bug#22795: 25.0.91; Can't write read only file on w32

[Ota, Takaaki]

After opening a read only file, execute read-only-mode, modify the
file and try to save the file under emacs 25.0.94 on Linux and Windows
file-ownership-preserved-p returns non nil value on Linux and nil on
Windows.

But I spoke too early about this.  After this, I then compared emacs
25.0.94 and 24.5 on Windows.  On both version
file-ownership-preserved-p returns nil while save succeeds on 24.5 and
25.0.94 fails with "Opening output file: Permission denined," error.

So file-ownership-preserved-p is not the root cause.  I still need to
continue to chase.

-Tak

Sat, 4 Jun 2016 12:01:29 +0300: Eli Zaretskii <eliz@gnu.org> wrote:

> > Date: Wed, 1 Jun 2016 10:22:53 -0700
> > CC: <22795@debbugs.gnu.org>
> > From: "Ota, Takaaki" <Takaaki.Ota@am.sony.com>
> > 
> > I still don't have a conclusion but the root cause seems to be related
> > to file-ownership-preserved-p that has some platform specific
> > implementation.  When I open a read only file on both Linux and
> > windows-nt, Linux returns t while windows-nt returns nil.
> 
> Thanks.  Just to make sure I understand you correctly: which function
> returns nil or t when you open a read-only file?
>