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bitmap: fix bitmap_equal on bitmaps with unset bits

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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.
This commit is contained in:
Martin Mikkelsen
2015-07-31 18:56:35 +02:00
parent aba8a9d1d2
commit d5fa819958
2 changed files with 22 additions and 3 deletions
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13
src/basic/bitmap.c
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@@ -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;
}