How to include a shared C library in a Python package

I have a project depending on a shared library. To get it right from the start: The shared library is a pure C library, not a Python library. For simplicity reasons, I created a small demo project called pkgtest, which I will discuss.

So here's the thing to do: Run the Makefile to compile the library and place the compiled shared library (called libhello.so

here) where it can be accessed from within the Python package.

So far, I have assumed to run the makefile as a preset, copy the file libhello.so

to the packages directory, and add it to the package_data

script install parameter . Once installed, the shared library is then placed in a directory site-packages/pkgtest/

and can be accessed from the module.

The package directory is just as simple:

pkgtest/
  src/
     libhello.c
     libhello.h
     Makefile
  pkgtest/
    __init__.py
    hello.py
  setup.py

      

        
        
        
      

    

My setup.py looks like this:

setup.py

import subprocess
from setuptools import setup
from distutils.command.install import install as _install


class install(_install):
    def run(self):
        subprocess.call(['make', 'clean', '-C', 'src'])
        subprocess.call(['make', '-C', 'src'])
        _install.run(self)


setup(
    name='pkgtest',
    version='0.0.1',
    author='stefan',
    packages=['pkgtest'],
    package_data={'pkgtest': ['libhello.so']},
    cmdclass={'install': install},
)

      

        
        
        
      

    

The Makefile actually builds the library and copies it to my python package directory.

CSI / Makefile

all: libhello.so

libhello.o: libhello.c
        gcc  -fPIC -Wall -g -c libhello.c

libhello.so: libhello.o
        gcc -shared -fPIC -o libhello.so libhello.o
        cp libhello.so ../pkgtest/libhello.so

clean:
        rm -f *.o *.so

      

        
        
        
      

    

So everything hello.py

actually loads the library and calls a function hello

that prints out some text. But for completeness, I'll show the code here:

pkgtest / hello.py

import os
import ctypes

basedir = os.path.abspath(os.path.dirname(__file__))
libpath = os.path.join(basedir, 'libhello.so')

dll = ctypes.CDLL(libpath)

def say_hello():
    dll.hello()

      

        
        
        
      

    

So this does work, but what I don't like about this approach is that the shared library lives in the Python package directory. I suppose it would be better to place it in some central library directory like / usr / lib /. But this requires root privileges during installation. Someone has some experience with this problem and would like to share a solution or a helpful idea. It would be great.