Re: [PATCH v4 28/34] qapi: Implement deprecated-output=hide for QMP command results

[Eric Blake]

On 3/17/20 6:54 AM, Markus Armbruster wrote:
> This policy suppresses deprecated bits in output, and thus permits
> "testing the future".  Implement it for QMP command results.  Example:
> when QEMU is run with -compat deprecated-output=hide, then
>
>      {"execute": "query-cpus-fast"}
>
> yields
>
>      {"return": [{"thread-id": 9805, "props": {"core-id": 0, "thread-id": 0, "socket-id": 0}, "qom-path": 
> "/machine/unattached/device[0]", "cpu-index": 0, "target": "x86_64"}]}
>
> instead of
>
>      {"return": [{"arch": "x86", "thread-id": 22436, "props": {"core-id": 0, "thread-id": 0, "socket-id": 0}, 
> "qom-path": "/machine/unattached/device[0]", "cpu-index": 0, "target": "x86_64"}]}
>
> Note the suppression of deprecated member "arch".
>
> Signed-off-by: Markus Armbruster <address@hidden>
> ---

> +++ b/tests/test-qmp-cmds.c
> @@ -1,4 +1,5 @@
>   #include "qemu/osdep.h"
> +#include "qapi/compat-policy.h"
>   #include "qapi/qmp/qdict.h"
>   #include "qapi/qmp/qjson.h"
>   #include "qapi/qmp/qnum.h"
> @@ -45,12 +46,17 @@ void qmp_user_def_cmd1(UserDefOne * ud1, Error **errp)
>   {
>   }
>   
> -void qmp_test_features0(FeatureStruct0 *fs0, FeatureStruct1 *fs1,
> -                       FeatureStruct2 *fs2, FeatureStruct3 *fs3,
> -                       FeatureStruct4 *fs4, CondFeatureStruct1 *cfs1,
> -                       CondFeatureStruct2 *cfs2, CondFeatureStruct3 *cfs3,
> -                       Error **errp)
> +FeatureStruct1 *qmp_test_features0(bool has_fs0, FeatureStruct0 *fs0,
> +                                   bool has_fs1, FeatureStruct1 *fs1,
> +                                   bool has_fs2, FeatureStruct2 *fs2,
> +                                   bool has_fs3, FeatureStruct3 *fs3,
> +                                   bool has_fs4, FeatureStruct4 *fs4,
> +                                   bool has_cfs1, CondFeatureStruct1 *cfs1,
> +                                   bool has_cfs2, CondFeatureStruct2 *cfs2,
> +                                   bool has_cfs3, CondFeatureStruct3 *cfs3,
> +                                   Error **errp)
>   {
> +    return g_new(FeatureStruct1, 1);

Should this be using g_new0, rather than random contents?

>   }
>   
>   void qmp_test_command_features1(Error **errp)
> @@ -271,6 +277,30 @@ static void test_dispatch_cmd_io(void)
>       qobject_unref(ret3);
>   }
>   
> +static void test_dispatch_cmd_ret_deprecated(void)
> +{
> +    const char *cmd = "{ 'execute': 'test-features0' }";
> +    QDict *ret;
> +
> +    memset(&compat_policy, 0, sizeof(compat_policy));
> +
> +    /* default accept */
> +    ret = qobject_to(QDict, do_qmp_dispatch(false, cmd));
> +    assert(ret && qdict_size(ret) == 1);
> +    qobject_unref(ret);
> +
> +    compat_policy.has_deprecated_output = true;
> +    compat_policy.deprecated_output = COMPAT_POLICY_OUTPUT_ACCEPT;

Of course, if we ever enable defaults in QAPI, we can get rid of 
has_deprecated_output by recording proper defaults for bools.  But 
that's a different project ;)

> +    ret = qobject_to(QDict, do_qmp_dispatch(false, cmd));
> +    assert(ret && qdict_size(ret) == 1);
> +    qobject_unref(ret);
> +
> +    compat_policy.deprecated_output = COMPAT_POLICY_OUTPUT_HIDE;
> +    ret = qobject_to(QDict, do_qmp_dispatch(false, cmd));
> +    assert(ret && qdict_size(ret) == 0);
> +    qobject_unref(ret);
> +}
> +

Otherwise,
Reviewed-by: Eric Blake <address@hidden>

--
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org