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

[Ota, Takaaki]

Thu, 25 Feb 2016 09:08:38 -0800 (Pacific Standard Time): "Ota, Takaaki" 
<Takaaki.Ota@am.sony.com> wrote:

> Thu, 25 Feb 2016 18:47:39 +0200: Eli Zaretskii <eliz@gnu.org> wrote:
> 
> > > Date: Wed, 24 Feb 2016 13:57:49 -0800
> > > CC: <22795@debbugs.gnu.org>
> > > From: "Ota, Takaaki" <Takaaki.Ota@am.sony.com>
> > > 
> > > Wed, 24 Feb 2016 21:09:57 +0200: Eli Zaretskii <eliz@gnu.org> wrote:
> > > 
> > > > > Date: Wed, 24 Feb 2016 08:44:02 -0800
> > > > > From: "Ota, Takaaki" <Takaaki.Ota@am.sony.com>
> > > > > 
> > > > > When a file is read only on w32 platform I used to be able to write a
> > > > > file by toggling the buffer's read-only-mode state and answering yes
> > > > > to this question "File memo is write-protected; try to save anyway?
> > > > > (yes or no)" but now the writing fails by an error message "Opening
> > > > > output file: Permission denied, c:/d/ota/memo"
> > > > 
> > > > I cannot reproduce this, neither with today's emacs-25 nor with the
> > > > last pretest of 25.1.  If I answer yes to that question, the file is
> > > > saved without any errors.
> > > > 
> > > > How did you make the file read-only?  (I used a Windows port of
> > > > 'chmod' and the 'attrib' command.)
> > > 
> > > I used Windows Explorer's GUI to open the file property window and
> > > placed a check on Read-only attribute.  I am using mingw to build the
> > > emacs.  I just tried with 24.5 and it works but not on 25.0.90/91.
> > > They are all build by the same mingw.
> > 
> > This doesn't happen for me even if I use the Explorer.
> > 
> > There's some other factor at work here.  Does this happen with any
> > file, anywhere on your filesystems?  E.g., can you try on a drive
> > other than C: ?
> > 
> > Also, do you, as the user, own the directory where this file lives, or
> > is its owner another user?
> > 
> > And what filesystem is that? NTFS or FAT32?
> > 
> > Finally, does this happen in "emacs -Q", or do you need some
> > customizations for the problem to happen?
> > 
> > Thanks.
> > 
> 
> Yes, I own and have full permission of the directory.  I noticed one
> thing when I tried other than C: drive.  An external USB drive with
> NTFS file system exhibits the same problem as C: drive.  A flash drive
> with FAT32 doesn't show the same problem.  Have you tried with NTFS?
> 
> -Tak

I tried "emacs -Q" (actually "./runemacs -Q") and the result is the
same.  On FAT32 the writing succeeds.  On NTFS the writing fails by
Permission denied error.

-Tak