Executing a shared library

If you want to catch them all, there is no other choice but to do full filesystem traversals. ldconfig knows only about the libraries in the standard paths and the extra paths it is configured to look in (usually defined in /etc/ld.so.conf*). The usual suspect places where other libraries can be found are $HOME and /opt, though there is no limit, especially when people build applications themselves.

If you don't trust the output of ldconfig -p, you can parse its cache directly. It's binary, but using strings removes all the garbage (5 so /lib/ matches):

strings -n5 /etc/ld.so.cache

On my system, they both give the same results, which I verified with this quicky:

a=$(ldconfig -p | awk -F'> ' '{print $2}' | sort); # get them to the same format
b=$(strings -n5 /etc/ld.so.cache | sort -u); 
echo -e "$a\n$b\n$b" | sort | uniq -u

Which checked if any library on the ldconfig -p list was not mentioned in the cache. Nothing was returned.

You can get information from an ELF file (executable or library) with readelf.

Looks like you're looking for the exported symbols, so use:

$ readelf --dyn-syms libyourthing.so

For C-type functions, you'll only get function names, not argument types or return values. For C++ functions, you'll get mangled names - pipe the output of that command through c++filt to get function names and argument types (still no return values though).
(Globals are also displayed in the output, with their names and size but not their type.)

Other useful tools are nm and objdump which provide similar information.

I'm not sure that'll help you though. You should also try strace to see if python is looking where you think it is. Something like:

$ strace -e trace=open python your_code_that_loads_your_lib.py

will show you all the open calls executed by python - look for your library name in there (there will be a lot logged by the above, filter it). Each call also shows the return code, so you might get a better idea about what is going on.

_{Oh, and do make sure you're not trying to load a 32bit library into a 64bit python runtime, or vice-versa.}