/// <summary>
/// Read from the stream
/// </summary>
/// <param name="buffer">the buffer to read</param>
/// <param name="offset">the offset at which to start</param>
/// <param name="count">the number of bytes to read</param>
/// <returns>the number of bytes actually read</returns>
public override int Read(byte[] buffer, int offset, int count)
{
int bytesToRead = count;
// Need to limit the # of bytes returned, if the stream is intended to have
// a definite length. This is especially useful when returning a stream for
// the uncompressed data directly to the application. The app won't
// necessarily read only the UncompressedSize number of bytes. For example
// wrapping the stream returned from OpenReader() into a StreadReader() and
// calling ReadToEnd() on it, We can "over-read" the zip data and get a
// corrupt string. The length limits that, prevents that problem.
if (_lengthLimit != CrcCalculatorStream.UnsetLengthLimit)
{
if (_Crc32.TotalBytesRead >= _lengthLimit)
{
return(0); // EOF
}
Int64 bytesRemaining = _lengthLimit - _Crc32.TotalBytesRead;
if (bytesRemaining < count)
{
bytesToRead = (int)bytesRemaining;
}
}
int n = _innerStream.Read(buffer, offset, bytesToRead);
if (n > 0)
{
_Crc32.SlurpBlock(buffer, offset, n);
}
return(n);
}
public override void Write(System.Byte[] buffer, int offset, int count)
{
// workitem 7159
// calculate the CRC on the unccompressed data (before writing)
if (crc != null)
{
crc.SlurpBlock(buffer, offset, count);
}
if (_streamMode == StreamMode.Undefined)
{
_streamMode = StreamMode.Writer;
}
else if (_streamMode != StreamMode.Writer)
{
throw new ZlibException("Cannot Write after Reading.");
}
if (count == 0)
{
return;
}
// first reference of z property will initialize the private var _z
z.InputBuffer = buffer;
_z.NextIn = offset;
_z.AvailableBytesIn = count;
bool done = false;
do
{
_z.OutputBuffer = workingBuffer;
_z.NextOut = 0;
_z.AvailableBytesOut = _workingBuffer.Length;
int rc = (_wantCompress)
? _z.Deflate(_flushMode)
: _z.Inflate(_flushMode);
if (rc != ZlibConstants.Z_OK && rc != ZlibConstants.Z_STREAM_END)
{
throw new ZlibException((_wantCompress ? "de" : "in") + "flating: " + _z.Message);
}
//if (_workingBuffer.Length - _z.AvailableBytesOut > 0)
_stream.Write(_workingBuffer, 0, _workingBuffer.Length - _z.AvailableBytesOut);
done = _z.AvailableBytesIn == 0 && _z.AvailableBytesOut != 0;
// If GZIP and de-compress, we're done when 8 bytes remain.
if (_flavor == ZlibStreamFlavor.GZIP && !_wantCompress)
{
done = (_z.AvailableBytesIn == 8 && _z.AvailableBytesOut != 0);
}
}while (!done);
}
