qom: Clean up fragile use of error_is_set() in set() methods
Using error_is_set(ERRP) to find out whether a function failed is
either wrong, fragile, or unnecessarily opaque. It's wrong when ERRP
may be null, because errors go undetected when it is. It's fragile
when proving ERRP non-null involves a non-local argument. Else, it's
unnecessarily opaque (see commit 84d18f0).
I guess the error_is_set(errp) in the ObjectProperty set() methods are
merely fragile right now, because I can't find a call chain that
passes a null errp argument.
Make the code more robust and more obviously correct: receive the
error in a local variable, then propagate it through the parameter.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Andreas Färber <afaerber@suse.de>
diff --git a/backends/rng.c b/backends/rng.c
index 8b8d5a4..0f2fc11 100644
--- a/backends/rng.c
+++ b/backends/rng.c
@@ -50,6 +50,7 @@
{
RngBackend *s = RNG_BACKEND(obj);
RngBackendClass *k = RNG_BACKEND_GET_CLASS(s);
+ Error *local_err = NULL;
if (value == s->opened) {
return;
@@ -61,12 +62,14 @@
}
if (k->opened) {
- k->opened(s, errp);
+ k->opened(s, &local_err);
+ if (local_err) {
+ error_propagate(errp, local_err);
+ return;
+ }
}
- if (!error_is_set(errp)) {
- s->opened = value;
- }
+ s->opened = true;
}
static void rng_backend_init(Object *obj)
