90 lines
2.7 KiB
C#
90 lines
2.7 KiB
C#
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//-----------------------------------------------------------------------------
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// Copyright (c) Microsoft Corporation. All rights reserved.
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//-----------------------------------------------------------------------------
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namespace Microsoft.InfoCards
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{
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using System;
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using System.Runtime.InteropServices;
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using Microsoft.InfoCards.Diagnostics;
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using System.Runtime.CompilerServices;
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using System.Runtime.ConstrainedExecution;
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using System.Security;
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using IDT = Microsoft.InfoCards.Diagnostics.InfoCardTrace;
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//
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// Summary:
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// Provides a wrapper over HGlobal alloc'd memory guaranteeing that the
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// contents will be released in the presence of rude app domain and thread aborts.
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//
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internal class HGlobalSafeHandle : SafeHandle
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{
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public static HGlobalSafeHandle Construct()
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{
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return new HGlobalSafeHandle();
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}
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public static HGlobalSafeHandle Construct(string managedString)
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{
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IDT.DebugAssert(!String.IsNullOrEmpty(managedString), "null string");
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int bytes = (managedString.Length + 1) * 2;
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return new HGlobalSafeHandle(Marshal.StringToHGlobalUni(managedString), bytes);
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}
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public static HGlobalSafeHandle Construct(int bytes)
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{
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IDT.DebugAssert(bytes > 0, "attempt to allocate a handle with <= 0 bytes");
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return new HGlobalSafeHandle(Marshal.AllocHGlobal(bytes), bytes);
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}
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[SuppressUnmanagedCodeSecurity]
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[ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)]
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[DllImport("Kernel32.dll", EntryPoint = "RtlZeroMemory", SetLastError = false)]
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public static extern void ZeroMemory(IntPtr dest, Int32 size);
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//
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// The number of bytes allocated.
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//
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private int m_bytes;
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[ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)]
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private HGlobalSafeHandle(IntPtr toManage, int length)
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: base(IntPtr.Zero, true)
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{
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m_bytes = length;
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SetHandle(toManage);
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}
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private HGlobalSafeHandle() : base(IntPtr.Zero, true) { }
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public override bool IsInvalid
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{
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get
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{
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return (IntPtr.Zero == base.handle);
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}
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}
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//
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// Summary:
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// Zero the string contents and release the handle
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//
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protected override bool ReleaseHandle()
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{
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IDT.DebugAssert(!IsInvalid, "handle is invalid in release handle");
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IDT.DebugAssert(0 != m_bytes, "invalid size");
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ZeroMemory(base.handle, m_bytes);
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Marshal.FreeHGlobal(base.handle);
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return true;
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}
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}
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}
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