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1 /**************************************************************************
2  *
3  * Copyright 2006 VMware, Inc., Bismarck, ND. USA.
4  * All Rights Reserved.
5  *
6  * Permission is hereby granted, free of charge, to any person obtaining a
7  * copy of this software and associated documentation files (the
8  * "Software"), to deal in the Software without restriction, including
9  * without limitation the rights to use, copy, modify, merge, publish,
10  * distribute, sub license, and/or sell copies of the Software, and to
11  * permit persons to whom the Software is furnished to do so, subject to
12  * the following conditions:
13  *
14  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
15  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
16  * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
17  * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
18  * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
19  * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
20  * USE OR OTHER DEALINGS IN THE SOFTWARE.
21  *
22  * The above copyright notice and this permission notice (including the
23  * next paragraph) shall be included in all copies or substantial portions
24  * of the Software.
25  *
26  **************************************************************************/
27 
28 /**
29  * \file
30  * List macros heavily inspired by the Linux kernel
31  * list handling. No list looping yet.
32  *
33  * Is not threadsafe, so common operations need to
34  * be protected using an external mutex.
35  */
36 
37 #ifndef _UTIL_LIST_H_
38 #define _UTIL_LIST_H_
39 
40 
41 #include <stdbool.h>
42 #include <stddef.h>
43 #include <assert.h>
44 
45 
46 struct list_head
47 {
48     struct list_head *prev;
49     struct list_head *next;
50 };
51 
list_inithead(struct list_head * item)52 static inline void list_inithead(struct list_head *item)
53 {
54     item->prev = item;
55     item->next = item;
56 }
57 
list_add(struct list_head * item,struct list_head * list)58 static inline void list_add(struct list_head *item, struct list_head *list)
59 {
60     item->prev = list;
61     item->next = list->next;
62     list->next->prev = item;
63     list->next = item;
64 }
65 
list_addtail(struct list_head * item,struct list_head * list)66 static inline void list_addtail(struct list_head *item, struct list_head *list)
67 {
68     item->next = list;
69     item->prev = list->prev;
70     list->prev->next = item;
71     list->prev = item;
72 }
73 
74 static inline bool list_empty(struct list_head *list);
75 
list_replace(struct list_head * from,struct list_head * to)76 static inline void list_replace(struct list_head *from, struct list_head *to)
77 {
78     if (list_empty(from)) {
79         list_inithead(to);
80     } else {
81         to->prev = from->prev;
82         to->next = from->next;
83         from->next->prev = to;
84         from->prev->next = to;
85     }
86 }
87 
list_del(struct list_head * item)88 static inline void list_del(struct list_head *item)
89 {
90     item->prev->next = item->next;
91     item->next->prev = item->prev;
92     item->prev = item->next = NULL;
93 }
94 
list_delinit(struct list_head * item)95 static inline void list_delinit(struct list_head *item)
96 {
97     item->prev->next = item->next;
98     item->next->prev = item->prev;
99     item->next = item;
100     item->prev = item;
101 }
102 
list_empty(struct list_head * list)103 static inline bool list_empty(struct list_head *list)
104 {
105    return list->next == list;
106 }
107 
108 /**
109  * Returns whether the list has exactly one element.
110  */
list_is_singular(const struct list_head * list)111 static inline bool list_is_singular(const struct list_head *list)
112 {
113    return list->next != NULL && list->next != list && list->next->next == list;
114 }
115 
list_length(struct list_head * list)116 static inline unsigned list_length(struct list_head *list)
117 {
118    struct list_head *node;
119    unsigned length = 0;
120    for (node = list->next; node != list; node = node->next)
121       length++;
122    return length;
123 }
124 
list_splice(struct list_head * src,struct list_head * dst)125 static inline void list_splice(struct list_head *src, struct list_head *dst)
126 {
127    if (list_empty(src))
128       return;
129 
130    src->next->prev = dst;
131    src->prev->next = dst->next;
132    dst->next->prev = src->prev;
133    dst->next = src->next;
134 }
135 
list_splicetail(struct list_head * src,struct list_head * dst)136 static inline void list_splicetail(struct list_head *src, struct list_head *dst)
137 {
138    if (list_empty(src))
139       return;
140 
141    src->prev->next = dst;
142    src->next->prev = dst->prev;
143    dst->prev->next = src->next;
144    dst->prev = src->prev;
145 }
146 
list_validate(struct list_head * list)147 static inline void list_validate(struct list_head *list)
148 {
149    struct list_head *node;
150    assert(list->next->prev == list && list->prev->next == list);
151    for (node = list->next; node != list; node = node->next)
152       assert(node->next->prev == node && node->prev->next == node);
153 }
154 
155 #define LIST_INITHEAD(__item) list_inithead(__item)
156 #define LIST_ADD(__item, __list) list_add(__item, __list)
157 #define LIST_ADDTAIL(__item, __list) list_addtail(__item, __list)
158 #define LIST_REPLACE(__from, __to) list_replace(__from, __to)
159 #define LIST_DEL(__item) list_del(__item)
160 #define LIST_DELINIT(__item) list_delinit(__item)
161 
162 #define LIST_ENTRY(__type, __item, __field)   \
163     ((__type *)(((char *)(__item)) - offsetof(__type, __field)))
164 
165 #define LIST_IS_EMPTY(__list)                   \
166     ((__list)->next == (__list))
167 
168 /**
169  * Cast from a pointer to a member of a struct back to the containing struct.
170  *
171  * 'sample' MUST be initialized, or else the result is undefined!
172  */
173 #ifndef container_of
174 #define container_of(ptr, sample, member)				\
175     (void *)((char *)(ptr)						\
176 	     - ((char *)&(sample)->member - (char *)(sample)))
177 #endif
178 
179 #define list_first_entry(ptr, type, member) \
180         LIST_ENTRY(type, (ptr)->next, member)
181 
182 #define list_last_entry(ptr, type, member) \
183         LIST_ENTRY(type, (ptr)->prev, member)
184 
185 
186 #define LIST_FOR_EACH_ENTRY(pos, head, member)				\
187    for (pos = NULL, pos = container_of((head)->next, pos, member);	\
188 	&pos->member != (head);						\
189 	pos = container_of(pos->member.next, pos, member))
190 
191 #define LIST_FOR_EACH_ENTRY_SAFE(pos, storage, head, member)	\
192    for (pos = NULL, pos = container_of((head)->next, pos, member),	\
193 	storage = container_of(pos->member.next, pos, member);	\
194 	&pos->member != (head);						\
195 	pos = storage, storage = container_of(storage->member.next, storage, member))
196 
197 #define LIST_FOR_EACH_ENTRY_SAFE_REV(pos, storage, head, member)	\
198    for (pos = NULL, pos = container_of((head)->prev, pos, member),	\
199 	storage = container_of(pos->member.prev, pos, member);		\
200 	&pos->member != (head);						\
201 	pos = storage, storage = container_of(storage->member.prev, storage, member))
202 
203 #define LIST_FOR_EACH_ENTRY_FROM(pos, start, head, member)		\
204    for (pos = NULL, pos = container_of((start), pos, member);		\
205 	&pos->member != (head);						\
206 	pos = container_of(pos->member.next, pos, member))
207 
208 #define LIST_FOR_EACH_ENTRY_FROM_REV(pos, start, head, member)		\
209    for (pos = NULL, pos = container_of((start), pos, member);		\
210 	&pos->member != (head);						\
211 	pos = container_of(pos->member.prev, pos, member))
212 
213 #define list_for_each_entry(type, pos, head, member)                    \
214    for (type *pos = LIST_ENTRY(type, (head)->next, member);             \
215 	&pos->member != (head);                                         \
216 	pos = LIST_ENTRY(type, pos->member.next, member))
217 
218 #define list_for_each_entry_safe(type, pos, head, member)               \
219    for (type *pos = LIST_ENTRY(type, (head)->next, member),             \
220 	     *__next = LIST_ENTRY(type, pos->member.next, member);      \
221 	&pos->member != (head);                                         \
222 	pos = __next,                                                   \
223         __next = LIST_ENTRY(type, __next->member.next, member))
224 
225 #define list_for_each_entry_rev(type, pos, head, member)                \
226    for (type *pos = LIST_ENTRY(type, (head)->prev, member);             \
227 	&pos->member != (head);                                         \
228 	pos = LIST_ENTRY(type, pos->member.prev, member))
229 
230 #define list_for_each_entry_safe_rev(type, pos, head, member)           \
231    for (type *pos = LIST_ENTRY(type, (head)->prev, member),             \
232 	     *__prev = LIST_ENTRY(type, pos->member.prev, member);      \
233 	&pos->member != (head);                                         \
234 	pos = __prev,                                                   \
235         __prev = LIST_ENTRY(type, __prev->member.prev, member))
236 
237 #define list_for_each_entry_from(type, pos, start, head, member)        \
238    for (type *pos = LIST_ENTRY(type, (start), member);                  \
239 	&pos->member != (head);                                         \
240 	pos = LIST_ENTRY(type, pos->member.next, member))
241 
242 #define list_for_each_entry_from_rev(type, pos, start, head, member)    \
243    for (type *pos = LIST_ENTRY(type, (start), member);                  \
244 	&pos->member != (head);                                         \
245 	pos = LIST_ENTRY(type, pos->member.prev, member))
246 
247 #endif /*_UTIL_LIST_H_*/
248