61 lines
1.6 KiB
Python
61 lines
1.6 KiB
Python
|
# Copyright 2004-2005 Elemental Security, Inc. All Rights Reserved.
|
||
|
|
# Licensed to PSF under a Contributor Agreement.
|
||
|
|
|
||
|
|
"""Safely evaluate Python string literals without using eval()."""
|
||
|
|
|
||
|
|
import re
|
||
|
|
|
||
|
|
simple_escapes = {"a": "\a",
|
||
|
|
"b": "\b",
|
||
|
|
"f": "\f",
|
||
|
|
"n": "\n",
|
||
|
|
"r": "\r",
|
||
|
|
"t": "\t",
|
||
|
|
"v": "\v",
|
||
|
|
"'": "'",
|
||
|
|
'"': '"',
|
||
|
|
"\\": "\\"}
|
||
|
|
|
||
|
|
def escape(m):
|
||
|
|
all, tail = m.group(0, 1)
|
||
|
|
assert all.startswith("\\")
|
||
|
|
esc = simple_escapes.get(tail)
|
||
|
|
if esc is not None:
|
||
|
|
return esc
|
||
|
|
if tail.startswith("x"):
|
||
|
|
hexes = tail[1:]
|
||
|
|
if len(hexes) < 2:
|
||
|
|
raise ValueError("invalid hex string escape ('\\%s')" % tail)
|
||
|
|
try:
|
||
|
|
i = int(hexes, 16)
|
||
|
|
except ValueError:
|
||
|
|
raise ValueError("invalid hex string escape ('\\%s')" % tail) from None
|
||
|
|
else:
|
||
|
|
try:
|
||
|
|
i = int(tail, 8)
|
||
|
|
except ValueError:
|
||
|
|
raise ValueError("invalid octal string escape ('\\%s')" % tail) from None
|
||
|
|
return chr(i)
|
||
|
|
|
||
|
|
def evalString(s):
|
||
|
|
assert s.startswith("'") or s.startswith('"'), repr(s[:1])
|
||
|
|
q = s[0]
|
||
|
|
if s[:3] == q*3:
|
||
|
|
q = q*3
|
||
|
|
assert s.endswith(q), repr(s[-len(q):])
|
||
|
|
assert len(s) >= 2*len(q)
|
||
|
|
s = s[len(q):-len(q)]
|
||
|
|
return re.sub(r"\\(\'|\"|\\|[abfnrtv]|x.{0,2}|[0-7]{1,3})", escape, s)
|
||
|
|
|
||
|
|
def test():
|
||
|
|
for i in range(256):
|
||
|
|
c = chr(i)
|
||
|
|
s = repr(c)
|
||
|
|
e = evalString(s)
|
||
|
|
if e != c:
|
||
|
|
print(i, c, s, e)
|
||
|
|
|
||
|
|
|
||
|
|
if __name__ == "__main__":
|
||
|
|
test()
|