On 20.06.19 03:03, John Snow wrote:
> Nobody calls the function like this currently, but we neither prohibit
> or cope with this behavior. I decided to make the function cope with it.
>
> Signed-off-by: John Snow <js...@redhat.com>
> ---
> util/hbitmap.c | 9 ++++++---
> 1 file changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/util/hbitmap.c b/util/hbitmap.c
> index 7905212a8b..45d1725daf 100644
> --- a/util/hbitmap.c
> +++ b/util/hbitmap.c
> @@ -781,8 +781,9 @@ bool hbitmap_can_merge(const HBitmap *a, const HBitmap *b)
> }
>
> /**
> - * Given HBitmaps A and B, let A := A (BITOR) B.
> - * Bitmap B will not be modified.
> + * Given HBitmaps A and B, let R := A (BITOR) B.
> + * Bitmaps A and B will not be modified,
> + * except when bitmap R is an alias of A or B.
> *
> * @return true if the merge was successful,
> * false if it was not attempted.
> @@ -797,7 +798,9 @@ bool hbitmap_merge(const HBitmap *a, const HBitmap *b,
> HBitmap *result)
> }
> assert(hbitmap_can_merge(b, result));
>
> - if (hbitmap_count(b) == 0) {
> + if ((!hbitmap_count(a) && result == b) ||
> + (!hbitmap_count(b) && result == a) ||
> + (!hbitmap_count(a) && !hbitmap_count(b))) {
> return true;
> }The rest of this function completely overwrites the @result bitmap. Therefor, @result does not need to be cleared when calling this function. Therfore, hbitmap_merge(hbitmap_alloc(), hbitmap_alloc(), output) should actually clear @output, I think. Max
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