On Mon, 2019-06-03 at 16:43 +0200, Ján Tomko wrote:
On Mon, Jun 03, 2019 at 04:31:51PM +0200, Andrea Bolognani wrote:
On Mon, 2019-06-03 at 14:10 +0200, Ján Tomko wrote:
if (b->nbits && a->nbits < b->nbits && virBitmapExpand(a, b->nbits -1) < 0) {
Yeah, you're right, we need to account for the zero-indexing of bits. I mean, it's not like the resulting bitmap would be incorrect either way, but we might end up allocating more memory than it's actually required.
Actually I do think it would be incorrect. The bitmap size is as important as its values - e.g. if the resulting bitmap had 4 set bits, a size of 4 vs 5 would alter the result of virBitmapIsAllSet.
Oh, right, that's something that I hadn't considered. This is pretty much exactly why I didn't trust my implementation to be correct O:-)
The first check seems unnecessary, though: the only case in which the argument to virBitmapExpand() would be incorrect is b->nbits == 0, but we know that both a->nbits and b->nbits are >= 0 and we also just verified that a->nbits < b->nbits, so b->nbits must be >= 1 and the argument to virBitmapExpand() will always be correct. Or am I missing something?
Right, it will work unless someone changes nbits from size_t to double.
So ACK to drop the first check while adopting your version of that hunk? -- Andrea Bolognani / Red Hat / Virtualization