Win32SafeHandles.cs source code in C# .NET

Source code for the .NET framework in C#

                        
Code:

                         / FX-1434 / FX-1434 / 1.0 / untmp / whidbey / REDBITS / ndp / clr / src / BCL / Microsoft / Win32 / SafeHandles / Win32SafeHandles.cs / 1 / Win32SafeHandles.cs
                        

                        
                            // ==++== 
//
//   Copyright (c) Microsoft Corporation.  All rights reserved.
//
// ==--== 
//
// Abstract derivations of SafeHandle designed to provide the common 
// functionality supporting Win32 handles. More specifically, they describe how 
// an invalid handle looks (for instance, some handles use -1 as an invalid
// handle value, others use 0). 
//
// Further derivations of these classes can specialise this even further (e.g.
// file or registry handles).
// 
//
 
using System; 
using System.Runtime.InteropServices;
using System.Runtime.CompilerServices; 
using System.Security.Permissions;
using System.Runtime.ConstrainedExecution;

namespace Microsoft.Win32.SafeHandles 
{
    // Class of safe handle which uses 0 or -1 as an invalid handle. 
    [SecurityPermission(SecurityAction.InheritanceDemand, UnmanagedCode=true)] 
    [SecurityPermission(SecurityAction.LinkDemand, UnmanagedCode=true)]
    public abstract class SafeHandleZeroOrMinusOneIsInvalid : SafeHandle 
    {
        [ReliabilityContract(Consistency.WillNotCorruptState, Cer.MayFail)]
        protected SafeHandleZeroOrMinusOneIsInvalid(bool ownsHandle) : base(IntPtr.Zero, ownsHandle)
        { 
        }
 
        public override bool IsInvalid { 
            get { return handle.IsNull() || handle == new IntPtr(-1); }
        } 
    }

    // Class of safe handle which uses only -1 as an invalid handle.
    [SecurityPermission(SecurityAction.InheritanceDemand, UnmanagedCode=true)] 
    [SecurityPermission(SecurityAction.LinkDemand, UnmanagedCode=true)]
    public abstract class SafeHandleMinusOneIsInvalid : SafeHandle 
    { 
        [ReliabilityContract(Consistency.WillNotCorruptState, Cer.MayFail)]
        protected SafeHandleMinusOneIsInvalid(bool ownsHandle) : base(new IntPtr(-1), ownsHandle) 
        {
        }

        public override bool IsInvalid { 
            get { return handle == new IntPtr(-1); }
        } 
    } 

    // Class of critical handle which uses 0 or -1 as an invalid handle. 
    [SecurityPermission(SecurityAction.InheritanceDemand, UnmanagedCode=true)]
    [SecurityPermission(SecurityAction.LinkDemand, UnmanagedCode=true)]
    public abstract class CriticalHandleZeroOrMinusOneIsInvalid : CriticalHandle
    { 
        [ReliabilityContract(Consistency.WillNotCorruptState, Cer.MayFail)]
        protected CriticalHandleZeroOrMinusOneIsInvalid() : base(IntPtr.Zero) 
        { 
        }
 
        public override bool IsInvalid {
            get { return handle.IsNull() || handle == new IntPtr(-1); }
        }
    } 

    // Class of critical handle which uses only -1 as an invalid handle. 
    [SecurityPermission(SecurityAction.InheritanceDemand, UnmanagedCode=true)] 
    [SecurityPermission(SecurityAction.LinkDemand, UnmanagedCode=true)]
    public abstract class CriticalHandleMinusOneIsInvalid : CriticalHandle 
    {
        [ReliabilityContract(Consistency.WillNotCorruptState, Cer.MayFail)]
        protected CriticalHandleMinusOneIsInvalid() : base(new IntPtr(-1))
        { 
        }
 
        public override bool IsInvalid { 
            get { return handle == new IntPtr(-1); }
        } 
    }

}

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