Source code for volatility3.cli.volargparse

# This file is Copyright 2020 Volatility Foundation and licensed under the Volatility Software License 1.0
# which is available at

import argparse
import gettext
import re
from typing import List, Optional, Sequence, Any, Union

# This effectively overrides/monkeypatches the core argparse module to provide more helpful output around choices
# We shouldn't really steal a private member from argparse, but otherwise we're just duplicating code

# HelpfulSubparserAction gives more information about the possible choices from a subparsed choice
# HelpfulArgParser gives the list of choices when no arguments are provided to a choice option whilst still using a

[docs]class HelpfulSubparserAction(argparse._SubParsersAction): """Class to either select a unique plugin based on a substring, or identify the alternatives.""" def __init__(self, *args, **kwargs) -> None: super().__init__(*args, **kwargs) # We don't want the action self-check to kick in, so we remove the choices list, the check happens in __call__ self.choices = None def __call__( self, parser: argparse.ArgumentParser, namespace: argparse.Namespace, values: Union[str, Sequence[Any], None], option_string: Optional[str] = None, ) -> None: parser_name = "" arg_strings = [] # type: List[str] if values is not None: for value in values: if not parser_name: parser_name = value else: arg_strings += [value] # set the parser name if requested if self.dest != argparse.SUPPRESS: setattr(namespace, self.dest, parser_name) matched_parsers = [ name for name in self._name_parser_map if parser_name in name ] if len(matched_parsers) < 1: msg = f"invalid choice {parser_name} (choose from {', '.join(self._name_parser_map)})" raise argparse.ArgumentError(self, msg) if len(matched_parsers) > 1: msg = f"plugin {parser_name} matches multiple plugins ({', '.join(matched_parsers)})" raise argparse.ArgumentError(self, msg) parser = self._name_parser_map[matched_parsers[0]] setattr(namespace, "plugin", matched_parsers[0]) # parse all the remaining options into the namespace # store any unrecognized options on the object, so that the top # level parser can decide what to do with them # In case this subparser defines new defaults, we parse them # in a new namespace object and then update the original # namespace for the relevant parts. subnamespace, arg_strings = parser.parse_known_args(arg_strings, None) for key, value in vars(subnamespace).items(): setattr(namespace, key, value) if arg_strings: vars(namespace).setdefault(argparse._UNRECOGNIZED_ARGS_ATTR, []) getattr(namespace, argparse._UNRECOGNIZED_ARGS_ATTR).extend(arg_strings)
[docs]class HelpfulArgParser(argparse.ArgumentParser): def _match_argument(self, action, arg_strings_pattern) -> int: # match the pattern for this action to the arg strings nargs_pattern = self._get_nargs_pattern(action) match = re.match(nargs_pattern, arg_strings_pattern) # raise an exception if we weren't able to find a match if match is None: nargs_errors = { None: gettext.gettext("expected one argument"), argparse.OPTIONAL: gettext.gettext("expected at most one argument"), argparse.ONE_OR_MORE: gettext.gettext("expected at least one argument"), } msg = nargs_errors.get(action.nargs) if msg is None: msg = ( gettext.ngettext( "expected %s argument", "expected %s arguments", action.nargs ) % action.nargs ) if action.choices: msg = f"{msg} (from: {', '.join(action.choices)})" raise argparse.ArgumentError(action, msg) # return the number of arguments matched return len(