On 03/28/2016 04:06 AM, eocallag...@alterapraxis.com wrote: > Determinism is always better regardless of how you get there. A > null pointer deference `on purpose` is a really poor idea in C. > I am somewhat surprised you are asking if its really better to > rely on undefined behavior vs. an assert.
I think the more important question is how this could get hit. Asserts do not exist in release builds. If the only way the assert could get hit is by a developer enabling an extension that they didn't actually implement, it's hard to get very excited about it. > I thought about using a if branch and just returning but I think > it is better to crash deterministically with a reason rather than > perhaps fail silently. Although I do see in other places a if branch > and a return was used in similar situations so I would be willing to > do the same if I must. That's only done in cases where it is valid for the driver to not provide a callback. > On 2016-03-28 16:08, Ilia Mirkin wrote: >> When would that happen? When a user force-enables >> ARB_query_buffer_object for a driver that's not ready for it? Is >> hitting a deterministic assert in that case any better than hitting a >> null deref? >> >> On Sun, Mar 27, 2016 at 11:52 PM, Edward O'Callaghan >> <eocallag...@alterapraxis.com> wrote: >>> Just because we miss a gallium driver callback don't dereference >>> invalid memory. >>> >>> Signed-off-by: Edward O'Callaghan <eocallag...@alterapraxis.com> >>> --- >>> src/mesa/state_tracker/st_cb_queryobj.c | 1 + >>> 1 file changed, 1 insertion(+) >>> >>> diff --git a/src/mesa/state_tracker/st_cb_queryobj.c >>> b/src/mesa/state_tracker/st_cb_queryobj.c >>> index cdb9efc..e9abc38 100644 >>> --- a/src/mesa/state_tracker/st_cb_queryobj.c >>> +++ b/src/mesa/state_tracker/st_cb_queryobj.c >>> @@ -402,6 +402,7 @@ st_StoreQueryResult(struct gl_context *ctx, >>> struct gl_query_object *q, >>> index = 0; >>> } >>> >>> + assert(pipe->get_query_result_resource); >>> pipe->get_query_result_resource(pipe, stq->pq, wait, result_type, >>> index, >>> stObj->buffer, offset); >>> } >>> -- >>> 2.5.5 >>> >>> _______________________________________________ >>> mesa-dev mailing list >>> mesa-dev@lists.freedesktop.org >>> https://lists.freedesktop.org/mailman/listinfo/mesa-dev > > _______________________________________________ > mesa-dev mailing list > mesa-dev@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/mesa-dev > _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/mesa-dev
