plugin.py

# plugin.py
# The interface for building DNF plugins.
#
# Copyright (C) 2012-2016 Red Hat, Inc.
#
# This copyrighted material is made available to anyone wishing to use,
# modify, copy, or redistribute it subject to the terms and conditions of
# the GNU General Public License v.2, or (at your option) any later version.
# This program is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY expressed or implied, including the implied warranties of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General
# Public License for more details.  You should have received a copy of the
# GNU General Public License along with this program; if not, write to the
# Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
# 02110-1301, USA.  Any Red Hat trademarks that are incorporated in the
# source code or documentation are not subject to the GNU General Public
# License and may only be used or replicated with the express permission of
# Red Hat, Inc.
#

from __future__ import absolute_import
from __future__ import print_function
from __future__ import unicode_literals

import fnmatch
import glob
import importlib
import inspect
import logging
import operator
import os
import rpm
import sys
import traceback

import libdnf
import dnf.logging
import dnf.pycomp
import dnf.util
from dnf.i18n import _

logger = logging.getLogger('dnf')

DYNAMIC_PACKAGE = 'dnf.plugin.dynamic'


class Plugin(object):
    """The base class custom plugins must derive from. #:api"""

    name = '<invalid>'
    config_name = None

    @classmethod
    def read_config(cls, conf):
        # :api
        parser = libdnf.conf.ConfigParser()
        name = cls.config_name if cls.config_name else cls.name
        files = ['%s/%s.conf' % (path, name) for path in conf.pluginconfpath]
        for file in files:
            if os.path.isfile(file):
                try:
                    parser.read(file)
                except Exception as e:
                    raise dnf.exceptions.ConfigError(_("Parsing file failed: %s") % str(e))
        return parser

    def __init__(self, base, cli):
        # :api
        self.base = base
        self.cli = cli

    def pre_config(self):
        # :api
        pass

    def config(self):
        # :api
        pass

    def resolved(self):
        # :api
        pass

    def sack(self):
        # :api
        pass

    def pre_transaction(self):
        # :api
        pass

    def transaction(self):
        # :api
        pass


class Plugins(object):
    def __init__(self):
        self.plugin_cls = []
        self.plugins = []

    def __del__(self):
        self._unload()

    def _caller(self, method):
        for plugin in self.plugins:
            try:
                getattr(plugin, method)()
            except dnf.exceptions.Error:
                raise
            except Exception:
                exc_type, exc_value, exc_traceback = sys.exc_info()
                except_list = traceback.format_exception(exc_type, exc_value, exc_traceback)
                logger.critical(''.join(except_list))

    def _check_enabled(self, conf, enable_plugins):
        """Checks whether plugins are enabled or disabled in configuration files
           and removes disabled plugins from list"""
        for plug_cls in self.plugin_cls[:]:
            name = plug_cls.name
            if any(fnmatch.fnmatch(name, pattern) for pattern in enable_plugins):
                continue
            parser = plug_cls.read_config(conf)
            # has it enabled = False?
            disabled = (parser.has_section('main')
                        and parser.has_option('main', 'enabled')
                        and not parser.getboolean('main', 'enabled'))
            if disabled:
                self.plugin_cls.remove(plug_cls)

    def _load(self, conf, skips, enable_plugins):
        """Dynamically load relevant plugin modules."""

        if DYNAMIC_PACKAGE in sys.modules:
            raise RuntimeError("load_plugins() called twice")
        sys.modules[DYNAMIC_PACKAGE] = package = dnf.pycomp.ModuleType(DYNAMIC_PACKAGE)
        package.__path__ = []

        files = _get_plugins_files(conf.pluginpath, skips, enable_plugins)
        _import_modules(package, files)
        self.plugin_cls = _plugin_classes()[:]
        self._check_enabled(conf, enable_plugins)
        if len(self.plugin_cls) > 0:
            names = sorted(plugin.name for plugin in self.plugin_cls)
            logger.debug(_('Loaded plugins: %s'), ', '.join(names))

    def _run_pre_config(self):
        self._caller('pre_config')

    def _run_config(self):
        self._caller('config')

    def _run_init(self, base, cli=None):
        for p_cls in self.plugin_cls:
            plugin = p_cls(base, cli)
            self.plugins.append(plugin)

    def run_sack(self):
        self._caller('sack')

    def run_resolved(self):
        self._caller('resolved')

    def run_pre_transaction(self):
        self._caller('pre_transaction')

    def run_transaction(self):
        self._caller('transaction')

    def _unload(self):
        if DYNAMIC_PACKAGE in sys.modules:
            logger.log(dnf.logging.DDEBUG, 'Plugins were unloaded.')
            del sys.modules[DYNAMIC_PACKAGE]

    def unload_removed_plugins(self, transaction):
        """
        Unload plugins that were removed in the `transaction`.
        """
        if not transaction.remove_set:
            return

        # gather all installed plugins and their files
        plugins = dict()
        for plugin in self.plugins:
            plugins[inspect.getfile(plugin.__class__)] = plugin

        # gather all removed files that are plugin files
        plugin_files = set(plugins.keys())
        erased_plugin_files = set()
        for pkg in transaction.remove_set:
            erased_plugin_files.update(plugin_files.intersection(pkg.files))
        if not erased_plugin_files:
            return

        # check whether removed plugin file is added at the same time (upgrade of a plugin)
        for pkg in transaction.install_set:
            erased_plugin_files.difference_update(pkg._header[rpm.RPMTAG_FILENAMES])

        # unload plugins that were removed in transaction
        for plugin_file in erased_plugin_files:
            self.plugins.remove(plugins[plugin_file])


def _plugin_classes():
    return Plugin.__subclasses__()


def _import_modules(package, py_files):
    for fn in py_files:
        path, module = os.path.split(fn)
        package.__path__.append(path)
        (module, ext) = os.path.splitext(module)
        name = '%s.%s' % (package.__name__, module)
        try:
            module = importlib.import_module(name)
        except Exception as e:
            logger.error(_('Failed loading plugin "%s": %s'), module, e)
            logger.log(dnf.logging.SUBDEBUG, '', exc_info=True)


def _get_plugins_files(paths, disable_plugins, enable_plugins):
    plugins = []
    disable_plugins = set(disable_plugins)
    enable_plugins = set(enable_plugins)
    pattern_enable_found = set()
    pattern_disable_found = set()
    for p in paths:
        for fn in glob.glob('%s/*.py' % p):
            (plugin_name, dummy) = os.path.splitext(os.path.basename(fn))
            matched = True
            enable_pattern_tested = False
            for pattern_skip in disable_plugins:
                if _plugin_name_matches_pattern(plugin_name, pattern_skip):
                    pattern_disable_found.add(pattern_skip)
                    matched = False
                    for pattern_enable in enable_plugins:
                        if _plugin_name_matches_pattern(plugin_name, pattern_enable):
                            matched = True
                            pattern_enable_found.add(pattern_enable)
                    enable_pattern_tested = True
            if not enable_pattern_tested:
                for pattern_enable in enable_plugins:
                    if _plugin_name_matches_pattern(plugin_name, pattern_enable):
                        pattern_enable_found.add(pattern_enable)
            if matched:
                plugins.append(fn)
    enable_not_found = enable_plugins.difference(pattern_enable_found)
    if enable_not_found:
        logger.warning(_("No matches found for the following enable plugin patterns: {}").format(
            ", ".join(sorted(enable_not_found))))
    disable_not_found = disable_plugins.difference(pattern_disable_found)
    if disable_not_found:
        logger.warning(_("No matches found for the following disable plugin patterns: {}").format(
            ", ".join(sorted(disable_not_found))))
    return plugins


def _plugin_name_matches_pattern(plugin_name, pattern):
    """
    Checks plugin name matches the pattern.

    The alternative plugin name using dashes instead of underscores is tried
    in case of original name is not matched.

    (see https://bugzilla.redhat.com/show_bug.cgi?id=1980712)
    """

    try_names = set((plugin_name, plugin_name.replace('_', '-')))
    return any(fnmatch.fnmatch(name, pattern) for name in try_names)


def register_command(command_class):
    # :api
    """A class decorator for automatic command registration."""
    def __init__(self, base, cli):
        if cli:
            cli.register_command(command_class)
    plugin_class = type(str(command_class.__name__ + 'Plugin'),
                        (dnf.Plugin,),
                        {"__init__": __init__,
                         "name": command_class.aliases[0]})
    command_class._plugin = plugin_class
    return command_class