Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System/compmod/microsoft/win32/safehandles/SafeThreadHandle.cs

@@ -0,0 +1,47 @@
+// ==++==
+// 
+//   Copyright (c) Microsoft Corporation.  All rights reserved.
+// 
+// ==--==
+/*============================================================
+**
+** Class:  SafeThreadHandle 
+**
+**
+** A wrapper for a thread handle
+**
+** 
+===========================================================*/
+
+using System;
+using System.Security;
+using System.Diagnostics;
+using System.Security.Permissions;
+using System.Runtime.InteropServices;
+using System.Runtime.CompilerServices;
+using Microsoft.Win32;
+using Microsoft.Win32.SafeHandles;
+using System.Runtime.ConstrainedExecution;
+
+namespace Microsoft.Win32.SafeHandles {
+    [SuppressUnmanagedCodeSecurityAttribute]
+    internal sealed class SafeThreadHandle : SafeHandleZeroOrMinusOneIsInvalid
+    { 
+        internal SafeThreadHandle() : base(true) {
+        } 
+
+        internal void InitialSetHandle(IntPtr h){
+            Debug.Assert(base.IsInvalid, "Safe handle should only be set once");
+            base.SetHandle(h);
+         }
+        
+        override  protected bool ReleaseHandle() {
+            return SafeNativeMethods.CloseHandle(handle);
+        }
+
+    }
+}
+
+
+
+