[Python-Dev] Windows: Remove support of bytes filenames in the os module? (original) (raw)

eryk sun eryksun at gmail.com
Tue Feb 9 08:27:39 EST 2016

On Tue, Feb 9, 2016 at 3:21 AM, Victor Stinner <victor.stinner at gmail.com> wrote:

2016-02-09 1:37 GMT+01:00 eryk sun <eryksun at gmail.com>:

For example, in codepage 932 (Japanese), it's an error if a lead byte (i.e. 0x81-0x9F, 0xE0-0xFC) is followed by a trailing byte with a value less than 0x40 (note that ASCII 0-9 is 0x30-0x39, so this is not uncommon). In this case the ANSI API substitutes the default character for Japanese, '・' (U+30FB, Katakana middle dot).

>>> locale.getpreferredencoding() 'cp932' >>> open(b'\xe05', 'w').close() >>> os.listdir('.') ['・'] >>> os.listdir(b'.') [b'\x81E'] Hum, I'm not sure that I understand your example.

Say I create a sequence of files with the names "file_à[N].txt" encoded in Latin-1, where N is 0-2. They all map to the same file in a Japanese system locale:

>>> open(b'file_\xe00.txt', 'w').close(); os.listdir('.')
['file_・.txt']
>>> open(b'file_\xe01.txt', 'w').close(); os.listdir('.')
['file_・.txt']
>>> open(b'file_\xe02.txt', 'w').close(); os.listdir('.')
['file_・.txt']
>>> os.listdir(b'.')
[b'file_\x81E.txt']

This isn't a problem with a single-byte codepage such as 1251. For example, codepage 1251 doesn't map b"\x98" to any character, but harmlessly maps it to "\x98" (SOS in the C1 Controls block).

Single-byte code pages still have the problem that when a filename is created using the wide-character API, listing it as bytes may use either an approximate mapping (e.g. "à" => "a" in 1251) or the codepage default character (e.g. "\xd7" => "?" in 1251).

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