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using System;
using System.Data.Common;
using Microsoft.SqlServer.Server;
namespace System.Data.SqlClient
{
sealed internal class SqlSequentialStreamSmi : System.IO.Stream
{
private SmiEventSink_Default _sink;
private ITypedGettersV3 _getters;
private int _columnIndex; // The index of out column in the table
private long _position; // Current position in the stream
private long _length; // Total length of the stream
internal SqlSequentialStreamSmi(SmiEventSink_Default sink, ITypedGettersV3 getters, int columnIndex, long length)
{
_sink = sink;
_getters = getters;
_columnIndex = columnIndex;
_length = length;
_position = 0;
}
public override bool CanRead
{
get { return ((_sink != null) && (_getters != null)); }
}
public override bool CanSeek
{
get { return false; }
}
public override bool CanWrite
{
get { return false; }
}
public override void Flush()
{ }
public override long Length
{
get { throw ADP.NotSupported(); }
}
public override long Position
{
get { throw ADP.NotSupported(); }
set { throw ADP.NotSupported(); }
}
internal int ColumnIndex
{
get { return _columnIndex; }
}
public override int Read(byte[] buffer, int offset, int count)
{
SqlSequentialStream.ValidateReadParameters(buffer, offset, count);
if (!CanRead)
{
throw ADP.ObjectDisposed(this);
}
try
{
// Read whichever is less: however much the user asked for, or however much we have
// NOTE: It is safe to do this since count <= Int32.MaxValue, therefore the Math.Min should always result in an int
int bytesNeeded = (int)Math.Min((long)count, _length - _position);
int bytesRead = 0;
if (bytesNeeded > 0)
{
bytesRead = ValueUtilsSmi.GetBytes_Unchecked(_sink, _getters, _columnIndex, _position, buffer, offset, bytesNeeded);
_position += bytesRead;
}
return bytesRead;
}
catch (SqlException ex)
{
// Stream.Read() can't throw a SqlException - so wrap it in an IOException
throw ADP.ErrorReadingFromStream(ex);
}
}
public override long Seek(long offset, IO.SeekOrigin origin)
{
throw ADP.NotSupported();
}
public override void SetLength(long value)
{
throw ADP.NotSupported();
}
public override void Write(byte[] buffer, int offset, int count)
{
throw ADP.NotSupported();
}
/// <summary>
/// Forces the stream to act as if it was closed (i.e. CanRead=false and Read() throws)
/// This does not actually close the stream, read off the rest of the data or dispose this
/// </summary>
internal void SetClosed()
{
_sink = null;
_getters = null;
}
protected override void Dispose(bool disposing)
{
if (disposing)
{
SetClosed();
}
base.Dispose(disposing);
}
}
}
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