Bug 219902

There's some weird breakage also with FC-6 i386. Check this out! The
image library deps are missing, the audio library deps from SDL are
duplicated:

$ ldd /usr/lib/libSDL_image-1.2.so.0.1.4
        linux-gate.so.1 =>  (0x00d93000)
        libSDL-1.2.so.0 => /usr/lib/libSDL-1.2.so.0 (0x02631000)
        libpthread.so.0 => /lib/libpthread.so.0 (0x00909000)
        libc.so.6 => /lib/libc.so.6 (0x0079b000)
        libdl.so.2 => /lib/libdl.so.2 (0x00903000)
        libesd.so.0 => /usr/lib/libesd.so.0 (0x07817000)
        libaudiofile.so.0 => /usr/lib/libaudiofile.so.0 (0x0787d000)
        libm.so.6 => /lib/libm.so.6 (0x008da000)
        /lib/ld-linux.so.2 (0x0077e000)
        libasound.so.2 => /lib/libasound.so.2 (0x076dd000)

It loads the libraries at run-time via SDL and their SONAMEs. Hence
no dependencies detected by rpmbuild:

-- dynamic libtiff -> libtiff.so.3
-- dynamic libjpeg -> libjpeg.so.62
-- dynamic libpng -> libpng.so.3

-DLOAD_TIF_DYNAMIC=\"libtiff.so.3\" -DLOAD_JPG_DYNAMIC=\"libjpeg.so.62\"
-DLOAD_PNG_DYNAMIC=\"libpng.so.3\"

./configure --help
  --enable-jpg-shared     dynamically load JPG support [default=yes]
  --enable-png-shared     dynamically load PNG support [default=yes]
  --enable-tif-shared     dynamically load TIFF support [default=yes]

(In reply to comment #2)
> It loads the libraries at run-time via SDL and their SONAMEs. Hence
> no dependencies detected by rpmbuild:
> 
> -- dynamic libpng -> libpng.so.3
> 
Interesting that this is detecting (and I assume using) libpng.so.3.  On x86_64:
$ ldd libSDL_image-1.2.so.0.1.4 |grep png
        libpng12.so.0 => /usr/lib64/libpng12.so.0 (0x00002aaaaacdf000)

This is starting to look like SDL_image on x86_64 is the one that's broken.

from nazghul's build logs:
/builddir/build/BUILD/nazghul-0.5.5/src/screen.c:872: undefined reference to
`png_create_write_struct'

It look like nazghul directly uses libpng.  It has been relying on SDL_image
pulling in libpng but should be doing its own configure check instead.

Yes, it seems that nazghul is indeed broken; it should link against libpng
itself.  What confused me is that the normally problematic x86_64 build is the
only one that worked.

An official log is still available:
http://buildsys.fedoraproject.org/logs/fedora-6-extras/22438-SDL_image-1.2.5-3.fc6/x86_64/build.log

Somebody who's familiar with libpng is needed, since:

* /usr/bin/libpng-config links to /usr/bin/libpng12-config
* libpng-config --libs
-lpng12
* /usr/lib/pkgconfig/libpng.pc links to libpng12.pc
* /usr/lib/libpng.so links to libpng12.so

So, in all these cases libpng12.so.0 is used, _not_ libpng.so.3

On i386, however, libpng.so.3 is detected and used and loaded
at run-time only. On x86_64, the dynamic loading is not enabled
(examining config.log might give a clue).

And the reason for the difference between i386 and x86_64 is that
/usr/lib is hardcoded in the configure script in code that searches
for the png/jpeg/tiff libs. It also searches for $path/libpng.so.[0-9]
which fails to find "libpng12.so.0". The configure options 

--disable-jpg-shared --disable-png-shared -disable-tif-shared

disable the run-time loading of the libs and bring back the
rpmbuild soname dependencies.

Michael, thanks for investigating this will I was gone this weekend.  Hopefully,
later today I can get some time to work on this.