Re: [PATCH 6/6] ptrlist: change return value of linearize_ptr_list()/ptr_list_to_array()

[Luc Van Oostenryck <luc.vanoostenryck@gmail.com>]

On Sat, Mar 06, 2021 at 04:43:21PM +0000, Ramsay Jones wrote:
> On 06/03/2021 10:05, Luc Van Oostenryck wrote:
> > Change this, so that this function returns the total number of
> > entries in the list, much like it's done for snprintf().
> 
> But this requires setting max == 0, right? This isn't documented.

No no, there is nothing special with max == 0 at the interface level.
If the list contains 3 elements but you're only interested in the cases
it contains 2, you now call:
	... array[2];
	int nbr = linearize_ptr_list(list, array, 2);
and it'll only fill 2 elements but it will return 3, so can you write:
	if (nbr == 2) {
		... do stuff ...
	}
IOW, it returns the number of elements that would have been written
to the array if 'max' would have been infinite.

Previously, it would have returned 2 because the return value was
capped to 'max' / it returned he number of elements written. So you
had no idea if the list effectively contained only 2 elements of if
there was some more and so you had to call it with one extra element
to check this:
	... array[3];
	int nbr = linearize_ptr_list(list, array, 3);
	if (nbr == 2) {
		...
	}

Thanks for noticing all these typos,
-- Luc