Cygwin doesn't support IO_REPARSE_TAG_APPEXECLINK

[Kagami Rosylight]

From: Marco Atzeri
> `Reply always with mailing list in copy, please
> and bottom posting as standard
>
> On 23.05.2020 18:34, Kagami Rosylight wrote:
> > Hi Marco,
> >
> > >Not clear why you expect that a Windows specific tag as
> > IO_REPARSE_TAG_APPEXECLINK should be supported on a Posix platform ?
> >
> > https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fcygwin.com%2Fgit%2F%3Fp%3Dnewlib-cygwin.git%3Ba%3Dblob%3Bf%3Dwinsup%2Fcygwin%2Fpath.cc%3Bh%3D36aa8278fd8495bdfe5ec82b8c36d7d3d7881ebb%3Bhb%3Drefs%2Fheads%2Fmaster%23l2473&data=02%7C01%7C%7Ca9040b39384d422d0b5808d7ffc595f1%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637259096391494659&sdata=Llf8pBA7JBtDEThlvynB7Di1E71xjJnLVUJsEI1N6u8%3D&reserved=0
> >
> >
> > Because Cygwin already supports common reparse points (such as symlinks)
> > and APPEXECLINK is also a common one used by Microsoft Store. This issue
> > causes some CLI tools depending on MSYS2 (which again on Cygwin) to fail
> > calling system Python executable.
> >
> > > that seems a bit short to help third party in properly using it.
> >
> > Good point, and that’s why I only could provide the prior works.
> > REPARSE_DATA_BUFFER_APPEXECLINK in the PowerShell patch shows how the
> > structure look like, but this definitely needs an official
> > documentation. I don’t think it’s a strict blocker given that there are
> > public working patches, though.
> >
> > -Kagami
> >
> > *From: *Marco Atzeri
> > *Sent: *Saturday, 23 May 2020 5:50 PM
> > *To: *cygwin@cygwin.com , saschanaz@outlook.com
> > *Subject: *Re: Cygwin doesn't support IO_REPARSE_TAG_APPEXECLINK
> >
> > 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://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.microsoft.com%2Fen-us%2Fp%2Fpython-38%2F9mssztt1n39l&data=02%7C01%7C%7Ca9040b39384d422d0b5808d7ffc595f1%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637259096391494659&sdata=tJ4DeDmHrHFYPrXIDzLiXZ6vQivQbZVV703SfOqMT%2BM%3D&reserved=0
> > (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://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fmsys2%2FMSYS2-packages%2Fissues%2F1943&data=02%7C01%7C%7Ca9040b39384d422d0b5808d7ffc595f1%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637259096391494659&sdata=9DVvWYnNcgR26LR7p%2FdX2n7uXI8rnL%2BE1nO7ct9ZBF0%3D&reserved=0)
> > but I think Cygwin is the right place to file this.
> > >
> > > Relevant prior works:
> > >
> > > * Python
> > https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fpython%2Fcpython%2Fcommit%2Fdf2d4a6f3d5da2839c4fc11d31511c8e028daf2c&data=02%7C01%7C%7Ca9040b39384d422d0b5808d7ffc595f1%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637259096391494659&sdata=PHB5ChU1IX4gfc7NF3XMJqghyoVBic4CJ5fDP1W7LAM%3D&reserved=0
> > > * libuv
> > https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Flibuv%2Flibuv%2Fcommit%2Fe7ebae26247d2fee0a04547eb7f9aa8f78d4a642&data=02%7C01%7C%7Ca9040b39384d422d0b5808d7ffc595f1%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637259096391504645&sdata=rA4UuMyybOHo35N6qPF0OYVxFLk0usYuviUH0NjymlU%3D&reserved=0
> > > * PowerShell
> > https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2FPowerShell%2FPowerShell%2Fpull%2F10331&data=02%7C01%7C%7Ca9040b39384d422d0b5808d7ffc595f1%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637259096391504645&sdata=cW19cfgbotWpc1loOfYJHoIIvFh2zdSSPhdbeRnIGnw%3D&reserved=0
> > >
> > > 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://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdocs.microsoft.com%2Fen-us%2Fopenspecs%2Fwindows_protocols%2Fms-fscc%2Fc8e77b37-3909-4fe6-a4ea-2b9d423b1ee4&data=02%7C01%7C%7Ca9040b39384d422d0b5808d7ffc595f1%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637259096391504645&sdata=EsAOzkEfbTP3RxYcFVsWuGax0s2dh2nf38%2FhfW%2Frre8%3D&reserved=0
> >
> > that seems a bit short to help third party in properly using it.
> >
> > Regards
> > Marco
> >
> >
> > PS: Python 3.8 is available as Cygwin binary
> >
>
>
> have you tested
>
> "cygstart
> /cygdrive/c/Users/Kagami/AppData/Local/Microsoft/WindowsApps/python3.8.exe
>   " ?
>
>
> Regards
> Marco
>

That works by opening a new window. MSYS2 doesn’t have it by default and I can’t add conditional cygstart calls everywhere just to workaround this issue, though.

Sorry for not keeping the standard style 😬. Which email client do you use to do the "bottom posting"? I copied the whole body from Outlook to my IDE and added ">" to write this, is this what you are doing? It seems there should be more straightforward way as all mailing list users are using this style.