MDL-36721 do not store passwords in config logs

lib/adminlib.php

@@ -1660,11 +1660,21 @@ abstract class admin_setting {
             rebuild_course_cache(0, true);
         }
 
-        add_to_config_log($name, $oldvalue, $value, $this->plugin);
+        $this->add_to_config_log($name, $oldvalue, $value);
 
         return true; // BC only
     }
 
+    /**
+     * Log config changes if necessary.
+     * @param string $name
+     * @param string $oldvalue
+     * @param string $value
+     */
+    protected function add_to_config_log($name, $oldvalue, $value) {
+        add_to_config_log($name, $oldvalue, $value, $this->plugin);
+    }
+
     /**
      * Returns current value of this setting
      * @return mixed array or string depending on instance, NULL means not set yet
@@ -2161,6 +2171,22 @@ class admin_setting_configpasswordunmask extends admin_setting_configtext {
         parent::__construct($name, $visiblename, $description, $defaultsetting, PARAM_RAW, 30);
     }
 
+    /**
+     * Log config changes if necessary.
+     * @param string $name
+     * @param string $oldvalue
+     * @param string $value
+     */
+    protected function add_to_config_log($name, $oldvalue, $value) {
+        if ($value !== '') {
+            $value = '********';
+        }
+        if ($oldvalue !== '' and $oldvalue !== null) {
+            $oldvalue = '********';
+        }
+        parent::add_to_config_log($name, $oldvalue, $value);
+    }
+
     /**
      * Returns XHTML for the field
      * Writes Javascript into the HTML below right before the last div