util: bitmap: Note that shrinking the bitmap requires clearing of unused bits

Note the fact that the unused portion of the last element in the bitmap
needs to be cleared, since we use functions which process only full-size
elements and don't really deal with individual bits.

diff --git a/src/util/virbitmap.c b/src/util/virbitmap.c
index 82b1f76427b6d2a62288fbb601af8e332f0b4a4b..0cc5292d8c4e19dc45d95b69e56f704b0e6abccc 100644 (file)
--- a/src/util/virbitmap.c
+++ b/src/util/virbitmap.c
@@ -45,6 +45,10 @@ struct _virBitmap {
     size_t nbits;
     size_t map_len;
     size_t map_alloc;
+
+    /* Note that code below depends on the fact that unused bits of the bitmap
+     * are not set. Any function decreasing the size of the map needs clear
+     * bits which don't belong to the bitmap any more. */
     unsigned long *map;
 };