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# -*- coding: utf-8 -*-
# Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
# See https://llvm.org/LICENSE.txt for license information.
# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
""" 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)]
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