SafeWaitHandle.cs source code in C# .NET

Source code for the .NET framework in C#

                        
Code:

                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / clr / src / BCL / Microsoft / Win32 / SafeHandles / SafeWaitHandle.cs / 1305376 / SafeWaitHandle.cs
                        

                        
                            // ==++== 
//
//   Copyright (c) Microsoft Corporation.  All rights reserved.
//
// ==--== 
/*============================================================
** 
** Class:  SafeWaitHandle 
**
** 
** A wrapper for Win32 events (mutexes, auto reset events, and
** manual reset events).  Used by WaitHandle.
**
** 
===========================================================*/
 
using System; 
using System.Security;
using System.Security.Permissions; 
using System.Runtime.InteropServices;
using System.Runtime.CompilerServices;
using System.Runtime.ConstrainedExecution;
using System.Runtime.Versioning; 
using Microsoft.Win32;
using System.Threading; 
 
namespace Microsoft.Win32.SafeHandles {
 
    [System.Security.SecurityCritical]  // auto-generated_required
    public sealed class SafeWaitHandle : SafeHandleZeroOrMinusOneIsInvalid
    {
 

    // Special case flags for Mutexes enables workaround for known OS bug at 
        // http://support.microsoft.com/default.aspx?scid=kb;en-us;889318 
        // One machine-wide mutex serializes all OpenMutex and CloseHandle operations.
 
        // bIsMutex: if true, we need to grab machine-wide mutex before doing any Close ops.
        // Initialized to false by the runtime.
        private bool bIsMutex;
 
        // bIsMutex: if true, we need to avoid grabbing the machine-wide mutex before Close ops,
        // since that mutex is, of course, this very handle. 
        // Initialized to false by the runtime. 
        private bool bIsReservedMutex;
 
        // Called by P/Invoke marshaler
        private SafeWaitHandle() : base(true)
        {
        } 

        [ReliabilityContract(Consistency.WillNotCorruptState, Cer.MayFail)] 
        public SafeWaitHandle(IntPtr existingHandle, bool ownsHandle) : base(ownsHandle) 
        {
            SetHandle(existingHandle); 
        }

        [System.Security.SecurityCritical]
        [ResourceExposure(ResourceScope.Machine)] 
        [ResourceConsumption(ResourceScope.Machine)]
        override protected bool ReleaseHandle() 
        { 
#if !FEATURE_CORECLR
            if (!bIsMutex || Environment.HasShutdownStarted) 
                return Win32Native.CloseHandle(handle);

            bool bReturn = false;
            bool bMutexObtained = false; 
            try
            { 
               if (!bIsReservedMutex) 
               {
                   Mutex.AcquireReservedMutex(ref bMutexObtained); 
               }
               bReturn = Win32Native.CloseHandle(handle);
            }
            finally 
            {
                if (bMutexObtained) 
                    Mutex.ReleaseReservedMutex(); 
            }
            return bReturn; 
#else
            return Win32Native.CloseHandle(handle);
#endif
        } 

        internal void SetAsMutex() 
        { 
            bIsMutex = true;
        } 

        [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)]
        internal void SetAsReservedMutex()
        { 
            bIsReservedMutex = true;
        } 
    } 
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.

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