util: Reintroduce virBitmapSubtract

Already introduced in the past with 9479642f, but then renamed to
virBitmapIntersect by a908e9e4.  This time we'll really use it.
Signed-off-by: NMartin Kletzander <mkletzan@redhat.com>
Reviewed-by: NJohn Ferlan <jferlan@redhat.com>

src/libvirt_private.syms

@@ -1376,6 +1376,7 @@ virBitmapSetAll;
 virBitmapSetBit;
 virBitmapSetBitExpand;
 virBitmapSize;
+virBitmapSubtract;
 virBitmapToData;
 virBitmapToDataBuf;
 virBitmapToString;

src/util/virbitmap.c

@@ -1174,3 +1174,25 @@ virBitmapIntersect(virBitmapPtr a,
     for (i = 0; i < max; i++)
         a->map[i] &= b->map[i];
 }
+
+
+/**
+ * virBitmapSubtract:
+ * @a: minuend/result
+ * @b: subtrahend
+ *
+ * Performs subtraction of two bitmaps: a = a - b
+ */
+void
+virBitmapSubtract(virBitmapPtr a,
+                  virBitmapPtr b)
+{
+    size_t i;
+    size_t max = a->map_len;
+
+    if (max > b->map_len)
+        max = b->map_len;
+
+    for (i = 0; i < max; i++)
+        a->map[i] &= ~b->map[i];
+}

src/util/virbitmap.h

@@ -150,4 +150,7 @@ bool virBitmapOverlaps(virBitmapPtr b1,
 void virBitmapIntersect(virBitmapPtr a, virBitmapPtr b)
     ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2);
 
+void virBitmapSubtract(virBitmapPtr a, virBitmapPtr b)
+    ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2);
+
 #endif

tests/virbitmaptest.c

@@ -701,6 +701,39 @@ test13(const void *opaque ATTRIBUTE_UNUSED)
 
 #undef TEST_MAP
 
+static int
+test14(const void *opaque)
+{
+    const struct testBinaryOpData *data = opaque;
+    virBitmapPtr amap = NULL;
+    virBitmapPtr bmap = NULL;
+    virBitmapPtr resmap = NULL;
+    int ret = -1;
+
+    if (virBitmapParse(data->a, &amap, 256) < 0 ||
+        virBitmapParse(data->b, &bmap, 256) < 0 ||
+        virBitmapParse(data->res, &resmap, 256) < 0)
+        goto cleanup;
+
+    virBitmapSubtract(amap, bmap);
+
+    if (!virBitmapEqual(amap, resmap)) {
+        fprintf(stderr,
+                "\n bitmap subtraction failed: '%s' - '%s' != '%s'\n",
+                data->a, data->b, data->res);
+        goto cleanup;
+    }
+
+    ret = 0;
+
+ cleanup:
+    virBitmapFree(amap);
+    virBitmapFree(bmap);
+    virBitmapFree(resmap);
+
+    return ret;
+}
+
 
 #define TESTBINARYOP(A, B, RES, FUNC) \
     testBinaryOpData.a = A; \
@@ -750,6 +783,15 @@ mymain(void)
     if (virTestRun("test13", test13, NULL) < 0)
         ret = -1;
 
+    virTestCounterReset("test14-");
+    TESTBINARYOP("0", "0", "0,^0", test14);
+    TESTBINARYOP("0-3", "0", "1-3", test14);
+    TESTBINARYOP("0-3", "0,3", "1-2", test14);
+    TESTBINARYOP("0,^0", "0", "0,^0", test14);
+    TESTBINARYOP("0-3", "0-3", "0,^0", test14);
+    TESTBINARYOP("0-3", "0,^0", "0-3", test14);
+    TESTBINARYOP("0,2", "1,3", "0,2", test14);
+
     return ret;
 }