mbedtls/scripts/config.py
Gilles Peskine 39bd5e7f9e 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.
2019-11-13 14:32:04 +00:00

299 lines
12 KiB
Python
Executable File

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