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// Copyright ?2004, 2010, Oracle and/or its affiliates. All rights reserved.
//
// MySQL Connector/NET is licensed under the terms of the GPLv2
// <http://www.gnu.org/licenses/old-licenses/gpl-2.0.html>, like most
// MySQL Connectors. There are special exceptions to the terms and
// conditions of the GPLv2 as it is applied to this software, see the
// FLOSS License Exception
// <http://www.mysql.com/about/legal/licensing/foss-exception.html>.
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published
// by the Free Software Foundation; version 2 of the License.
//
// This program is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
// or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
// for more details.
//
// You should have received a copy of the GNU General Public License along
// with this program; if not, write to the Free Software Foundation, Inc.,
// 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
#if MYSQL_6_9
using System;
using System.IO;
using zlib;
using Externals.MySql.Data.MySqlClient.Properties;
using Externals.MySql.Data.Common;
namespace Externals.MySql.Data.MySqlClient
{
/// <summary>
/// Summary description for CompressedStream.
/// </summary>
internal class CompressedStream : Stream
{
// writing fields
private Stream baseStream;
private MemoryStream cache;
// reading fields
private byte[] localByte;
private byte[] inBuffer;
private byte[] lengthBytes;
private WeakReference inBufferRef;
private int inPos;
private int maxInPos;
private ZInputStream zInStream;
public CompressedStream(Stream baseStream)
{
this.baseStream = baseStream;
localByte = new byte[1];
lengthBytes = new byte[7];
cache = new MemoryStream();
inBufferRef = new WeakReference(inBuffer, false);
}
#region Properties
public override bool CanRead
{
get { return baseStream.CanRead; }
}
public override bool CanWrite
{
get { return baseStream.CanWrite; }
}
public override bool CanSeek
{
get { return baseStream.CanSeek; }
}
public override long Length
{
get { return baseStream.Length; }
}
public override long Position
{
get { return baseStream.Position; }
set { baseStream.Position = value; }
}
#endregion
public override void Close()
{
base.Close();
baseStream.Close();
cache.Dispose();
}
public override void SetLength(long value)
{
throw new NotSupportedException(Resources.CSNoSetLength);
}
public override int ReadByte()
{
try
{
Read(localByte, 0, 1);
return localByte[0];
}
catch (EndOfStreamException)
{
return -1;
}
}
public override bool CanTimeout
{
get
{
return baseStream.CanTimeout;
}
}
public override int ReadTimeout
{
get
{
return baseStream.ReadTimeout;
}
set
{
baseStream.ReadTimeout = value;
}
}
public override int WriteTimeout
{
get
{
return baseStream.WriteTimeout;
}
set
{
baseStream.WriteTimeout = value;
}
}
public override int Read(byte[] buffer, int offset, int count)
{
if (buffer == null)
throw new ArgumentNullException("buffer", Resources.BufferCannotBeNull);
if (offset < 0 || offset >= buffer.Length)
throw new ArgumentOutOfRangeException("offset", Resources.OffsetMustBeValid);
if ((offset + count) > buffer.Length)
throw new ArgumentException(Resources.BufferNotLargeEnough, "buffer");
if (inPos == maxInPos)
PrepareNextPacket();
int countToRead = Math.Min(count, maxInPos - inPos);
int countRead;
if (zInStream != null)
countRead = zInStream.read(buffer, offset, countToRead);
else
countRead = baseStream.Read(buffer, offset, countToRead);
inPos += countRead;
// release the weak reference
if (inPos == maxInPos)
{
zInStream = null;
if (!Platform.IsMono())
{
inBufferRef = new WeakReference(inBuffer, false);
inBuffer = null;
}
}
return countRead;
}
private void PrepareNextPacket()
{
MySqlStream.ReadFully(baseStream, lengthBytes, 0, 7);
int compressedLength = lengthBytes[0] + (lengthBytes[1] << 8) + (lengthBytes[2] << 16);
// lengthBytes[3] is seq
int unCompressedLength = lengthBytes[4] + (lengthBytes[5] << 8) +
(lengthBytes[6] << 16);
if (unCompressedLength == 0)
{
unCompressedLength = compressedLength;
zInStream = null;
}
else
{
ReadNextPacket(compressedLength);
MemoryStream ms = new MemoryStream(inBuffer);
zInStream = new ZInputStream(ms);
zInStream.maxInput = compressedLength;
}
inPos = 0;
maxInPos = unCompressedLength;
}
private void ReadNextPacket(int len)
{
if (!Platform.IsMono())
inBuffer = inBufferRef.Target as byte[];
if (inBuffer == null || inBuffer.Length < len)
inBuffer = new byte[len];
MySqlStream.ReadFully(baseStream, inBuffer, 0, len);
}
private MemoryStream CompressCache()
{
// small arrays almost never yeild a benefit from compressing
if (cache.Length < 50)
return null;
byte[] cacheBytes = cache.GetBuffer();
MemoryStream compressedBuffer = new MemoryStream();
ZOutputStream zos = new ZOutputStream(compressedBuffer, zlibConst.Z_DEFAULT_COMPRESSION);
zos.Write(cacheBytes, 0, (int)cache.Length);
zos.finish();
// if the compression hasn't helped, then just return null
if (compressedBuffer.Length >= cache.Length)
return null;
return compressedBuffer;
}
private void CompressAndSendCache()
{
long compressedLength, uncompressedLength;
// we need to save the sequence byte that is written
byte[] cacheBuffer = cache.GetBuffer();
byte seq = cacheBuffer[3];
cacheBuffer[3] = 0;
// first we compress our current cache
MemoryStream compressedBuffer = CompressCache();
// now we set our compressed and uncompressed lengths
// based on if our compression is going to help or not
MemoryStream memStream;
if (compressedBuffer == null)
{
compressedLength = cache.Length;
uncompressedLength = 0;
memStream = cache;
}
else
{
compressedLength = compressedBuffer.Length;
uncompressedLength = cache.Length;
memStream = compressedBuffer;
}
// Make space for length prefix (7 bytes) at the start of output
long dataLength = memStream.Length;
int bytesToWrite = (int)dataLength + 7;
memStream.SetLength(bytesToWrite);
byte[] buffer = memStream.GetBuffer();
Array.Copy(buffer, 0, buffer, 7, (int)dataLength);
// Write length prefix
buffer[0] = (byte)(compressedLength & 0xff);
buffer[1] = (byte)((compressedLength >> 8) & 0xff);
buffer[2] = (byte)((compressedLength >> 16) & 0xff);
buffer[3] = seq;
buffer[4] = (byte)(uncompressedLength & 0xff);
buffer[5] = (byte)((uncompressedLength >> 8) & 0xff);
buffer[6] = (byte)((uncompressedLength >> 16) & 0xff);
baseStream.Write(buffer, 0, bytesToWrite);
baseStream.Flush();
cache.SetLength(0);
if (compressedBuffer != null)
{
compressedBuffer.Dispose();
}
}
public override void Flush()
{
if (!InputDone()) return;
CompressAndSendCache();
}
private bool InputDone()
{
// if we have not done so yet, see if we can calculate how many bytes we are expecting
if ( baseStream is TimedStream && (( TimedStream )baseStream ).IsClosed ) return false;
if (cache.Length < 4) return false;
byte[] buf = cache.GetBuffer();
int expectedLen = buf[0] + (buf[1] << 8) + (buf[2] << 16);
if (cache.Length < (expectedLen + 4)) return false;
return true;
}
public override void WriteByte(byte value)
{
cache.WriteByte(value);
}
public override void Write(byte[] buffer, int offset, int count)
{
cache.Write(buffer, offset, count);
}
public override long Seek(long offset, SeekOrigin origin)
{
return baseStream.Seek(offset, origin);
}
}
}
#endif