From d5fa81995849cb263ecfcd0aa6ab661360d9213e Mon Sep 17 00:00:00 2001 From: Martin Mikkelsen Date: Fri, 31 Jul 2015 18:56:35 +0200 Subject: bitmap: fix bitmap_equal on bitmaps with unset bits Given two bitmaps and the following code: Bitmap *a = bitmap_new(), *b = bitmap_new(); bitmap_set(a, 0); bitmap_unset(a, 0); These two bitmaps should now have the same bits set and they should be equal but bitmap_equal() will return false in this case because the bitmaps array in a is larger because of the bit which was previously set. Fix this by comparing only the bits which exists in both bitmaps and then check that the rest of the bits (if any) is all zero. This also adds test code for this issue. --- src/basic/bitmap.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) (limited to 'src/basic/bitmap.c') diff --git a/src/basic/bitmap.c b/src/basic/bitmap.c index bf9d8d4d7c..e7e19b3b66 100644 --- a/src/basic/bitmap.c +++ b/src/basic/bitmap.c @@ -184,6 +184,9 @@ bool bitmap_iterate(Bitmap *b, Iterator *i, unsigned *n) { } bool bitmap_equal(Bitmap *a, Bitmap *b) { + size_t common_n_bitmaps; + Bitmap *c; + unsigned i; if (!a ^ !b) return false; @@ -191,8 +194,14 @@ bool bitmap_equal(Bitmap *a, Bitmap *b) { if (!a) return true; - if (a->n_bitmaps != b->n_bitmaps) + common_n_bitmaps = MIN(a->n_bitmaps, b->n_bitmaps); + if (memcmp(a->bitmaps, b->bitmaps, sizeof(uint64_t) * common_n_bitmaps) != 0) return false; - return memcmp(a->bitmaps, b->bitmaps, sizeof(uint64_t) * a->n_bitmaps) == 0; + c = a->n_bitmaps > b->n_bitmaps ? a : b; + for (i = common_n_bitmaps; i < c->n_bitmaps; i++) + if (c->bitmaps[i] != 0) + return false; + + return true; } -- cgit v1.2.3-54-g00ecf