python - 如何将具有无效 UTF-8 字符的文件名转换回字节？

Question

如何将 os.listdir 的输出转换为 bytes 列表(来自 Unicode str 列表)？即使文件名是无效的 UTF-8，它也必须工作，例如:

$ locale
LANG=
LANGUAGE=
LC_CTYPE=en_US.UTF-8
LC_NUMERIC="POSIX"
LC_TIME="POSIX"
LC_COLLATE="POSIX"
LC_MONETARY="POSIX"
LC_MESSAGES="POSIX"
LC_PAPER="POSIX"
LC_NAME="POSIX"
LC_ADDRESS="POSIX"
LC_TELEPHONE="POSIX"
LC_MEASUREMENT="POSIX"
LC_IDENTIFICATION="POSIX"
LC_ALL=
$ python3
Python 3.4.0 (default, Apr 11 2014, 13:05:11) 
[GCC 4.8.2] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import os
>>> open(b'\x80', 'w')
<_io.TextIOWrapper name=b'\x80' mode='w' encoding='UTF-8'>
>>> os.listdir('.')
['\udc80']
>>> import sys
>>> [fn.encode(sys.getfilesystemencoding()) for fn in os.listdir('.')]
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 1, in <listcomp>
UnicodeEncodeError: 'utf-8' codec can't encode character '\udc80' in position 0: surrogates not allowed
>>> [... for fn in os.listdir('.')]
[b'\x80']

那么我需要向上面的 ... 写入什么才能使其工作？

请注意，在这种情况下，不能选择重命名文件、使用 Python 2.x 或使用纯 ASCII 文件名。我不是在寻找解决方法，我是在寻找代替 ... 的代码。

Answer 1

使用错误处理器；在这种情况下，surrogateescape 错误处理程序看起来很合适:

Value: 'surrogateescape'
Meaning: On decoding, replace byte with individual surrogate code ranging fromU+DC80toU+DCFF. This code will then be turned back into the same byte when the'surrogateescape'` error handler is used when encoding the data. (See PEP 383 for more.)

os.fsencode() utility function使用后一个选项；当适用于您的操作系统时，它使用代理转义错误处理程序编码为 sys.getfilesystemencoding():

Encode filename to the filesystem encoding with 'surrogateescape' error handler, or 'strict' on Windows; return bytes unchanged.

实际上它只会在文件系统编码为mbcs 时使用'strict'，参见os module source ，一种仅在 Windows 上可用的编解码器。

演示:

>>> import sys
>>> ld = ['\udc80']
>>> [fn.encode(sys.getfilesystemencoding()) for fn in ld]
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 1, in <listcomp>
UnicodeEncodeError: 'utf-8' codec can't encode character '\udc80' in position 0: surrogates not allowed
>>> [fn.encode(sys.getfilesystemencoding(), 'surrogateescape') for fn in ld]
[b'\x80']
>>> import os
>>> [os.fsencode(fn) for fn in ld]
[b'\x80']