On 11/10/2015 11:51 PM, Eric Blake wrote: > Previously, working with alternates required two lookup arrays > and some indirection: for type Foo, we created Foo_qtypes[] > which maps each qtype to a value of the generated FooKind enum, > then look up that value in FooKind_lookup[] like we do for other > union types. > > This has a couple of subtle bugs. First, the generator was > creating a call with a parameter '(int *) &(*obj)->type' where > type is an enum type; this is unsafe if the compiler chooses > to store the enum type in a different size than int, where > assigning through the wrong size pointer can corrupt data or > cause a SIGBUS.
Yuck - we still have this bug for enums:
> void visit_type_OnOffAuto(Visitor *v, OnOffAuto *obj, const char *name, Error
> **errp)
> {
> visit_type_enum(v, (int *)obj, OnOffAuto_lookup, "OnOffAuto", name, errp);
> }
I guess I just added more work to my plate.
But at the same time, no one has complained of the (int*)Enum causing
SIGBUS on any of our platforms for either enums or alternates, so while
we are doing gross things, I don't think we have to rush a fix into 2.5
for this particular bug.
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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