Fix error handling of LDAPControl_to_List() (#89)

LDAPControls_to_List() may have returned a partly filled list
in case Py_BuildValue() fails.
In case of an error, DECREF the list and return NULL.

https://github.com/python-ldap/python-ldap/pull/89
Closes: https://github.com/python-ldap/python-ldap/issues/22
Signed-off-by: Christian Heimes <cheimes@redhat.com>

CHANGES

@@ -34,6 +34,7 @@ Modules/
 * Fix reference leak in result4
 * Fix several compiler warnings
 * Fix memory leak in whoami
+* Fix internal error handling of LDAPControl_to_List()
 and, thanks to Michael Ströder:
 * removed unused code schema.c
 * moved code from version.c to ldapmodule.c

Modules/ldapcontrol.c

@@ -172,22 +172,21 @@ LDAPControls_to_List(LDAPControl **ldcs)
     if (tmp)
         while (*tmp++) num_ctrls++;
 
-    if (!(res = PyList_New(num_ctrls)))
-        goto endlbl;
+    if ((res = PyList_New(num_ctrls)) == NULL) {
+        return NULL;
+    }
 
     for (i = 0; i < num_ctrls; i++) {
-        if (!(pyctrl = Py_BuildValue("sbO&", ldcs[i]->ldctl_oid,
-                                     ldcs[i]->ldctl_iscritical,
-                                     LDAPberval_to_object,
-                                     &ldcs[i]->ldctl_value))) {
-            goto endlbl;
+        pyctrl = Py_BuildValue("sbO&",
+                               ldcs[i]->ldctl_oid,
+                               ldcs[i]->ldctl_iscritical,
+                               LDAPberval_to_object, &ldcs[i]->ldctl_value);
+        if (pyctrl == NULL) {
+            Py_DECREF(res);
+            return NULL;
         }
         PyList_SET_ITEM(res, i, pyctrl);
     }
-    Py_INCREF(res);
-
- endlbl:
-    Py_XDECREF(res);
     return res;
 }