System.IO.MemoryMappedFiles.MemoryMappedFile.CreateCore C# (CSharp) Method

        private static SafeMemoryMappedFileHandle CreateCore(
            FileStream fileStream, string mapName, HandleInheritability inheritability,
            MemoryMappedFileAccess access, MemoryMappedFileOptions options, long capacity)
        {
            SafeFileHandle fileHandle = fileStream != null ? fileStream.SafeFileHandle : null;
            Interop.Kernel32.SECURITY_ATTRIBUTES secAttrs = GetSecAttrs(inheritability);


            SafeMemoryMappedFileHandle handle = fileHandle != null ?
                Interop.CreateFileMapping(fileHandle, ref secAttrs, GetPageAccess(access) | (int)options, capacity, mapName) :
                Interop.CreateFileMapping(INVALID_HANDLE_VALUE, ref secAttrs, GetPageAccess(access) | (int)options, capacity, mapName);

            int errorCode = Marshal.GetLastWin32Error();
            if (!handle.IsInvalid)
            {
                if (errorCode == Interop.Errors.ERROR_ALREADY_EXISTS)
                {
                    handle.Dispose();
                    throw Win32Marshal.GetExceptionForWin32Error(errorCode);
                }
            }
            else // handle.IsInvalid
            {
                handle.Dispose();
                throw Win32Marshal.GetExceptionForWin32Error(errorCode);
            }

            return handle;
        }