src/util/list.h

   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
  52 static inline void list_inithead(struct list_head *item)
  53 {
  54     item->prev = item;
  55     item->next = item;
  56 }
  57
  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
  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
  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
  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
  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
 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  */
 111 static inline bool list_is_singular(const struct list_head *list)
 112 {
 113    return list->next != NULL && list->next->next == list;
 114 }
 115
 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
 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
 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
 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_*/