shutil.copystat fails with PermissionError in WSL

[peter-schmidbauer]

BPO	38633
Nosy	@pfmoore, @tjguk, @zware, @zooba, @ben-spiller, @peter-schmidbauer

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2019-10-29.14:34:38.648>
labels = ['3.7', '3.8', 'type-bug', 'library', 'OS-windows']
title = 'shutil.copystat fails with PermissionError in WSL'
updated_at = <Date 2022-01-20.01:11:33.016>
user = 'https://github.com/peter-schmidbauer'

bugs.python.org fields:

activity = <Date 2022-01-20.01:11:33.016>
actor = 'sam.park'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)', 'Windows']
creation = <Date 2019-10-29.14:34:38.648>
creator = 'pspeter'
dependencies = []
files = []
hgrepos = []
issue_num = 38633
keywords = []
message_count = 3.0
messages = ['355655', '365377', '410998']
nosy_count = 7.0
nosy_names = ['paul.moore', 'tim.golden', 'zach.ware', 'steve.dower', 'benspiller', 'pspeter', 'sam.park']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue38633'
versions = ['Python 3.6', 'Python 3.7', 'Python 3.8']

Linked PRs

• gh-82814: fix shutil access error on WSL #103790

[peter-schmidbauer]

Using shutil.copystat (and therefore also shutil.copytree) in WSL on any directories from a mounted Windows drive (i.e. /mnt/c/...) raises an shutil.Error "[Errno 13] Permission denied".

It seems to fail when copying the extended filesystem attribute "system.wsl_case_sensitive" using os.setxattr() here:

cpython/Lib/shutil.py

Line 322 in da6ce58

os.setxattr(dst, name, value, follow_symlinks=follow_symlinks)

Note that this only happens when both src and dst are on the mounted drive. If only one is on the drive and the other is e.g. in the home directory /home/username/, it will not raise an error.

Quick way to test:

cd /mnt/c/ && mkdir test1 && mkdir test2 && python -c "import shutil; shutil.copystat('test1', 'test2')"

[ben-spiller]

Looks like on WSL the errno is errno.EACCES rather than EPERM, so we just need to change the shutil._copyxattr error handler to also cope with that error code:

             except OSError as e:
-                 if e.errno not in (errno.EPERM, errno.ENOTSUP, errno.ENODATA):
+                 if e.errno not in (errno.EPERM, errno.ENOTSUP, errno.ENODATA, errno.EACCES):
                     raise

If anyone needs a workaround until this is fixed in shutil itself, you can do it by monkey-patching _copyxattr:

import errno, shutil
# have to monkey patch to work with WSL as workaround for https://bugs.python.org/issue38633
orig_copyxattr = shutil._copyxattr
def patched_copyxattr(src, dst, *, follow_symlinks=True):
	try:
		orig_copyxattr(src, dst, follow_symlinks=follow_symlinks)
	except OSError as ex:
		if ex.errno != errno.EACCES: raise
shutil._copyxattr = patched_copyxattr

[sampark]

FWIW I just ran into this today on Ubuntu 18.04 container on GKE 1.21.5-gke.1302 and on a Ubuntu-with-Docker underlying node (if that's relevant). Applying the monkeypatch solves the issue as well.

[zooba]

This seems like a nice easy contribution opportunity. Given the other errors that are silently handled, also handling EACCES seems fine to me.

[ethanhs]

Looks like this was fixed in #103790 ?