util: Factor out Python module load

Create a utility function for loading a Python module by its name
in UTF-8.

Author: danielkitta

decoder.c

@@ -597,7 +597,7 @@ static int check_method(PyObject *py_dec, const char *mod_name,
  */
 SRD_API int srd_decoder_load(const char *module_name)
 {
-	PyObject *py_modname, *py_basedec, *py_apiver;
+	PyObject *py_basedec, *py_apiver;
 	struct srd_decoder *d;
 	long apiver;
 	int is_subclass;
@@ -617,13 +617,7 @@ SRD_API int srd_decoder_load(const char *module_name)
 
 	d = g_malloc0(sizeof(struct srd_decoder));
 
-	/* Import the Python module. */
-	py_modname = PyUnicode_FromString(module_name);
-	if (!py_modname)
-		goto except_out;
-
-	d->py_mod = PyImport_Import(py_modname);
-	Py_DECREF(py_modname);
+	d->py_mod = py_import_by_name(module_name);
 	if (!d->py_mod)
 		goto except_out;
 
@@ -806,15 +800,9 @@ static void srd_decoder_load_all_zip_path(char *path)
 	char *prefix;
 	size_t prefix_len;
 
-	zipimport_mod = NULL;
 	set = files = prefix_obj = zipimporter = zipimporter_class = NULL;
 
-	modname = PyUnicode_FromString("zipimport");
-	if (!modname)
-		goto err_out;
-
-	zipimport_mod = PyImport_Import(modname);
-	Py_DECREF(modname);
+	zipimport_mod = py_import_by_name("zipimport");
 	if (zipimport_mod == NULL)
 		goto err_out;
 

exception.c

@@ -84,7 +84,7 @@ SRD_PRIV void srd_exception_catch(const char *format, ...)
 {
 	va_list args;
 	PyObject *py_etype, *py_evalue, *py_etraceback;
-	PyObject *py_modname, *py_mod, *py_func, *py_tracefmt;
+	PyObject *py_mod, *py_func, *py_tracefmt;
 	char *msg, *etype_name, *evalue_str, *tracefmt_str;
 	const char *etype_name_fallback;
 
@@ -118,13 +118,7 @@ SRD_PRIV void srd_exception_catch(const char *format, ...)
 	if (!py_etraceback)
 		goto cleanup;
 
-	py_modname = PyUnicode_FromString("traceback");
-	if (!py_modname)
-		goto cleanup;
-
-	py_mod = PyImport_Import(py_modname);
-	Py_DECREF(py_modname);
-
+	py_mod = py_import_by_name("traceback");
 	if (!py_mod)
 		goto cleanup;
 

libsigrokdecode-internal.h

@@ -96,6 +96,7 @@ SRD_PRIV PyObject *srd_logic_type_new(void);
 PyMODINIT_FUNC PyInit_sigrokdecode(void);
 
 /* util.c */
+SRD_PRIV PyObject *py_import_by_name(const char *name);
 SRD_PRIV int py_attr_as_str(PyObject *py_obj, const char *attr, char **outstr);
 SRD_PRIV int py_dictitem_as_str(PyObject *py_obj, const char *key, char **outstr);
 SRD_PRIV int py_str_as_str(PyObject *py_str, char **outstr);

util.c

@@ -21,6 +21,32 @@
 #include <config.h>
 #include "libsigrokdecode-internal.h" /* First, so we avoid a _POSIX_C_SOURCE warning. */
 
+/**
+ * Import a Python module by name.
+ *
+ * This function is implemented in terms of PyImport_Import() rather than
+ * PyImport_ImportModule(), so that the import hooks are not bypassed.
+ *
+ * @param[in] name The name of the module to load as UTF-8 string.
+ * @return The Python module object, or NULL if an exception occurred. The
+ *  caller is responsible for evaluating and clearing the Python error state.
+ *
+ * @private
+ */
+SRD_PRIV PyObject *py_import_by_name(const char *name)
+{
+	PyObject *py_mod, *py_modname;
+
+	py_modname = PyUnicode_FromString(name);
+	if (!py_modname)
+		return NULL;
+
+	py_mod = PyImport_Import(py_modname);
+	Py_DECREF(py_modname);
+
+	return py_mod;
+}
+
 /**
  * Get the value of a Python object's attribute, returned as a newly
  * allocated char *.
@@ -196,6 +222,8 @@ SRD_PRIV int py_strseq_to_char(PyObject *py_strseq, char ***out_strv)
  *
  * @param[in] py_obj The Python object. Must not be NULL.
  * @return A floating reference to a new variant, or NULL on failure.
+ *
+ * @private
  */
 SRD_PRIV GVariant *py_obj_to_variant(PyObject *py_obj)
 {