libudev: always return NULL in _unref() APIs

Returning anything else but NULL would suggest the caller's reference
might still be valid, but it isn't, because the caller just invoked
_unref() after all.

This turns the return value into a typesafe shortcut that allows
unreffing and resetting a reference in one line. In contrast to
solutions for this which take a pointer to a pointer to accomplish the
same this solution is just syntactic sugar the developer can make use of
but doesn't have to, and this is particularly useful when immediately
unreffing objects returned by function calls.

1 files changed, 2 insertions, 2 deletions

diff --git a/src/libudev/libudev-monitor.c b/src/libudev/libudev-monitor.c
index 24efdc65e2..56a6c5e39a 100644
--- a/src/libudev/libudev-monitor.c
+++ b/src/libudev/libudev-monitor.c
@@ -408,7 +408,7 @@ _public_ struct udev_monitor *udev_monitor_ref(struct udev_monitor *udev_monitor
  * the bound socket will be closed, and the resources of the monitor
  * will be released.
  *
- * Returns: the passed udev monitor if it has still an active reference, or #NULL otherwise.
+ * Returns: #NULL
  **/
 _public_ struct udev_monitor *udev_monitor_unref(struct udev_monitor *udev_monitor)
 {
@@ -416,7 +416,7 @@ _public_ struct udev_monitor *udev_monitor_unref(struct udev_monitor *udev_monit
                 return NULL;
         udev_monitor->refcount--;
         if (udev_monitor->refcount > 0)
-                return udev_monitor;
+                return NULL;
         if (udev_monitor->sock >= 0)
                 close(udev_monitor->sock);
         udev_list_cleanup(&udev_monitor->filter_subsystem_list);