Rework uwsgi module handling

This partially reverts some of the work done in
1881628.

This removes some code reordering done in the above commit to work
around the fact that, starting in 3.12, `PyImport_AppendInittab()` could
no longer be called after `Py_Initialize()`.

This patch reverts this reordering, and takes a different approach to
add the `uwsgi` python module to the plugin.

This is mainly done to support the https://pypi.org/project/pyuwsgi/ use
case where the uwsgi server itself is a python module, and hence the
interpreter will always be initialized before uwsgi even starts.

It's also a bit cleaner, there's less code getting rearranged to support
3.12.

plugins/python/python_plugin.c

@@ -233,21 +233,6 @@ void uwsgi_python_pthread_child(void) {
 PyMethodDef uwsgi_spit_method[] = { {"uwsgi_spit", py_uwsgi_spit, METH_VARARGS, ""} };
 PyMethodDef uwsgi_write_method[] = { {"uwsgi_write", py_uwsgi_write, METH_VARARGS, ""} };
 
-PyDoc_STRVAR(uwsgi_py_doc, "uWSGI api module.");
-
-#ifdef PYTHREE
-static PyModuleDef uwsgi_module3 = {
-	PyModuleDef_HEAD_INIT,
-	"uwsgi",
-	uwsgi_py_doc,
-	-1,
-	NULL,
-};
-PyObject *init_uwsgi3(void) {
-	return PyModule_Create(&uwsgi_module3);
-}
-#endif
-
 int uwsgi_python_init() {
 
 	char *pyversion = strchr(Py_GetVersion(), '\n');
@@ -313,9 +298,6 @@ int uwsgi_python_init() {
 	wchar_t *pname = uwsgi_calloc(sizeof(wchar_t) * (strlen(program_name)+1));
 	mbstowcs(pname, program_name, strlen(program_name)+1);
 	Py_SetProgramName(pname);
-#ifdef UWSGI_PY312
-	PyImport_AppendInittab("uwsgi", init_uwsgi3);
-#endif
 #else
 	Py_SetProgramName(program_name);
 #endif
@@ -678,6 +660,21 @@ void init_uwsgi_vars() {
 
 
 
+PyDoc_STRVAR(uwsgi_py_doc, "uWSGI api module.");
+
+#ifdef PYTHREE
+static PyModuleDef uwsgi_module3 = {
+	PyModuleDef_HEAD_INIT,
+	"uwsgi",
+	uwsgi_py_doc,
+	-1,
+	NULL,
+};
+PyObject *init_uwsgi3(void) {
+	return PyModule_Create(&uwsgi_module3);
+}
+#endif
+
 void init_uwsgi_embedded_module() {
 	PyObject *new_uwsgi_module, *zero;
 	int i;
@@ -700,11 +697,21 @@ void init_uwsgi_embedded_module() {
 #ifdef PYTHREE
 #ifndef UWSGI_PY312
 	PyImport_AppendInittab("uwsgi", init_uwsgi3);
-#endif
 	new_uwsgi_module = PyImport_AddModule("uwsgi");
-#else
+#else // UWSGI_PY312
+	// From python 3.12 onwards, PyImport_AppendInittab() can no
+	// longer be called after Py_Initialize(). Dynamically
+	// add the module instead
+	PyObject *sys_modules;
+	PyImport_AddModule("uwsgi");
+	new_uwsgi_module = init_uwsgi3();
+	sys_modules = PyImport_GetModuleDict();
+	PyDict_SetItemString(sys_modules, "uwsgi", new_uwsgi_module);
+	Py_DECREF(new_uwsgi_module);
+#endif // UWSGI_PY312
+#else // PYTHREE
 	new_uwsgi_module = Py_InitModule3("uwsgi", NULL, uwsgi_py_doc);
-#endif
+#endif // PYTHREE
 	if (new_uwsgi_module == NULL) {
 		uwsgi_log("could not initialize the uwsgi python module\n");
 		exit(1);