[Qemu-devel] [PATCH] qom: abort on error in property setter if caller passed errp == NULL

[Igor Mammedov <imammedo@redhat.com>]

in case if caller setting property doesn't care about error and
passes in NULL as errp argument but error occurs in property setter,
it is silently discarded leaving object in undefined state.

As result it leads to hard to find bugs, so if caller doesn't
care about error it must be sure that property exists and
accepts provided value, otherwise it's better to abort early
since error case couldn't be handled gracefully and find
invalid usecase early.

In addition multitude of property setters will be always
guarantied to have error object present and won't be required
to handle this condition individually.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
---
 qom/object.c | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/qom/object.c b/qom/object.c
index fc19cf6..2c0bb64 100644
--- a/qom/object.c
+++ b/qom/object.c
@@ -792,16 +792,25 @@ void object_property_get(Object *obj, Visitor *v, const char *name,
 void object_property_set(Object *obj, Visitor *v, const char *name,
                          Error **errp)
 {
-    ObjectProperty *prop = object_property_find(obj, name, errp);
-    if (prop == NULL) {
-        return;
+    Error *local_error = NULL;
+    ObjectProperty *prop = object_property_find(obj, name, &local_error);
+    if (local_error) {
+        goto out;
     }
 
     if (!prop->set) {
-        error_set(errp, QERR_PERMISSION_DENIED);
+        error_set(&local_error, QERR_PERMISSION_DENIED);
     } else {
-        prop->set(obj, v, prop->opaque, name, errp);
+        prop->set(obj, v, prop->opaque, name, &local_error);
     }
+out:
+    if (local_error) {
+        if (!errp) {
+            assert_no_error(local_error);
+        }
+        error_propagate(errp, local_error);
+    }
+
 }
 
 void object_property_set_str(Object *obj, const char *value,
-- 
1.8.3.1