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os.makedirs fails on long-path UNC-paths if it is the first sub-folder #85871
Description
| BPO | 41705 |
|---|---|
| Nosy | @pfmoore, @tjguk, @zware, @eryksun, @zooba, @Safihre |
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 2020-09-03.19:28:37.918>
labels = ['type-bug', '3.8', 'OS-windows']
title = 'os.makedirs fails on long-path UNC-paths if it is the first sub-folder'
updated_at = <Date 2020-09-03.22:01:32.759>
user = 'https://github.com/Safihre'bugs.python.org fields:
activity = <Date 2020-09-03.22:01:32.759>
actor = 'eryksun'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Windows']
creation = <Date 2020-09-03.19:28:37.918>
creator = 'Safihre'
dependencies = []
files = []
hgrepos = []
issue_num = 41705
keywords = []
message_count = 2.0
messages = ['376312', '376326']
nosy_count = 6.0
nosy_names = ['paul.moore', 'tim.golden', 'zach.ware', 'eryksun', 'steve.dower', 'Safihre']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue41705'
versions = ['Python 3.8']
Activity
Safihre commentedon Sep 3, 2020
It consistently fails on the first directory in a long-path UNC notation server-folder.
The second level directory is working correctly as expected:
>>> os.makedirs(r"\\?\UNC\DiskStation\already_exists\new") Traceback (most recent call last): File "<input>", line 1, in <module> File "C:\Users\safihre\AppData\Local\Programs\Python\Python38\lib\os.py", line 223, in makedirs mkdir(name, mode) FileExistsError: [WinError 183] Cannot create a file when that file already exists: '\\\\?\\UNC\\DiskStation\\test_get2\\test2'Inspecting the code, I think the problem is in the os.path.exists function that is called from within os.makedirs, the line in os.makedirs says:
if head and tail and not path.exists(head):
So it wrongly goes ahead and tries to create \\?\UNC\DiskStation
[-]os.makedirs fails long-path UNC-paths if it is the first sub-folder[/-][+]os.makedirs fails on long-path UNC-paths if it is the first sub-folder[/+][-]os.makedirs fails long-path UNC-paths if it is the first sub-folder[/-][+]os.makedirs fails on long-path UNC-paths if it is the first sub-folder[/+]eryksun commentedon Sep 3, 2020
This behavior is due to bpo-37609, i.e. ntpath.splitdrive fails for "UNC" device paths.
>>> ntpath.splitdrive('//?/UNC/server/share') ('//?/UNC', '/server/share')The result should be "//?/UNC/server/share". A path on the "UNC" device requires a share component, on which is mounted a local or remote filesystem directory. It's functionally part of the 'drive' path. Using just the root path or a server path on the "UNC" device is malformed in the context of a normal file API open. The former fails as ERROR_INVALID_NAME (123), and the latter fails as ERROR_BAD_PATHNAME (161).
The incorrect splitdrive result in turn makes ntpath.split misbehave:
>>> ntpath.split('//?/UNC/server/share') ('//?/UNC/server', 'share') >>> ntpath.split('//?/UNC/server') ('//?/UNC/', 'server')The correct result should be ('//?/UNC/server/share', '').
Safihre commentedon Jun 11, 2022
@barneygale can you confirm if this is also resolved with your patch? The source of the problem is indicated by @eryksun to be in
splitdrive.#85871 (comment)
picnixz commentedon Dec 3, 2024
@barneygale friendly ping for confirmation (otherwise, we can close this issue)