Re: [Qemu-devel] [Nbd] [PATCH] Further tidy-up on block status

[Wouter Verhelst <w@uter.be>]

On Thu, Dec 15, 2016 at 04:32:23PM +0000, Alex Bligh wrote:
> Wouter,
> 
> > This reads a bit awkward. I would do:
> > 
> > s/save that:/except as explained below/
> 
> Possibly a British English thing. Will fix.

It's mostly that the "save that:" suggests to me that the exception
follows immediately (i.e., in the next paragraph). As you wrote it, it
doesn't; it shows up in the paragraph after that, with a "however"
clause. This was very confusing; I had to read it several times before I
understood what you wanted to say.

> >>    If one or more queries are sent, then the server MUST return
> >>    those metadata contexts that are available to the client to
> >>    select on the given export with `NBD_OPT_SET_META_CONTEXT`,
> >>    and which match one or more of the queries given. The
> >>    support of wildcarding within the leaf-name portion of
> >>    the query string is dependent upon the namespace.
> >> 
> >>    In either case, however, for any given namespace the
> >>    server MAY, instead of exhaustively listing every
> >>    matching context available to select (or every context
> >>    available to select where no query is given), send
> >>    sufficient context records back to allow a client with
> >>    knowledge of the namespace to select any context. Each
> >>    namespace returned MUST still satisfy the rules for
> >>    namespaces (i.e. they must begin with the relevant
> >>    namespace, followed by a colon, then printable non-whitespace
> >>    UTF-8 characters,
> > 
> > Why restrict to non-whitespace characters? (printable makes sense...)
> 
> Because the namespaces and leaf-names are already restricted to
> non-whitespace characters. I thought having tabs, line feeds,
> returns, em-space, en-space etc. was not particularly useful.
> I could be persuaded to relent re spaces.

I could imagine that the context might include as part of its name a
user-defined bit. If we're going to disallow whitespace, then that would
mean namespaces would have to do all sorts of escaping etc. I don't
think that's a good idea.

-- 
< ron> I mean, the main *practical* problem with C++, is there's like a dozen
       people in the world who think they really understand all of its rules,
       and pretty much all of them are just lying to themselves too.
 -- #debian-devel, OFTC, 2016-02-12