def _readProcessLog(self, name, offset, length, channel):
        group, process = self._getGroupAndProcess(name)

        logfile = getattr(process.config, '%s_logfile' % channel)

        if logfile is None or not os.path.exists(logfile):
            raise RPCError(Faults.NO_FILE, logfile)

        try:
            return readFile(logfile, int(offset), int(length))
        except ValueError, inst:
            why = inst.args[0]
            raise RPCError(getattr(Faults, why))

    def readLog(self, offset, length):
        """ 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
        """
        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 readFile(logfile, int(offset), int(length))
        except ValueError, inst:
            why = inst.args[0]
            raise RPCError(getattr(Faults, why))