// Lastly, return the read archive header
return(archiveHeader);
}
