[PATCH - v2 branch ] Internal function names conflict with Jasper about openjpeg HOT 19 CLOSED

Please, fix it as soon as possible.
It took me 2 days to detect this problem in my program and I'm very angry!
Every Qt application that is linked with libopenjpeg and runs in the system, 
where KDE is installed, can potentionally crash, cause it loads kimg_jp2.so 
plugin, linked with libjasper.

All *external* openjpeg V2 functions have an 'opj' prefix. IMHO, libjasper has 
not been cautious enough by defining external functions without a jasper 
prefix. 

If we apply the provided patch and want to remain consistent, we should 
actually rename all openjpeg functions with an 'opj' prefix. Do you guys see 
another less invasive solution ?

I disagree with the first two comments. C++ namespace were designed for that. 
For C project this is an issue application developer needs to work with.

In GDCM we use the following mangling:

http://gdcm.git.sourceforge.net/git/gitweb.cgi?p=gdcm/gdcm;a=blob;f=Utilities/gd
cmopenjpeg/openjpeg_mangle.h.in;h=62f15ece8340cb402c319d9e756c3f30be01f921;hb=HE
AD

Selon [email protected]:

I didn't mention that I met the issue on Linux where the fact that symbols are
internal or external isn't really taken into account by the dynamic
loader/symbol resolver (internal symbols are still visible from the outside,
unless you use the visibility option of GCC4, but even in that case I've found
that it doesn't solve all situations). On Windows, this issue doesn't probably
exist however.

The symbol mangling done for GDCM isn't really an option for GDAL, where we
don't embed openjpeg code in our source tree, but rely on using the "official"
source code that the user has built independantly of GDAL.

I agree that the Jasper devs have probably not been very careful about the
namespace pollution, but as the jp2_decode and jp2_encode symbols are public for
Jasper and private for OpenJpeg, it seems more reasonable to rename them in
OpenJpeg... Now, do you need to rename all openjpeg functions with an 'opj'
prefix ? Well, it is up to you. It seems to be a pretty big change. Basically I
compared the output of nm on libjasper.so and libopenjpeg.so, and the only
intersection was jp2_encode and jp2_decode.

Jasper seems to be a dead project. Actually, that library sucks, it can easily 
crash you program.
I think, the future belongs to openjpeg, so you must add 'opj' prefix to all 
its functions.
I can make a complete patch. Just promise, that it will be applied :)

nice, nobody cares (

[email protected] : can you still make a complete patch (for both trunk and 
v2) ?

I'll try this week

here is the patch for trunk
please let me know if it is suitable

Thanks a lot. 

It seems to work ok for libopenjpeg but the patch didn't succeed in folders 
jp3d, JavaOpenJPEG and OPJViewer. Maybe a problem of file encoding ... I'll 
investigate this and keep you posted. Thanks again.

I cannot manage to patch the JP3D folder (see patchreport attached). 
Do you have an idea on how to solve this ?

I tried to check out from trunk and apply the patch.
It works well.
Maybe you need to do some synchronization?

Oops, I see, something wrong with the encoding.
I'll try to fix it.

thanks ! I wait for an updated patch then.

Fixed for now the conflicting function (jp2_encode and jp2_decode). 

volkov0aa, your patch is still welcome however :-).

Cheers,

Antonin

even, I am tempted to close this bug. This should be handled now, within issue 
#177

I think we can close it now with the 2.0 release
all the public api used opj_ prefix now and the great majority of the ABI also