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The Labs \ Source Viewer \ SSCLI \ Microsoft.Win32.SafeHandles \ CriticalHandleZeroOrMinusOneIsInvalid

SSCLI
  1. // ==++==
  2. //
  3. //
  4. // Copyright (c) 2006 Microsoft Corporation. All rights reserved.
  5. //
  6. // The use and distribution terms for this software are contained in the file
  7. // named license.txt, which can be found in the root of this distribution.
  8. // By using this software in any fashion, you are agreeing to be bound by the
  9. // terms of this license.
  10. //
  11. // You must not remove this notice, or any other, from this software.
  12. //
  13. //
  14. // ==--==
  15. //
  16. // Abstract derivations of SafeHandle designed to provide the common
  17. // functionality supporting Win32 handles. More specifically, they describe how
  18. // an invalid handle looks (for instance, some handles use -1 as an invalid
  19. // handle value, others use 0).
  20. //
  21. // Further derivations of these classes can specialise this even further (e.g.
  22. // file or registry handles).
  23. //
  24. //
  26. using System;
  27. using System.Runtime.InteropServices;
  28. using System.Runtime.CompilerServices;
  29. using System.Security.Permissions;
  30. using System.Runtime.ConstrainedExecution;
  32. namespace Microsoft.Win32.SafeHandles
  33. {
  34.     // Class of safe handle which uses 0 or -1 as an invalid handle.
  35.     [SecurityPermission(SecurityAction.InheritanceDemand, UnmanagedCode = true)]
  36.     [SecurityPermission(SecurityAction.LinkDemand, UnmanagedCode = true)]
  37.     public abstract class SafeHandleZeroOrMinusOneIsInvalid : SafeHandle
  38.     {
  39.         [ReliabilityContract(Consistency.WillNotCorruptState, Cer.MayFail)]
  40.         protected SafeHandleZeroOrMinusOneIsInvalid(bool ownsHandle) : base(IntPtr.Zero, ownsHandle)
  41.         {
  42.         }
  43.        
  44.         public override bool IsInvalid {
  45.             get { return handle.IsNull() || handle == new IntPtr(-1); }
  46.         }
  47.     }
  48.    
  49.     // Class of safe handle which uses only -1 as an invalid handle.
  50.     [SecurityPermission(SecurityAction.InheritanceDemand, UnmanagedCode = true)]
  51.     [SecurityPermission(SecurityAction.LinkDemand, UnmanagedCode = true)]
  52.     public abstract class SafeHandleMinusOneIsInvalid : SafeHandle
  53.     {
  54.         [ReliabilityContract(Consistency.WillNotCorruptState, Cer.MayFail)]
  55.         protected SafeHandleMinusOneIsInvalid(bool ownsHandle) : base(new IntPtr(-1), ownsHandle)
  56.         {
  57.         }
  58.        
  59.         public override bool IsInvalid {
  60.             get { return handle == new IntPtr(-1); }
  61.         }
  62.     }
  63.    
  64.     // Class of critical handle which uses 0 or -1 as an invalid handle.
  65.     [SecurityPermission(SecurityAction.InheritanceDemand, UnmanagedCode = true)]
  66.     [SecurityPermission(SecurityAction.LinkDemand, UnmanagedCode = true)]
  67.     public abstract class CriticalHandleZeroOrMinusOneIsInvalid : CriticalHandle
  68.     {
  69.         [ReliabilityContract(Consistency.WillNotCorruptState, Cer.MayFail)]
  70.         protected CriticalHandleZeroOrMinusOneIsInvalid() : base(IntPtr.Zero)
  71.         {
  72.         }
  73.        
  74.         public override bool IsInvalid {
  75.             get { return handle.IsNull() || handle == new IntPtr(-1); }
  76.         }
  77.     }
  78.    
  79.     // Class of critical handle which uses only -1 as an invalid handle.
  80.     [SecurityPermission(SecurityAction.InheritanceDemand, UnmanagedCode = true)]
  81.     [SecurityPermission(SecurityAction.LinkDemand, UnmanagedCode = true)]
  82.     public abstract class CriticalHandleMinusOneIsInvalid : CriticalHandle
  83.     {
  84.         [ReliabilityContract(Consistency.WillNotCorruptState, Cer.MayFail)]
  85.         protected CriticalHandleMinusOneIsInvalid() : base(new IntPtr(-1))
  86.         {
  87.         }
  88.        
  89.         public override bool IsInvalid {
  90.             get { return handle == new IntPtr(-1); }
  91.         }
  92.     }
  93.    
  94. }

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