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# -*- coding: utf-8 -*-
# Copyright 2018 The Chromium OS Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
"""Whitelist functions."""
from __future__ import print_function
import os
import glob
import re
# Matching a string of length m in an NFA of size n is O(mn^2), but the
# performance also depends largely on the implementation. It appears to be fast
# enough according to the tests.
#
# The performance bottleneck of this script is readelf. Unless this becomes
# slower than readelf, don't waste time here.
def is_whitelisted(list_name, pattern):
"""Check whether the given pattern is specified in the whitelist.
Args:
list_name: name of the whitelist.
pattern: the target string.
Returns:
True if matched otherwise False.
"""
return pattern and whitelists[list_name].match(pattern)
def prepare_whitelist(patterns):
"""Join and compile the re patterns.
Args:
patterns: regex patterns.
Returns:
A compiled re object.
"""
return re.compile('|'.join(patterns))
def load_whitelists(dirname):
"""Load whitelists under dirname.
A whitelist ends with .whitelist.
Args:
dirname: path to the dir.
Returns:
A dictionary of 'filename' -> whitelist matcher.
"""
wlist = {}
for fn in glob.glob(os.path.join(dirname, '*.whitelist')):
key = os.path.splitext(os.path.basename(fn))[0]
with open(fn, 'r', encoding='utf-8') as f:
patterns = f.read().splitlines()
patterns = [l for l in patterns if l != '']
patterns = [l for l in patterns if l[0] != '#']
wlist[key] = prepare_whitelist(patterns)
return wlist
whitelists = load_whitelists(os.path.dirname(__file__))
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