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// **********************************************************************
//
// Copyright (c) 2003-2016 ZeroC, Inc. All rights reserved.
//
// This copy of Ice is licensed to you under the terms described in the
// ICE_LICENSE file included in this distribution.
//
// **********************************************************************
namespace IceInternal
{
using System;
using System.Diagnostics;
using System.IO;
using System.Text;
//
// Class to provide a System.IO.Stream interface on top of a BasicStream.
// We use this to serialize arbitrary .NET serializable classes into
// a Slice byte sequence.
//
// For input streams, this class is a wrapper around the BasicStream
// class that passes all methods through.
//
// For output streams, we use a different stragegy:
// Slice sequences are encoded on the wire as a count of elements, followed
// by the sequence contents. For arbitrary .NET classes, we do not know how
// big the sequence that is eventually written will be. To avoid excessive
// data copying, this class mantains a private bytes_ array of 254 bytes and,
// initially, writes data into that array. If more than 254 bytes end up being
// written, we write a dummy sequence size of 255 (which occupies five bytes
// on the wire) into the BasicStream and, once this class is disposed, patch
// that size to match the actual size. Otherwise, if the bytes_ buffer contains
// fewer than 255 bytes when this class is disposed, we write the sequence size
// as a single byte, followed by the contents of the bytes_ buffer.
//
enum StreamType { Read, Write };
public class StreamWrapper : System.IO.Stream, System.IDisposable
{
//
// Writeable stream constructor
//
public StreamWrapper(BasicStream s)
{
type_ = StreamType.Write;
s_ = s;
spos_ = s.pos();
bytes_ = new byte[254];
pos_ = 0;
length_ = 0;
}
//
// Readable stream constructor
//
public StreamWrapper(int size, BasicStream s)
{
type_ = StreamType.Read;
s_ = s;
spos_ = 0;
bytes_ = null;
pos_ = 0;
length_ = size;
}
public override int Read(byte[] buffer, int offset, int count)
{
Debug.Assert(buffer != null && offset >= 0 && count >= 0 && offset + count <= buffer.Length);
try
{
s_.getBuffer().b.get(buffer, offset, count);
}
catch(System.Exception ex)
{
throw new IOException("could not read from stream", ex);
}
return count;
}
public override int ReadByte()
{
try
{
return s_.getBuffer().b.get();
}
catch(System.Exception ex)
{
throw new IOException("could not read from stream", ex);
}
}
public override void Write(byte[] array, int offset, int count)
{
Debug.Assert(type_ == StreamType.Write);
Debug.Assert(array != null && offset >= 0 && count >= 0 && offset + count <= array.Length);
try
{
if(bytes_ != null)
{
//
// If we can fit the data into the first 254 bytes, write it to bytes_.
//
if(count <= bytes_.Length - pos_)
{
System.Buffer.BlockCopy(array, offset, bytes_, pos_, count);
pos_ += count;
return;
}
s_.writeSize(255); // Dummy size, until we know how big the stream
// really is and can patch the size.
if(pos_ > 0)
{
//
// Write the current contents of bytes_.
//
s_.expand(pos_);
s_.getBuffer().b.put(bytes_, 0, pos_);
}
bytes_ = null;
}
//
// Write data passed by caller.
//
s_.expand(count);
s_.getBuffer().b.put(array, offset, count);
pos_ += count;
}
catch(System.Exception ex)
{
throw new IOException("could not write to stream", ex);
}
}
public override void WriteByte(byte value)
{
Debug.Assert(type_ == StreamType.Write);
try
{
if(bytes_ != null)
{
//
// If we can fit the data into the first 254 bytes, write it to bytes_.
//
if(pos_ < bytes_.Length)
{
bytes_[pos_++] = value;
return;
}
s_.writeSize(255); // Dummy size, until we know how big the stream
// really is and can patch the size.
if(pos_ > 0)
{
//
// Write the current contents of bytes_.
//
s_.expand(pos_);
s_.getBuffer().b.put(bytes_, 0, pos_);
}
bytes_ = null;
}
//
// Write data passed by caller.
//
s_.expand(1);
s_.getBuffer().b.put(value);
pos_ += 1;
}
catch(System.Exception ex)
{
throw new IOException("could not write to stream", ex);
}
}
public override bool CanRead
{
get
{
return true;
}
}
public override bool CanWrite
{
get
{
return type_ == StreamType.Write;
}
}
public override bool CanSeek
{
get
{
if(AssemblyUtil.runtime_ == AssemblyUtil.Runtime.Mono)
{
//
// The Mono deserialization implementation has a bug that causes a call to Seek() such
// that the reading position is set to -1.
//
return false;
}
else
{
return type_ == StreamType.Read;
}
}
}
public override void Flush()
{
try
{
if(bytes_ != null)
{
Debug.Assert(pos_ <= bytes_.Length);
s_.pos(spos_);
s_.writeSize(pos_);
s_.expand(pos_);
s_.getBuffer().b.put(bytes_, 0, pos_);
}
else
{
int currentPos = s_.pos();
s_.pos(spos_);
s_.writeSize(pos_); // Patch previously-written dummy value.
s_.pos(currentPos);
}
}
catch(System.Exception ex)
{
throw new IOException("could not flush stream", ex);
}
}
public override long Length
{
get
{
return length_;
}
}
public override long Position
{
get
{
return pos_;
}
set
{
Seek(value, SeekOrigin.Begin);
}
}
public override long Seek(long offset, SeekOrigin origin)
{
Debug.Assert(type_ != StreamType.Write);
// Deliberately no size check here--positioning beyond the limit of the stream is legal.
switch(origin)
{
case SeekOrigin.Begin:
{
pos_ = (int)offset;
break;
}
case SeekOrigin.Current:
{
pos_ += (int)offset;
break;
}
case SeekOrigin.End:
{
pos_ = (int)length_ + (int)offset;
break;
}
default:
{
Debug.Assert(false);
break;
}
}
s_.pos(pos_);
return pos_;
}
public override void SetLength(long value)
{
Debug.Assert(type_ == StreamType.Write && value >= 0);
length_ = value;
}
private StreamType type_;
private BasicStream s_;
private int spos_;
private byte[] bytes_;
private int pos_;
private long length_;
}
}
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