Re: [libvirt] [RFC] Defining firmware (OVMF, et al) metadata format & file
On 04/06/18 20:10, Eric Blake wrote:
On 04/06/2018 12:28 PM, Laszlo Ersek wrote:
> I've created an RFC-level "qapi/firmware.json" schema file, based on
> this discussion. It "builds", and the generated documentation looks
> acceptable, superficially speaking.
>
> Before I post "qapi/firmware.json" for getting comments, I'd like to
> write JSON text that (a) describes firmware that I use, and (b)
> conforms to the schema. IOW, I'd like to validate whether the schema
> is good enough for describing at least such firmware that I know.
>
> Is there a tool that generates example JSON objects from a given
> schema?
I know the QMP shell (scripts/qmp/qmp-shell) lets you enter commands
with a lot less typing than full JSON, and has a mode where it will
then echo the full JSON command it constructed from what you typed. To
be able to quickly validate examples, it may be sufficient to
temporarily add a new QMP command 'check-firmware':
{ 'command': 'check-firmware', 'boxed': true, 'data':
'Firmware' }
assuming 'Firmware' is your top-level 'struct' in the QAPI file, then
implement a trivial:
qmp_check_firmware(Firmware *obj, Error **errp) {
return 0;
}
so that you can then run QMP shell, and type:
check-firmware arg1=foo arg2=bar ...
which will then generate the corresponding JSON, then either
successfully do nothing (what you typed validated, AND you have the
JSON output printed), or print an error (what you typed failed QAPI
validation, perhaps because it had an unrecognized key, was missing a
required key, used a wrong type, etc).
> I vaguely recall there used to be one. Otherwise, writing the
> examples manually looks arduous (and I wouldn't know how to verify
> them against the schema).
Similarly, if you generate a command the produces a 'Firmware' as the
return value, then you can populate the generated C struct (since you
did manage to run the QAPI generator over your new file, you should be
able to look at the C struct it generated), then output that over QMP
to show the counterpart JSON that matches the struct as populated.
The top level structure is complex / nested, but that doesn't appear to
be an issue. According to the script,
# key=value pairs also support Python or JSON object literal subset notations,
# without spaces. Dictionaries/objects {} are supported as are arrays [].
#
# example-command
arg-name1={'key':'value','obj'={'prop':"value"}}
#
# Both JSON and Python formatting should work, including both styles of
# string literal quotes. Both paradigms of literal values should work,
# including null/true/false for JSON and None/True/False for Python.
This looks awesome, because it should let me provide messy nested input
(which I'll obviously compose in my $EDITOR and then paste it), and then
the QMP shell will both validate and pretty print that. I'm going to try
this.
Thank you, Eric!
Laszlo