bindings/python: Handle import failures without crashing

When the import of gi.repository.GLib failed, we would get a NULL
pointer that we passed along without any checking. In this situation,
the entire program would crash with a segmentation fault, and no
message to indicate the problem.

When the import fails, abort the SWIG init and print a message. The
Python interpreter then prints out a backtrace, which can be useful
in tracking down the problem.

diff --git a/bindings/python/sigrok/core/classes.i b/bindings/python/sigrok/core/classes.i
index 12e7df32ca58fb932f14931874f2e7baa4e2f81d..2afe579124196e42f7782c95da099dc2e8c858f9 100644 (file)
--- a/bindings/python/sigrok/core/classes.i
+++ b/bindings/python/sigrok/core/classes.i
@@ -45,9 +45,11 @@ which provides access to the error code and description."
 %module(docstring=DOCSTRING) classes
 
 %{
+#include <stdio.h>
 #include <pygobject.h>
 #include <numpy/arrayobject.h>
 
+PyObject *PyGObject_lib;
 PyObject *GLib;
 PyTypeObject *IOChannel;
 PyTypeObject *PollFD;
@@ -63,8 +65,18 @@ typedef guint pyg_flags_type;
 %}
 
 %init %{
-    pygobject_init(-1, -1, -1);
+    PyGObject_lib = pygobject_init(-1, -1, -1);
+    if (!PyGObject_lib)
+        fprintf(stderr, "pygobject initialization failed.\n");
     GLib = PyImport_ImportModule("gi.repository.GLib");
+    /*
+     * This check can't save us if the import fails, but at least it gives us
+     * a starting point to trace the issue versus straight out crashing.
+     */
+    if (!GLib) {
+        fprintf(stderr, "Import of gi.repository.GLib failed.\n");
+        return;
+    }
     IOChannel = (PyTypeObject *) PyObject_GetAttrString(GLib, "IOChannel");
     PollFD = (PyTypeObject *) PyObject_GetAttrString(GLib, "PollFD");
     import_array();