python: Move PyList_AsStringList to common code so we can reuse

BUG: https://bugzilla.samba.org/show_bug.cgi?id=15289

Signed-off-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>

python/modules.c

@@ -71,3 +71,38 @@ error:
 	Py_XDECREF(mod_sys);
 	return false;
 }
+
+const char **PyList_AsStringList(TALLOC_CTX *mem_ctx, PyObject *list, 
+				 const char *paramname)
+{
+	const char **ret;
+	Py_ssize_t i;
+	if (!PyList_Check(list)) {
+		PyErr_Format(PyExc_TypeError, "%s is not a list", paramname);
+		return NULL;
+	}
+	ret = talloc_array(NULL, const char *, PyList_Size(list)+1);
+	if (ret == NULL) {
+		PyErr_NoMemory();
+		return NULL;
+	}
+
+	for (i = 0; i < PyList_Size(list); i++) {
+		const char *value;
+		Py_ssize_t size;
+		PyObject *item = PyList_GetItem(list, i);
+		if (!PyUnicode_Check(item)) {
+			PyErr_Format(PyExc_TypeError, "%s should be strings", paramname);
+			return NULL;
+		}
+		value = PyUnicode_AsUTF8AndSize(item, &size);
+		if (value == NULL) {
+			talloc_free(ret);
+			return NULL;
+		}
+		ret[i] = talloc_strndup(ret, value, size);
+	}
+	ret[i] = NULL;
+	return ret;
+}
+