1 #if !defined(_BLKID_LIST_H) && !defined(LIST_HEAD_INIT)
2 #define _BLKID_LIST_H
3
4 #ifdef __cplusplus
5 extern "C" {
6 #endif
7
8 #ifdef HAVE_INTTYPES_H
9 #include <inttypes.h>
10 #else
11 #ifdef HAVE_STDINT_H
12 #include <stdint.h>
13 #endif
14 #endif
15
16 #ifdef __GNUC__
17 #define _INLINE_ static __inline__
18 #else /* For Watcom C */
19 #define _INLINE_ static inline
20 #endif
21
22 /*
23 * Simple doubly linked list implementation.
24 *
25 * Some of the internal functions ("__xxx") are useful when
26 * manipulating whole lists rather than single entries, as
27 * sometimes we already know the next/prev entries and we can
28 * generate better code by using them directly rather than
29 * using the generic single-entry routines.
30 */
31
32 struct list_head {
33 struct list_head *next, *prev;
34 };
35
36 #define LIST_HEAD_INIT(name) { &(name), &(name) }
37
38 #define INIT_LIST_HEAD(ptr) do { \
39 (ptr)->next = (ptr); (ptr)->prev = (ptr); \
40 } while (0)
41
42 /*
43 * Insert a new entry between two known consecutive entries.
44 *
45 * This is only for internal list manipulation where we know
46 * the prev/next entries already!
47 */
__list_add(struct list_head * add,struct list_head * prev,struct list_head * next)48 _INLINE_ void __list_add(struct list_head * add,
49 struct list_head * prev,
50 struct list_head * next)
51 {
52 next->prev = add;
53 add->next = next;
54 add->prev = prev;
55 prev->next = add;
56 }
57
58 /**
59 * list_add - add a new entry
60 * @add: new entry to be added
61 * @head: list head to add it after
62 *
63 * Insert a new entry after the specified head.
64 * This is good for implementing stacks.
65 */
list_add(struct list_head * add,struct list_head * head)66 _INLINE_ void list_add(struct list_head *add, struct list_head *head)
67 {
68 __list_add(add, head, head->next);
69 }
70
71 /**
72 * list_add_tail - add a new entry
73 * @add: new entry to be added
74 * @head: list head to add it before
75 *
76 * Insert a new entry before the specified head.
77 * This is useful for implementing queues.
78 */
list_add_tail(struct list_head * add,struct list_head * head)79 _INLINE_ void list_add_tail(struct list_head *add, struct list_head *head)
80 {
81 __list_add(add, head->prev, head);
82 }
83
84 /*
85 * Delete a list entry by making the prev/next entries
86 * point to each other.
87 *
88 * This is only for internal list manipulation where we know
89 * the prev/next entries already!
90 */
__list_del(struct list_head * prev,struct list_head * next)91 _INLINE_ void __list_del(struct list_head * prev,
92 struct list_head * next)
93 {
94 next->prev = prev;
95 prev->next = next;
96 }
97
98 /**
99 * list_del - deletes entry from list.
100 * @entry: the element to delete from the list.
101 *
102 * list_empty() on @entry does not return true after this, @entry is
103 * in an undefined state.
104 */
list_del(struct list_head * entry)105 _INLINE_ void list_del(struct list_head *entry)
106 {
107 __list_del(entry->prev, entry->next);
108 }
109
110 /**
111 * list_del_init - deletes entry from list and reinitialize it.
112 * @entry: the element to delete from the list.
113 */
list_del_init(struct list_head * entry)114 _INLINE_ void list_del_init(struct list_head *entry)
115 {
116 __list_del(entry->prev, entry->next);
117 INIT_LIST_HEAD(entry);
118 }
119
120 /**
121 * list_empty - tests whether a list is empty
122 * @head: the list to test.
123 */
list_empty(struct list_head * head)124 _INLINE_ int list_empty(struct list_head *head)
125 {
126 return head->next == head;
127 }
128
129 /**
130 * list_splice - join two lists
131 * @list: the new list to add.
132 * @head: the place to add it in the first list.
133 */
list_splice(struct list_head * list,struct list_head * head)134 _INLINE_ void list_splice(struct list_head *list, struct list_head *head)
135 {
136 struct list_head *first = list->next;
137
138 if (first != list) {
139 struct list_head *last = list->prev;
140 struct list_head *at = head->next;
141
142 first->prev = head;
143 head->next = first;
144
145 last->next = at;
146 at->prev = last;
147 }
148 }
149
150 /**
151 * list_entry - get the struct for this entry
152 * @ptr: the &struct list_head pointer.
153 * @type: the type of the struct this is embedded in.
154 * @member: the name of the list_struct within the struct.
155 */
156 #define list_entry(ptr, type, member) \
157 ((type *)((char *)(ptr)-(unsigned long)(intptr_t)(&((type *)0)->member)))
158
159 /**
160 * list_for_each - iterate over elements in a list
161 * @pos: the &struct list_head to use as a loop counter.
162 * @head: the head for your list.
163 */
164 #define list_for_each(pos, head) \
165 for (pos = (head)->next; pos != (head); pos = pos->next)
166
167 /**
168 * list_for_each_safe - iterate over elements in a list, but don't dereference
169 * pos after the body is done (in case it is freed)
170 * @pos: the &struct list_head to use as a loop counter.
171 * @pnext: the &struct list_head to use as a pointer to the next item.
172 * @head: the head for your list (not included in iteration).
173 */
174 #define list_for_each_safe(pos, pnext, head) \
175 for (pos = (head)->next, pnext = pos->next; pos != (head); \
176 pos = pnext, pnext = pos->next)
177
178 #undef _INLINE_
179
180 #ifdef __cplusplus
181 }
182 #endif
183
184 #endif /* _BLKID_LIST_H */
185