Re: sshx protocol from MS Windows occasionally cuts off results in M-x rgrep

[Jim Porter]

I also discovered that `direct-async-process' doesn't fix things: that
setting has no effect for the sshx method! It turns out that, while I
was trying to get `M-x rgrep' to work locally on MS Windows, I added a
bunch of MSYS2 tools to my PATH (I already had them thanks to the MS
Windows version of Git). I wanted to get `find' and `grep', but it
turns out this also came with `ssh', so I was using a different build
of SSH. On the one hand, it works correctly (I can even use the scpx
method on files with spaces![1]); on the other hand, it would be nice
if we could figure out how to get this to work with the
Microsoft-provided version.

This makes me a lot more confident that there's a bug in the native
Win32 version of OpenSSH. I'm not totally sure what to do about it
though. While I always prefer to report bugs so they can get fixed
upstream, it's taken a lot of work to debug this, and there still
isn't enough information that I could forward this on to Microsoft for
them to fix it. Since I (and every other MS Windows system with a Git
installation) have a more-reliable version of ssh already available,
there's an argument that we should just give up on Win32-OpenSSH and
rely on the MSYS2 port instead.

- Jim

[1] This is *without* the fix you merged in
c5f1f9bfa82f07d7e8912fde3e3a6748a093f9d9. I'll test that patch with
Win32-OpenSSH (v7.7 and v8.1) as well as the MSYS2 port when I get the
chance this week.

On Thu, May 6, 2021 at 11:20 AM Jim Porter <jporterbugs@gmail.com> wrote:
>
> On Thu, May 6, 2021 at 9:24 AM Michael Albinus <michael.albinus@gmx.de> wrote:
> >
> > Oh, rgrep is as good as something else to test. After you ran it for the
> > first time, you can place the cursor in the *grep* buffer, and type
> > again and again 'g' (revert-buffer). This re-invokes the async
> > process. I have tested it it this way, w/o pain.
>
> rgrep is pretty easy to test this with, although if this is really a
> Win32-OpenSSH bug, it'll be helpful to have a test case that doesn't
> require someone to install Emacs or check out the Tramp repository. :)
>
> > > However, I *don't* see this issue when I run `M-x shell-command RET
> > > python3 test.py RET'. I always see the full output.
> >
> > This doesn't count. shell-command runs a synchronous process, which is a
> > completely different story. In order to test it asynchronously, you
> > must call async-shell-command.
>
> Ah ha. Using `async-shell-command' (or appending an "&" to my command)
> does show the bug again. That's at least helped me narrow things down
> a bit further, to where Tramp gets involved. I'm sure you've gotten
> well past this point already, but I'm hoping that if I can narrow this
> down enough, I can make a Python script that reproduces the issue
> (assuming it's a Win32-OpenSSH bug). Then I should have something
> simple enough that I can tell Microsoft about it. Hopefully with more
> information, we can work around the problem in Emacs/Tramp too.
>
> - Jim