Add support for ctypes to python3's recipe

Should be mentioned that the current test app for python3 has been modified by adding libffi to the requirements because the ui for the app has some button to test the ctypes module.

References: This commit partially fixes some of the points mentioned in issue number #1455

Author: opacam

pythonforandroid/bootstraps/sdl2/build/src/main/java/org/kivy/android/PythonUtil.java

@@ -37,6 +37,7 @@ protected static ArrayList<String> getLibraries(File filesDir) {
         ArrayList<String> libsList = new ArrayList<String>();
         addLibraryIfExists(libsList, "crystax", libsDir);
         addLibraryIfExists(libsList, "sqlite3", libsDir);
+        addLibraryIfExists(libsList, "ffi", libsDir);
         libsList.add("SDL2");
         libsList.add("SDL2_image");
         libsList.add("SDL2_mixer");

pythonforandroid/recipes/python3/__init__.py

@@ -1,4 +1,4 @@
-from pythonforandroid.recipe import TargetPythonRecipe
+from pythonforandroid.recipe import TargetPythonRecipe, Recipe
 from pythonforandroid.toolchain import shprint, current_directory
 from pythonforandroid.logger import logger, info
 from pythonforandroid.util import ensure_dir, walk_valid_filens
@@ -33,13 +33,53 @@
 
 
 class Python3Recipe(TargetPythonRecipe):
+    '''
+    .. note::
+        In order to build certain python modules, we need to add some extra
+        recipes to our build requirements:
+
+            - ctypes: you must add the recipe for ``libffi``.
+    '''
     version = '3.7.1'
     url = 'https://www.python.org/ftp/python/{version}/Python-{version}.tgz'
     name = 'python3'
 
     depends = ['hostpython3']
     conflicts = ['python3crystax', 'python2']
-    # opt_depends = ['openssl', 'sqlite3']
+    opt_depends = ['libffi']  # 'openssl', 'sqlite3'
+
+    configure_args = (
+        '--host={android_host}',
+        '--build={android_build}',
+        '--enable-shared',
+        '--disable-ipv6',
+        'ac_cv_file__dev_ptmx=yes',
+        'ac_cv_file__dev_ptc=no',
+        '--without-ensurepip',
+        'ac_cv_little_endian_double=yes',
+        '--prefix={prefix}',
+        '--exec-prefix={exec_prefix}')
+
+    def set_libs_flags(self, env, arch):
+        '''Takes care to properly link libraries with python depending on our
+        requirements and the attribute :attr:`opt_depends`.
+        '''
+        def add_flags(include_flags, link_flags):
+            env['CPPFLAGS'] = env.get('CPPFLAGS', '') + include_flags
+            env['LDFLAGS'] = env.get('LDFLAGS', '') + link_flags
+
+        if 'libffi' in self.ctx.recipe_build_order:
+            info('Activating flags for libffi')
+            recipe = Recipe.get_recipe('libffi', self.ctx)
+            include = ' -I' + ' -I'.join(recipe.get_include_dirs(arch))
+            ldflag = ' -L' + join(recipe.get_build_dir(arch.arch),
+                                   recipe.get_host(arch), '.libs') + ' -lffi'
+            add_flags(include, ldflag)
+            # libffi needs some extra configurations
+            env['LIBFFI_CFLAGS'] = env.get('CFLAGS', '') + include
+            env['LIBFFI_LIBS'] = ldflag
+            self.configure_args += ('--with-system-ffi',)
+        return env
 
     def build_arch(self, arch):
         recipe_build_dir = self.get_build_dir(arch.arch)
@@ -112,22 +152,15 @@ def build_arch(self, arch):
 
             env['SYSROOT'] = sysroot
 
+            env = self.set_libs_flags(env, arch)
+
             if not exists('config.status'):
                 shprint(sh.Command(join(recipe_build_dir, 'configure')),
-                        *(' '.join(('--host={android_host}',
-                                    '--build={android_build}',
-                                    '--enable-shared',
-                                    '--disable-ipv6',
-                                    'ac_cv_file__dev_ptmx=yes',
-                                    'ac_cv_file__dev_ptc=no',
-                                    '--without-ensurepip',
-                                    'ac_cv_little_endian_double=yes',
-                                    '--prefix={prefix}',
-                                    '--exec-prefix={exec_prefix}')).format(
-                                        android_host=android_host,
-                                        android_build=android_build,
-                                        prefix=sys_prefix,
-                                        exec_prefix=sys_exec_prefix)).split(' '), _env=env)
+                        *(' '.join(self.configure_args).format(
+                            android_host=android_host,
+                            android_build=android_build,
+                            prefix=sys_prefix,
+                            exec_prefix=sys_exec_prefix)).split(' '), _env=env)
 
             if not exists('python'):
                 shprint(sh.make, 'all', _env=env)

testapps/setup_testapp_python3.py

@@ -2,7 +2,7 @@
 from distutils.core import setup
 from setuptools import find_packages
 
-options = {'apk': {'requirements': 'sdl2,pyjnius,kivy,python3',
+options = {'apk': {'requirements': 'libffi,sdl2,pyjnius,kivy,python3',
                    'android-api': 27,
                    'ndk-api': 21,
                    'dist-name': 'bdisttest_python3_googlendk',