shared/c-list: re-import from latest c-util/c-list

$ git subtree pull --prefix shared/c-list/ git@github.com:c-util/c-list.git 071841c28d96e9104761af815a7ea367390c3174 --squash

shared/c-list/src/c-list.h

@@ -366,6 +366,25 @@ static inline CList *c_list_last(CList *list) {
              _iter = (_safe),                                                   \
              _safe = c_list_entry((_safe)->_m.next, __typeof__(*_iter), _m))    \
 
+/**
+ * c_list_flush() - flush all entries from a list
+ * @list:               list to flush
+ *
+ * This unlinks all entries from the given list @list and reinitializes their
+ * link-nodes via C_LIST_INIT().
+ *
+ * Note that the entries are not modified in any other way, nor is their memory
+ * released. This function just unlinks them and resets all the list nodes. It
+ * is particularly useful with temporary lists on the stack in combination with
+ * the GCC-extension __attribute__((__cleanup__(arg))).
+ */
+static inline void c_list_flush(CList *list) {
+        CList *iter, *safe;
+
+        c_list_for_each_safe_unlink(iter, safe, list)
+                /* empty */ ;
+}
+
 /**
  * c_list_length() - return number of linked entries, excluding the head
  * @list:               list to operate on

shared/c-list/src/test-api.c

@@ -26,6 +26,7 @@ static void test_api(void) {
         assert(c_list_length(&list) == 0);
         assert(c_list_contains(&list, &list));
         assert(!c_list_contains(&list, &node.link));
+        c_list_flush(&list);
 
         /* basic link / unlink calls */
 

shared/c-list/src/test-basic.c

@@ -157,9 +157,28 @@ static void test_splice(void) {
         assert(c_list_last(&target) == &e2);
 }
 
+static void test_flush(void) {
+        CList e1 = C_LIST_INIT(e1), e2 = C_LIST_INIT(e2);
+
+        {
+                __attribute__((__cleanup__(c_list_flush))) CList list1 = C_LIST_INIT(list1);
+                __attribute__((__cleanup__(c_list_flush))) CList list2 = C_LIST_INIT(list2);
+
+                c_list_link_tail(&list2, &e1);
+                c_list_link_tail(&list2, &e2);
+
+                assert(c_list_is_linked(&e1));
+                assert(c_list_is_linked(&e2));
+        }
+
+        assert(!c_list_is_linked(&e1));
+        assert(!c_list_is_linked(&e2));
+}
+
 int main(int argc, char **argv) {
         test_iterators();
         test_swap();
         test_splice();
+        test_flush();
         return 0;
 }