Hi all.

I keep getting this error from many applications from mplayer for example and others. I have this problem either with the original libpng that comes with Slackware 12.0 and with the recent update.

The only way to fix it is to compile my own libpng, then the error disappears.

This is odd, does this mean there's something wrong with the libpng that comes with Slackware ? Maybe it wasn't compiled properly ?

Do you have VMWare installed?
Google'ing this error shows mainly VMWare related links.

I know, I searched google plenty for it and all I got were vmware links like you said. I actually do NOT have vmware installed.

Do other people notice this problem ? One good example is gmplayer, whenever I run it on the command line it always gives this 'warning', it's not really an error because it doesn't crash, but other things do crash such as some games I've tried.

No, I don't get this error. Just tried it with gmplayer...
Have you tried the solutions in these Google results (making symlinks)? I know they're about VMWare, but the error is the same.
I would try that.

EDIT:
Sorry, that was a stupid answer, ignore it.
If I had read a little better, I could have seen that you don't have the issue with this library when you compiled it yourself...

Just searched through the forums today because I also got this error. It has something to do with the way libpng is built in slackware. Apparently its built without a version dependency of some sort, however if you built your own version of libpng, it will create a file /usr/lib/libpng.la. Then after that, ANY program that links to libpng will be versioned and you will also notice that any program that requires libpng or requires any library that links to libpng will not compile if you use the slackware libpng WITHOUT libpng.la.

I dont really see the purpose of this at all. So far i can only see two solutions:

1. Revert to slackware packaged libpng, and rebuild anything that depended on this that was built AFTER you built your own libpng some time ago.

2. Keep your built libpng but realise that the ones that come with slackware will no longer be sufficient...

Some hints on where i got this info from: http://forums.slamd64.com/viewtopic....69d9126949cd04

Can anyone tell me why libpng is built in such a way? I noticed in the slackbuild scripts, they dont do the standard configure make, but manually replaced the makefile with one from the source/script directory.

Thanks for the reply.

Well, in the slackbuild script I see that it is built by using the 'makefile.linux' which as it state:
does NOT install 'libpng12.la'. Yet in the one I built it says in 'libpng12.la':
Then if the '.la' is needed for linking, why is it not included in the official Slackware package ? Something to do with version issues ?

I'd like an explanation for why this is done. I don't see anything about it in any of the README-type files that come with Slackware.

It's not needed for linking - you can carry on just fine without libpng.la - it's absence is not an error, and you can safely ignore any messages to the contrary.

If you rebuild libpng from the SlackBuild, it will not generate libpng.la. On libpng, this file is only produced if you use the full autotools to generate and build libpng.

Slackware does not do this since the autotools support in libpng is rather new, and the old method of building libpng works very well (it also makes a few other incompatible changes by dropping certain exported functions; which, IIRC Slackware would have to work around, until other software gets fixed not to rely on them).

What you really _don't_ want to do is to add this libpng.la file to your system (e.g. by rebuilding libpng yourself, or modifying the SlackBuild to not use the hardcoded Makefile), build new packages against this libpng.la, and then downgrade back to the Slackware libpng.la-free package: it's a rather nasty mess to sort out when you want to start compiling packages against libpng again later.

So, there will be problems if I uninstalled the one that came with Slackware, built my own from the latest source and installed that ? Just because of this 'libpng12.la' ?

There won't be problems unless you remove your own compiled libpng when still having programs built against it. AFAIK, slackbuild builds la file (didn't check though).

No, the SlackBuild does _not_ build libpng.la and never has.

And yes, I really have double checked to make sure this is still the case

Got this from from slamd64 forum (linked above):
I expected that slackbuilds are mostly the same. It seems I was wrong.

No, this was a bug on Slamd64 that has long since been fixed.

Background:

Fred had problems getting libpng to build on x86-64 with the Slackware method, so switched to the fully autotools based method.

This caused problems with other applications (e.g. CUPS), and also broke with Slackware.

A patch I dug up fixed the build issue issue, so we switched back to the hardcoded Makefile (as Slackware uses, to keep divergence to a minimum), _but_ we ended up with the mess described - we removed libpng.la, though had lots of packages still dependent on it.

A lot of work later, and we finally rebuilt the last of the packages that had this libpng.la dependency to remove it. This was done over the 12.0 development cycle, and also backported to 11.0 (the only other stable Slamd64 release).

Moral of the story? When I say adding then removing libpng.la is a pain, I'm speaking from experience, alas.

Hello,

I'm curently trying to run a program called praat. And when I try to run it from the command line, it gives me the error that you described up above, the libpng12.so.0 file missing. The exact error is this:

./praat /usr/lib/libpng12.so.0: no version information available( required by ./praat)

So I didnt quite understand what to do to solve this. I looked on SBo and there is a librairy called libglpng version 1.45. Is this the one I should be compiling before running praat? Because I've tried it and it doesnt work. Also, I ran the following command and got the following answer:

slapt-get --search libpng
libpng-1.2.37-i486-1 [inst=yes]: libpng (Portable Network Graphics library)

What is the problem? Do I need to rebuild libpng? Where can I find libpng? It doesnt seem to be available at SBo other than under the libglpng librairy... IF that is the correct one...

I need praat for my roomate's school projects. So I have the task to build him a nice slackware laptop that he can use at work. So any help on this topic would be much appreciated. My roomate would be so happy that I could get this praat program working. It seems quite easy with Ubuntu, you can install it with apt-get, but I'm guessing thats why slackware is so cool and different from other OS's, you gotta work hard to make things work (= wich I dont mind of course. All you great people are here to help, right? (=

Thanks,
Dumdadum

Oh and I tried Alien Bob's place, no libpng there. Waiting for your enlightments...

Dumdadum

@dumdadum how did you install praat?
The "no version information available" is mostly seen on binaries compiled on an debian based distribution.
On distributions like ubuntu there are 3 things thats not in upstream version of libpng and there for not in Slackware.
And one of them are "versioned symbols"

From README.Debian
This version diverges from upstream in 3 ways :
1) the library is explicitly linked with -lm -lz
2) libpng.so.3 is just a compatibility symlink
3) symbols are versioned

So did you use an precompiled debian binary instead of compiling from source?