Allow a configuration to be pre-loaded as if from a file

With a dynamic configuration, it is not desirable to load from literal files
By storing a configuration object against a filepath, subsequent calls to
getConfig work transparently, bypassing the disk load step.

lib/SimpleSAML/Configuration.php

@@ -194,6 +194,35 @@ class SimpleSAML_Configuration implements \SimpleSAML\Utils\ClearableState
         self::$configDirs[$configSet] = $path;
     }
 
+    /**
+     * Store a pre-initialized configuration.
+     *
+     * Allows consumers to create configuration objects without having them
+     * loaded from a file.
+     *
+     * @param SimpleSAML_Configuration $config  The configuration object to store
+     * @param string $filename  The name of the configuration file.
+     * @param string $configSet  The configuration set. Optional, defaults to 'simplesaml'.
+     */
+    public static function setPreLoadedConfig(SimpleSAML_Configuration $config, $filename = 'config.php', $configSet = 'simplesaml')
+    {
+        assert(is_string($filename));
+        assert(is_string($configSet));
+
+        if (!array_key_exists($configSet, self::$configDirs)) {
+            if ($configSet !== 'simplesaml') {
+                throw new Exception('Configuration set \'' . $configSet . '\' not initialized.');
+            } else {
+                self::$configDirs['simplesaml'] = dirname(dirname(dirname(__FILE__))) . '/config';
+            }
+        }
+
+        $dir = self::$configDirs[$configSet];
+        $filePath = $dir . '/' . $filename;
+
+        self::$loadedConfigs[$filePath] = $config;
+    }
+
 
     /**
      * Load a configuration file from a configuration set.