1 files changed, 63 insertions, 0 deletions
diff --git a/src/c-ares/ares_llist.c b/src/c-ares/ares_llist.c
new file mode 100644
index 000000000..36ca84c43
--- /dev/null
+++ b/src/c-ares/ares_llist.c
@@ -0,0 +1,63 @@
+
+/* Copyright 1998 by the Massachusetts Institute of Technology.
+ *
+ * Permission to use, copy, modify, and distribute this
+ * software and its documentation for any purpose and without
+ * fee is hereby granted, provided that the above copyright
+ * notice appear in all copies and that both that copyright
+ * notice and this permission notice appear in supporting
+ * documentation, and that the name of M.I.T. not be used in
+ * advertising or publicity pertaining to distribution of the
+ * software without specific, written prior permission.
+ * M.I.T. makes no representations about the suitability of
+ * this software for any purpose.  It is provided "as is"
+ * without express or implied warranty.
+ */
+
+#include "ares_setup.h"
+
+#include "ares.h"
+#include "ares_private.h"
+
+/* Routines for managing doubly-linked circular linked lists with a
+ * dummy head.
+ */
+
+/* Initialize a new head node */
+void ares__init_list_head(struct list_node* head) {
+  head->prev = head;
+  head->next = head;
+  head->data = NULL;
+}
+
+/* Initialize a list node */
+void ares__init_list_node(struct list_node* node, void* d) {
+  node->prev = NULL;
+  node->next = NULL;
+  node->data = d;
+}
+
+/* Returns true iff the given list is empty */
+int ares__is_list_empty(struct list_node* head) {
+  return ((head->next == head) && (head->prev == head));
+}
+
+/* Inserts new_node before old_node */
+void ares__insert_in_list(struct list_node* new_node,
+                          struct list_node* old_node) {
+  new_node->next = old_node;
+  new_node->prev = old_node->prev;
+  old_node->prev->next = new_node;
+  old_node->prev = new_node;
+}
+
+/* Removes the node from the list it's in, if any */
+void ares__remove_from_list(struct list_node* node) {
+  if (node->next != NULL) {
+    node->prev->next = node->next;
+    node->next->prev = node->prev;
+    node->prev = NULL;
+    node->next = NULL;
+  }
+}
+