Fix/avoid serving expired file (#562)

* Preventing serving expired cache, when directly serving file

* Preventing serving expired cache, when directly serving file

* Fix spaces in new code

Minor change: Fix indention of new code, and add spaces in code.

wp-cache-phase2.php

@@ -104,6 +104,7 @@ function wp_cache_serve_cache_file() {
 		}
 	} else { // no $cache_file
 		global $wpsc_save_headers;
+		global $cache_max_time;
 		// last chance, check if a supercache file exists. Just in case .htaccess rules don't work on this host
 		$filename = supercache_filename();
 		$file = get_current_url_supercache_dir() . $filename;
@@ -119,6 +120,9 @@ function wp_cache_serve_cache_file() {
 		} elseif ( isset( $wpsc_save_headers ) && $wpsc_save_headers ) {
 			wp_cache_debug( 'Saving headers. Cannot serve a supercache file.' );
 			return false;
+		} elseif ( ( filemtime( $file ) + $cache_max_time ) < time() ) {
+			wp_cache_debug( sprintf( "Cache has expired and is older than %d seconds old.", $cache_max_time ) );
+			return false;
 		}
 
 		if ( isset( $wp_cache_mfunc_enabled ) == false )