| 1 | # -*- coding: utf-8 -*- |
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| 2 | # Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
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| 3 | # See https://llvm.org/LICENSE.txt for license information. |
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| 4 | # SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
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| 5 | """ This module implements basic shell escaping/unescaping methods. """ |
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| 6 | |
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| 7 | import re |
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| 8 | import shlex |
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| 9 | |
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| 10 | __all__ = ['encode', 'decode'] |
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| 11 | |
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| 12 | |
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| 13 | def encode(command): |
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| 14 | """ Takes a command as list and returns a string. """ |
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| 15 | |
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| 16 | def needs_quote(word): |
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| 17 | """ Returns true if arguments needs to be protected by quotes. |
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| 18 | |
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| 19 | Previous implementation was shlex.split method, but that's not good |
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| 20 | for this job. Currently is running through the string with a basic |
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| 21 | state checking. """ |
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| 22 | |
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| 23 | reserved = {' ', '$', '%', '&', '(', ')', '[', ']', '{', '}', '*', '|', |
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| 24 | '<', '>', '@', '?', '!'} |
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| 25 | state = 0 |
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| 26 | for current in word: |
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| 27 | if state == 0 and current in reserved: |
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| 28 | return True |
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| 29 | elif state == 0 and current == '\\': |
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| 30 | state = 1 |
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| 31 | elif state == 1 and current in reserved | {'\\'}: |
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| 32 | state = 0 |
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| 33 | elif state == 0 and current == '"': |
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| 34 | state = 2 |
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| 35 | elif state == 2 and current == '"': |
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| 36 | state = 0 |
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| 37 | elif state == 0 and current == "'": |
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| 38 | state = 3 |
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| 39 | elif state == 3 and current == "'": |
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| 40 | state = 0 |
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| 41 | return state != 0 |
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| 42 | |
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| 43 | def escape(word): |
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| 44 | """ Do protect argument if that's needed. """ |
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| 45 | |
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| 46 | table = {'\\': '\\\\', '"': '\\"'} |
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| 47 | escaped = ''.join([table.get(c, c) for c in word]) |
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| 48 | |
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| 49 | return '"' + escaped + '"' if needs_quote(word) else escaped |
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| 50 | |
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| 51 | return " ".join([escape(arg) for arg in command]) |
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| 52 | |
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| 53 | |
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| 54 | def decode(string): |
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| 55 | """ Takes a command string and returns as a list. """ |
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| 56 | |
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| 57 | def unescape(arg): |
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| 58 | """ Gets rid of the escaping characters. """ |
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| 59 | |
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| 60 | if len(arg) >= 2 and arg[0] == arg[-1] and arg[0] == '"': |
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| 61 | arg = arg[1:-1] |
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| 62 | return re.sub(r'\\(["\\])', r'\1', arg) |
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| 63 | return re.sub(r'\\([\\ $%&\(\)\[\]\{\}\*|<>@?!])', r'\1', arg) |
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| 64 | |
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| 65 | return [unescape(arg) for arg in shlex.split(string)] |
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| 66 | |
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