//------------------------------------------------------
//
// Private Methods
//
//------------------------------------------------------
private void EnsurePieceStream(bool isLastPiece)
{
if (_pieceStream != null)
{
// Normally, the pieces are actually closed automatically for us by the
// underlying ZipIO logic, but in the case of the last piece (when we
// are called by our own Dispose(bool) method) we must close it explicitly.
if (isLastPiece)
{
_pieceStream.Close();
}
// We detect that the stream has been closed by inspecting the CanWrite property
// since this is guaranteed not to throw even when the stream is disposed.
if (!_pieceStream.CanWrite)
{
// increment our piece number so we can generate the correct
// one below
checked { ++_currentPieceNumber; }
// release it to trigger the new piece creation below
_pieceStream = null;
}
}
if (_pieceStream == null)
{
string pieceName = PieceNameHelper.CreatePieceName(
_partName,
_currentPieceNumber,
isLastPiece);
string pieceZipName = ZipPackage.GetZipItemNameFromOpcName(pieceName);
ZipFileInfo zipFileInfo = _archive.AddFile(pieceZipName, _compressionMethod, _deflateOption);
// We've just created the file, so the mode can only be Create, not CreateNew.
// (At least, this is part of ZipFileInfo's belief system.)
_pieceStream = zipFileInfo.GetStream(FileMode.Create, _access);
}
}
/// <summary>
/// If the logical end precedes the physical end, delete invalidated pieces
/// and rename the logical end to a name containing ".last".
/// </summary>
private void UpdatePhysicalEndIfNecessary()
{
if (!_logicalEndPrecedesPhysicalEnd)
{
return;
}
// Delete invalidated pieces.
int pieceNumber = _lastPieceIndex + 1;
while (pieceNumber < _sortedPieceInfoList.Count)
{
_zipArchive.DeleteFile(_sortedPieceInfoList[pieceNumber].ZipFileInfo.Name);
pieceNumber++;
}
_sortedPieceInfoList.RemoveRange(_lastPieceIndex + 1, _sortedPieceInfoList.Count - (_lastPieceIndex + 1));
// Since there is no rename in Zip I/O, getting the last piece to have .last
// in its name necessarily involves creating a new piece. The simplest and most
// effective solution consists in adding an empty terminal piece.
// Number of the new physical last piece.
int lastPiece = _lastPieceIndex + 1;
// Record the compression parameters of the first piece to apply them to the new piece.
// (Though this part will be created as empty, it may grow later.)
ZipFileInfo firstPieceInfo = _sortedPieceInfoList[0].ZipFileInfo;
CompressionMethodEnum compressionMethod = firstPieceInfo.CompressionMethod;
DeflateOptionEnum deflateOption = firstPieceInfo.DeflateOption;
// We have to special-case SetLength(0), because in that case, there is no nonempty
// piece at all; and only the last piece is allowed to be empty.
if (_lastPieceIndex == 0 && _pieceStreamInfoList[0].Stream.Length == 0)
{
_zipArchive.DeleteFile(firstPieceInfo.Name);
// The list of piece descriptors now becomes totally empty.
// This temporarily violates an invariant that should obtain again
// on exiting this function.
_indexOfLastPieceStreamInfoAccessed = -1;
//Remove all the items in the list
_pieceStreamInfoList.Clear();
lastPiece = 0; // Create "[0].last.piece"
}
string newLastPieceFileName = PieceNameHelper.CreatePieceName(
_sortedPieceInfoList[0].PrefixName,
lastPiece,
true /* last piece */);
ZipFileInfo newLastPieceInfo = _zipArchive.AddFile(newLastPieceFileName,
compressionMethod, deflateOption);
_lastPieceIndex = lastPiece;
//We need to update the _sortedPieceInfoList with this new last piece information
_sortedPieceInfoList.Add(
new PieceInfo(
newLastPieceInfo,
_sortedPieceInfoList[0].PartUri,
_sortedPieceInfoList[0].PrefixName,
_lastPieceIndex,
true /* last piece */));
// If we have been creating [0].last.piece, create a stream descriptor for it.
// (In other cases, create on demand, as usual.)
if (lastPiece == 0)
{
Stream pieceStream = newLastPieceInfo.GetStream(_fileMode, _fileAccess);
_indexOfLastPieceStreamInfoAccessed = 0;
//The list should be empty at this point
Invariant.Assert(_pieceStreamInfoList.Count == 0);
_pieceStreamInfoList.Add(new PieceStreamInfo(pieceStream, 0 /*startOffset*/));
}
// Mark update complete.
_logicalEndPrecedesPhysicalEnd = false;
}