Re: Cygwin doesn't support IO_REPARSE_TAG_APPEXECLINK

[Marco Atzeri <marco.atzeri@gmail.com>]

On 23.05.2020 17:09, Kagami Rosylight via Cygwin wrote:
> Hi Cygwin community,
> 
> I found that Cygwin can’t run UWP based CLI tools, as they expose their executables as reparse points with the tag IO_REPARSE_TAG_APPEXECLINK which Cygwin does not support.
> 
> Way to reproduce this issue on Cygwin:
> 
> 1. Install Python from Microsoft Store: https://www.microsoft.com/en-us/p/python-38/9mssztt1n39l (assuming you don’t already have python3.8 on your PATH.)
> 2. Try running `python3.8` on Cygwin. It will say “/cygdrive/c/Users/Kagami/AppData/Local/Microsoft/WindowsApps/python3.8: Permission denied”
> 3. Check it’s real path by `get-childitem -path C:/Users/Kagami/AppData/Local/Microsoft/WindowsApps/python3.8.exe` on PowerShell. It’s `C:\Program Files\WindowsApps\PythonSoftwareFoundation.Python.3.8_3.8.1008.0_x64__qbz5n2kfra8p0\python3.8.exe`.
> 4. Try running python again with that path. This succeeds.
> 
> I posted this issue on MSYS2 GitHub repo (https://github.com/msys2/MSYS2-packages/issues/1943) but I think Cygwin is the right place to file this.
> 
> Relevant prior works:
> 
> * Python https://github.com/python/cpython/commit/df2d4a6f3d5da2839c4fc11d31511c8e028daf2c
> * libuv https://github.com/libuv/libuv/commit/e7ebae26247d2fee0a04547eb7f9aa8f78d4a642
> * PowerShell https://github.com/PowerShell/PowerShell/pull/10331
> 
> Thanks,
> 
> -Kagami
> 

Not clear why you expect that a Windows specific tag as
IO_REPARSE_TAG_APPEXECLINK should be supported on a Posix platform ?

Moreover all the documentation from MS seems

https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-fscc/c8e77b37-3909-4fe6-a4ea-2b9d423b1ee4

that seems a bit short to help third party in properly using it.

Regards
Marco


PS: Python 3.8 is available as Cygwin binary