[libvirt] [PATCHv2] util: fix off-by-one when expanding a bitmap

To make sure bit 'b' fits into the bitmap, we need to allocate b+1 bits, since we number from 0. Adjust the bitmap test to set a bit at a multiple of 16. That way the test fails without this fix, because the VIR_REALLOC call clears the newly added memory even if the original pointer has not changed. --- src/util/virbitmap.c | 2 +- tests/virbitmaptest.c | 6 +++--- 2 files changed, 4 insertions(+), 4 deletions(-) v2: use a multiple of 16 instead of just 8 to actually reproduce the failure in the test. diff --git a/src/util/virbitmap.c b/src/util/virbitmap.c index 0c04f1a..1b47d74 100644 --- a/src/util/virbitmap.c +++ b/src/util/virbitmap.c @@ -187,7 +187,7 @@ int virBitmapSetBit(virBitmapPtr bitmap, size_t b) */ static int virBitmapExpand(virBitmapPtr map, size_t b) { - size_t new_len = VIR_DIV_UP(b, VIR_BITMAP_BITS_PER_UNIT); + size_t new_len = VIR_DIV_UP(b + 1, VIR_BITMAP_BITS_PER_UNIT); /* resize the memory if necessary */ if (map->map_len < new_len) { diff --git a/tests/virbitmaptest.c b/tests/virbitmaptest.c index a17ef82..3ee07ff 100644 --- a/tests/virbitmaptest.c +++ b/tests/virbitmaptest.c @@ -639,15 +639,15 @@ test12(const void *opaque ATTRIBUTE_UNUSED) TEST_MAP(0, ""); - if (virBitmapSetBitExpand(map, 100) < 0) + if (virBitmapSetBitExpand(map, 128) < 0) goto cleanup; - TEST_MAP(101, "100"); + TEST_MAP(129, "128"); if (virBitmapClearBitExpand(map, 150) < 0) goto cleanup; - TEST_MAP(151, "100"); + TEST_MAP(151, "128"); virBitmapFree(map); if (virBitmapParseUnlimited("34,1023", &map) < 0) -- 2.10.2