Fix: Do correct error handling in 'PyObject_GetAttrString'.

Author: fangerer

graalpython/com.oracle.graal.python.cext/src/object.c

@@ -592,7 +592,11 @@ int PyObject_Print(PyObject* object, FILE* fd, int flags) {
 }
 
 PyObject* PyObject_GetAttrString(PyObject* obj, const char* attr) {
-    return to_sulong(truffle_read(to_java(obj), truffle_read_string(attr)));
+    void* result = polyglot_invoke(PY_TRUFFLE_CEXT, "PyObject_GetAttr", to_java(obj), polyglot_from_string(attr, "utf-8"));
+    if (result == ERROR_MARKER) {
+        return NULL;
+    }
+    return to_sulong(result);
 }
 
 int PyObject_SetAttrString(PyObject* obj, const char* attr, PyObject* value) {

graalpython/lib-graalpython/python_cext.py

@@ -787,6 +787,11 @@ def PyObject_AsFileDescriptor(obj):
     return int(result)
 
 
+@may_raise
+def PyObject_GetAttr(obj, attr):
+    return getattr(obj, attr)
+
+
 @may_raise(-1)
 def PyObject_SetAttr(obj, attr, value):
     setattr(obj, attr, value)