Clear opcode caches after writing to the config file, fixes #3372

lib/config.php

@@ -187,7 +187,7 @@ class OC_Config{
 		}
 		// Prevent others not to read the config
 		@chmod($filename, 0640);
-
+		OC_Util::clearOpcodeCache();
 		return true;
 	}
 }

lib/util.php

@@ -822,5 +822,24 @@ class OC_Util {
 		return $theme;
 	}
 
+	/**
+	 * Clear the opcode cache if one exists
+	 * This is necessary for writing to the config file
+	 * in case the opcode cache doesn't revalidate files
+	 */
+	public static function clearOpcodeCache() {
+		// APC
+		if (function_exists('apc_clear_cache')) {
+			apc_clear_cache();
+		}
+		// Zend Opcache
+		if (function_exists('accelerator_reset')) {
+			accelerator_reset();
+		}
+		// XCache
+		if (function_exists('xcache_clear_cache')) {
+			xcache_clear_cache(XC_TYPE_VAR, 0);
+		}
+	}
 
 }