virbitmap: Extract and reuse buffer size calculation into a function

Calculating the number of element can come handy in multiple places,
extract it from virBitmapNew.

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 a1a8c5d1269f702e6ebcf293c5264e6832c7b990..7dc63da6dbdf52cec120e689f0cb4fa32e05b014 100644 (file)
--- a/src/util/virbitmap.c
+++ b/src/util/virbitmap.c
@@ -49,6 +49,22 @@ struct _virBitmap {
 #define VIR_BITMAP_BIT(b)         (1UL << VIR_BITMAP_BIT_OFFSET(b))
 
 
+/**
+ * Calculates and returns the number of elements in the bitmap buffer to fit @bits.
+ */
+static size_t
+virBitmapBuffsize(size_t nbits)
+{
+    if (SIZE_MAX - VIR_BITMAP_BITS_PER_UNIT < nbits) {
+        /* VIR_DIV_UP would overflow, let's overallocate by 1 entry instead of
+         * the potential overflow */
+        return (nbits / VIR_BITMAP_BITS_PER_UNIT) + 1;
+    }
+
+    return VIR_DIV_UP(nbits, VIR_BITMAP_BITS_PER_UNIT);
+}
+
+
 /**
  * virBitmapNew:
  * @size: number of bits
@@ -61,15 +77,7 @@ virBitmap *
 virBitmapNew(size_t size)
 {
     virBitmap *bitmap;
-    size_t sz;
-
-    if (SIZE_MAX - VIR_BITMAP_BITS_PER_UNIT < size) {
-        /* VIR_DIV_UP would overflow, let's overallocate by 1 entry instead of
-         * the potential overflow */
-        sz = (size / VIR_BITMAP_BITS_PER_UNIT) + 1;
-    } else {
-        sz = VIR_DIV_UP(size, VIR_BITMAP_BITS_PER_UNIT);
-    }
+    size_t sz = virBitmapBuffsize(size);
 
     bitmap = g_new0(virBitmap, 1);
 
@@ -133,7 +141,7 @@ static void
 virBitmapExpand(virBitmap *map,
                 size_t b)
 {
-    size_t new_len = VIR_DIV_UP(b + 1, VIR_BITMAP_BITS_PER_UNIT);
+    size_t new_len = virBitmapBuffsize(b + 1);
 
     /* resize the memory if necessary */
     if (map->map_len < new_len) {