Re: [patch] search for versioned shared libraries

[Bryce McKinlay <mckinlay at redhat dot com>]

Thomas Fitzsimmons wrote:

> This patch makes libltdl search for versioned .sos in addition to .la
> and unversioned .so files.  The search order
> is .la, .so.${libgcj_major_version}, .so.  This search order is useful
> when multiple versions of the same .so are installed in the same place.
> The unversioned .la file can be removed and the proper library will
> always be resolved.
>
> Also, there was a Makefile.am bug that prevented libgcj.so from being
> linked when libltdl was modified.  I've included a fix in this patch.
>
> OK to commit?
>  

I'm not sure that modifying ltdl to implement this is a good idea. 
Firstly, it creates potential maintainance headaches because we're 
diverging from the upstream sources. Have you asked the libtool/ltdl 
guys if they want to implement something like this? Also, implementing 
it at the ltdl level could create inconsistent behaviour for, say, 
loading a 3rd party JNI library, where a different version might get 
loaded in libgcj (for the same Java code) compared to other VMs.

Perhaps you can explain the motivation for this patch? Is the idea to 
allow 3rd party packages/libraries to append libgcj's "ABI version 
number" to their soname, so its clear which ABI they were compiled for? 
Or is it just so that the correct versions of libgcj's own libraries can 
be found when multiple versions are installed in the same place?

If its the later, maybe a naming convention like 
libwhatever-<gcjversion>.so would be better? This way, the version could 
be appended by libgcj before it calls into ltdl.

Bryce