Re: [Valgrind-developers] Client callback offsets for skins

[Nicholas N. <nj...@ca...>]

On 10 Oct 2002, Jeremy Fitzhardinge wrote:

> At the moment, not many skins have client callbacks (only memcheck, I
> think).  However, if other skins follow memcheck's example of starting
> callbacks at VG_USERREQ__FINAL_DUMMY_CLIENT_REQUEST + 1, they will all
> end up with overlapping numbers.
>
> This means that if a particular program under study has callbacks for
> different skins, they will end up doing the wrong thing if run with the
> wrong skin.  It seems to me that there needs to be a systematic way for
> skins to distinguish their callback numbers from each other.

Yes, good point.

> Well, since there seems to be a de-facto standard for each skin to have
> a two letter code, I implemented a scheme to use it as a way for skins
> to distinguish their client requests.
>
> I also made it not an error for a callback to be unimplemented, since
> Valgrind is getting more capable with more skins, it will be common to
> have a program with client requests inserted for multiple skins.  As
> part of this, I changed the interface to SK_(handle_client_request) so
> that a skin can indicate that it did not handle the request, so that the
> proper default return value can be returned.
>
> Patch against CVS head.

This seems like a good way to do it, although I think I'll implement it
slightly differently using a template function -- that must be defined if
the client_requests need is set -- that returns the two letter prefix.

Thanks for the good suggestion.

N