This method fails with an error when it finds a character or block device (like those found in /dev on macOS). However, in the same machine, with the same Python version, the alternative os.walk() performs basically the same job with no errors. I am not sure if that error is the expected behaviour, but I wasn't able to find a clear explanation in the docs. Anyway, it seems to me, as a user, that the os.walk() error-less behaviour is more desirable.

$ python3
Python 3.7.0b4 (v3.7.0b4:eb96c37699, May  2 2018, 04:13:13) 
[Clang 6.0 (clang-600.0.57)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import os
>>> from pathlib import Path
>>> [f for f in Path(os.path.expanduser('/dev')).rglob("*") if f.is_file()]
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 1, in <listcomp>
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/pathlib.py", line 1344, in is_file
    return S_ISREG(self.stat().st_mode)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/pathlib.py", line 1140, in stat
    return self._accessor.stat(self)
OSError: [Errno 9] Bad file descriptor: '/dev/fd/3'
>>> 

This is fairly odd behaviour of macOS, the same error can be seen from a bash session:

$ stat /dev/fd/3
stat: /dev/fd/3: stat: Bad file descriptor

The reason os.walk() works while the Path().is_file doesn't is that os.walk() explicitly guards against OSError exceptions raised by os.stat().

Looking at the documentation this could be seen as a bug in macOS, as the manual page for stat(2) doesn't mention EBADF as a valid error for this system call.

I'm not sure at this point if we should add a workaround for this. An actual patch would be easy enough, "just" add EBADF to the list of ignored errno values in the implementation of is_file (and related method) in pathlib.py

I tried to fix this issue and I found this should be related to os.stat() in os.py. But I can't find the os.stat() API in the file, any ideas?

Os.stat is defined in C code, in particular in Modules/posixmodule.c.

Op 20 jul. 2018 om 10:44 heeft Windson Yang <report@bugs.python.org> het volgende geschreven:

Windson Yang <wiwindson@gmail.com> added the comment:

I tried to fix this issue and I found this should be related to os.stat() in os.py. But I can't find the os.stat() API in the file, any ideas?

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nosy: +Windson Yang

---

Python tracker <report@bugs.python.org>
<https://bugs.python.org/issue33635\>

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New changeset 216b745 by Steve Dower (Przemysław Spodymek) in branch 'master':
bpo-33635: Handling Bad file descriptor in Path.is_file and related. (GH-8542)
216b745

New changeset 2cf3316 by Miss Islington (bot) in branch '3.7':
bpo-33635: Handling Bad file descriptor in Path.is_file and related. (GH-8542)
2cf3316