adlist: fix listJoin() to handle empty lists.

MrGoogol · May 3, 2017 · 79226cb · 79226cb
1 parent 6798736
commit 79226cb
Showing 1 changed file with 8 additions and 2 deletions.
diff --git a/src/adlist.c b/src/adlist.c
@@ -345,8 +345,14 @@ void listRotate(list *list) {
 /* Add all the elements of the list 'o' at the end of the
  * list 'l'. The list 'other' remains empty but otherwise valid. */
 void listJoin(list *l, list *o) {
- l->tail->next = o->head;
- o->head->prev = l->tail;
+ if (o->head)
+ o->head->prev = l->tail;
+
+ if (l->tail)
+ l->tail->next = o->head;
+ else
+ l->head = o->head;
+
  l->tail = o->tail;
 
  /* Setup other as an empty list. */