Re: [Qemu-devel] [PATCH 8/9] QMP: Introduce qmp_check_input_obj()

[Markus Armbruster <armbru@redhat.com>]

Luiz Capitulino <lcapitulino@redhat.com> writes:

> This is similar to qmp_check_client_args(), but checks if
> the input object follows the specification (QMP/qmp-spec.txt
> section 2.3).
>
> As we're limited to three keys, the work here is quite simple:
> we iterate over the input object, each time checking if the
> given argument complies to the specification.
>
> Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
> ---
>  monitor.c |   45 +++++++++++++++++++++++++++++++++++++++++++++
>  1 files changed, 45 insertions(+), 0 deletions(-)
>
> diff --git a/monitor.c b/monitor.c
> index 1875731..654b193 100644
> --- a/monitor.c
> +++ b/monitor.c
> @@ -4271,6 +4271,45 @@ static int qmp_check_client_args(const mon_cmd_t *cmd, QDict *client_args)
>      return res.result;
>  }
>  
> +/*
> + * Input object checking rules
> + *
> + * 1. "execute" key must exist (not checked here)
> + * 2. "execute" key must be a string
> + * 3. "arguments" key must be a dict
> + * 4. "id" key can be anything (ie. json-value)

Really?  Checking qmp-spec.txt... yes, really.  Is it a good idea to
permit objects and arrays?

> + * 5. Any argument not listed above is invalid
> + */
> +static void qmp_check_input_obj(const char *input_obj_arg_name,
> +                                QObject *input_obj_arg, void *opaque)
> +{
> +    int *err = opaque;
> +
> +    if (*err < 0) {
> +        /* report only the first error */
> +        return;
> +    }
> +
> +    if (!strcmp(input_obj_arg_name, "execute")) {
> +        if (qobject_type(input_obj_arg) != QTYPE_QSTRING) {
> +            qerror_report(QERR_QMP_BAD_INPUT_OBJECT_MEMBER, "execute",
> +                          "string");
> +            *err = -1;
> +        }
> +    } else if (!strcmp(input_obj_arg_name, "arguments")) {
> +        if (qobject_type(input_obj_arg) != QTYPE_QDICT) {
> +            qerror_report(QERR_QMP_BAD_INPUT_OBJECT_MEMBER, "arguments",
> +                          "object");
> +            *err = -1;
> +        }
> +    } else if (!strcmp(input_obj_arg_name, "id")) {
> +        /* nothing to do */
> +    } else {
> +        qerror_report(QERR_QMP_INVALID_INPUT_OBJECT_MEMBER, input_obj_arg_name);
> +        *err = -1;
> +    }
> +}
> +
>  static void handle_qmp_command(JSONMessageParser *parser, QList *tokens)
>  {
>      int err;
> @@ -4295,6 +4334,12 @@ static void handle_qmp_command(JSONMessageParser *parser, QList *tokens)
>  
>      input = qobject_to_qdict(obj);
>  
> +    err = 0;
> +    qdict_iter(input, qmp_check_input_obj, &err);
> +    if (err < 0) {
> +        goto err_out;
> +    }
> +
>      mon->mc->id = qdict_get(input, "id");
>      qobject_incref(mon->mc->id);

More contortions caused by iterator use...