Re: updating libwebp

On Fri, 20 Jul 2018, Shane D. Bishop wrote:
>
>> The 1.0.0 version is claimed to be ABI compatible with 0.6.1/0.6.0 so
>> it should be a drop-in upgrade for 0.6.0. However 0.6.0 is not ABI
>> compatible with earlier versions so it is not a drop-in upgrade for
>> earlier versions.

> So theoretically, trying to run 0.6.x in place of the 0.5.2-1 could 
> cause problems anyway, even if it seems to be working for the most 
> part, right? Since I have used ldconfig on the /usr/local/lib/ 
> folder, I wondered if GM was using the newer version currently, but 
> the 0.5.2 library is named libwebp.so.6 and the 0.6.1 library is 
> named libwebp.so.7. I'm not real familiar with the naming 
> conventions there, but would the difference in file names be due to 
> the ABI breakage? I did try changing the symlinks, restarted 
> php-fpm, and it worked on a test image, but if the ABI is not 
> compatible I should probably not use that in production.

The difference between the library number is there to prevent the 
wrong library from being accidentally used.  If you intentionally 
force using the newer library you are likely to encounter severe 
problems such as error reports or core dumps.  There are large 
functionality differences between libwebp 0.5 and 0.6.

Use

   ldd `which gm`

to see what shared libraries are being used:

% ldd `which gm`
         linux-vdso.so.1 =>  (0x00007fff2d66a000)
         libjbig.so.0 => /usr/lib/x86_64-linux-gnu/libjbig.so.0 (0x00007fc6f978d000)
         libwebp.so.5 => /usr/lib/x86_64-linux-gnu/libwebp.so.5 (0x00007fc6f9535000)
.
.
.

>>> I suspect the best solution long-term is to compile GM from scratch,
>>> but I'm not quite ready to make that jump at the moment, so I'm
>>> hoping that a simple update of the libraries is sufficient here.
>
>> It is not difficult to compile GM from scratch on a Debian system.
>> You just need to add various -dev packages.
>
> I thought it might come to that. When I have time, I'll dig into the dependencies and see what I can do. Thanks!

Just look at the library dependencies claimed for the existing 
GraphicsMagick package (e.g. libpng) and then install -dev versions of 
those dependencies.  Given that the necessary development versions are 
installed, compiling and installing GraphicsMagick is very easy.

Bob
-- 
Bob Friesenhahn
[email protected], http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/

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