| # -*- coding: utf-8 -*- |
| # The LLVM Compiler Infrastructure |
| # |
| # This file is distributed under the University of Illinois Open Source |
| # License. See LICENSE.TXT for details. |
| """ This module implements basic shell escaping/unescaping methods. """ |
| |
| import re |
| import shlex |
| |
| __all__ = ['encode', 'decode'] |
| |
| |
| def encode(command): |
| """ Takes a command as list and returns a string. """ |
| |
| def needs_quote(word): |
| """ Returns true if arguments needs to be protected by quotes. |
| |
| Previous implementation was shlex.split method, but that's not good |
| for this job. Currently is running through the string with a basic |
| state checking. """ |
| |
| reserved = {' ', '$', '%', '&', '(', ')', '[', ']', '{', '}', '*', '|', |
| '<', '>', '@', '?', '!'} |
| state = 0 |
| for current in word: |
| if state == 0 and current in reserved: |
| return True |
| elif state == 0 and current == '\\': |
| state = 1 |
| elif state == 1 and current in reserved | {'\\'}: |
| state = 0 |
| elif state == 0 and current == '"': |
| state = 2 |
| elif state == 2 and current == '"': |
| state = 0 |
| elif state == 0 and current == "'": |
| state = 3 |
| elif state == 3 and current == "'": |
| state = 0 |
| return state != 0 |
| |
| def escape(word): |
| """ Do protect argument if that's needed. """ |
| |
| table = {'\\': '\\\\', '"': '\\"'} |
| escaped = ''.join([table.get(c, c) for c in word]) |
| |
| return '"' + escaped + '"' if needs_quote(word) else escaped |
| |
| return " ".join([escape(arg) for arg in command]) |
| |
| |
| def decode(string): |
| """ Takes a command string and returns as a list. """ |
| |
| def unescape(arg): |
| """ Gets rid of the escaping characters. """ |
| |
| if len(arg) >= 2 and arg[0] == arg[-1] and arg[0] == '"': |
| arg = arg[1:-1] |
| return re.sub(r'\\(["\\])', r'\1', arg) |
| return re.sub(r'\\([\\ $%&\(\)\[\]\{\}\*|<>@?!])', r'\1', arg) |
| |
| return [unescape(arg) for arg in shlex.split(string)] |
