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3rdparty/c-ares-1.18.1/src/lib/ares_llist.c 1.82 KB
73ef4ff3   Hu Chunming   提交三方库
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  /* 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;
    }
  }