core-admin/qubes/tools/__init__.py

#!/usr/bin/python2 -O
# vim: fileencoding=utf-8

#
# The Qubes OS Project, https://www.qubes-os.org/
#
# Copyright (C) 2015  Joanna Rutkowska <joanna@invisiblethingslab.com>
# Copyright (C) 2015  Wojtek Porczyk <woju@invisiblethingslab.com>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty 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.
#

'''Qubes' command line tools
'''

import argparse
import importlib
import logging
import os

import qubes.log


class PropertyAction(argparse.Action):
    '''Action for argument parser that stores a property.'''
    # pylint: disable=redefined-builtin,too-few-public-methods
    def __init__(self,
            option_strings,
            dest,
            metavar='NAME=VALUE',
            required=False,
            help='set property to a value'):
        super(PropertyAction, self).__init__(option_strings, 'properties',
            metavar=metavar, default={}, help=help)

    def __call__(self, parser, namespace, values, option_string=None):
        try:
            prop, value = values.split('=', 1)
        except ValueError:
            parser.error('invalid property token: {!r}'.format(values))

        getattr(namespace, self.dest)[prop] = value


class SinglePropertyAction(argparse.Action):
    '''Action for argument parser that stores a property.'''

    # pylint: disable=redefined-builtin,too-few-public-methods
    def __init__(self,
            option_strings,
            dest,
            metavar='VALUE',
            const=None,
            nargs=None,
            required=False,
            help=None):
        if help is None:
            help = 'set {!r} property to a value'.format(dest)
            if const is not None:
                help += ' {!r}'.format(const)

        if const is not None:
            nargs = 0

        super(SinglePropertyAction, self).__init__(option_strings, 'properties',
            metavar=metavar, help=help, default={}, const=const,
            nargs=nargs)

        self.name = dest


    def __call__(self, parser, namespace, values, option_string=None):
        getattr(namespace, self.dest)[self.name] = values \
            if self.const is None else self.const


class QubesArgumentParser(argparse.ArgumentParser):
    '''Parser preconfigured for use in most of the Qubes command-line tools.

    :param bool want_app: instantiate :py:class:`qubes.Qubes` object
    :param bool want_app_no_instance: don't actually instantiate \
        :py:class:`qubes.Qubes` object, just add argument for custom xml file
    :param bool want_force_root: add ``--force-root`` option
    :param bool want_vm: add ``VMNAME`` as first positional argument
    *kwargs* are passed to :py:class:`argparser.ArgumentParser`.

    Currenty supported options:
        ``--force-root`` (optional)
        ``--qubesxml`` location of :file:`qubes.xml` (help is suppressed)
        ``--verbose`` and ``--quiet``
    '''

    def __init__(self,
            want_app=True,
            want_app_no_instance=False,
            want_force_root=False,
            want_vm=False,
            **kwargs):

        super(QubesArgumentParser, self).__init__(**kwargs)

        self._want_app = want_app
        self._want_app_no_instance = want_app_no_instance
        self._want_force_root = want_force_root
        self._want_vm = want_vm

        if self._want_app:
            self.add_argument('--qubesxml', metavar='FILE',
                action='store', dest='app',
                help=argparse.SUPPRESS)

        self.add_argument('--verbose', '-v',
            action='count',
            help='increase verbosity')

        self.add_argument('--quiet', '-q',
            action='count',
            help='decrease verbosity')

        if self._want_force_root:
            self.add_argument('--force-root',
                action='store_true', default=False,
                help='force to run as root')

        if self._want_vm:
            self.add_argument('vm', metavar='VMNAME',
                action='store',
                help='name of the domain')

        self.set_defaults(verbose=1, quiet=0)


    def parse_args(self, *args, **kwargs):
        namespace = super(QubesArgumentParser, self).parse_args(*args, **kwargs)

        if self._want_app and not self._want_app_no_instance:
            self.set_qubes_verbosity(namespace)
            namespace.app = qubes.Qubes(namespace.app)

            if self._want_vm:
                try:
                    namespace.vm = namespace.app.domains[namespace.vm]
                except KeyError:
                    self.error('no such domain: {!r}'.format(namespace.vm))

        if self._want_force_root:
            self.dont_run_as_root(namespace)

        return namespace


    def error_runtime(self, message):
        '''Runtime error, without showing usage.

        :param str message: message to show
        '''
        self.exit(1, '{}: error: {}\n'.format(self.prog, message))


    def dont_run_as_root(self, namespace):
        '''Prevent running as root.

        :param argparse.Namespace args: if there is ``.force_root`` attribute \
            set to true, run anyway
        '''
        try:
            euid = os.geteuid()
        except AttributeError: # no geteuid(), probably NT
            return

        if euid == 0 and not namespace.force_root:
            self.error_runtime(
                'refusing to run as root; add --force-root to override')


    @staticmethod
    def get_loglevel_from_verbosity(namespace):
        return (namespace.quiet - namespace.verbose) * 10 + logging.WARNING


    @staticmethod
    def set_qubes_verbosity(namespace):
        '''Apply a verbosity setting.

        This is done by configuring global logging.
        :param argparse.Namespace args: args as parsed by parser
        '''

        verbose = namespace.verbose - namespace.quiet

        if verbose >= 2:
            qubes.log.enable_debug()
        elif verbose >= 1:
            qubes.log.enable()


def get_parser_for_command(command):
    '''Get parser for given qvm-tool.

    :param str command: command name
    :rtype: argparse.ArgumentParser
    :raises ImportError: when command's module is not found
    :raises AttributeError: when parser was not found
    '''

    module = importlib.import_module(
        '.' + command.replace('-', '_'), 'qubes.tools')

    try:
        parser = module.parser
    except AttributeError:
        try:
            parser = module.get_parser()
        except AttributeError:
            raise AttributeError('cannot find parser in module')

    return parser