ctypes changes between Python 2 and Python 3

capabilities.py

import ctypes
import ctypes.util


def load_libcap(lib_name=None):
    if lib_name is None:
        lib_name = 'cap'

    if not load_libcap.loaded_library:
        libcap_name = ctypes.util.find_library(lib_name)

        if not libcap_name:
            raise LookupError('Failed to load libcap, no library found with name %s' % lib_name)

        lib = ctypes.cdll.LoadLibrary(libcap_name)

        if not lib:
            raise IOError('Failed to load libcap, LoadLibrary(%s) failed' % libcap_name)

        load_libcap.loaded_library = lib

    return load_libcap.loaded_library

load_libcap.loaded_library = None


libcap = load_libcap()

capabilities = libcap.cap_get_proc()

# Always negative integer (example -1585665644) in Python 3,
# always positive integer (example 15452516) in Python 2
print(capabilities)

# Segfaults in Python 3,
# Real output (example = cap_chown,cap_dac_override,cap_dac_read_search,) in Python 2
libcap.cap_to_text.restype = ctypes.c_char_p
print(libcap.cap_to_text(capabilities, None))