Description

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'

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

1. Safihre commented on Sep 3, 2020

   

   Safihremannequin

   on Sep 3, 2020

   MannequinAuthor

   More actions

   It consistently fails on the first directory in a long-path UNC notation server-folder.

   >>> os.makedirs(r"\\?\UNC\DiskStation\already_exists", exist_ok=True)
   Traceback (most recent call last):
     File "<input>", line 1, in <module>
     File "C:\Users\safihre\AppData\Local\Programs\Python\Python38\lib\os.py", line 213, in makedirs
       makedirs(head, exist_ok=exist_ok)
     File "C:\Users\safihre\AppData\Local\Programs\Python\Python38\lib\os.py", line 213, in makedirs
       makedirs(head, exist_ok=exist_ok)
     File "C:\Users\safihre\AppData\Local\Programs\Python\Python38\lib\os.py", line 223, in makedirs
       mkdir(name, mode)
   OSError: [WinError 123] The filename, directory name, or volume label syntax is incorrect: '\\\\?\\UNC\\'
   
   >>> os.makedirs(r"\\?\UNC\DiskStation\already_exists")
   Traceback (most recent call last):
     File "<input>", line 1, in <module>
     File "C:\Users\safihre\AppData\Local\Programs\Python\Python38\lib\os.py", line 213, in makedirs
       makedirs(head, exist_ok=exist_ok)
     File "C:\Users\safihre\AppData\Local\Programs\Python\Python38\lib\os.py", line 213, in makedirs
       makedirs(head, exist_ok=exist_ok)
     File "C:\Users\safihre\AppData\Local\Programs\Python\Python38\lib\os.py", line 223, in makedirs
       mkdir(name, mode)
   OSError: [WinError 123] The filename, directory name, or volume label syntax is incorrect: '\\\\?\\UNC\\'

   The second level directory is working correctly as expected:

   >> os.makedirs(r"\\?\UNC\DiskStation\already_exists\new")

   >>> 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):

   But:
   >>> head, tail = path.split(r"\\?\UNC\DiskStation\already_exists")
   ('\\\\?\\UNC\\DiskStation', 'already_exists')
   
   >>> os.path.exists(r'\\?\UNC\DiskStation')
   False
   >>> os.path.exists(r'\\DiskStation')
   False

   So it wrongly goes ahead and tries to create \\?\UNC\DiskStation
2. Safihre

   added

   3.8 (EOL)end of lifeend of life

   OS-windows

   type-crashA hard crash of the interpreter, possibly with a core dumpA hard crash of the interpreter, possibly with a core dump

   on Sep 3, 2020
3. Safihre

   changed the title [-]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[/+] on Sep 3, 2020
4. Safihre

   added

   type-crashA hard crash of the interpreter, possibly with a core dumpA hard crash of the interpreter, possibly with a core dump

   on Sep 3, 2020
5. Safihre

   changed the title [-]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[/+] on Sep 3, 2020
6. eryksun commented on Sep 3, 2020

   

   eryksun

   on Sep 3, 2020

   Contributor

   More actions

   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', '').
7. eryksun

   added

   type-bugAn unexpected behavior, bug, or errorAn unexpected behavior, bug, or error

   and removed

   type-crashA hard crash of the interpreter, possibly with a core dumpA hard crash of the interpreter, possibly with a core dump

   on Sep 3, 2020
8. ezio-melotti

   transferred this issue fromon Apr 10, 2022
9. Safihre commented on Jun 11, 2022

   

   Safihre

   on Jun 11, 2022

   Author

   More actions

   @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)
10. iritkatriel

    added

    stdlibStandard Library Python modules in the Lib/ directoryStandard Library Python modules in the Lib/ directory

    on Nov 29, 2023
11. picnixz commented on Dec 3, 2024

    

    picnixz

    on Dec 3, 2024

    Member

    More actions

    @barneygale friendly ping for confirmation (otherwise, we can close this issue)
12. picnixz

    added

    pendingThe issue will be closed if no feedback is providedThe issue will be closed if no feedback is provided

    and removed

    3.8 (EOL)end of lifeend of life

    on Dec 3, 2024
13. serhiy-storchaka

    added this to OS issues 💻on Jul 3, 2026
14. github-project-automation

    moved this to Todo in OS issues 💻on Jul 3, 2026

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