70 lines
2.8 KiB
C#
70 lines
2.8 KiB
C#
//------------------------------------------------------------------------------
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// <copyright file="PinnedArraySegment.cs" company="Microsoft">
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// Copyright (c) Microsoft Corporation. All rights reserved.
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// </copyright>
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//------------------------------------------------------------------------------
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namespace System.Web.Util {
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using System;
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using System.Diagnostics.CodeAnalysis;
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using System.Runtime.InteropServices;
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using System.Security.Permissions;
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// Utility class for pinning an ArraySegment<T> so that it can be passed to unmanaged code.
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//
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// This type is not thread safe.
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[SecurityPermission(SecurityAction.LinkDemand, UnmanagedCode = true)]
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internal sealed class PinnedArraySegment<T> : IDisposable {
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private int _count;
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private GCHandle _gcHandle;
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[SuppressMessage("Microsoft.Reliability", "CA2006:UseSafeHandleToEncapsulateNativeResources", Justification = @"This is a memory pointer, not a handle. The handle is in the _gcHandle field, and its lifetime is controlled by the caller.")]
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private IntPtr _pointer;
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internal unsafe PinnedArraySegment(ArraySegment<T> segment) {
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// Structs - like ArraySegment<T> - can be "torn" by malicious users trying to take
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// advantage of race conditions that occur as a result of their copy-by-value semantics.
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// Since we'll pass the ArraySegment<T> to unmanaged code, we need to perform validation
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// to make sure that this hasn't happened. The ArraySegment<T> constructor can be used
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// to perform this validation. (MSRC 10170)
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segment = new ArraySegment<T>(segment.Array, segment.Offset, segment.Count);
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_gcHandle = GCHandle.Alloc(segment.Array, GCHandleType.Pinned); // pin the array so that unmanaged code can access it
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_pointer = Marshal.UnsafeAddrOfPinnedArrayElement(segment.Array, segment.Offset);
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_count = segment.Count;
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}
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public int Count {
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get {
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ThrowIfDisposed();
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return _count;
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}
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}
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public IntPtr Pointer {
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get {
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ThrowIfDisposed();
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return _pointer;
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}
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}
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[SuppressMessage("Microsoft.Usage", "CA2216:DisposableTypesShouldDeclareFinalizer", Justification = @"We don't own native resources.")]
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public void Dispose() {
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if (_pointer != IntPtr.Zero) {
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// only free the GCHandle once
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_pointer = IntPtr.Zero;
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_gcHandle.Free();
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}
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}
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private void ThrowIfDisposed() {
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if (_pointer == IntPtr.Zero) {
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throw new ObjectDisposedException(GetType().FullName);
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}
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}
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}
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}
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