png-mng-implement

[png-mng-implement] png_set_strip_16 unavailable in libpng10 >= 1.0.51

[Paul H. <pa...@ci...>]

Changes to pngconf.h in libpng 1.0.51 include suppressing the 
declaration of PNG_READ_16_TO_8_SUPPORTED if PNG_1_0_X is defined. This 
in turn results in the unavailability of png_set_strip_16 in libpng 
1.0.51 and above. Is this intentional?

One of the results of this (and it's possible that other symbols are 
affected that I haven't come across) is that the ancient gnome-libs 
1.4.2 won't build against libpng10 >= 1.0.51, as per this build log:

http://linux.dell.com/files/fedora/FixBuildRequires/mock-results/x86_64/gnome-libs-1.4.2-15.fc12.src.rpm/result/build.log

Looks like a regression to me, as the same package builds just fine 
against 1.0.50.

Paul.

Re: [png-mng-implement] png_set_strip_16 unavailable in libpng10 >= 1.0.51

[Glenn Randers-P. <gl...@gm...>]

I'll look into it.  I don't recall that change being intentional.

However, libpng-1.0.x are not meant for use in building anything.
They are only supposed to provide a shared library to satisfy old apps
that were linked against libpng-1.0.x years ago.

Glenn

On Thu, Jan 14, 2010 at 8:09 AM, Paul Howarth <pa...@ci...> wrote:

> Changes to pngconf.h in libpng 1.0.51 include suppressing the
> declaration of PNG_READ_16_TO_8_SUPPORTED if PNG_1_0_X is defined. This
> in turn results in the unavailability of png_set_strip_16 in libpng
> 1.0.51 and above. Is this intentional?
>
> One of the results of this (and it's possible that other symbols are
> affected that I haven't come across) is that the ancient gnome-libs
> 1.4.2 won't build against libpng10 >= 1.0.51, as per this build log:
>
>
> http://linux.dell.com/files/fedora/FixBuildRequires/mock-results/x86_64/gnome-libs-1.4.2-15.fc12.src.rpm/result/build.log
>
> Looks like a regression to me, as the same package builds just fine
> against 1.0.50.
>
> Paul.
>
>
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Re: [png-mng-implement] png_set_strip_16 unavailable in libpng10 >= 1.0.51

[Paul H. <pa...@ci...>]

On 14/01/10 14:41, Glenn Randers-Pehrson wrote:
> I'll look into it.  I don't recall that change being intentional.
>
> However, libpng-1.0.x are not meant for use in building anything.
> They are only supposed to provide a shared library to satisfy old apps
> that were linked against libpng-1.0.x years ago.

I understand that, but periodically it's necessary to rebuild legacy 
apps to fix security issues etc. and those builds will change as little 
as possible to avoid unintended regressions, hence not updating to 
current libpng versions.

In order to ensure that such rebuilds are as painless as possible, 
Fedora rebuilds everything in the distribution from source from time to 
time to ensure that everything is still buildable, and it was one of 
those test builds that uncovered this issue.

Cheers, Paul.

Re: [png-mng-implement] png_set_strip_16 unavailable in libpng10 >= 1.0.51

[Glenn Randers-P. <gl...@gm...>]

Please try libpng-1.0.53beta01 from
ftp://ftp.simplesystems.org/pub/png-group/src
or from http://libpng.sf.net (in the 03-libpng-legacy branch)

Glenn

On Thu, Jan 14, 2010 at 10:06 AM, Paul Howarth <pa...@ci...> wrote:

> On 14/01/10 14:41, Glenn Randers-Pehrson wrote:
> > I'll look into it.  I don't recall that change being intentional.
> >
> > However, libpng-1.0.x are not meant for use in building anything.
> > They are only supposed to provide a shared library to satisfy old apps
> > that were linked against libpng-1.0.x years ago.
>
> I understand that, but periodically it's necessary to rebuild legacy
> apps to fix security issues etc. and those builds will change as little
> as possible to avoid unintended regressions, hence not updating to
> current libpng versions.
>
> In order to ensure that such rebuilds are as painless as possible,
> Fedora rebuilds everything in the distribution from source from time to
> time to ensure that everything is still buildable, and it was one of
> those test builds that uncovered this issue.
>
>
Thanks for the report.  Tests are a good thing.

I don't remember why the #ifdef's were introduced.  It must have
been a cut-and-paste error on my part.

The CHANGES file for 1.0.53/1.2.43 will say:
  Removed "#ifdef PNG_1_0_X / #endif" surrounding
    PNG_READ_16_TO_8_SUPPORTED and PNG_READ_GRAY_TO_RGB_SUPPORTED
    in pngconf.h.  These were added in libpng-1.2.41beta08 and
libpng-1.0.51,
    introducing a binary incompatibility with libpng-1.0.50.

Glenn

Re: [png-mng-implement] png_set_strip_16 unavailable in libpng10 >= 1.0.51

[Paul H. <pa...@ci...>]

On 14/01/10 16:00, Glenn Randers-Pehrson wrote:
> Please try libpng-1.0.53beta01 from
> ftp://ftp.simplesystems.org/pub/png-group/src
> or from http://libpng.sf.net (in the 03-libpng-legacy branch)
>
> Glenn
>
> On Thu, Jan 14, 2010 at 10:06 AM, Paul Howarth <pa...@ci...
> <mailto:pa...@ci...>> wrote:
>
>     On 14/01/10 14:41, Glenn Randers-Pehrson wrote:
>      > I'll look into it.  I don't recall that change being intentional.
>      >
>      > However, libpng-1.0.x are not meant for use in building anything.
>      > They are only supposed to provide a shared library to satisfy old
>     apps
>      > that were linked against libpng-1.0.x years ago.
>
>     I understand that, but periodically it's necessary to rebuild legacy
>     apps to fix security issues etc. and those builds will change as little
>     as possible to avoid unintended regressions, hence not updating to
>     current libpng versions.
>
>     In order to ensure that such rebuilds are as painless as possible,
>     Fedora rebuilds everything in the distribution from source from time to
>     time to ensure that everything is still buildable, and it was one of
>     those test builds that uncovered this issue.
>
> Thanks for the report.  Tests are a good thing.
>
> I don't remember why the #ifdef's were introduced.  It must have
> been a cut-and-paste error on my part.
>
> The CHANGES file for 1.0.53/1.2.43 will say:
>    Removed "#ifdef PNG_1_0_X / #endif" surrounding
>      PNG_READ_16_TO_8_SUPPORTED and PNG_READ_GRAY_TO_RGB_SUPPORTED
>      in pngconf.h.  These were added in libpng-1.2.41beta08 and
> libpng-1.0.51,
>      introducing a binary incompatibility with libpng-1.0.50.

Thanks, this seems to have resolved the problem.

Cheers, Paul.