Add error checking to dbus_py_variant_level_get() and call sites.

3 files changed, 27 insertions, 3 deletions

diff --git a/_dbus_bindings/abstract.c b/_dbus_bindings/abstract.c
index af2ea8e..3fdf286 100644
--- a/_dbus_bindings/abstract.c
+++ b/_dbus_bindings/abstract.c
@@ -44,17 +44,33 @@ dbus_py_variant_level_get(PyObject *obj)
 {
     PyObject *vl_obj;
     PyObject *key = PyLong_FromVoidPtr(obj);
+    long variant_level;
 
     if (!key) {
-        return 0;
+        return -1;
     }
 
     vl_obj = PyDict_GetItem(_dbus_py_variant_levels, key);
     Py_CLEAR(key);
 
-    if (!vl_obj)
+    if (!vl_obj) {
+        /* PyDict_GetItem() does not set an exception when the key is missing.
+         * In our case, it just means that there was no entry in the variant
+         * dictionary for this object.  Semantically, this is equivalent to a
+         * variant level of 0.
+         */
         return 0;
-    return PyInt_AsLong(vl_obj);
+    }
+    variant_level = PyInt_AsLong(vl_obj);
+    if (variant_level == -1 && PyErr_Occurred()) {
+        /* variant_level < 0 can never be inserted into the dictionary; see
+         * dbus_py_variant_level_set() below.  The semantics of setting
+         * variant_level < 0 is to delete it from the dictionary.
+         */
+        return -1;
+    }
+    assert(variant_level >= 0);
+    return variant_level;
 }
 
 dbus_bool_t
diff --git a/_dbus_bindings/containers.c b/_dbus_bindings/containers.c
index f74476c..86a7675 100644
--- a/_dbus_bindings/containers.c
+++ b/_dbus_bindings/containers.c
@@ -519,7 +519,11 @@ Struct_tp_repr(PyObject *self)
     if (!sig) sig = Py_None;
     sig_repr = PyObject_Repr(sig);
     if (!sig_repr) goto finally;
+
     variant_level = dbus_py_variant_level_get(self);
+    if (variant_level < 0)
+        goto finally;
+    
     if (variant_level > 0) {
         my_repr = PyUnicode_FromFormat("%s(%V, signature=%V, "
                                        "variant_level=%ld)",
diff --git a/_dbus_bindings/message-append.c b/_dbus_bindings/message-append.c
index 587195f..ea12a7d 100644
--- a/_dbus_bindings/message-append.c
+++ b/_dbus_bindings/message-append.c
@@ -171,6 +171,10 @@ _signature_string_from_pyobject(PyObject *obj, long *variant_level_ptr)
 {
     PyObject *magic_attr;
     long variant_level = get_variant_level(obj);
+
+    if (variant_level < 0)
+        return NULL;
+
     if (variant_level_ptr) {
         *variant_level_ptr = variant_level;
     }