Re: configure tests for graphics libraries

Re: configure tests for graphics libraries

[Richard Stallman]

    Yes.  One change checks for the necessary version of the jpeg library.
    The other defaults to not using libungif and tells you if it's found a
    copy that may be dangerous and that you have to enable it explicitly,
    knowing you have a suitable version.  (I guess that's subject to
    problems if you run the binary on a system with a different shared
    library, but that's too bad.)

I see.  That sounds like maybe the right thing--people are talking
about doing just that.  I think none of us realized that your patch
did this.  Perhaps everyone else misunderstood the description just as
I did.

    I just saw a suggestion that the existence of the function
    EGifPutExtensionLast will distinguish the newer version of libungif
    from the problematic one, but I can't currently check that.

Can anyone else verify that?

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Re: configure tests for graphics libraries

[Eli Zaretskii]

On Sun, 24 Feb 2002, Richard Stallman wrote:

>     I just saw a suggestion that the existence of the function
>     EGifPutExtensionLast will distinguish the newer version of libungif
>     from the problematic one, but I can't currently check that.
> 
> Can anyone else verify that?

Verified; it's true.  Version 4.1.0 doesn't have this function, while 
v4.1.0b1 does.

So we now have a reliable way of detecting the buggy ungif library, we 
just need to ask the maintainers to never remove that function from the 
library ;-)

Thanks, Dave.

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Re: configure tests for graphics libraries

[Richard Stallman]

Would you like to adapt Dave's configure.in patch to test
EGifPutExtensionLast, and install it?  There is a simple
autoconf macro to do that kind of test, and I think Emacs
already uses it.

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Re: configure tests for graphics libraries

[Eli Zaretskii]

On Tue, 26 Feb 2002, Richard Stallman wrote:

> Would you like to adapt Dave's configure.in patch to test
> EGifPutExtensionLast, and install it?

I'll try.

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Re: configure tests for graphics libraries

[Dave Love]

Richard Stallman <rms@gnu.org> writes:

> Would you like to adapt Dave's configure.in patch to test
> EGifPutExtensionLast, and install it?  There is a simple
> autoconf macro to do that kind of test, and I think Emacs
> already uses it.

It's trivial.  You should include the jpeg test too.

Index: configure.in
===================================================================
RCS file: /cvs/emacs/configure.in,v
retrieving revision 1.267.4.7
diff -u -p -c -r1.267.4.7 configure.in
cvs server: conflicting specifications of output style
*** configure.in	28 Jan 2002 16:37:30 -0000	1.267.4.7
--- configure.in	28 Feb 2002 21:20:54 -0000
*************** if test "${HAVE_X11}" = "yes"; then
*** 1851,1856 ****
--- 1851,1866 ----
  
    if test "${HAVE_JPEG}" = "yes"; then
      AC_DEFINE(HAVE_JPEG)
+     AC_EGREP_CPP(
+ changequote({, })dnl avoid leadingspace on the next line
+ {version= *(6[2-9]|[7-9][0-9])},
+ changequote([, ])dnl
+         [#include <jpeglib.h>
+ 	 version=JPEG_LIB_VERSION
+ ],    
+         AC_DEFINE(HAVE_JPEG),
+         [AC_MSG_WARN([libjpeg found, but not version 6b or later])
+         HAVE_JPEG=no])
    fi
  fi
    
*************** HAVE_GIF=no
*** 1888,1894 ****
  if test "${HAVE_X11}" = "yes"; then
    if test "${with_gif}" != "no"; then
      AC_CHECK_HEADER(gif_lib.h,
!       AC_CHECK_LIB(ungif, DGifOpen, HAVE_GIF=yes))
    fi
  
    if test "${HAVE_GIF}" = "yes"; then
--- 1898,1906 ----
  if test "${HAVE_X11}" = "yes"; then
    if test "${with_gif}" != "no"; then
      AC_CHECK_HEADER(gif_lib.h,
! # EGifPutExtensionLast only exists from version libungif-4.1.0b1.
! # Earlier versions can crash Emacs.
!       AC_CHECK_LIB(ungif, EGifPutExtensionLast, HAVE_GIF=yes))
    fi
  
    if test "${HAVE_GIF}" = "yes"; then

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Re: configure tests for graphics libraries

[Richard Stallman]

Thanks.  I installed both changes.  Now Emacs will refuse to use an
old libungif version that would cause crashes.

ISTR that someone was working on trying to prevent the crashes
using old libungif versions.  If that is successful enough,
maybe it is ok for Emacs to link with old libungif versions now.
Should I remove that change?

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Re: configure tests for graphics libraries

[Pavel Janík]

   From: Richard Stallman <rms@gnu.org>
   Date: Fri, 1 Mar 2002 14:24:10 -0700 (MST)

   > ISTR that someone was working on trying to prevent the crashes
   > using old libungif versions.  If that is successful enough,
   > maybe it is ok for Emacs to link with old libungif versions now.
   > Should I remove that change?

No, I have identified only additional bug in GIF support. This bug is now
fixed in both RC and HEAD. Emacs still can crash with broken libungif and
I think it is too much work to identify the problem in old version of
libungif. I have asked libungif author to release new version with better
version informations.
-- 
Pavel Janík

prom_printf("Detected PenguinPages, getting out of here.\n");
                  -- 2.0.38 arch/sparc/mm/srmmu.c

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Re: configure tests for graphics libraries

[Richard Stallman]

Ok.  It looks like there is nothing more that we need to do about the
GIF problem.


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Re: configure tests for graphics libraries

[Dave Love]

Richard Stallman <rms@gnu.org> writes:

> Ok.  It looks like there is nothing more that we need to do about the
> GIF problem.

I don't understand why you think it's OK by default to link with a
version of a library if it can crash Emacs when (a) it's trivial to
prevent that (b) there's a fix (c) and it's for a politically unsound
format, thus not something anyone should put much effort into.

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Re: configure tests for graphics libraries

[Richard Stallman]

    > Ok.  It looks like there is nothing more that we need to do about the
    > GIF problem.

    I don't understand why you think it's OK by default to link with a
    version of a library if it can crash Emacs when (a) it's trivial to
    prevent that (b) there's a fix

My understanding of the situation is that we have now installed changes
to prevent that.  If you think there is still a problem, would you please
describe the remaining problem instead of attacking me personally?


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Re: configure tests for graphics libraries

[Dave Love]

Richard Stallman <rms@gnu.org> writes:

> My understanding of the situation is that we have now installed
> changes to prevent that.  If you think there is still a problem,
> would you please describe the remaining problem

Pavel did that in the preceding message.

> instead of attacking me personally?

Oh, please.  I've been trying to help you (for years, often under
adverse circumstances and in the face of some fairly galling
comments).  Recently it seems to be nigh impossible.  Not long ago I'd
have just installed the relevant changes, it would have DTRT, you
wouldn't have had to spend time on it, and everyone would have been
happy.

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Re: configure tests for graphics libraries

[Richard Stallman]

    > instead of attacking me personally?

    Oh, please.  I've been trying to help you (for years, often under
    adverse circumstances and in the face of some fairly galling
    comments).

I don't know what the adverse circumstances are, but I have been making
a great effort to be polite to you.  I asked a civil question for
a constructive reason.  I wish you would not attack me for it.


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Re: configure tests for graphics libraries

[Richard Stallman]

    > My understanding of the situation is that we have now installed
    > changes to prevent that.  If you think there is still a problem,
    > would you please describe the remaining problem

    Pavel did that in the preceding message.

Getting 400 messages a day as I do, and dealing with so many issues,
I have trouble keeping track.  Could one of you please tell me
what the remaining problem is?

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Re: configure tests for graphics libraries

[Eli Zaretskii]

On Mon, 18 Mar 2002, Richard Stallman wrote:

> Getting 400 messages a day as I do, and dealing with so many issues,
> I have trouble keeping track.  Could one of you please tell me
> what the remaining problem is?

I don't think there are any remaining problems with this issue, now
that Dave's test is installed.

If Dave is somehow unable to install changes in the CVS, I'm willing to 
try to correct whatever problems which prevent that.  AFAICS on savannah, 
there should be no problems with Dave's write access, but perhaps I'm 
missing something.

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Re: configure tests for graphics libraries

[Dave Love]

Richard Stallman <rms@gnu.org> writes:

>     > My understanding of the situation is that we have now installed
>     > changes to prevent that.  If you think there is still a problem,
>     > would you please describe the remaining problem
> 
>     Pavel did that in the preceding message.
> 
> Getting 400 messages a day as I do, and dealing with so many issues,
> I have trouble keeping track.

Of course.  I've always made significant effort to keep mail off you.
It's bad news you're not shielded from so much noise.

> Could one of you please tell me what the remaining problem is?

This was in the one you replied to, when you said nothing needed to be
done:

  No, I have identified only additional bug in GIF support. This bug
  is now fixed in both RC and HEAD. Emacs still can crash with broken
  libungif and I think it is too much work to identify the problem in
  old version of libungif. I have asked libungif author to release new
  version with better version informations.

Fixing future versions of libungif won't help when building against
current libraries and is unnecessary with the autoconf test.  That,
and the similar jpeg test, didn't get installed for Emacs 21.2, so
people can still build a version using the default configuration which
crashes when they get sent a GIF file by mail.  (I reported the
problem against 21.1 to bug-gnu-emacs; it subsequently got diverted to
emacs-devel.)

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Re: configure tests for graphics libraries

[Dave Love]

Eli Zaretskii <eliz@is.elta.co.il> writes:

> If Dave is somehow unable to install changes in the CVS, I'm willing
> to try to correct whatever problems which prevent that.

As far as I know I can write to CVS.  Latterly when I did, I just got
told off and I can do without the grief.

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Re: configure tests for graphics libraries

[Richard Stallman]

    Fixing future versions of libungif won't help when building against
    current libraries and is unnecessary with the autoconf test.  That,
    and the similar jpeg test, didn't get installed for Emacs 21.2, 

It is installed in HEAD, though, right?

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Re: configure tests for graphics libraries

[Eli Zaretskii]

> Date: Fri, 29 Mar 2002 20:44:04 -0700 (MST)
> From: Richard Stallman <rms@gnu.org>
> 
>     Fixing future versions of libungif won't help when building against
>     current libraries and is unnecessary with the autoconf test.  That,
>     and the similar jpeg test, didn't get installed for Emacs 21.2, 
> 
> It is installed in HEAD, though, right?

Yes, it is.

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