On Mon, 2022-08-15 at 17:47 -0700, Jakub Kicinski wrote:
> On Mon, 15 Aug 2022 22:09:11 +0200 Johannes Berg wrote:
> > On Wed, 2022-08-10 at 19:23 -0700, Jakub Kicinski wrote:
> > >
> > > + attributes:
> > > + description: List of attributes in the space.
> > > + type: array
> > > + items:
> > > + type: object
> > > + required: [ name, type ]
> > > + additionalProperties: False
> > > + properties:
> > > + name:
> > > + type: string
> > > + type: &attr-type
> > > + enum: [ unused, flag, binary, u8, u16, u32, u64, s32, s64,
> > > + nul-string, multi-attr, nest, array-nest, nest-type-value ]
> >
> > nest-type-value?
>
> It's the incredibly inventive nesting format used in genetlink policy
> dumps where the type of the sub-attr(s there are actually two levels)
> carry a value (index of the policy and attribute) rather than denoting
> a type :S :S :S
Hmm, OK, in the policy dump (not specific to genetlink, btw, can be used
for any policy, but is only generically hooked up for genetlink), we
have
[policy_idx] = {
[attr_idx] = {
[NL_POLICY_TYPE_ATTR_...] = ...
}
}
Is that what you mean?
I guess I never really thought about this format much from a description
POV, no need to have a policy since you simply iterate (for_each_attr)
when reading it, and don't really need to care about the attribute
index, at least.
For future reference, how would you suggest to have done this instead?
> > > + description:
> > > + description: Documentation of the attribute.
> > > + type: string
> > > + type-value:
> > > + description: Name of the value extracted from the type of a nest-type-value attribute.
> > > + type: array
> > > + items:
> > > + type: string
> > > + len:
> > > + oneOf: [ { type: string }, { type: integer }]
> > > + sub-type: *attr-type
> > > + nested-attributes:
> > > + description: Name of the space (sub-space) used inside the attribute.
> > > + type: string
> >
> > Maybe expand that description a bit, it's not really accurate for
> > "array-nest"?
>
> Slightly guessing but I think I know what you mean -> the value of the
> array is a nest with index as the type and then inside that is the
> entry of the array with its attributes <- and that's where the space is
> applied, not at the first nest level?
Right.
> Right, I should probably put that in the docs rather than the schema,
> array-nests are expected to strip one layer of nesting and put the
> value taken from the type (:D) into an @idx member of the struct
> representing the values of the array. Or at least that's what I do in
> the C codegen.
Well mostly you're not supposed to care about the 'value'/'type', I
guess?
> Not that any of these beautiful, precious formats should be encouraged
> going forward. multi-attr all the way!
multi-attr?
> > Do you mean the "name of the enumeration" or the "name of the
> > enumeration constant"? (per C99 concepts) I'm a bit confused? I guess
> > you mean the "name of the enumeration constant" though I agree most
> > people probably don't know the names from C99 (I had to look them up too
> > for the sake of being precise here ...)
>
> I meant the type. I think. When u32 carries values of an enum.
> Enumeration constant for the attribute type is constructed from
> it's name and the prefix/suffix kludge.
>
Indeed, I confused myself too ...
johannes
