Get a list of all system files, belonging to the Debian package manager.

def __get_managed_files_dpkg(self):
        '''
        Get a list of all system files, belonging to the Debian package manager.
        '''
        dirs = set()
        links = set()
        files = set()

        for pkg_name in salt.utils.stringutils.to_str(self._syscall("dpkg-query", None, None,
                                                        '-Wf', '${binary:Package}\\n')[0]).split(os.linesep):
            pkg_name = pkg_name.strip()
            if not pkg_name:
                continue
            for resource in salt.utils.stringutils.to_str(self._syscall("dpkg", None, None, '-L', pkg_name)[0]).split(os.linesep):
                resource = resource.strip()
                if not resource or resource in ['/', './', '.']:
                    continue
                if os.path.isdir(resource):
                    dirs.add(resource)
                elif os.path.islink(resource):
                    links.add(resource)
                elif os.path.isfile(resource):
                    files.add(resource)

        return sorted(files), sorted(dirs), sorted(links)