REST API: sub-requests must always use dispatch.

Props xknown, johnbillion, joehoyle, jorbin, sergeybiryukov, ehtis, desrosj.

git-svn-id: https://develop.svn.wordpress.org/trunk@62769 602fd350-edb4-49c9-b593-d223f7449a82

Author: desrosj

src/wp-includes/rest-api.php

@@ -450,6 +450,15 @@ function rest_api_loaded() {
 		return;
 	}
 
+	// Short-circuit before define()/die() if a REST dispatch is already in flight.
+	// serve_request() enforces this too; guarding here avoids the trailing die().
+	if ( isset( $GLOBALS['wp_rest_server'] )
+		&& $GLOBALS['wp_rest_server'] instanceof WP_REST_Server
+		&& $GLOBALS['wp_rest_server']->is_dispatching()
+	) {
+		return;
+	}
+
 	// Return an error message if query_var is not a string.
 	if ( ! is_string( $GLOBALS['wp']->query_vars['rest_route'] ) ) {
 		$rest_type_error = new WP_Error(

src/wp-includes/rest-api/class-wp-rest-server.php

@@ -283,6 +283,12 @@ protected function get_json_encode_options( WP_REST_Request $request ) {
 	 * @return null|false Null if not served and a HEAD request, false otherwise.
 	 */
 	public function serve_request( $path = null ) {
+		// Refuse to start a fresh top-level REST cycle while another dispatch
+		// is already in flight. Internal sub-requests must use dispatch().
+		if ( $this->is_dispatching() ) {
+			return false;
+		}
+
 		/* @var WP_User|null $current_user */
 		global $current_user;