Re: [Qemu-devel] [PATCH v3] add input-send-event command

[Eric Blake <eblake@redhat.com>]

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On 09/29/2014 12:56 PM, Marcelo Tosatti wrote:
> 
> Which allows specification of absolute/relative,
> up/down and console parameters.
> 
> Suggested by Gerd Hoffman.
> 
> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
> 
> ---
>  qapi-schema.json | 17 +++++++++++++++
>  qmp-commands.hx  | 63 +++++++++++++++++++++++++++++++++++++++++++++++++++++
>  ui/input.c       | 31 ++++++++++++++++++++++++++
>  3 files changed, 111 insertions(+)
> 
> diff --git a/qapi-schema.json b/qapi-schema.json
> index 4bfaf20..2e9e261 100644
> --- a/qapi-schema.json
> +++ b/qapi-schema.json
> @@ -3233,6 +3233,23 @@
>                'abs'     : 'InputMoveEvent' } }
>  
>  ##
> +# @input-send-event
> +#
> +# Send input event(s) to guest.
> +#
> +# @console: Which console to send event(s) to.
> +#
> +# @events: List of InputEvent union.
> +#
> +# Returns: Nothing on success.
> +#
> +# Since: 2.2
> +#
> +##
> +{ 'command': 'input-send-event',
> +  'data': { 'console':'int', 'events': [ 'InputEvent' ] } }

'console' is mandatory; I guess that's okay.

Are we guaranteed that either all events are sent? Or is there a need to
worry about partial success (on a list of 3 events, the first gets sent,
then some error is encountered on the second, and the third is not
attempted)?  Are the only errors due to something that can be detected
up front (such as trying to send a mouse event to a console that has
only keyboard support)?


> +The consoles are visible in the qom tree, under
> +/backend/console[$index]. They have a device link and head property, so
> +its possible to map which console belongs to which device and display.

s/its/it's/ (or 'it is')


> +void qmp_input_send_event(int64_t console, InputEventList *events,
> +                          Error **errp)
> +{
> +    InputEventList *e;
> +    QemuConsole *con;
> +
> +    con = qemu_console_lookup_by_index(console);
> +    if (!con) {
> +        error_setg(errp, "console %" PRId64 " not found", console);
> +        return;
> +    }
> +
> +    if (!runstate_is_running() && !runstate_check(RUN_STATE_SUSPENDED)) {
> +        error_setg(errp, "VM not running");
> +        return;
> +    }
> +
> +    for (e = events; e != NULL; e = e->next) {
> +        InputEvent *event = e->value;
> +
> +        if (!qemu_input_find_handler(1 << event->kind, con)) {
> +            error_setg(errp, "Input handler not found for "
> +                             "event type %s",
> +                            InputEventKind_lookup[event->kind]);
> +            return;


Ouch. You can return mid-loop.  I'd be more comfortable with a two-pass
algorithm (first pass ensures all list elements have a handler, second
actually calls qemu_input_event_send) or with a return that gives an
integer count of how many list items were processed.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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