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ByteaHandler.cs
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#region License
// The PostgreSQL License
//
// Copyright (C) 2017 The Npgsql Development Team
//
// Permission to use, copy, modify, and distribute this software and its
// documentation for any purpose, without fee, and without a written
// agreement is hereby granted, provided that the above copyright notice
// and this paragraph and the following two paragraphs appear in all copies.
//
// IN NO EVENT SHALL THE NPGSQL DEVELOPMENT TEAM BE LIABLE TO ANY PARTY
// FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES,
// INCLUDING LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS
// DOCUMENTATION, EVEN IF THE NPGSQL DEVELOPMENT TEAM HAS BEEN ADVISED OF
// THE POSSIBILITY OF SUCH DAMAGE.
//
// THE NPGSQL DEVELOPMENT TEAM SPECIFICALLY DISCLAIMS ANY WARRANTIES,
// INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
// AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
// ON AN "AS IS" BASIS, AND THE NPGSQL DEVELOPMENT TEAM HAS NO OBLIGATIONS
// TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
#endregion
using System;
using System.IO;
using System.Threading;
using System.Threading.Tasks;
using Npgsql.BackendMessages;
using NpgsqlTypes;
using System.Data;
using JetBrains.Annotations;
using Npgsql.PostgresTypes;
namespace Npgsql.TypeHandlers
{
/// <remarks>
/// http://www.postgresql.org/docs/current/static/datatype-binary.html
/// </remarks>
[TypeMapping("bytea", NpgsqlDbType.Bytea, DbType.Binary, new[] { typeof(byte[]), typeof(ArraySegment<byte>) })]
class ByteaHandler : ChunkingTypeHandler<byte[]>
{
internal ByteaHandler(PostgresType postgresType) : base(postgresType) {}
public override async ValueTask<byte[]> Read(ReadBuffer buf, int len, bool async, FieldDescription fieldDescription = null)
{
var bytes = new byte[len];
var pos = 0;
while (true)
{
var toRead = Math.Min(len - pos, buf.ReadBytesLeft);
buf.ReadBytes(bytes, pos, toRead);
pos += toRead;
if (pos == len)
break;
await buf.ReadMore(async);
}
return bytes;
}
public long GetBytes(DataRowMessage row, int offset, [CanBeNull] byte[] output, int outputOffset, int len, FieldDescription field)
{
if (output == null)
return row.ColumnLen;
row.SeekInColumn(offset, false).GetAwaiter().GetResult();
// Attempt to read beyond the end of the column
if (offset + len > row.ColumnLen)
len = row.ColumnLen - offset;
var read = row.Buffer.ReadAllBytes(output, outputOffset, len, false, false).Result;
row.PosInColumn += read;
return read;
}
#region Write
public override int ValidateAndGetLength(object value, ref LengthCache lengthCache, NpgsqlParameter parameter=null)
{
if (value is ArraySegment<byte>)
{
var arraySegment = (ArraySegment<byte>)value;
return parameter == null || parameter.Size <= 0 || parameter.Size >= arraySegment.Count
? arraySegment.Count
: parameter.Size;
}
var asArray = value as byte[];
if (asArray != null)
return parameter == null || parameter.Size <= 0 || parameter.Size >= asArray.Length
? asArray.Length
: parameter.Size;
throw CreateConversionException(value.GetType());
}
protected override async Task Write(object value, WriteBuffer buf, LengthCache lengthCache, [CanBeNull] NpgsqlParameter parameter,
bool async, CancellationToken cancellationToken)
{
ArraySegment<byte> segment;
if (value is ArraySegment<byte>)
{
segment = (ArraySegment<byte>)value;
if (!(parameter == null || parameter.Size <= 0 || parameter.Size >= segment.Count))
segment = new ArraySegment<byte>(segment.Array, segment.Offset, parameter.Size);
}
else
{
var array = (byte[])value;
var len = parameter == null || parameter.Size <= 0 || parameter.Size >= array.Length
? array.Length
: parameter.Size;
segment = new ArraySegment<byte>(array, 0, len);
}
// The entire segment fits in our buffer, copy it as usual.
if (segment.Count <= buf.WriteSpaceLeft)
{
buf.WriteBytes(segment.Array, segment.Offset, segment.Count);
return;
}
// The segment is larger than our buffer. Flush whatever is currently in the buffer and
// write the array directly to the socket.
await buf.Flush(async, cancellationToken);
buf.DirectWrite(segment.Array, segment.Offset, segment.Count);
}
internal Task WriteInternal(object value, WriteBuffer buf, LengthCache lengthCache,
[CanBeNull] NpgsqlParameter parameter,
bool async, CancellationToken cancellationToken)
=> Write(value, buf, lengthCache, parameter, async, cancellationToken);
#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.ReadAllBytes(buffer, offset, count, true, false).Result;
_row.PosInColumn += read;
return read;
}
public override Task<int> ReadAsync([NotNull] byte[] buffer, int offset, int count, CancellationToken token)
{
CheckDisposed();
return SynchronizationContextSwitcher.NoContext(async () =>
{
count = Math.Min(count, _row.ColumnLen - _row.PosInColumn);
var read = await _row.Buffer.ReadAllBytes(buffer, offset, count, true, true);
_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 => true;
public override bool CanSeek => false;
public override bool CanWrite => 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
}