dynamic library loading, missing symbols

[dfj225 at gmail.com]

> Did you verify, using nm -D, that the symbol is indeed present in
> the shared object, not just in the source code?

Yes, the symbol is found in the shared object when using nm.

> What flags are given to that dlopen call?

dlopen(lib, RTLD_NOW | RTLD_GLOBAL);


> No. The dynamic linker doesn't search files to resolve symbols; instead,
> it searches the process' memory. It first loads the referenced shared
> libraries (processing the DT_NEEDED records in each one); that uses
> the LD_LIBRARY_PATH. Then, symbol resolution needs to find everything
> in the libraries that have already been loaded.

Ok, so if the linker is searching the process address space, then I
suppose what really comes into play here is how the Python interpreter
dynamically loaded my module, a module which is in turn calling code
that does the dlopen above. If the Python interpreter is not loading
my library as global, does that mean the linker will not find them
when subsequent libraries are loaded?

> There are various ways to control which subset of in-memory symbols
> the dynamic linker considers: the RTLD_GLOBAL/RTLD_LOCAL flags play
> a role, the -Bsymbolic flag given to the static linker has an impact,
> and so does the symbol visibility (hidden/internal/protected).

Ok, any other suggestions for things to try? Since all of the dlopen
calls happen in 3rd party code, I won't really be able to modify them.
I will try looking into more compile time flags for the linker and see
what I can come up with. Keep in mind that this code works when it is
all C++. Only when I add the Boost.Python wrapper to my code and then
import in Python do I get this symbol error.

Thank you for your help,
~Doug