From: Peter Krempa <pkrempa@redhat.com>
Date: Thu, 17 Oct 2024 11:55:23 +0000 (+0200)
Subject: util: bitmap: Rewrite virBitmapShrink using new helpers
X-Git-Tag: v10.9.0-rc1~27
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=7cbe9e94c443a6961dd1e4a5d474163405644281;p=thirdparty%2Flibvirt.git

util: bitmap: Rewrite virBitmapShrink using new helpers

Rather than reimplement everything manually use virBitmapBuffsize to
find the current number of units, realloc the buffer and clear the tail
using virBitmapClearTail().

This fixes a corner case where the buffer would be over-allocated by one
unit when shrinking to the boundary of the unit size.

Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Jiri Denemark <jdenemar@redhat.com>
---

diff --git a/src/util/virbitmap.c b/src/util/virbitmap.c
index 35cf729a22..138c1ac5af 100644
--- a/src/util/virbitmap.c
+++ b/src/util/virbitmap.c
@@ -1187,33 +1187,13 @@ void
 virBitmapShrink(virBitmap *map,
                 size_t b)
 {
-    size_t toremove;
-    size_t nl = 0;
-    size_t nb = 0;
-
-    if (!map)
-        return;
-
-    if (map->nbits >= b)
-        map->nbits = b;
-
-    nl = map->nbits / VIR_BITMAP_BITS_PER_UNIT;
-    nb = map->nbits % VIR_BITMAP_BITS_PER_UNIT;
-
-    /* If we're at the end of the allocation the attempt to clear 'map->nbit'
-     * and further would be beyond the end of the bitmap */
-    if (nl >= map->map_alloc)
+    if (!map ||
+        map->nbits <= b)
         return;
 
-    map->map[nl] &= ((1UL << nb) - 1);
-
-    toremove = map->map_alloc - (nl + 1);
-
-    if (toremove == 0)
-        return;
-
-    VIR_SHRINK_N(map->map, map->map_alloc, toremove);
-
-    /* length needs to be fixed as well */
-    map->map_len = map->map_alloc;
+    map->nbits = b;
+    map->map_len = virBitmapBuffsize(b);
+    map->map = g_renew(unsigned long, map->map, map->map_len);
+    map->map_alloc = map->map_len;
+    virBitmapClearTail(map);
 }