bug#70415: 30.0.50; [Cygwin] `lock-file' creates a symlink with funny name

[Ken Brown]

On 5/2/2024 10:26 AM, Ken Brown wrote:
> On 5/2/2024 2:21 AM, Eli Zaretskii wrote:
> > > Date: Wed, 1 May 2024 17:20:20 -0400
> > > Cc: yamaoka@jpl.org, 70415@debbugs.gnu.org
> > > From: Ken Brown <kbrown@cornell.edu>
> > >
> > > >       char const *lock_info_fmt = (boot
> > > >                  ? "%s@%s.%"PRIdMAX":%"PRIdMAX
> > > >                  : "%s@%s.%"PRIdMAX);
> > > >       int len = snprintf (lock_info_str, sizeof lock_info_str,
> > > >             lock_info_fmt, user_name, host_name, pid, boot);
> > > >
> > > > get_boot_sec calls get_boot_time, which is a Gnulib function (see
> > > > lib/boot-time.c).  So I guess the key to unlock this puzzle is
> > > > somewhere there.
> > >
> > > I took a quick look at get_boot_time and found a bug, which may explain
> > > why some Cygwin systems behave differently from others.  I've reported
> > > it here:
> > >
> > >     https://lists.gnu.org/archive/html/bug-gnulib/2024-05/msg00008.html
> >
> > Thanks.  This probably explains why the ":-NNNN" part sometimes
> > appears and sometimes doesn't appear in Cygwin builds of Emacs, but
> > AFAIU it does NOT explain why unlinking the symlink (when the file is
> > unlocked) fails when the lock file name includes the ":-NNNN" part.
> > Right?
>
> Yes, that's right.  I still need to look into that.

It turns out that there was a Cygwin bug (already fixed in the Cygwin 
development sources) that affected only version 3.5.3, and Bruno added a 
workaround to Gnulib.  I now see the ":NNNN" part on my system, without 
a minus sign, and the lock file is deleted properly.

Katsumi, can you apply Bruno's two patches and confirm that the bug is 
fixed?

Ken