Fix race in g_cancellable_cancel()

We need to check priv->cancelled after taking the lock. Previously we
only checked it just before taking the lock, which left a small chance
for a race.

diff --git a/gio/gcancellable.c b/gio/gcancellable.c
index 2d600c9..32d01ae 100644 (file)
--- a/gio/gcancellable.c
+++ b/gio/gcancellable.c
@@ -622,6 +622,11 @@ g_cancellable_cancel (GCancellable *cancellable)
   priv = cancellable->priv;
 
   G_LOCK(cancellable);
+  if (priv->cancelled)
+    {
+      G_UNLOCK (cancellable);
+      return;
+    }
 
   priv->cancelled = TRUE;
   priv->cancelled_running = TRUE;