Cygwin doesn't support IO_REPARSE_TAG_APPEXECLINK

[Brian Inglis]

On 2020-05-23 09:50, Marco Atzeri via Cygwin wrote:
> On 23.05.2020 17:09, Kagami Rosylight via Cygwin wrote:

>> 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

> 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.

I think the general point being made is that /some/ Windows tools can not be run
from Cygwin.
I wonder what happens if the OP runs "cygstart python3.8"?

-- 
Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada

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