(list_replace): New function.

@@ -31,6 +31,7 @@ extern int list_prepend  __P ((list_t, void *item));
 extern int list_is_empty __P ((list_t));
 extern int list_count    __P ((list_t, size_t *pcount));
 extern int list_remove   __P ((list_t, void *item));
+extern int list_replace  __P ((list_t list, void *old_item, void *new_item));  
 extern int list_get      __P ((list_t, size_t _index, void **pitem));
 
 typedef int list_action_t __PMT ((void* item, void* cbdata));

@@ -151,7 +151,29 @@ list_remove (list_t list, void *item)
 	}
     }
   monitor_unlock (list->monitor);
-  return ENOENT;
+  return status;
+}
+
+int
+list_replace (list_t list, void *old_item, void *new_item)
+{
+  struct list_data *current, *previous;
+  int status = ENOENT;
+  if (list == NULL)
+    return EINVAL;
+  monitor_wrlock (list->monitor);
+  for (previous = &(list->head), current = list->head.next;
+       current != &(list->head); previous = current, current = current->next)
+    {
+      if (current->item == old_item)
+	{
+	  current->item = new_item;
+	  status = 0;
+	  break;
+	}
+    }
+  monitor_unlock (list->monitor);
+  return status;
 }
 
 /* FIXME: FIXME: FIXME: URGENT: