Paolo Bonzini <pbonz...@redhat.com> writes:
> On 24/11/2015 06:22, Fam Zheng wrote:
>> case OFORMAT_JSON:
>> - printf("%s{ \"start\": %"PRId64", \"length\": %"PRId64", \"depth\":
>> %d,"
>> - " \"zero\": %s, \"data\": %s",
>> - (e->start == 0 ? "[" : ",\n"),
>> - e->start, e->length, e->depth,
>> - (e->flags & BDRV_BLOCK_ZERO) ? "true" : "false",
>> - (e->flags & BDRV_BLOCK_DATA) ? "true" : "false");
>> + if (e->start == 0) {
>> + printf("[");
>> + } else {
>> + printf(",");
>> + }
>> +
>> + dict = qdict_new();
>> + qdict_put(dict, "start", qint_from_int(e->start));
>> + qdict_put(dict, "length", qint_from_int(e->length));
>> + qdict_put(dict, "depth", qint_from_int(e->depth));
>> + qdict_put(dict, "zero", qbool_from_bool(e->flags &
>> BDRV_BLOCK_ZERO));
>> + qdict_put(dict, "data", qbool_from_bool(e->flags &
>> BDRV_BLOCK_DATA));
>> if (e->flags & BDRV_BLOCK_OFFSET_VALID) {
>> - printf(", \"offset\": %"PRId64"", e->offset);
>> + qdict_put(dict, "offset", qint_from_int(e->offset));
>> }
>> - putchar('}');
>> + str = qobject_to_json(QOBJECT(dict));
>> + printf("%s\n", qstring_get_str(str));
>
> I think it's better if you use QAPI for this. You can make MapEntry a
> QAPI struct and generate the QObject through a QMP visitor.
>
> The reason is that we could add JSON visitors that let us parse or
> produce JSON without going through the expensive QObject creation. Even
> though that is far away, the least explicit QObject manipulation we
> have, the better.
I concur.
Manual messing with QDict is of course fine when a higher-level
interface doesn't fit. But here, we serialize a struct to JSON, and
that's something QAPI is meant to do. Having to define a QAPI type may
be a bit of a bother, but once that's done, the "serialize this struct
to JSON" code becomes less tedious. qemu-img.c already has a few
examples; search for qmp_output_visitor_new().
