Linking against c++ standard library?

[Maurizio Cimadamore]

Unfortunately, the JDK only loads with RTLD_LAZY, not GLOBAL.

That said, you might try calling dlopen directly using the linker, and 
passing the required flags.

Have you tried using LD_PRELOAD?

Maurizio

On 03/08/2023 16:16, Christoph Läubrich wrote:
> Hi Maurizio
>
> thanks for your fast replay, in the stackoverflow there is a hint that 
> says:
>
> > If you load libmono dynamically at runtime
> (I think thats my case)
>
> > you'll have to load in libstdc++ first, using something like this:
> > void * cxxlib = dlopen("libstdc++.so.6", RTLD_LAZY | RTLD_GLOBAL);
>
> (that's what I tried with System.load)
>
> BUT:
> > Key thing here is the RTLD_GLOBAL flag, which will add all symbols 
> to the global table, so they can be found when you're trying to load 
> libmono.
>
> So it seems this RTLD_GLOBAL flag is somehow the missing magic (and 
> System.load probabbly is not using that), can I somehow issue an 
> dlopen with panama that includes this flag?
>
> Also I can recompile the lib but have no clue what would be the 
> "right" way to add the dependency and of course then it only works 
> with custom compiled version so I hopped I can somehow trick the JVM 
> here :-)
>
> best
> Christoph
>
>
> Am 03.08.23 um 17:03 schrieb Maurizio Cimadamore:
>> Hi,
>> not an expert on the topic, but also found this:
>>
>> https://stackoverflow.com/questions/67910722/how-to-deal-with-undefined-symbols-when-loading-mono-libraries-in-linux 
>>
>>
>> It seems like libmono doesn't come with the right dynamic 
>> dependencies on it? (so library loading would fail).
>>
>> I don't think this is something you can fix on the Java side. You 
>> need a library that has the right set of dependencies.
>>
>> Maurizio
>>
>> On 03/08/2023 15:53, Christoph Läubrich wrote:
>>> I used an older lib of "mono" [1] (v5) with panama without a problem 
>>> and everything worked out quite well but with v6 of the lib I can't 
>>> load it anymore because it fails [2] with "undefined symbol: 
>>> _ZTIPi", the maintainer of the lib responded that
>>>
>>> "though on modern Mono, you need to link against a C++ standard 
>>> library"
>>>
>>> so my first guess was to add System.load("stdc++") but this seem not 
>>> working (at least it results in the same error message).
>>>
>>> So I wonder if there is anything special I can do to tell panama to 
>>> link/load a c++ standard library?
>>>
>>>
>>>
>>> [1] https://www.mono-project.com/
>>> [2] https://github.com/mono/mono/issues/21676