C# 如何判断文件属性（like: readonly)

IniFile ini = new IniFile(Application.StartupPath + "\\CWSDB.ini");

                FileAttributes att = File.GetAttributes(Application.StartupPath + "\\CWSDB.ini");

                if ((att & FileAttributes.ReadOnly) == FileAttributes.ReadOnly)
                {
                    MessageBox.Show(Resources.ResourceManager.GetString("InvlaidFile"), Resources.ResourceManager.GetString("ProduceTitle"), MessageBoxButtons.OK, MessageBoxIcon.Error, MessageBoxDefaultButton.Button1);
                    return;
                }