Path manipulation issue in Python - likely broken API in Wine

[Sebastian M. Ernst]

Hi all,

I am working with CPython on top of Wine 4.14. I know for certain that
some path manipulation logic in Wine is broken but I am having trouble
tracking down the root cause.

I am launching Python like this:

user at comp:/path/other> WINEDEBUG=-all PYTHONHOME="z:\\path\\.to\\target"
wine /path/.to/target/python.exe

Notice that the environment variable PYTHONHOME contains a folder with a
leading dot (`.to`). Python should pick it up and expose it as the path
to its executable - like this:

user at comp:/path/other> WINEDEBUG=-all PYTHONHOME="z:\\path\\.to\\target"
wine /path/.to/target/python.exe -c "import sys; print(sys.executable)"
Z:\pathto\target\python.exe

Notice that `\.` is missing from the path that is being printed.

It gets even weirder if the folder name starts with two leading dots,
i.e. `..to` - like this:

user at comp:/path/other> WINEDEBUG=-all
PYTHONHOME="z:\\path\\..to\\target" wine /path/..to/target/python.exe -c
"import sys; print(sys.executable)"
Z:\to\target\python.exe

Now an even longer segment is missing: `path\..`

I confirmed that the above steps work correctly on Windows 10, so it is
very likely a bug in Wine. I collected all necessary steps required for
reproducing this bug below this email.

The startup code of CPython is somewhat convoluted, which is why I am
having trouble identifying the Wine/Windows API in question. Any help is
greatly appreciated.

Best regards,
Sebastian


---


user at comp:/path/.to/target> wget
https://www.python.org/ftp/python/3.7.4/python-3.7.4-embed-win32.zip 2>
/dev/null
user at comp:/path/.to/target> unzip python-3.7.4-embed-win32.zip >
/dev/null; rm python-3.7.4-embed-win32.zip
user at comp:/path/.to/target> rm python37._pth
user at comp:/path/.to/target> mkdir Lib; mv python37.zip Lib/; cd Lib;
unzip python37.zip > /dev/null; rm python37.zip; cd ..
user at comp:/path/.to/target> cd /path/other/
user at comp:/path/other> WINEDEBUG=-all PYTHONHOME="z:\\path\\.to\\target"
wine /path/.to/target/python.exe
Python 3.7.4 (tags/v3.7.4:e09359112e, Jul  8 2019, 19:29:22) [MSC v.1916
32 bit (Intel)] on win32
Type "help", "copyright", "credits" or "license" for more information.
Traceback (most recent call last):
  File "/etc/pythonstart", line 7, in <module>
    import readline
ModuleNotFoundError: No module named 'readline'
>>> exit()
user at comp:/path/other> WINEDEBUG=-all PYTHONHOME="z:\\path\\.to\\target"
wine /path/.to/target/python.exe -c "import sys; print(sys.executable)"
Z:\pathto\target\python.exe