[PATCH v2 0/2] Handle "app execution aliases"

[Johannes Schindelin]

Hi Corinna,

On Tue, 23 Mar 2021, Corinna Vinschen wrote:

> On Mar 22 16:51, Johannes Schindelin via Cygwin-patches wrote:
> > When installing e.g. Python via the Windows Store, it is common that the
> > `python3.exe` entry in the `PATH` is not actually an executable at all,
> > but an "app executaion alias" (i.e. a special class of reparse point).
> >
> > These filesystem entries are presented as 0-size files, but they are not
> > readable, which is why Cygwin has problems to execute them, with the error
> > message "Permission denied".
> >
> > This issue has been reported a couple of times in the Git for Windows and
> > in the MSYS2 project, and even in Cygwin
> > (https://cygwin.com/pipermail/cygwin/2020-May/244969.html, the thread
> > devolved into a discussion about Thunderbird vs Outlook before long,
> > though).
> >
> > The second patch fixes that, and for good measure, the first patch teaches
> > Cygwin to treat these reparse points as symbolic links.
> >
> > Changes since v1:
> >
> > - Introduce and use `struct _REPARSE_APPEXECLINK_BUFFER`.
> >
> > Johannes Schindelin (2):
> >   Treat Windows Store's "app execution aliases" as symbolic links
> >   Allow executing Windows Store's "app execution aliases"
> >
> >  winsup/cygwin/path.cc  | 40 ++++++++++++++++++++++++++++++++++++++++
> >  winsup/cygwin/spawn.cc |  7 +++++++
> >  2 files changed, 47 insertions(+)
>
> I decided to apply this now, while we're still discussing the osf handle
> problem.
>
> Pushed with two fixes.  I prepended "Cygwin:" to the git log subject and
> I patched this compile time problem:
>
>   path.cc: In function ‘int check_reparse_point_target(HANDLE, bool, PREPARSE_DATA_BUFFER, PUNICODE_STRING)’:
>   path.cc:2581:25: error: ‘struct _REPARSE_APPEXECLINK_BUFFER’ has no member named ‘Strings’
>    2581 |       WCHAR *buf = rpl->Strings;
> 	|                         ^~~~~~~

Uh oh. Sorry for the breakage. I thought I had test-compiled it...
Apparently I didn't (or I ignored a warning or something).
>
> I also added this to the release notes.

Thank you!

Ciao,
Johannes