list: fix list_replace() for empty lists

Before, it would happily copy list_head next/prev (ie. pointer to the
*from* list_head), leaving things in a confused state and causing much
mayhem.

Signed-off-by: Rob Clark <robdclark@gmail.com>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>

1 files changed, 10 insertions, 4 deletions

diff --git a/src/util/list.h b/src/util/list.h
index f0dec5d..e8a99ac 100644
--- a/src/util/list.h
+++ b/src/util/list.h
@@ -71,12 +71,18 @@ static inline void list_addtail(struct list_head *item, struct list_head *list)
     list->prev = item;
 }
 
+static inline bool list_empty(struct list_head *list);
+
 static inline void list_replace(struct list_head *from, struct list_head *to)
 {
-    to->prev = from->prev;
-    to->next = from->next;
-    from->next->prev = to;
-    from->prev->next = to;
+    if (list_empty(from)) {
+        list_inithead(to);
+    } else {
+        to->prev = from->prev;
+        to->next = from->next;
+        from->next->prev = to;
+        from->prev->next = to;
+    }
 }
 
 static inline void list_del(struct list_head *item)