function _assertChannelDir()
    {
        if (!file_exists($this->channelsdir)) {
            if (!$this->hasWriteAccess()) {
                return false;
            }

            require_once 'System.php';
            if (!System::mkdir(array('-p', $this->channelsdir))) {
                return $this->raiseError("could not create directory '{$this->channelsdir}'");
            }
        } elseif (!is_dir($this->channelsdir)) {
            return $this->raiseError("could not create directory '{$this->channelsdir}" .
                "', it already exists and is not a directory");
        }

        if (!file_exists($this->channelsdir . DIRECTORY_SEPARATOR . '.alias')) {
            if (!$this->hasWriteAccess()) {
                return false;
            }

            require_once 'System.php';
            if (!System::mkdir(array('-p', $this->channelsdir . DIRECTORY_SEPARATOR . '.alias'))) {
                return $this->raiseError("could not create directory '{$this->channelsdir}/.alias'");
            }
        } elseif (!is_dir($this->channelsdir . DIRECTORY_SEPARATOR . '.alias')) {
            return $this->raiseError("could not create directory '{$this->channelsdir}" .
                "/.alias', it already exists and is not a directory");
        }

        return true;
    }