mirror of
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118 lines
4.9 KiB
Python
118 lines
4.9 KiB
Python
# This file is Copyright 2020 Volatility Foundation and licensed under the Volatility Software License 1.0
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# which is available at https://www.volatilityfoundation.org/license/vsl-v1.0
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#
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import argparse
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import gettext
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import re
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from typing import Optional, Sequence, Any, Union
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# This effectively overrides/monkeypatches the core argparse module to provide more helpful output around choices
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# We shouldn't really steal a private member from argparse, but otherwise we're just duplicating code
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# HelpfulSubparserAction gives more information about the possible choices from a subparsed choice
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# HelpfulArgParser gives the list of choices when no arguments are provided to a choice option whilst still using a
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class HelpfulSubparserAction(argparse._SubParsersAction):
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"""Class to either select a unique plugin based on a substring, or identify
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the alternatives."""
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def __init__(self, *args, **kwargs) -> None:
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super().__init__(*args, **kwargs)
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def __call__(
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self,
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parser: argparse.ArgumentParser,
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namespace: argparse.Namespace,
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values: Union[str, Sequence[Any], None],
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option_string: Optional[str] = None,
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) -> None:
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parser_name = ""
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arg_strings = [] # type: List[str]
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if values is not None:
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for value in values:
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if not parser_name:
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parser_name = value
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else:
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arg_strings += [value]
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# set the parser name if requested
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if self.dest != argparse.SUPPRESS:
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setattr(namespace, self.dest, parser_name)
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matched_parsers = [
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name for name in self._name_parser_map if parser_name in name
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]
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if len(matched_parsers) < 1:
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msg = f"invalid choice {parser_name} (choose from {', '.join(self._name_parser_map)})"
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raise argparse.ArgumentError(self, msg)
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if len(matched_parsers) > 1:
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msg = f"plugin {parser_name} matches multiple plugins ({', '.join(matched_parsers)})"
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raise argparse.ArgumentError(self, msg)
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parser = self._name_parser_map[matched_parsers[0]]
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setattr(namespace, "plugin", matched_parsers[0])
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# parse all the remaining options into the namespace
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# store any unrecognized options on the object, so that the top
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# level parser can decide what to do with them
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# In case this subparser defines new defaults, we parse them
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# in a new namespace object and then update the original
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# namespace for the relevant parts.
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subnamespace, arg_strings = parser.parse_known_args(arg_strings, None)
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for key, value in vars(subnamespace).items():
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setattr(namespace, key, value)
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if arg_strings:
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vars(namespace).setdefault(argparse._UNRECOGNIZED_ARGS_ATTR, [])
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getattr(namespace, argparse._UNRECOGNIZED_ARGS_ATTR).extend(arg_strings)
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class HelpfulArgParser(argparse.ArgumentParser):
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def _match_argument(self, action, arg_strings_pattern) -> int:
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# match the pattern for this action to the arg strings
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nargs_pattern = self._get_nargs_pattern(action)
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match = re.match(nargs_pattern, arg_strings_pattern)
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# raise an exception if we weren't able to find a match
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if match is None:
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nargs_errors = {
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None: gettext.gettext("expected one argument"),
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argparse.OPTIONAL: gettext.gettext("expected at most one argument"),
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argparse.ONE_OR_MORE: gettext.gettext("expected at least one argument"),
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}
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msg = nargs_errors.get(action.nargs)
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if msg is None:
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msg = (
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gettext.ngettext(
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"expected %s argument", "expected %s arguments", action.nargs
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)
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% action.nargs
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)
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if action.choices:
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msg = f"{msg} (from: {', '.join(action.choices)})"
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raise argparse.ArgumentError(action, msg)
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# return the number of arguments matched
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return len(match.group(1))
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def _check_value(self, action: argparse.Action, value: Any) -> None:
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"""This is called to ensure a value is correct/valid
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In normal operation, it would check that a value provided is valid and return None
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If it was not valid, it would throw an ArgumentError
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When people provide a partial plugin name, we want to look for a matching plugin name
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which happens in the HelpfulSubparserAction's __call_method
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To get there without tripping the check_value failure, we have to prevent the exception
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being thrown when the value is a HelpfulSubparserAction. This therefore affects no other
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checks for normal parameters.
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"""
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if not isinstance(action, HelpfulSubparserAction):
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super()._check_value(action, value)
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return None
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