w32-find-bdf-fonts does not close file handles of files examined

w32-find-bdf-fonts does not close file handles of files examined

[Michael Schierl]

Please write in English if possible, because the Emacs maintainers
usually do not have translators to read other languages for them.

Your bug report will be posted to the bug-gnu-emacs@gnu.org mailing list,
and to the gnu.emacs.bug news group.

Please describe exactly what actions triggered the bug
and the precise symptoms of the bug:


Start with emacs -Q and run this code:

(let* ((tmpdir (make-temp-file "bugdir-" t))
       (tmpfile (expand-file-name "dummy.bdf" tmpdir)))
  (with-current-buffer (find-file-noselect tmpfile)
    (insert "STARTFONT 2.1\n")
    (save-buffer 0))
  (w32-find-bdf-fonts tmpdir)
  (delete-file tmpfile)
  (delete-directory tmpdir))

It will signal an error at delete-file because it cannot delete the
given file. When removing the w32-find-bdf-fonts call, everything works
as expected. This is annoying if you want to test new bdf fonts on
Windows, because if you do not like them you cannot delete them until
Emacs is closed (and Windows will close all file handles). It is okay to
keep the file open while in use, but it should IMHO be closed if not used.


In GNU Emacs 22.1.1 (i386-mingw-nt5.1.2600)
 of 2007-06-02 on RELEASE
Windowing system distributor `Microsoft Corp.', version 5.1.2600
configured using `configure --with-gcc (3.4) --cflags -Ic:/gnuwin32/include'

Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: nil
  value of $LC_CTYPE: nil
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: nil
  value of $LANG: DEU
  locale-coding-system: cp1252
  default-enable-multibyte-characters: t

Major mode: Lisp Interaction

Minor modes in effect:
  encoded-kbd-mode: t
  tooltip-mode: t
  tool-bar-mode: t
  mouse-wheel-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  unify-8859-on-encoding-mode: t
  utf-translate-cjk-mode: t
  auto-compression-mode: t
  line-number-mode: t

Recent input:
M-x r e p o r t - e m a c s - b u g <return>

Recent messages:
("D:\\Progs\\emacs\\bin\\emacs.exe" "-Q")
Loading encoded-kb...done
For information about the GNU Project and its goals, type C-h C-p.
Loading emacsbug...
Loading regexp-opt...done
Loading emacsbug...done

Re: w32-find-bdf-fonts does not close file handles of files examined

[Jason Rumney]

Michael Schierl wrote:
> Start with emacs -Q and run this code:
>
> (let* ((tmpdir (make-temp-file "bugdir-" t))
>        (tmpfile (expand-file-name "dummy.bdf" tmpdir)))
>   (with-current-buffer (find-file-noselect tmpfile)
>     (insert "STARTFONT 2.1\n")
>     (save-buffer 0))
>   (w32-find-bdf-fonts tmpdir)
>   (delete-file tmpfile)
>   (delete-directory tmpdir))
>
> It will signal an error at delete-file because it cannot delete the
> given file.

Thanks for the report. I have fixed this in the Emacs 22 branch now.
Although the file was being closed, it was still mapped into memory, so
the OS was keeping it open.

Re: w32-find-bdf-fonts does not close file handles of files examined

[Eli Zaretskii]

> Date: Wed, 20 Jun 2007 22:29:07 +0100
> From: Jason Rumney <jasonr@gnu.org>
> Cc: bug-gnu-emacs@gnu.org
> 
> Michael Schierl wrote:
> > Start with emacs -Q and run this code:
> >
> > (let* ((tmpdir (make-temp-file "bugdir-" t))
> >        (tmpfile (expand-file-name "dummy.bdf" tmpdir)))
> >   (with-current-buffer (find-file-noselect tmpfile)
> >     (insert "STARTFONT 2.1\n")
> >     (save-buffer 0))
> >   (w32-find-bdf-fonts tmpdir)
> >   (delete-file tmpfile)
> >   (delete-directory tmpdir))
> >
> > It will signal an error at delete-file because it cannot delete the
> > given file.
> 
> Thanks for the report. I have fixed this in the Emacs 22 branch now.
> Although the file was being closed, it was still mapped into memory, so
> the OS was keeping it open.

Btw, why are we using memory-mapped files for this functionality?

Re: w32-find-bdf-fonts does not close file handles of files examined

[Jason Rumney]

Eli Zaretskii wrote:
> Btw, why are we using memory-mapped files for this functionality?
>   

It predates the inclusion of w32bdf.c in Emacs (the implementation is
based on mw32bdf.c from Meadow, a Japanese fork of Emacs 20), but I
think the reason for using memory mapping is that some East Asian fonts
are very large, and ten years ago when this code was written, the
difference between reading a file into memory and mapping it mattered a
lot more. I can see that in this particular function where the file is
closed again immediately, it offers no advantage, and is actually a loss
on Windows 9X, which doesn't support swapping directly from
memory-mapped files, but the new font backend in Emacs 23 will
eventually replace this code anyway, so there is not much point in
making major changes now.

Re: w32-find-bdf-fonts does not close file handles of files examined

[Eli Zaretskii]

> Date: Fri, 22 Jun 2007 14:22:20 +0100
> From: Jason Rumney <jasonr@gnu.org>
> Cc: bug-gnu-emacs@gnu.org
> 
> Eli Zaretskii wrote:
> > Btw, why are we using memory-mapped files for this functionality?
> >   
> 
> It predates the inclusion of w32bdf.c in Emacs (the implementation is
> based on mw32bdf.c from Meadow, a Japanese fork of Emacs 20), but I
> think the reason for using memory mapping is that some East Asian fonts
> are very large, and ten years ago when this code was written, the
> difference between reading a file into memory and mapping it mattered a
> lot more. I can see that in this particular function where the file is
> closed again immediately, it offers no advantage, and is actually a loss
> on Windows 9X, which doesn't support swapping directly from
> memory-mapped files, but the new font backend in Emacs 23 will
> eventually replace this code anyway, so there is not much point in
> making major changes now.

Thanks for the explanation.  I wondered about this precisely because
we close the file immediately.