qemu-img: Factor out code for merging bitmaps

The next patch will add another client that wants to merge dirty
bitmaps; it will be easier to refactor the code to construct the QAPI
struct correctly into a helper function.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20200521192137.1120211-4-eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

qemu-img.c

@@ -1638,6 +1638,24 @@ out4:
     return ret;
 }
 
+/* Convenience wrapper around qmp_block_dirty_bitmap_merge */
+static void do_dirty_bitmap_merge(const char *dst_node, const char *dst_name,
+                                  const char *src_node, const char *src_name,
+                                  Error **errp)
+{
+    BlockDirtyBitmapMergeSource *merge_src;
+    BlockDirtyBitmapMergeSourceList *list;
+
+    merge_src = g_new0(BlockDirtyBitmapMergeSource, 1);
+    merge_src->type = QTYPE_QDICT;
+    merge_src->u.external.node = g_strdup(src_node);
+    merge_src->u.external.name = g_strdup(src_name);
+    list = g_new0(BlockDirtyBitmapMergeSourceList, 1);
+    list->value = merge_src;
+    qmp_block_dirty_bitmap_merge(dst_node, dst_name, list, errp);
+    qapi_free_BlockDirtyBitmapMergeSourceList(list);
+}
+
 enum ImgConvertBlockStatus {
     BLK_DATA,
     BLK_ZERO,
@@ -4714,21 +4732,11 @@ static int img_bitmap(int argc, char **argv)
             qmp_block_dirty_bitmap_disable(bs->node_name, bitmap, &err);
             op = "disable";
             break;
-        case BITMAP_MERGE: {
-            BlockDirtyBitmapMergeSource *merge_src;
-            BlockDirtyBitmapMergeSourceList *list;
-
-            merge_src = g_new0(BlockDirtyBitmapMergeSource, 1);
-            merge_src->type = QTYPE_QDICT;
-            merge_src->u.external.node = g_strdup(src_bs->node_name);
-            merge_src->u.external.name = g_strdup(act->src);
-            list = g_new0(BlockDirtyBitmapMergeSourceList, 1);
-            list->value = merge_src;
-            qmp_block_dirty_bitmap_merge(bs->node_name, bitmap, list, &err);
-            qapi_free_BlockDirtyBitmapMergeSourceList(list);
+        case BITMAP_MERGE:
+            do_dirty_bitmap_merge(bs->node_name, bitmap, src_bs->node_name,
+                                  act->src, &err);
             op = "merge";
             break;
-        }
         default:
             g_assert_not_reached();
         }