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//------------------------------------------------------------------------------
// <copyright file="GCUtil.cs" company="Microsoft">
// Copyright (c) Microsoft Corporation. All rights reserved.
// </copyright>
//------------------------------------------------------------------------------
namespace System.Web.Util {
using System;
using System.Runtime.InteropServices;
using System.Security.Permissions;
// Provides helper methods for wrapping managed objects so that they can be passed to and from unmanaged code.
// Unmanaged code can't actually inspect these objects at all since they're just GCHandles. And these handles
// cannot be reused (they're single-shot).
[SecurityPermission(SecurityAction.LinkDemand, UnmanagedCode = true)]
internal static class GCUtil {
public static IntPtr RootObject(object obj) {
return (obj != null)
? (IntPtr)GCHandle.Alloc(obj)
: IntPtr.Zero;
}
public static object UnrootObject(IntPtr pointer) {
if (pointer != IntPtr.Zero) {
GCHandle gcHandle = (GCHandle)pointer;
if (gcHandle.IsAllocated) {
object target = gcHandle.Target;
gcHandle.Free();
return target;
}
}
return null;
}
}
// This wrapper around a managed object is opaque to SizedReference GC handle
// and therefore helps with calculating size of only relevant graph of objects
internal class DisposableGCHandleRef<T> : IDisposable
where T : class, IDisposable {
GCHandle _handle;
[PermissionSet(SecurityAction.Assert, Unrestricted = true)]
public DisposableGCHandleRef(T t) {
Debug.Assert(t != null);
_handle = GCHandle.Alloc(t);
}
public T Target {
[PermissionSet(SecurityAction.Assert, Unrestricted = true)]
get {
Debug.Assert(_handle.IsAllocated);
return (T)_handle.Target;
}
}
[PermissionSet(SecurityAction.Assert, Unrestricted = true)]
public void Dispose() {
Target.Dispose();
Debug.Assert(_handle.IsAllocated);
if (_handle.IsAllocated) {
_handle.Free();
}
}
}
}
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