On 2/16/22 15:27, Adrian Moreno wrote: > Multi-variable loop iterators avoid potential undefined behavior by > using an internal iterator variable to perform the iteration and only > referencing the containing object (via OBJECT_CONTAINING) if the > iterator has been validated via the second expression of the for > statement. > > That way, the user can easily implement a loop that never tries to > obtain the object containing NULL or stack-allocated non-contained > nodes. > > When the loop ends normally (not via "break;") the user-provided > variable is set to NULL. > > Signed-off-by: Adrian Moreno <amore...@redhat.com> > ---
Hi Adrian, It feels a bit weird that these new macros are not used anywhere yet (until we apply the next patches in the series). On the other hand I don't think it's easy to split the series otherwise so, with a small nit below: Acked-by: Dumitru Ceara <dce...@redhat.com> Thanks, Dumitru > include/openvswitch/util.h | 44 ++++++++++++++++++++++++++++++++++++++ > 1 file changed, 44 insertions(+) > > diff --git a/include/openvswitch/util.h b/include/openvswitch/util.h > index 228b185c3..9c09e8aea 100644 > --- a/include/openvswitch/util.h > +++ b/include/openvswitch/util.h > @@ -145,6 +145,50 @@ OVS_NO_RETURN void ovs_assert_failure(const char *, > const char *, const char *); > #define INIT_CONTAINER(OBJECT, POINTER, MEMBER) \ > ((OBJECT) = NULL, ASSIGN_CONTAINER(OBJECT, POINTER, MEMBER)) > > + Nit: We don't need this extra line. > +/* Multi-variable container iterators. > + * > + * The following macros facilitate safe iteration over data structures > + * contained in objects. It does so by using an internal iterator variable of > + * the type of the member object pointer (i.e: pointer to the data > structure). > + */ > + > +/* Multi-variable iterator variable name. > + * Returns the name of the internal iterator variable. > + */ > +#define ITER_VAR(NAME) NAME ## __iterator__ > + > +/* Multi-variable initialization. Creates an internal iterator variable that > + * points to the provided pointer. The type of the iterator variable is > + * ITER_TYPE*. It must be the same type as &VAR->MEMBER. > + * > + * The _EXP version evaluates the extra expressions once. > + */ > +#define INIT_MULTIVAR(VAR, MEMBER, POINTER, ITER_TYPE) \ > + INIT_MULTIVAR_EXP(VAR, MEMBER, POINTER, ITER_TYPE, (void) 0) > + > +#define INIT_MULTIVAR_EXP(VAR, MEMBER, POINTER, ITER_TYPE, ...) \ > + ITER_TYPE *ITER_VAR(VAR) = ( __VA_ARGS__ , (ITER_TYPE *) POINTER) > + > +/* Multi-variable condition. > + * Evaluates the condition expression (that must be based on the internal > + * iterator variable). Only if the result of expression is true, the OBJECT > is > + * set to the object containing the current value of the iterator variable. > + * > + * It is up to the caller to make sure it is safe to run OBJECT_CONTAINING on > + * the pointers that verify the condition. > + */ > +#define CONDITION_MULTIVAR(VAR, MEMBER, EXPR) > \ > + ((EXPR) ? > \ > + (((VAR) = OBJECT_CONTAINING(ITER_VAR(VAR), VAR, MEMBER)), 1) : > \ > + (((VAR) = NULL), 0)) > + > +/* Multi-variable update. > + * Evaluates the expresssion that is supposed to update the iterator > variable. > + */ > +#define UPDATE_MULTIVAR(VAR, EXPR) > \ > + ((EXPR), (VAR) = NULL) > + > /* Returns the number of elements in ARRAY. */ > #define ARRAY_SIZE(ARRAY) __ARRAY_SIZE(ARRAY) > _______________________________________________ dev mailing list d...@openvswitch.org https://mail.openvswitch.org/mailman/listinfo/ovs-dev
