Re: [Qemu-devel] [PATCH v3 8/9] qga: process_event() simplification

[Michael Roth]

Quoting Marc-André Lureau (2018-08-25 08:57:23)
> Simplify the code around qmp_dispatch():
> - rely on qmp_dispatch/check_obj() for message checking
> - have a single send_response() point
> - constify send_response() argument
> 
> It changes a couple of error messages:
> 
> * When @req isn't a dictionary, from
>     Invalid JSON syntax
>   to
>     QMP input must be a JSON object
> 
> * When @req lacks member "execute", from
>     this feature or command is not currently supported
>   to
>     QMP input lacks member 'execute'
> 
> CC: Michael Roth <address@hidden>
> Signed-off-by: Marc-André Lureau <address@hidden>
> ---
>  qga/main.c | 47 +++++++++--------------------------------------
>  1 file changed, 9 insertions(+), 38 deletions(-)
> 
> diff --git a/qga/main.c b/qga/main.c
> index 6d70242d05..f0ec035996 100644
> --- a/qga/main.c
> +++ b/qga/main.c
> @@ -544,15 +544,15 @@ fail:
>  #endif
>  }
> 
> -static int send_response(GAState *s, QDict *payload)
> +static int send_response(GAState *s, const QDict *rsp)
>  {
>      const char *buf;
>      QString *payload_qstr, *response_qstr;
>      GIOStatus status;
> 
> -    g_assert(payload && s->channel);
> +    g_assert(rsp && s->channel);
> 
> -    payload_qstr = qobject_to_json(QOBJECT(payload));
> +    payload_qstr = qobject_to_json(QOBJECT(rsp));
>      if (!payload_qstr) {
>          return -EINVAL;
>      }
> @@ -578,53 +578,24 @@ static int send_response(GAState *s, QDict *payload)
>      return 0;
>  }
> 
> -static void process_command(GAState *s, QDict *req)
> -{
> -    QDict *rsp;
> -    int ret;
> -
> -    g_assert(req);
> -    g_debug("processing command");
> -    rsp = qmp_dispatch(&ga_commands, QOBJECT(req), false);
> -    if (rsp) {
> -        ret = send_response(s, rsp);
> -        if (ret < 0) {
> -            g_warning("error sending response: %s", strerror(-ret));
> -        }
> -        qobject_unref(rsp);
> -    }

We used to check here for the success-response=false scenario (e.g.
guest-shutdown qga command). Now we pass the result of qmp_dispatch()
directly to send_response(), which looks like that might cause an
assertion now. Do we need to add handling for this?

> -}
> -
>  /* handle requests/control events coming in over the channel */
>  static void process_event(void *opaque, QObject *obj, Error *err)
>  {
>      GAState *s = opaque;
> -    QDict *req, *rsp;
> +    QDict *rsp;
>      int ret;
> 
>      g_debug("process_event: called");
>      assert(!obj != !err);
>      if (err) {
> -        goto err;
> -    }
> -    req = qobject_to(QDict, obj);
> -    if (!req) {
> -        error_setg(&err, "Input must be a JSON object");
> -        goto err;
> -    }
> -    if (!qdict_haskey(req, "execute")) {
> -        g_warning("unrecognized payload format");
> -        error_setg(&err, QERR_UNSUPPORTED);
> -        goto err;
> +        rsp = qmp_error_response(err);
> +        goto end;
>      }
> 
> -    process_command(s, req);
> -    qobject_unref(obj);
> -    return;
> +    g_debug("processing command");
> +    rsp = qmp_dispatch(&ga_commands, obj, false);
> 
> -err:
> -    g_warning("failed to parse event: %s", error_get_pretty(err));
> -    rsp = qmp_error_response(err);
> +end:
>      ret = send_response(s, rsp);
>      if (ret < 0) {
>          g_warning("error sending error response: %s", strerror(-ret));
> -- 
> 2.18.0.547.g1d89318c48
>