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ByteaHandler.cs
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executable file
·228 lines (193 loc) · 6.49 KB
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using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Diagnostics.Contracts;
using System.IO;
using System.Linq;
using System.Runtime.CompilerServices;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using Npgsql.BackendMessages;
using NpgsqlTypes;
using System.Data;
namespace Npgsql.TypeHandlers
{
/// <remarks>
/// http://www.postgresql.org/docs/current/static/datatype-binary.html
/// </remarks>
[TypeMapping("bytea", NpgsqlDbType.Bytea, DbType.Binary, new Type[] { typeof(byte[]), typeof(ArraySegment<byte>) })]
internal class ByteaHandler : TypeHandler<byte[]>,
IChunkingTypeReader<byte[]>, IChunkingTypeWriter
{
bool _returnedBuffer;
byte[] _bytes;
int _pos;
NpgsqlBuffer _buf;
public void PrepareRead(NpgsqlBuffer buf, int len, FieldDescription fieldDescription)
{
_bytes = new byte[len];
_pos = 0;
_buf = buf;
}
public bool Read(out byte[] result)
{
var toRead = Math.Min(_bytes.Length - _pos, _buf.ReadBytesLeft);
_buf.ReadBytesSimple(_bytes, _pos, toRead);
_pos += toRead;
if (_pos == _bytes.Length)
{
result = _bytes;
_bytes = null;
_buf = null;
return true;
}
result = null;
return false;
}
public long GetBytes(DataRowMessage row, int offset, byte[] output, int outputOffset, int len, FieldDescription field)
{
if (output == null) {
return row.ColumnLen;
}
row.SeekInColumn(offset);
// Attempt to read beyond the end of the column
if (offset + len > row.ColumnLen) {
len = row.ColumnLen - offset;
}
row.Buffer.ReadBytes(output, outputOffset, len, true);
row.PosInColumn += len;
return len;
}
#region Write
ArraySegment<byte> _value;
public int ValidateAndGetLength(object value, ref LengthCache lengthCache, NpgsqlParameter parameter=null)
{
if (value is ArraySegment<byte>)
{
var arraySegment = (ArraySegment<byte>)value;
if (arraySegment.Array == null)
throw new InvalidCastException("Array in ArraySegment<byte> is null");
return parameter == null || parameter.Size <= 0 || parameter.Size >= arraySegment.Count
? arraySegment.Count
: parameter.Size;
}
else
{
var array = (byte[])value;
return parameter == null || parameter.Size <= 0 || parameter.Size >= array.Length
? array.Length
: parameter.Size;
}
}
public void PrepareWrite(object value, NpgsqlBuffer buf, LengthCache lengthCache, NpgsqlParameter parameter=null)
{
_buf = buf;
if (value is ArraySegment<byte>)
{
_value = (ArraySegment<byte>)value;
if (!(parameter == null || parameter.Size <= 0 || parameter.Size >= _value.Count))
{
_value = new ArraySegment<byte>(_value.Array, _value.Offset, parameter.Size);
}
}
else
{
var array = (byte[])value;
var len = parameter == null || parameter.Size <= 0 || parameter.Size >= array.Length
? array.Length
: parameter.Size;
_value = new ArraySegment<byte>(array, 0, len);
}
}
// ReSharper disable once RedundantAssignment
public bool Write(ref DirectBuffer directBuf)
{
// If the entire array fits in our buffer, copy it as usual.
// Otherwise, switch to direct write from the user-provided buffer
if (_value.Count <= _buf.WriteSpaceLeft)
{
_buf.WriteBytesSimple(_value.Array, _value.Offset, _value.Count);
return true;
}
if (!_returnedBuffer)
{
directBuf.Buffer = _value.Array;
directBuf.Offset = _value.Offset;
directBuf.Size = _value.Count;
_returnedBuffer = true;
return false;
}
_returnedBuffer = false;
return true;
}
#endregion
}
#region Stream
class SequentialByteaStream : Stream
{
readonly DataRowMessage _row;
bool _disposed;
internal SequentialByteaStream(DataRowMessage row)
{
_row = row;
}
public override int Read(byte[] buffer, int offset, int count)
{
CheckDisposed();
count = Math.Min(count, _row.ColumnLen - _row.PosInColumn);
var read = _row.Buffer.ReadBytes(buffer, offset, count, false);
_row.PosInColumn += read;
return read;
}
public override long Length
{
get
{
CheckDisposed();
return _row.ColumnLen;
}
}
public override long Position
{
get
{
CheckDisposed();
return _row.PosInColumn;
}
set { throw new NotSupportedException(); }
}
protected override void Dispose(bool disposing)
{
_disposed = true;
}
public override bool CanRead { get { return true; } }
public override bool CanSeek { get { return false; } }
public override bool CanWrite { get { return false; } }
void CheckDisposed()
{
if (_disposed) {
throw new ObjectDisposedException(null);
}
}
#region Not Supported
public override void Flush()
{
throw new NotSupportedException();
}
public override long Seek(long offset, SeekOrigin origin)
{
throw new NotSupportedException();
}
public override void SetLength(long value)
{
throw new NotSupportedException();
}
public override void Write(byte[] buffer, int offset, int count)
{
throw new NotSupportedException();
}
#endregion
}
#endregion
}