'Read length bytes from the main log starting at offset
@param int offset         offset to start reading from.
@param int length         number of bytes to read from the log.
@return string result     Bytes of log'

def readLog(self, offset, length):

    self._update('readLog')
    logfile = self.supervisord.options.logfile
    if ((logfile is None) or (not os.path.exists(logfile))):
        raise RPCError(Faults.NO_FILE, logfile)
    try:
        return as_string(readFile(logfile, int(offset), int(length)))
    except ValueError as inst:
        why = inst.args[0]
        raise RPCError(getattr(Faults, why))
