Implement the size of an assembly stream

This will make it possible to act propely on moves of future files if we
need to know the size (like for max size virus scanning).

Signed-off-by: Roeland Jago Douma <[email protected]>

Author: rullzer

apps/dav/lib/Upload/AssemblyStream.php

@@ -170,7 +170,13 @@ public function stream_truncate($size) {
 	 * @return array
 	 */
 	public function stream_stat() {
-		return [];
+		$size = array_reduce($this->nodes, function(int $size, IFile $node) {
+			return $size + $node->getSize();
+		}, 0);
+
+		return [
+			'size' => $size,
+		];
 	}
 
 	/**