Read last position from file, store as current position

def _read_file_and_pos(self):
        """ Read last position from file, store as current position
        """
        try:
            with open(self.pos_storage_filename, 'r+') as f:
                _pos = f.read()
                _logger.debug('Got position "%s" from file %s'
                              % (_pos, self.pos_storage_filename))
                if not _pos:
                    return
                log_file, log_pos = _pos.split(':')
                try:
                    log_file = str(log_file)
                    log_pos = int(log_pos)
                except (ValueError, TypeError) as e:
                    _logger.critical('Can not read position: %s' % e)
                    sys.exit(13)
                self._log_file = log_file
                self._log_pos = log_pos
        except IOError as e:
            _logger.error(e)