Mbed TLS configuration file manipulation library and tool
This is meant to be a drop-in replacement for config.pl which can additionally be used as a library in a Python script. So far this script supports the commands 'get', 'set' and 'realfull' but not the other built-in configurations.
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Gilles Peskine
Darryl Green
parent
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commit
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1 changed files with 298 additions and 0 deletions
298
scripts/config.py
Executable file
298
scripts/config.py
Executable file
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#!/usr/bin/env python3
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"""Mbed TLS configuration file manipulation library and tool
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Basic usage, to read the Mbed TLS or Mbed Crypto configuration:
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config = ConfigFile()
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if 'MBEDTLS_RSA_C' in config: print('RSA is enabled')
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"""
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## Copyright (C) 2019, ARM Limited, All Rights Reserved
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## SPDX-License-Identifier: Apache-2.0
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##
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## Licensed under the Apache License, Version 2.0 (the "License"); you may
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## not use this file except in compliance with the License.
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## You may obtain a copy of the License at
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##
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## http://www.apache.org/licenses/LICENSE-2.0
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##
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## Unless required by applicable law or agreed to in writing, software
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## distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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## WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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## See the License for the specific language governing permissions and
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## limitations under the License.
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##
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## This file is part of Mbed TLS (https://tls.mbed.org)
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import re
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class Setting:
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"""Representation of one Mbed TLS config.h setting.
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Fields:
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* name: the symbol name ('MBEDTLS_xxx').
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* value: the value of the macro. The empty string for a plain #define
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with no value.
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* active: True if name is defined, False if a #define for name is
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present in config.h but commented out.
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"""
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# pylint: disable=too-few-public-methods
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def __init__(self, active, name, value=''):
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self.active = active
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self.name = name
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self.value = value
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class Config:
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"""Representation of the Mbed TLS configuration.
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In the documentation of this class, a symbol is said to be *active*
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if there is a #define for it that is not commented out, and *known*
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if there is a #define for it whether commented out or not.
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This class supports the following protocols:
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* `name in config` is True if the symbol `name` is set in the
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configuration, False otherwise (whether `name` is known but commented
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out or not known at all).
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* `config[name]` is the value of the macro `name`. If `name` is not
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set, raise `KeyError` (even if a definition for `name` is present
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but commented out).
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* `config[name] = value` sets the value associated to `name`. `name`
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must be known, but does not need to be set. This does not cause
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name to become set.
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"""
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def __init__(self):
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self.settings = {}
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def __contains__(self, name):
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"""True if the given symbol is active (i.e. set).
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False if the given symbol is not set, even if a definition
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is present but commented out.
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"""
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return name in self.settings and self.settings[name].active
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def all(self, *names):
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"""True if all the elements of names are active (i.e. set)."""
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return all(self.__contains__(name) for name in names)
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def any(self, *names):
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"""True if at least one symbol in names are active (i.e. set)."""
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return any(self.__contains__(name) for name in names)
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def known(self, name):
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"""True if a #define for name is present, whether it's commented out or not."""
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return name in self.settings
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def __getitem__(self, name):
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"""Get the value of name, i.e. what the preprocessor symbol expands to.
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If name is not known, raise KeyError. name does not need to be active.
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"""
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return self.settings[name].value
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def get(self, name, default=None):
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"""Get the value of name. If name is inactive (not set), return default.
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If a #define for name is present and not commented out, return
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its expansion, even if this is the empty string.
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If a #define for name is present but commented out, return default.
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"""
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if name in self.settings:
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return self.settings[name].value
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else:
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return default
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def __setitem__(self, name, value):
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"""If name is known, set its value.
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If name is not known, raise KeyError.
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"""
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self.settings[name].value = value
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def set(self, name, value=None):
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"""Set name to the given value and make it active.
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If value is None and name is already known, don't change its value.
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If value is None and name is not known, set its value to the empty
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string.
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"""
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if name in self.settings:
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if value is not None:
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self.settings[name].value = value
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self.settings[name].active = True
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else:
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self.settings[name] = Setting(True, name, value=value)
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def unset(self, name):
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"""Make name unset (inactive).
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name remains known.
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"""
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self.set(name)
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self.settings[name].active = False
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def adapt(self, adapter):
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"""Run adapter on each known symbol and (de)activate it accordingly.
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`adapter` must be a function that returns a boolean. It is called as
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`adapter(name, active)` for each setting, where `active` is `True`
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if `name` is set and `False` if `name` is known but unset. If
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`adapter` returns `True`, then set `name` (i.e. make it active),
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otherwise unset `name` (i.e. make it known but inactive).
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"""
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for setting in self.settings.values():
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setting.active = adapter(setting.name, setting.active)
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def realfull_adapter(_name, _set):
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"""Uncomment everything."""
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return True
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class ConfigFile(Config):
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"""Representation of the Mbed TLS configuration read for a file.
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See the documentation of the `Config` class for methods to query
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and modify the configuration.
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"""
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default_path = 'include/mbedtls/config.h'
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def __init__(self, filename=None):
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"""Read the Mbed TLS configuration file."""
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if filename is None:
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filename = self.default_path
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super().__init__()
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self.filename = filename
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with open(filename) as file:
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self.templates = [self._parse_line(line) for line in file]
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def set(self, name, value=None):
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if name not in self.settings:
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self.templates.append((name, '', '#define ' + name + ' '))
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super().set(name, value)
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_define_line_regexp = (r'(?P<indentation>\s*)' +
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r'(?P<commented_out>(//\s*)?)' +
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r'(?P<define>#\s*define\s+)' +
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r'(?P<name>\w+)' +
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r'(?P<arguments>(?:\((?:\w|\s|,)*\))?)' +
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r'(?P<separator>\s*)' +
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r'(?P<value>.*)')
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def _parse_line(self, line):
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"""Parse a line in config.h and return the corresponding template."""
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line = line.rstrip('\r\n')
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m = re.match(self._define_line_regexp, line)
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if m:
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active = not m.group('commented_out')
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name = m.group('name')
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value = m.group('value')
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template = (name,
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m.group('indentation'),
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m.group('define') + name +
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m.group('arguments') + m.group('separator'))
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self.settings[name] = Setting(active, name, value)
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return template
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else:
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return line
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def _format_template(self, name, indent, middle):
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"""Build a line for config.h for the given setting.
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The line has the form "<indent>#define <name><middle> <value>".
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"""
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setting = self.settings[name]
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return ''.join([indent,
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'' if setting.active else '//',
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middle,
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setting.value]).rstrip()
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def write_to_stream(self, output):
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"""Write the whole configuration to output."""
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for template in self.templates:
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if isinstance(template, str):
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line = template
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else:
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line = self._format_template(*template)
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output.write(line + '\n')
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def write(self, filename=None):
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"""Write the whole configuration to the file it was read from.
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If filename is specified, write to this file instead.
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"""
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if filename is None:
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filename = self.filename
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with open(filename, 'w') as output:
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self.write_to_stream(output)
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if __name__ == '__main__':
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def main():
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"""Command line config.h manipulation tool."""
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parser = argparse.ArgumentParser(description="""
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Mbed TLS and Mbed Crypto configuration file manipulation tool.
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""")
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parser.add_argument('--file', '-f',
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help="""File to read (and modify if requested).
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Default: {}.
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""".format(ConfigFile.default_path))
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parser.add_argument('--force', '-o',
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help="""For the set command, if SYMBOL is not
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present, add a definition for it.""")
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subparsers = parser.add_subparsers(dest='command',
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title='Commands')
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parser_get = subparsers.add_parser('get',
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help="""Find the value of SYMBOL
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and print it. Exit with
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status 0 if a #define for SYMBOL is
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found, 1 otherwise.
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""")
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parser_get.add_argument('symbol', metavar='SYMBOL')
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parser_set = subparsers.add_parser('set',
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help="""Set SYMBOL to VALUE.
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If VALUE is omitted, just uncomment
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the #define for SYMBOL.
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Error out of a line defining
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SYMBOL (commented or not) is not
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found, unless --force is passed.
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""")
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parser_set.add_argument('symbol', metavar='SYMBOL')
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parser_set.add_argument('value', metavar='VALUE', nargs='?')
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parser_unset = subparsers.add_parser('unset',
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help="""Comment out the #define
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for SYMBOL. Do nothing if none
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is present.""")
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parser_unset.add_argument('symbol', metavar='SYMBOL')
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def add_adapter(name, function, description):
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subparser = subparsers.add_parser(name, help=description)
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subparser.set_defaults(adapter=function)
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add_adapter('realfull', realfull_adapter,
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"""Uncomment all #defines. No exceptions.""")
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args = parser.parse_args()
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config = ConfigFile(args.file)
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if args.command == 'get':
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if args.symbol in config:
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value = config[args.symbol]
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if value:
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sys.stdout.write(value + '\n')
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return args.symbol not in config
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elif args.command == 'set':
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if not args.force and args.symbol not in config:
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sys.stderr.write("A #define for the symbol {} "
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"was not found in {}"
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.format(args.symbol, args.file))
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return 1
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config.set(args.symbol, value=args.value)
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elif args.command == 'unset':
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config.unset(args.symbol)
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else:
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config.adapt(args.adapter)
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config.write()
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# Import modules only used by main only if main is defined and called.
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# pylint: disable=wrong-import-position
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import argparse
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import sys
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sys.exit(main())
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