On Mon, Jul 19, 2021 at 12:40:32PM +0200, Paolo Bonzini wrote: > This new adaptor visitor takes a single field of the adaptee, and exposes it > with a different name. > > This will be used for QOM alias properties. Alias targets can of course > have a different name than the alias property itself (e.g. a machine's > pflash0 might be an alias of a property named 'drive'). When the target's > getter or setter invokes the visitor, it will use a different name than > what the caller expects, and the visitor will not be able to find it > (or will consume erroneously).
How does this differ from Kevin's attempt to add QMP aliasing, https://lists.gnu.org/archive/html/qemu-devel/2021-02/msg04097.html > > The solution is for alias getters and setters to wrap the incoming > visitor, and forward the sole field that the target is expecting while > renaming it appropriately. > > Signed-off-by: Paolo Bonzini <pbonz...@redhat.com> > --- > diff --git a/include/qapi/forward-visitor.h b/include/qapi/forward-visitor.h > new file mode 100644 > index 0000000000..c7002d53e6 > --- /dev/null > +++ b/include/qapi/forward-visitor.h > + > +typedef struct ForwardFieldVisitor ForwardFieldVisitor; > + > +/* > + * The forwarding visitor only expects a single name, @from, to be passed for > + * toplevel fields. It is converted to @to and forward to the @target > visitor. and forwarded > + * Calls within a struct are forwarded without changing the name. > + */ > +Visitor *visitor_forward_field(Visitor *target, const char *from, const char > *to); > + > +#endif > +++ b/qapi/qapi-forward-visitor.c > @@ -0,0 +1,307 @@ > +/* > + * Forward Visitor > + * > + * Copyright (C) 2021 Red Hat, Inc. > + * > + * This work is licensed under the terms of the GNU LGPL, version 2.1 or > later. > + * See the COPYING.LIB file in the top-level directory. > + * > + */ > + > +#include "qemu/osdep.h" > +#include <math.h> Did you really use math.h? > + > +static void forward_field_complete(Visitor *v, void *opaque) > +{ > + /* > + * Do nothing, the complete method will be called at due time s/at/in/ > + * on the target visitor. > + */ > +} > + > +++ b/tests/unit/test-forward-visitor.c > @@ -0,0 +1,165 @@ > +/* > + * QAPI Forwarding Visitor unit-tests. Otherwise it looks like it does what it advertises. I don't know if Markus will have any opinions, but I'm comfortable with: Reviewed-by: Eric Blake <ebl...@redhat.com> -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org
