os.path.realpath fails with WinError 161

[Spacetown]

BPO	44817
Nosy	@pfmoore, @tjguk, @zware, @eryksun, @zooba, @Spacetown
PRs	bpo-44817: Ignore WinError 161 (ERROR_BAD_PATHNAME) #27574

^{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 2021-08-03.05:24:11.950>
labels = ['type-bug', '3.9', '3.10', '3.11', 'library', 'OS-windows']
title = 'os.path.realpath fails with WinError 161'
updated_at = <Date 2021-08-05.07:29:35.809>
user = 'https://github.com/Spacetown'

bugs.python.org fields:

activity = <Date 2021-08-05.07:29:35.809>
actor = 'Spacetown'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)', 'Windows']
creation = <Date 2021-08-03.05:24:11.950>
creator = 'Spacetown'
dependencies = []
files = []
hgrepos = []
issue_num = 44817
keywords = ['patch']
message_count = 5.0
messages = ['398814', '398835', '398931', '398956', '398972']
nosy_count = 6.0
nosy_names = ['paul.moore', 'tim.golden', 'zach.ware', 'eryksun', 'steve.dower', 'Spacetown']
pr_nums = ['27574']
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue44817'
versions = ['Python 3.9', 'Python 3.10', 'Python 3.11']

[Spacetown]

Using os.path.realpath(...) in the MVFS of Clearcase SCM (virtual file system) in Windows 10 a exception occures:

X:\my_view\tools\python\3_8>python.exe
Python 3.8.5 (tags/v3.8.5:580fbb0, Jul 20 2020, 15:57:54) [MSC v.1924 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import os
>>> os.path.realpath('.')
Traceback (most recent call last):
  File "X:\my_view\tools\python\3_8\lib\ntpath.py", line 647, in realpath
    path = _getfinalpathname(path)
OSError: [WinError 87] Falscher Parameter: 'X:\\my_view\\tools\\python\\3_8\\.'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "X:\my_view\tools\python\3_8\lib\ntpath.py", line 651, in realpath
    path = _getfinalpathname_nonstrict(path)
  File "X:\my_view\tools\python\3_8\lib\ntpath.py", line 601, in _getfinalpathname_nonstrict
    path = _getfinalpathname(path)
FileNotFoundError: [WinError 161] Der angegebene Pfadname ist ungültig: 'X:\\'
>>> 

The error 161 (ERROR_BAD_PATHNAME) should also be ignored in _getfinalpathname_nonstrict.

[eryksun]

It should also ignore ERROR_BAD_NETPATH (53).

[Spacetown]

Updated with ERROR_BAD_NETPATH (53).
What about following errors:

• ERROR_LOCK_VIOLATION (33)
• ERROR_DEV_NOT_EXIST (52)
• ERROR_BAD_NET_RESP (58)
• ERROR_UNEXP_NET_ERR (59)
• ERROR_NETNAME_DELETED (64)
• ERROR_NETWORK_ACCESS_DENIED (65)
• ERROR_BAD_DEV_TYPE (66)

[eryksun]

ERROR_NETWORK_ACCESS_DENIED (65) should probably be added to the ignore list. I don't know whether it occurs in practice, but we have it mapped to EACCES in PC/errmap.h. The common access error is ERROR_ACCESS_DENIED (5), even on a UNC share with restricted access.

Add ERROR_DEV_NOT_EXIST (55) only if you have a case that fails with this error code. It's from the NT status code STATUS_DEVICE_DOES_NOT_EXIST. This might occur when trying to automount a device that's pending removal (see the implementation in ReactOS IopMountVolume [1]), but I can't create this condition. I think a device object would need to be practically stuck in the pending removal state for this to be a practical problem.

ERROR_LOCK_VIOLATION (33) isn't relevant. It's an I/O access error for a locked range of a file. realpath() doesn't read or write file data.

For the others, I'd wait for an issue to be reported.

---

[1] https://github.com/reactos/reactos/blob/master/ntoskrnl/io/iomgr/volume.c#L457

[Spacetown]

Done.