Re: [Qemu-devel] [PATCH v2 1/3] libqtest: Ignore QMP events when parsing the response for HMP commands

[John Snow <jsnow@redhat.com>]

On 03/30/2017 03:50 AM, Thomas Huth wrote:
> When running certain HMP commands (like "device_del") via QMP, we
> can sometimes get a QMP event in the response first, so that the
> "g_assert(ret)" statement in qtest_hmp() triggers and the test
> fails. Fix this by ignoring such QMP events while looking for the
> real return value from QMP.
> 
> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
>  tests/libqtest.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/tests/libqtest.c b/tests/libqtest.c
> index a5c3d2b..c9b2d76 100644
> --- a/tests/libqtest.c
> +++ b/tests/libqtest.c
> @@ -580,6 +580,12 @@ char *qtest_hmpv(QTestState *s, const char *fmt, va_list ap)
>                       " 'arguments': {'command-line': %s}}",
>                       cmd);
>      ret = g_strdup(qdict_get_try_str(resp, "return"));
> +    while (ret == NULL && qdict_get_try_str(resp, "event")) {
> +        /* Ignore asynchronous QMP events */
> +        QDECREF(resp);
> +        resp = qtest_qmp_receive(s);
> +        ret = g_strdup(qdict_get_try_str(resp, "return"));
> +    }
>      g_assert(ret);
>      QDECREF(resp);
>      g_free(cmd);
> 

You've probably been asked this, but can you just shove the QMP response
you don't want into the event queue for consumption by other calls?

--js