MDL-44707 block_html: copy files when copying instance

blocks/html/block_html.php

@@ -104,6 +104,23 @@ function instance_delete() {
         return true;
     }
 
+    /**
+     * Copy any block-specific data when copying to a new block instance.
+     * @param int $fromid the id number of the block instance to copy from
+     * @return boolean
+     */
+    public function instance_copy($fromid) {
+        $fromcontext = context_block::instance($fromid);
+        $fs = get_file_storage();
+        // This extra check if file area is empty adds one query if it is not empty but saves several if it is.
+        if (!$fs->is_area_empty($fromcontext->id, 'block_html', 'content', 0, false)) {
+            $draftitemid = 0;
+            file_prepare_draft_area($draftitemid, $fromcontext->id, 'block_html', 'content', 0, array('subdirs' => true));
+            file_save_draft_area_files($draftitemid, $this->context->id, 'block_html', 'content', 0, array('subdirs' => true));
+        }
+        return true;
+    }
+
     function content_is_trusted() {
         global $SCRIPT;