Adjust project structure

src/Shared/HandyControl_Shared/Tools/Interop/SafeFileMappingHandle.cs

@@ -0,0 +1,50 @@
+using System;
+using System.Runtime.InteropServices;
+using System.Security;
+using System.Security.Permissions;
+using Microsoft.Win32.SafeHandles;
+
+namespace HandyControl.Tools.Interop
+{
+    internal sealed class SafeFileMappingHandle : SafeHandleZeroOrMinusOneIsInvalid
+    {
+        [SecurityCritical]
+        internal SafeFileMappingHandle(IntPtr handle) : base(false)
+        {
+            SetHandle(handle);
+        }
+
+        [SecurityCritical, SecuritySafeCritical]
+        internal SafeFileMappingHandle() : base(true)
+        {
+        }
+
+        public override bool IsInvalid
+        {
+            [SecurityCritical, SecuritySafeCritical]
+            get => handle == IntPtr.Zero;
+        }
+
+        [SecurityCritical, SecuritySafeCritical]
+        protected override bool ReleaseHandle()
+        {
+            new SecurityPermission(SecurityPermissionFlag.UnmanagedCode).Assert();
+            try
+            {
+                return CloseHandleNoThrow(new HandleRef(null, handle));
+            }
+            finally
+            {
+                CodeAccessPermission.RevertAssert();
+            }
+        }
+
+        [SecurityCritical]
+        public static bool CloseHandleNoThrow(HandleRef handle)
+        {
+            HandleCollector.Remove((IntPtr)handle, CommonHandles.Kernel);
+            var result = UnsafeNativeMethods.IntCloseHandle(handle);
+            return result;
+        }
+    }
+}