diff -r be944660c56a -r 3d72ae0968f4 wp/wp-includes/rest-api/endpoints/class-wp-rest-edit-site-export-controller.php
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/wp/wp-includes/rest-api/endpoints/class-wp-rest-edit-site-export-controller.php	Tue Sep 27 16:37:53 2022 +0200
@@ -0,0 +1,94 @@
+<?php
+/**
+ * REST API: WP_REST_Edit_Site_Export_Controller class
+ *
+ * @package    WordPress
+ * @subpackage REST_API
+ */
+
+/**
+ * Controller which provides REST endpoint for exporting current templates
+ * and template parts.
+ *
+ * @since 5.9.0
+ *
+ * @see WP_REST_Controller
+ */
+class WP_REST_Edit_Site_Export_Controller extends WP_REST_Controller {
+
+	/**
+	 * Constructor.
+	 *
+	 * @since 5.9.0
+	 */
+	public function __construct() {
+		$this->namespace = 'wp-block-editor/v1';
+		$this->rest_base = 'export';
+	}
+
+	/**
+	 * Registers the site export route.
+	 *
+	 * @since 5.9.0
+	 */
+	public function register_routes() {
+		register_rest_route(
+			$this->namespace,
+			'/' . $this->rest_base,
+			array(
+				array(
+					'methods'             => WP_REST_Server::READABLE,
+					'callback'            => array( $this, 'export' ),
+					'permission_callback' => array( $this, 'permissions_check' ),
+				),
+			)
+		);
+	}
+
+	/**
+	 * Checks whether a given request has permission to export.
+	 *
+	 * @since 5.9.0
+	 *
+	 * @return WP_Error|true True if the request has access, or WP_Error object.
+	 */
+	public function permissions_check() {
+		if ( current_user_can( 'edit_theme_options' ) ) {
+			return true;
+		}
+
+		return new WP_Error(
+			'rest_cannot_export_templates',
+			__( 'Sorry, you are not allowed to export templates and template parts.' ),
+			array( 'status' => rest_authorization_required_code() )
+		);
+	}
+
+	/**
+	 * Output a ZIP file with an export of the current templates
+	 * and template parts from the site editor, and close the connection.
+	 *
+	 * @since 5.9.0
+	 *
+	 * @return WP_Error|void
+	 */
+	public function export() {
+		// Generate the export file.
+		$filename = wp_generate_block_templates_export_file();
+
+		if ( is_wp_error( $filename ) ) {
+			$filename->add_data( array( 'status' => 500 ) );
+
+			return $filename;
+		}
+
+		$theme_name = basename( get_stylesheet() );
+		header( 'Content-Type: application/zip' );
+		header( 'Content-Disposition: attachment; filename=' . $theme_name . '.zip' );
+		header( 'Content-Length: ' . filesize( $filename ) );
+		flush();
+		readfile( $filename );
+		unlink( $filename );
+		exit;
+	}
+}