[Firebird-net-provider] [FB-Tracker] Created: (DNET-944) Compression buffer too small error thrown

[tonim (JIRA) <tr...@fi...>]

Compression buffer too small error thrown
-----------------------------------------

                 Key: DNET-944
                 URL: http://tracker.firebirdsql.org/browse/DNET-944
             Project: .NET Data provider
          Issue Type: Bug
          Components: ADO.NET Provider
    Affects Versions: vNext
         Environment: Firebird.net provider selecting rows, more frequent selecting data containing blobs, for example SELECT * FROM RDB$PROCEDURES on a database width some procedures. You can reproduce the bug easily setting the CompressionBufferSize to 8192 for example
            Reporter: tonim
            Assignee: Jiri Cincura


Any environment, when selecting Compression=true in Connection string, more common selecting packetsize=32000

A big constant decompression buffer size is defined in FirebirdNetwordStream. 
		const int CompressionBufferSize = 1 *  1024 * 1024;

Any decompression bigger than this size throws an exception in HandleDecompression function.

I provide a tested fix, the buffer will grow dynamically, depending on the uncompressed size.

                // There is no need to define a big buffer size, it will grow as needed
		const int CompressionBufferSize = 32000;



		int HandleDecompression(byte[] buffer, int count)
		{
			_decompressor.OutputBuffer = _compressionBuffer;
			_decompressor.InputBuffer = buffer;
			_decompressor.NextOut = 0;
			_decompressor.NextIn = 0;
			_decompressor.AvailableBytesIn = count;
			do
			{
				// Double the buffer size until the decompression fits in the output buffer
				_decompressor.OutputBuffer = _compressionBuffer;
				_decompressor.AvailableBytesOut = _compressionBuffer.Length - _decompressor.NextOut;
				var rc = _decompressor.Inflate(Ionic.Zlib.FlushType.None);
				if (rc != Ionic.Zlib.ZlibConstants.Z_OK)
					throw new IOException($"Error '{rc}' while decompressing the data.");
				if (_decompressor.AvailableBytesIn != 0)
				{
					byte[] newCompressionBuffer = new byte[_compressionBuffer.Length * 2];
					Array.Copy(_compressionBuffer, newCompressionBuffer, _decompressor.NextOut);
					_compressionBuffer = newCompressionBuffer;
				}
			} while (_decompressor.AvailableBytesIn != 0);
			return _decompressor.NextOut;
		}




-- 
This message is automatically generated by JIRA.
-
If you think it was sent incorrectly contact one of the administrators: http://tracker.firebirdsql.org/secure/Administrators.jspa
-
For more information on JIRA, see: http://www.atlassian.com/software/jira