ctypes loading a c shared library that has dependencies

Question

On Linux, I have a c shared library that depends on other libs. LD_LIBRARY_PATH is properly set to allow the linker to load all the libraries. When I do:

libgidcwf    = ctypes.cdll.LoadLibrary(libidcwf_path)

I get the following error:

Traceback (most recent call last):
  File "libwfm_test.py", line 12, in <module>
    libgidcwf    = ctypes.cdll.LoadLibrary(libidcwf_path)
  File "/usr/lib/python2.5/ctypes/__init__.py", line 431, in LoadLibrary
    return self._dlltype(name)
  File "/usr/lib/python2.5/ctypes/__init__.py", line 348, in __init__
    self._handle = _dlopen(self._name, mode)
OSError: path-to-my-lib/libwav.so: undefined symbol: ODBCGeneralQuery

It seems that LD_LIBRARY_PATH has no effect here. Is there a way to have these dependency library "loadable" ?

Thanks in advance for the help.

Answer 1

It would seem that libwav.so does not declare it's dependency on the library defining ODBCGeneralQuery. Try running ldd path-to-my-lib/libwav.so and see if there's something missing. If this is a shared library that you are building you should add -llibname to the linking command (the one that is something like gcc -shared -o libwav.so a.o b.o c.o) for each library that the library's code uses. Any other libraries referenced by the original shared library in this way should automatically be loaded as well.