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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
/*============================================================
**
**
**
**
**
** Purpose: Pins a byte[], exposing it as an unmanaged memory
** stream. Used in ResourceReader for corner cases.
**
**
===========================================================*/
using System;
using System.Runtime.InteropServices;
using System.Diagnostics;
using System.Diagnostics.Contracts;
namespace System.IO {
internal sealed unsafe class PinnedBufferMemoryStream : UnmanagedMemoryStream
{
private byte[] _array;
private GCHandle _pinningHandle;
// The new inheritance model requires a Critical default ctor since base (UnmanagedMemoryStream) has one
private PinnedBufferMemoryStream():base(){}
internal PinnedBufferMemoryStream(byte[] array)
{
Debug.Assert(array != null, "Array can't be null");
int len = array.Length;
// Handle 0 length byte arrays specially.
if (len == 0) {
array = new byte[1];
len = 0;
}
_array = array;
_pinningHandle = new GCHandle(array, GCHandleType.Pinned);
// Now the byte[] is pinned for the lifetime of this instance.
// But I also need to get a pointer to that block of memory...
fixed(byte* ptr = &_array[0])
Initialize(ptr, len, len, FileAccess.Read);
}
~PinnedBufferMemoryStream()
{
Dispose(false);
}
protected override void Dispose(bool disposing)
{
if (_isOpen) {
_pinningHandle.Free();
_isOpen = false;
}
#if _DEBUG
// To help track down lifetime issues on checked builds, force
//a full GC here.
if (disposing) {
GC.Collect();
GC.WaitForPendingFinalizers();
}
#endif
base.Dispose(disposing);
}
}
}
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