Re: [Qemu-devel] [PATCH V2 5/8] block/qcow2: read and write the compress format extension

["Daniel P. Berrange" <berrange@redhat.com>]

On Thu, Jul 13, 2017 at 05:00:39PM +0200, Peter Lieven wrote:
> Am 13.07.2017 um 16:58 schrieb Daniel P. Berrange:
> > On Thu, Jul 13, 2017 at 04:18:13PM +0200, Peter Lieven wrote:
> > > Okay, so it has to be a mix of QAPI parsing and manual parameter checking,
> > > right?
> > Yeah. It does feel like a valid RFE for QAPI to add a permitted range to
> > 'int' types though, which would simplify the code in future.
> > 
> > > I currently have the following:
> > > 
> > >      options = qemu_opts_to_qdict(opts, NULL);
> > >      qdict_extract_subqdict(options, &compressopts, "compress.");
> > >      v = qobject_input_visitor_new_keyval(QOBJECT(compressopts));
> > >      visit_start_struct(v, NULL, NULL, 0, &local_err);
> > >      if (local_err) {
> > >          ret= -EINVAL;
> > >          goto finish;
> > >      }
> > >      visit_type_Qcow2Compress_members(v, &compress, &local_err);
> > >      if (local_err) {
> > >          ret= -EINVAL;
> > >          goto finish;
> > >      }
> > >      visit_end_struct(v, NULL);
> > >      visit_free(v);
> > >      QDECREF(compressopts);
> > >      QDECREF(options)
> > Looks good.
> > 
> > > And I have the following 2 questions:
> > >   a) I have to specifiy compress.format and compress.level otherwise I will get an error. How can I fix that the settings are optional?
> > Put an '*' as the first character of any field name if it should be optional.
> > 
> > >   b) If I just specify a compress.format can I default the compress.level to 0 without an error?
> > I believe you'd get compress.level as 0 automatically for an 'int' type.
> 
> I still face the issue that I now always have to specify a compress.format.
> I tried to solve it like this:

[snip]

that's not needed if you name the parameter '*level' in the QAPI schema

Regards,
Daniel
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