Use json encoded data to avoid serialization issues.

Author: peterwilsoncc

src/wp-includes/collaboration/class-wp-sync-post-meta-storage.php

@@ -79,7 +79,8 @@ public function add_update( string $room, $update ): bool {
 			return false;
 		}
 
-		$meta_id = add_post_meta( $post_id, self::SYNC_UPDATE_META_KEY, $update, false );
+		$update  = wp_json_encode( $update );
+		$meta_id = add_post_meta( $post_id, wp_slash( self::SYNC_UPDATE_META_KEY ), wp_slash( $update ), false );
 
 		return (bool) $meta_id;
 	}
@@ -266,7 +267,7 @@ public function get_updates_after_cursor( string $room, int $cursor ): array {
 
 		$updates = array();
 		foreach ( $rows as $row ) {
-			$updates[] = maybe_unserialize( $row->meta_value );
+			$updates[] = json_decode( $row->meta_value, true );
 		}
 
 		return $updates;

tests/phpunit/tests/rest-api/rest-sync-server.php

@@ -670,7 +670,7 @@ private function inject_update(): void {
 				add_post_meta(
 					$this->storage_post_id,
 					WP_Sync_Post_Meta_Storage::SYNC_UPDATE_META_KEY,
-					$this->injected_update,
+					wp_slash( wp_json_encode( $this->injected_update ) ),
 					false
 				);
 			}