python - 如何取消转义系统名称？

Question

Systemd 以这种方式记录了其在单元名称中转义非字母数字字符的主要规则:

any "/" character is replaced by "-", and all other characters which are not ASCII alphanumerics or "_" are replaced by C-style "\x2d" escapes.

还有一个转义的例子:

$ systemd-escape -u 'Hall\xc3\xb6chen\x2c\x20Meister'Hallöchen, Meister

(More info in the docs here and here)

Let's ignore the trivial replacement "/" -> "-". I'm trying to unescape systemd names in Python (without 3rd party libraries). Many solutions I tried did not work, they converted the two bytes UTF-8 "ö" to two characters.

Finally this seems to produce the correct answer:

>>> esc=r'Hall\xc3\xb6chen\x2c\x20Meister'
>>> esc.encode('latin-1').decode('unicode_escape').encode('latin-1').decode('utf-8')
'Hallöchen, Meister'

如您所见:str -> bytes -> str -> bytes -> str。可以以某种方式简化吗？

Answer 1

使用字节字符串 esc = b'...' 代替原始字符串esc = r'...'，如 python3 示例所示:

>>> esc = b'Hall\xc3\xb6chen\x2c\x20Meister'
>>> esc.decode('utf-8')
'Hallöchen, Meister'