Re: [Qemu-devel] [PATCH v2 2/2] vl: Partial support for non-scalar properties with -object

[Eric Blake]

On 08/11/2017 11:05 AM, Markus Armbruster wrote:
> We've wanted -object to support non-scalar properties for a while.
> Dan Berrange tried in "[PATCH v4 00/10]Provide a QOM-based
> authorization API".  Review led to the conclusion that we need to
> replace rather than add to QemuOpts.  Initial work towards that goal
> has been merged to provide -blockdev (commit 8746709), but there's
> substantial work left, mostly due to an bewildering array of
> compatibility problems.
> 
> Even if a full solution is still out of reach, we can have a partial
> solution now: accept -object argument in JSON syntax.  This should
> unblock development work that needs non-scalar properties with
> -object.
> 
> The implementation is similar to -blockdev, except we use the new
> infrastructure only for the new JSON case, and stick to QemuOpts for
> the existing KEY=VALUE,... case, to sidestep compatibility problems.
> 
> If we did this for more options, we'd have to factor out common code.
> But for one option, this will do.
> 
> Signed-off-by: Markus Armbruster <address@hidden>
> ---
>  qapi-schema.json | 14 +++++++++++---
>  vl.c             | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 62 insertions(+), 3 deletions(-)
> 
>  static void object_create(bool (*type_predicate)(const char *))
>  {
> +    ObjectOptionsQueueEntry *e, *next;
> +
> +    QSIMPLEQ_FOREACH_SAFE(e, &oo_queue, entry, next) {
> +        if (!type_predicate(e->oo->qom_type)) {
> +            continue;
> +        }
> +
> +        loc_push_restore(&e->loc);
> +        qmp_object_add(e->oo->qom_type, e->oo->id,
> +                       e->oo->has_props, e->oo->props, &error_fatal);
> +        loc_pop(&e->loc);
> +
> +        QSIMPLEQ_REMOVE(&oo_queue, e, ObjectOptionsQueueEntry, entry);
> +        qapi_free_ObjectOptions(e->oo);
> +    }
> +
>      if (qemu_opts_foreach(qemu_find_opts("object"),

This handles all JSON forms prior to any QemuOpt forms (within the two
priority levels), such that a command line using:

 -object type,id=1,oldstyle... -object '{'id':2, 'type':..., newstyle...}'

processes the arguments in a different order than

 -object type,id=1,oldstyle... -object type,id=2,oldstyle

But I don't see that as too bad (ideally, someone using the {} JSON
style will use it consistently).

Reviewed-by: Eric Blake <address@hidden>

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org

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