Re: [Qemu-devel] [PATCH 1/8] qdict: fix unbounded stack for qdict_array_entries

[Daniel P. Berrange]

On Tue, Mar 08, 2016 at 05:30:31PM +0100, Kevin Wolf wrote:
> Am 08.03.2016 um 17:21 hat Eric Blake geschrieben:
> > On 03/08/2016 03:19 AM, Kevin Wolf wrote:
> > > Am 08.03.2016 um 09:22 hat Markus Armbruster geschrieben:
> > >> Cc: Kevin, because he added the array in question.
> > >>
> > >> Peter Xu <address@hidden> writes:
> > >>
> > 
> > >> Unrelated to your patch: I think we've pushed QDict use father than
> > >> sensible.  Encoding multiple keys in a string so you can use a flat
> > >> associative array as your catch-all data structure is appropriate in
> > >> AWK, but in C?  Not so much...
> > > 
> > > We'll always to that, because it's the command line syntax. What you may
> > > criticise is that we convert QAPI objects to the command line
> > > representation instead of the other way around, but changing that (which
> > > I think would be far from trivial, for relatively little use) wouldn't
> > > get rid of this kind of key parsing, but just move it a bit closer to
> > > the command line handling.
> > 
> > I actually WANT us to try that conversion (a great GSoC project, if
> > someone wants it) for 2.7.  We already did it for SocketAddress, and it
> > makes the code easier to maintain when you can just access foo->data
> > instead of doing qdict_lookup(foo, "data") all over the place.
> 
> I think you're underestimating the difference in difficulty between
> using SocketAddress everywhere and using BlockdevOptions everywhere,
> which is the reason why I never even put it on my todo list.
> 
> Of course, I would be fine with your trying anyway, but it would
> probably be fairer if we not let a poor student fail with this.

I think a more sensible/practical first step would be to change the block
layer to using the nested QDicts as its primary representation, instead
of the flat QDicts. In APIs which get a flat qdict (CLI QemuOpts & HMP),
it should really immediately crumple it into a nested QDict before usage.

Regards,
Daniel
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