def _read_string_data(f):
 length = _read_long(f)
 if (length > 0):
  length = _read_long(f)
  string_data = _read_bytes(f, length)
  _align_32(f)
 else:
  string_data = ''
 return string_data

def _read_string_data ( f ) : length = _read_long ( f ) if ( length > 0 ) : length = _read_long ( f ) string_data = _read_bytes ( f , length ) _align_32 ( f ) else : string_data = '' return string_data
read a data string .