How to use the letsencrypt.errors.CertStorageError function in letsencrypt

def current_version(self, kind):
        """Returns numerical version of the specified item.

        For example, if kind is "chain" and the current chain link
        points to a file named "chain7.pem", returns the integer 7.

        :param str kind: the lineage member item ("cert", "privkey",
            "chain", or "fullchain")

        :returns: the current version of the specified member.
        :rtype: int

        """
        if kind not in ALL_FOUR:
            raise errors.CertStorageError("unknown kind of item")
        pattern = re.compile(r"^{0}([0-9]+)\.pem$".format(kind))
        target = self.current_target(kind)
        if target is None or not os.path.exists(target):
            logger.debug("Current-version target for %s "
                         "does not exist at %s.", kind, target)
            target = ""
        matches = pattern.match(os.path.basename(target))
        if matches:
            return int(matches.groups()[0])
        else:
            logger.debug("No matches for target %s.", kind)
            return None

def current_target(self, kind):
        """Returns full path to which the specified item currently points.

        :param str kind: the lineage member item ("cert", "privkey",
            "chain", or "fullchain")

        :returns: The path to the current version of the specified
            member.
        :rtype: str or None

        """
        if kind not in ALL_FOUR:
            raise errors.CertStorageError("unknown kind of item")
        link = getattr(self, kind)
        if not os.path.exists(link):
            logger.debug("Expected symlink %s for %s does not exist.",
                         link, kind)
            return None
        target = os.readlink(link)
        if not os.path.isabs(target):
            target = os.path.join(os.path.dirname(link), target)
        return os.path.abspath(target)

# self.configuration should be used to read parameters that
        # may have been chosen based on default values from the
        # systemwide renewal configuration; self.configfile should be
        # used to make and save changes.
        try:
            self.configfile = configobj.ConfigObj(config_filename)
        except configobj.ConfigObjError:
            raise errors.CertStorageError(
                "error parsing {0}".format(config_filename))
        # TODO: Do we actually use anything from defaults and do we want to
        #       read further defaults from the systemwide renewal configuration
        #       file at this stage?
        self.configuration = config_with_defaults(self.configfile)

        if not all(x in self.configuration for x in ALL_FOUR):
            raise errors.CertStorageError(
                "renewal config file {0} is missing a required "
                "file reference".format(self.configfile))

        self.cert = self.configuration["cert"]
        self.privkey = self.configuration["privkey"]
        self.chain = self.configuration["chain"]
        self.fullchain = self.configuration["fullchain"]

        self._fix_symlinks()

"""What are the subject names of this certificate?

        (If no version is specified, use the current version.)

        :param int version: the desired version number
        :returns: the subject names
        :rtype: `list` of `str`
        :raises .CertStorageError: if could not find cert file.

        """
        if version is None:
            target = self.current_target("cert")
        else:
            target = self.version("cert", version)
        if target is None:
            raise errors.CertStorageError("could not find cert file")
        with open(target) as f:
            return crypto_util.get_sans_from_cert(f.read())

"""The filename that corresponds to the specified version and kind.

        .. warning:: The specified version may not exist in this
           lineage. There is no guarantee that the file path returned
           by this method actually exists.

        :param str kind: the lineage member item ("cert", "privkey",
            "chain", or "fullchain")
        :param int version: the desired version

        :returns: The path to the specified version of the specified member.
        :rtype: str

        """
        if kind not in ALL_FOUR:
            raise errors.CertStorageError("unknown kind of item")
        where = os.path.dirname(self.current_target(kind))
        return os.path.join(where, "{0}{1}.pem".format(kind, version))

# This attempts to read the renewer config file and augment or replace
        # the renewer defaults with any options contained in that file.  If
        # renewer_config_file is undefined or if the file is nonexistent or
        # empty, this .merge() will have no effect.
        config.merge(configobj.ConfigObj(cli_config.renewer_config_file))

        # Examine the configuration and find the new lineage's name
        for i in (cli_config.renewal_configs_dir, cli_config.archive_dir,
                  cli_config.live_dir):
            if not os.path.exists(i):
                os.makedirs(i, 0700)
                logger.debug("Creating directory %s.", i)
        config_file, config_filename = le_util.unique_lineage_name(
            cli_config.renewal_configs_dir, lineagename)
        if not config_filename.endswith(".conf"):
            raise errors.CertStorageError(
                "renewal config file name must end in .conf")

        # Determine where on disk everything will go
        # lineagename will now potentially be modified based on which
        # renewal configuration file could actually be created
        lineagename = os.path.basename(config_filename)[:-len(".conf")]
        archive = os.path.join(cli_config.archive_dir, lineagename)
        live_dir = os.path.join(cli_config.live_dir, lineagename)
        if os.path.exists(archive):
            raise errors.CertStorageError(
                "archive directory exists for " + lineagename)
        if os.path.exists(live_dir):
            raise errors.CertStorageError(
                "live directory exists for " + lineagename)
        os.mkdir(archive)
        os.mkdir(live_dir)

le_util.make_or_verify_dir(cli_config.work_dir,
                               constants.CONFIG_DIRS_MODE, uid)

    for renewal_file in os.listdir(cli_config.renewal_configs_dir):
        print "Processing", renewal_file
        try:
            # TODO: Before trying to initialize the RenewableCert object,
            #       we could check here whether the combination of the config
            #       and the rc_config together disables all autorenewal and
            #       autodeployment applicable to this cert.  In that case, we
            #       can simply continue and don't need to instantiate a
            #       RenewableCert object for this cert at all, which could
            #       dramatically improve performance for large deployments
            #       where autorenewal is widely turned off.
            cert = storage.RenewableCert(renewal_file, cli_config)
        except errors.CertStorageError:
            # This indicates an invalid renewal configuration file, such
            # as one missing a required parameter (in the future, perhaps
            # also one that is internally inconsistent or is missing a
            # required parameter).  As a TODO, maybe we should warn the
            # user about the existence of an invalid or corrupt renewal
            # config rather than simply ignoring it.
            continue
        if cert.should_autorenew():
            # Note: not cert.current_version() because the basis for
            # the renewal is the latest version, even if it hasn't been
            # deployed yet!
            old_version = cert.latest_common_version()
            renew(cert, old_version)
            notify.notify("Autorenewed a cert!!!", "root", "It worked!")
            # TODO: explain what happened
        if cert.should_autodeploy():

def _update_link_to(self, kind, version):
        """Make the specified item point at the specified version.

        (Note that this method doesn't verify that the specified version
        exists.)

        :param str kind: the lineage member item ("cert", "privkey",
            "chain", or "fullchain")
        :param int version: the desired version

        """
        if kind not in ALL_FOUR:
            raise errors.CertStorageError("unknown kind of item")
        link = getattr(self, kind)
        filename = "{0}{1}.pem".format(kind, version)
        # Relative rather than absolute target directory
        target_directory = os.path.dirname(os.readlink(link))
        # TODO: it could be safer to make the link first under a temporary
        #       filename, then unlink the old link, then rename the new link
        #       to the old link; this ensures that this process is able to
        #       create symlinks.
        # TODO: we might also want to check consistency of related links
        #       for the other corresponding items
        os.unlink(link)
        os.symlink(os.path.join(target_directory, filename), link)

cli_config.renewal_configs_dir, lineagename)
        if not config_filename.endswith(".conf"):
            raise errors.CertStorageError(
                "renewal config file name must end in .conf")

        # Determine where on disk everything will go
        # lineagename will now potentially be modified based on which
        # renewal configuration file could actually be created
        lineagename = os.path.basename(config_filename)[:-len(".conf")]
        archive = os.path.join(cli_config.archive_dir, lineagename)
        live_dir = os.path.join(cli_config.live_dir, lineagename)
        if os.path.exists(archive):
            raise errors.CertStorageError(
                "archive directory exists for " + lineagename)
        if os.path.exists(live_dir):
            raise errors.CertStorageError(
                "live directory exists for " + lineagename)
        os.mkdir(archive)
        os.mkdir(live_dir)
        logger.debug("Archive directory %s and live "
                     "directory %s created.", archive, live_dir)
        relative_archive = os.path.join("..", "..", "archive", lineagename)

        # Put the data into the appropriate files on disk
        target = dict([(kind, os.path.join(live_dir, kind + ".pem"))
                       for kind in ALL_FOUR])
        for kind in ALL_FOUR:
            os.symlink(os.path.join(relative_archive, kind + "1.pem"),
                       target[kind])
        with open(target["cert"], "w") as f:
            logger.debug("Writing certificate to %s.", target["cert"])
            f.write(cert)