list: fix back link in cfl_list_add_after()

include/cfl/cfl_list.h

@@ -140,7 +140,7 @@ static inline void cfl_list_add_after(struct cfl_list *_new,
     }
 
     next = prev->next;
-    next->prev = prev;
+    next->prev = _new;
     _new->next = next;
     _new->prev = prev;
     prev->next = _new;

tests/list.c

@@ -91,9 +91,65 @@ static void add()
     free(nodes);
 }
 
+static void add_after()
+{
+    int i;
+    int expected[] = {0, 1, 2, 3, 4};
+    struct cfl_list list;
+    struct cfl_list *head;
+    struct cfl_list *tmp;
+    struct node {
+        int value;
+        struct cfl_list _head;
+    };
+    struct node nodes[5];
+    struct node *node;
+
+    for (i = 0; i < 5; i++) {
+        nodes[i].value = i;
+    }
+
+    cfl_list_init(&list);
+    cfl_list_add(&nodes[0]._head, &list);
+    cfl_list_add(&nodes[2]._head, &list);
+
+    /* insert in the middle and after the tail */
+    cfl_list_add_after(&nodes[1]._head, &nodes[0]._head, &list);
+    cfl_list_add_after(&nodes[3]._head, &nodes[2]._head, &list);
+
+    /* the next entry must point back to the inserted one */
+    TEST_CHECK(nodes[2]._head.prev == &nodes[1]._head);
+    TEST_CHECK(list.prev == &nodes[3]._head);
+
+    /* a tail insert must keep the entry added after the old tail */
+    cfl_list_add(&nodes[4]._head, &list);
+
+    i = 0;
+    cfl_list_foreach(head, &list) {
+        node = cfl_list_entry(head, struct node, _head);
+        TEST_CHECK(i < 5 && node->value == expected[i]);
+        i++;
+    }
+    TEST_CHECK(i == 5);
+
+    i = 4;
+    for (head = list.prev; head != &list; head = head->prev) {
+        node = cfl_list_entry(head, struct node, _head);
+        TEST_CHECK(i >= 0 && node->value == expected[i]);
+        i--;
+    }
+    TEST_CHECK(i == -1);
+
+    cfl_list_foreach_safe(head, tmp, &list) {
+        cfl_list_del(head);
+    }
+    TEST_CHECK(cfl_list_is_empty(&list));
+}
+
 TEST_LIST = {
     {"checks",  checks},
     {"add", 	add},
+    {"add_after", add_after},
     { 0 }
 };