release/src/router/busybox/e2fsprogs/blkid/list.c

   1 /* vi: set sw=4 ts=4: */
   2
   3 #include "list.h"
   4
   5 /*
   6  * Insert a new entry between two known consecutive entries.
   7  *
   8  * This is only for internal list manipulation where we know
   9  * the prev/next entries already!
  10  */
  11 void __list_add(struct list_head * add,
  12         struct list_head * prev,
  13         struct list_head * next)
  14 {
  15         next->prev = add;
  16         add->next = next;
  17         add->prev = prev;
  18         prev->next = add;
  19 }
  20
  21 /*
  22  * list_add - add a new entry
  23  * @add:        new entry to be added
  24  * @head:       list head to add it after
  25  *
  26  * Insert a new entry after the specified head.
  27  * This is good for implementing stacks.
  28  */
  29 void list_add(struct list_head *add, struct list_head *head)
  30 {
  31         __list_add(add, head, head->next);
  32 }
  33
  34 /*
  35  * list_add_tail - add a new entry
  36  * @add:        new entry to be added
  37  * @head:       list head to add it before
  38  *
  39  * Insert a new entry before the specified head.
  40  * This is useful for implementing queues.
  41  */
  42 void list_add_tail(struct list_head *add, struct list_head *head)
  43 {
  44         __list_add(add, head->prev, head);
  45 }
  46
  47 /*
  48  * Delete a list entry by making the prev/next entries
  49  * point to each other.
  50  *
  51  * This is only for internal list manipulation where we know
  52  * the prev/next entries already!
  53  */
  54 void __list_del(struct list_head * prev, struct list_head * next)
  55 {
  56         next->prev = prev;
  57         prev->next = next;
  58 }
  59
  60 /*
  61  * list_del - deletes entry from list.
  62  * @entry:      the element to delete from the list.
  63  *
  64  * list_empty() on @entry does not return true after this, @entry is
  65  * in an undefined state.
  66  */
  67 void list_del(struct list_head *entry)
  68 {
  69         __list_del(entry->prev, entry->next);
  70 }
  71
  72 /*
  73  * list_del_init - deletes entry from list and reinitialize it.
  74  * @entry:      the element to delete from the list.
  75  */
  76 void list_del_init(struct list_head *entry)
  77 {
  78         __list_del(entry->prev, entry->next);
  79         INIT_LIST_HEAD(entry);
  80 }
  81
  82 /*
  83  * list_empty - tests whether a list is empty
  84  * @head:       the list to test.
  85  */
  86 int list_empty(struct list_head *head)
  87 {
  88         return head->next == head;
  89 }
  90
  91 /*
  92  * list_splice - join two lists
  93  * @list:       the new list to add.
  94  * @head:       the place to add it in the first list.
  95  */
  96 void list_splice(struct list_head *list, struct list_head *head)
  97 {
  98         struct list_head *first = list->next;
  99
 100         if (first != list) {
 101                 struct list_head *last = list->prev;
 102                 struct list_head *at = head->next;
 103
 104                 first->prev = head;
 105                 head->next = first;
 106
 107                 last->next = at;
 108                 at->prev = last;
 109         }
 110 }