1
2 /* Copyright 1998 by the Massachusetts Institute of Technology.
3 *
4 * Permission to use, copy, modify, and distribute this
5 * software and its documentation for any purpose and without
6 * fee is hereby granted, provided that the above copyright
7 * notice appear in all copies and that both that copyright
8 * notice and this permission notice appear in supporting
9 * documentation, and that the name of M.I.T. not be used in
10 * advertising or publicity pertaining to distribution of the
11 * software without specific, written prior permission.
12 * M.I.T. makes no representations about the suitability of
13 * this software for any purpose. It is provided "as is"
14 * without express or implied warranty.
15 */
16
17 #include "ares_setup.h"
18
19 #include "ares.h"
20 #include "ares_private.h"
21
22 /* Routines for managing doubly-linked circular linked lists with a
23 * dummy head.
24 */
25
26 /* Initialize a new head node */
ares__init_list_head(struct list_node * head)27 void ares__init_list_head(struct list_node* head) {
28 head->prev = head;
29 head->next = head;
30 head->data = NULL;
31 }
32
33 /* Initialize a list node */
ares__init_list_node(struct list_node * node,void * d)34 void ares__init_list_node(struct list_node* node, void* d) {
35 node->prev = NULL;
36 node->next = NULL;
37 node->data = d;
38 }
39
40 /* Returns true iff the given list is empty */
ares__is_list_empty(struct list_node * head)41 int ares__is_list_empty(struct list_node* head) {
42 return ((head->next == head) && (head->prev == head));
43 }
44
45 /* Inserts new_node before old_node */
ares__insert_in_list(struct list_node * new_node,struct list_node * old_node)46 void ares__insert_in_list(struct list_node* new_node,
47 struct list_node* old_node) {
48 new_node->next = old_node;
49 new_node->prev = old_node->prev;
50 old_node->prev->next = new_node;
51 old_node->prev = new_node;
52 }
53
54 /* Removes the node from the list it's in, if any */
ares__remove_from_list(struct list_node * node)55 void ares__remove_from_list(struct list_node* node) {
56 if (node->next != NULL) {
57 node->prev->next = node->next;
58 node->next->prev = node->prev;
59 node->prev = NULL;
60 node->next = NULL;
61 }
62 }
63
64