248 lines
7.5 KiB
Python
248 lines
7.5 KiB
Python
#
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# Copyright (C) 2018 Red Hat, Inc.
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#
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# This copyrighted material is made available to anyone wishing to use,
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# modify, copy, or redistribute it subject to the terms and conditions of
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# the GNU General Public License v.2, or (at your option) any later version.
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# This program is distributed in the hope that it will be useful, but WITHOUT
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# ANY WARRANTY expressed or implied, including the implied warranties of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
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# Public License for more details. You should have received a copy of the
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# GNU General Public License along with this program; if not, write to the
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# Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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# 02110-1301, USA. Any Red Hat trademarks that are incorporated in the
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# source code or documentation are not subject to the GNU General Public
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# License and may only be used or replicated with the express permission of
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# Red Hat, Inc.
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#
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# Author(s): Vendula Poncova <vponcova@redhat.com>
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#
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import configparser
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import os
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from abc import ABC
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class ConfigurationError(Exception):
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"""A general configuration error."""
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class ConfigurationFileError(ConfigurationError):
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"""An error in the configuration file."""
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def __init__(self, msg, filename):
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super().__init__(msg)
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self._filename = filename
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def __str__(self):
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return "The following error has occurred while handling the configuration file '{}': " \
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"{}".format(self._filename, super().__str__())
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class ConfigurationDataError(ConfigurationError):
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"""An error in the configuration data."""
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def __init__(self, msg, section, option):
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super().__init__(msg)
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self._section = section
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self._option = option
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def __str__(self):
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return "The following error has occurred while handling the option '{}' in the section " \
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"'{}': {}".format(self._option, self._section, super().__str__())
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def create_parser():
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"""Create a new config parser.
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:return: an instance of ConfigParser
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"""
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return configparser.ConfigParser()
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def read_config(parser, path):
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"""Read a configuration file.
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:param parser: an instance of ConfigParser
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:param path: a path to the file
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:raises: ConfigurationFileError
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"""
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try:
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with open(path, "r") as f:
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parser.read_file(f, path)
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except (configparser.Error, OSError) as e:
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raise ConfigurationFileError(str(e), path) from e
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def write_config(parser, path):
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"""Write a configuration file.
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:param parser: an instance of ConfigParser
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:param path: a path to the file
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:raises: ConfigurationFileError
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"""
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try:
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with open(path, "w") as f:
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parser.write(f)
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except (configparser.Error, OSError) as e:
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raise ConfigurationFileError(str(e), path) from e
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def get_option(parser, section_name, option_name, converter=None):
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"""Get a converted value of the option.
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The converter should accept a string and return a converted value.
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For example: int
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:param parser: an instance of ConfigParser
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:param section_name: a section name
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:param option_name: an option name
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:param converter: a function or None
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:return: a converted value
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:raises: ConfigurationAccessError
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"""
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try:
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# Return a string.
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if converter is None:
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return parser.get(section_name, option_name)
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# Return a boolean.
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if converter is bool:
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return parser.getboolean(section_name, option_name)
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# Return a converted value.
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return converter(parser.get(section_name, option_name))
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except (configparser.Error, ValueError) as e:
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raise ConfigurationDataError(str(e), section_name, option_name) from e
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def set_option(parser, section_name, option_name, value):
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"""Set the option.
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:param parser: an instance of ConfigParser
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:param section_name: a section name
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:param option_name: an option name
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:param value: an option value
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:raises: ConfigurationAccessError
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"""
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try:
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# Make sure that the section and option exists.
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parser.get(section_name, option_name)
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# Set the option to the string representation of the value.
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parser[section_name][option_name] = str(value)
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except (configparser.Error, ValueError) as e:
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raise ConfigurationDataError(str(e), section_name, option_name) from e
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class Section(ABC):
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"""A base class for representation of a configuration section."""
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def __init__(self, section_name, parser):
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self._section_name = section_name
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self._parser = parser
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def _has_option(self, option_name):
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"""Is the specified option defined?.
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:param option_name: an option name
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:return: True or False
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"""
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return self._parser.has_option(self._section_name, option_name)
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def _get_option(self, option_name, converter=None):
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"""Get a converted value of the option.
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:param option_name: an option name
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:param converter: a function or None
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:return: a converted value
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"""
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return get_option(self._parser, self._section_name, option_name, converter)
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def _set_option(self, option_name, value):
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"""Set the option.
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:param option_name: an option name
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:param value: an option value
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"""
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set_option(self._parser, self._section_name, option_name, value)
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class Configuration(object):
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"""A base class for representation of a configuration handler."""
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def __init__(self):
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"""Initialize the configuration."""
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self._sources = []
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self._parser = create_parser()
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def get_parser(self):
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"""Get the configuration parser.
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:return: instance of the ConfigParser
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"""
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return self._parser
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def get_sources(self):
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"""Get the configuration sources.
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:return: a list of file names
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"""
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return self._sources
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def read(self, path):
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"""Read a configuration file.
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:param path: a path to the file
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"""
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read_config(self._parser, path)
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self._sources.append(path)
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def read_from_directory(self, path):
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"""Read all configuration files in a directory
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Find and read all *.conf files sorted by their name.
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:return: a path to the directory
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"""
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for filename in sorted(os.listdir(path)):
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if not filename.endswith(".conf"):
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continue
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self.read(os.path.join(path, filename))
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def write(self, path):
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"""Write a configuration file.
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:param path: a path to the file
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"""
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write_config(self._parser, path)
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def validate(self):
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"""Validate the configuration."""
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self._validate_members(self)
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def _validate_members(self, obj):
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"""Validate members of the object.
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The main goal of this method is to check if all sections
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are accessible and all options readable and convertible.
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The implementation actually tries to access all public
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members of the given object and its sections.
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"""
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for member_name in dir(obj):
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# Skip private members.
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if member_name.startswith("_"):
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continue
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# Try to get the value of the member.
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value = getattr(obj, member_name)
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# Validate the sections of the configuration object.
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if isinstance(obj, Configuration) and isinstance(value, Section):
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self._validate_members(value)
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