Unable to link against installed GRASS libraries

[iwishiwasaneagle]

Using pybind11, I'm trying to interface with a modified r.viewshed source code (copied into my source directory for now). However, when I try to import the function in python I get

package.cpython-39-x86_64-linux-gnu.so: undefined symbol: _ZN16mm_register_initD1Ev

Inspecting the so file:

$ nm -D package.cpython-39-x86_64-linux-gnu.so| grep mm_register_init
                 U _ZN16mm_register_initC1Ev
                 U _ZN16mm_register_initD1Ev

With U meaning that the symbol is undefined (see man nm).

Checking if any libgrass files that are visibile by ldconfig contain the symbol draws a blank too, as well as checking every .so file on the filesystem.

ldconfig -p  | grep -o "/opt/grass/.*" | xargs nm -D | grep mm_register_init
# and
fd "libgrass" / -e so | xargs nm -D | grep mm_register_init

Calling grass launches grass without an issue.

The only solution I can see is adding the source code as a submodule and statically linking every required function which is not what I'd like to do.

[marisn]

GRASS modules are functional within a GRASS work session. When you launch GRASS, it is setting up environment variables including adding GRASS .so files to LD search path. GRASS code base has certain assumptions on the environment when it runs thus if you are trying to bypass startup mechanism, its on to you to ensure sanity of the environment.

TL;DR: start your python interpreter from a GRASS session.

[iwishiwasaneagle]

Hi @marisn, thanks for taking the time to reply. I was starting to assume as much. Thanks for confirming!

[wenzeslaus]

...and there is a Python API for it: grass.script.setup.init (see the surrounding documentation; there is little more what needs to be done).