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 #include "c99_compat.h"
  45
  46
  47 struct list_head
  48 {
  49     struct list_head *prev;
  50     struct list_head *next;
  51 };
  52
  53 static inline void list_inithead(struct list_head *item)
  54 {
  55     item->prev = item;
  56     item->next = item;
  57 }
  58
  59 static inline void list_add(struct list_head *item, struct list_head *list)
  60 {
  61     item->prev = list;
  62     item->next = list->next;
  63     list->next->prev = item;
  64     list->next = item;
  65 }
  66
  67 static inline void list_addtail(struct list_head *item, struct list_head *list)
  68 {
  69     item->next = list;
  70     item->prev = list->prev;
  71     list->prev->next = item;
  72     list->prev = item;
  73 }
  74
  75 static inline bool list_empty(struct list_head *list);
  76
  77 static inline void list_replace(struct list_head *from, struct list_head *to)
  78 {
  79     if (list_empty(from)) {
  80         list_inithead(to);
  81     } else {
  82         to->prev = from->prev;
  83         to->next = from->next;
  84         from->next->prev = to;
  85         from->prev->next = to;
  86     }
  87 }
  88
  89 static inline void list_del(struct list_head *item)
  90 {
  91     item->prev->next = item->next;
  92     item->next->prev = item->prev;
  93     item->prev = item->next = NULL;
  94 }
  95
  96 static inline void list_delinit(struct list_head *item)
  97 {
  98     item->prev->next = item->next;
  99     item->next->prev = item->prev;
 100     item->next = item;
 101     item->prev = item;
 102 }
 103
 104 static inline bool list_empty(struct list_head *list)
 105 {
 106    return list->next == list;
 107 }
 108
 109 /**
 110  * Returns whether the list has exactly one element.
 111  */
 112 static inline bool list_is_singular(const struct list_head *list)
 113 {
 114    return list->next != NULL && list->next != list && list->next->next == list;
 115 }
 116
 117 static inline unsigned list_length(struct list_head *list)
 118 {
 119    struct list_head *node;
 120    unsigned length = 0;
 121    for (node = list->next; node != list; node = node->next)
 122       length++;
 123    return length;
 124 }
 125
 126 static inline void list_splice(struct list_head *src, struct list_head *dst)
 127 {
 128    if (list_empty(src))
 129       return;
 130
 131    src->next->prev = dst;
 132    src->prev->next = dst->next;
 133    dst->next->prev = src->prev;
 134    dst->next = src->next;
 135 }
 136
 137 static inline void list_splicetail(struct list_head *src, struct list_head *dst)
 138 {
 139    if (list_empty(src))
 140       return;
 141
 142    src->prev->next = dst;
 143    src->next->prev = dst->prev;
 144    dst->prev->next = src->next;
 145    dst->prev = src->prev;
 146 }
 147
 148 static inline void list_validate(struct list_head *list)
 149 {
 150    struct list_head *node;
 151    assert(list->next->prev == list && list->prev->next == list);
 152    for (node = list->next; node != list; node = node->next)
 153       assert(node->next->prev == node && node->prev->next == node);
 154 }
 155
 156 #define LIST_INITHEAD(__item) list_inithead(__item)
 157 #define LIST_ADD(__item, __list) list_add(__item, __list)
 158 #define LIST_ADDTAIL(__item, __list) list_addtail(__item, __list)
 159 #define LIST_REPLACE(__from, __to) list_replace(__from, __to)
 160 #define LIST_DEL(__item) list_del(__item)
 161 #define LIST_DELINIT(__item) list_delinit(__item)
 162
 163 #define LIST_ENTRY(__type, __item, __field)   \
 164     ((__type *)(((char *)(__item)) - offsetof(__type, __field)))
 165
 166 #define LIST_IS_EMPTY(__list)                   \
 167     ((__list)->next == (__list))
 168
 169 /**
 170  * Cast from a pointer to a member of a struct back to the containing struct.
 171  *
 172  * 'sample' MUST be initialized, or else the result is undefined!
 173  */
 174 #ifndef container_of
 175 #define container_of(ptr, sample, member)                               \
 176     (void *)((char *)(ptr)                                              \
 177              - ((char *)&(sample)->member - (char *)(sample)))
 178 #endif
 179
 180 #define list_first_entry(ptr, type, member) \
 181         LIST_ENTRY(type, (ptr)->next, member)
 182
 183 #define list_last_entry(ptr, type, member) \
 184         LIST_ENTRY(type, (ptr)->prev, member)
 185
 186
 187 #define LIST_FOR_EACH_ENTRY(pos, head, member)                          \
 188    for (pos = NULL, pos = container_of((head)->next, pos, member);      \
 189         &pos->member != (head);                                         \
 190         pos = container_of(pos->member.next, pos, member))
 191
 192 #define LIST_FOR_EACH_ENTRY_SAFE(pos, storage, head, member)    \
 193    for (pos = NULL, pos = container_of((head)->next, pos, member),      \
 194         storage = container_of(pos->member.next, pos, member);  \
 195         &pos->member != (head);                                         \
 196         pos = storage, storage = container_of(storage->member.next, storage, member))
 197
 198 #define LIST_FOR_EACH_ENTRY_SAFE_REV(pos, storage, head, member)        \
 199    for (pos = NULL, pos = container_of((head)->prev, pos, member),      \
 200         storage = container_of(pos->member.prev, pos, member);          \
 201         &pos->member != (head);                                         \
 202         pos = storage, storage = container_of(storage->member.prev, storage, member))
 203
 204 #define LIST_FOR_EACH_ENTRY_FROM(pos, start, head, member)              \
 205    for (pos = NULL, pos = container_of((start), pos, member);           \
 206         &pos->member != (head);                                         \
 207         pos = container_of(pos->member.next, pos, member))
 208
 209 #define LIST_FOR_EACH_ENTRY_FROM_REV(pos, start, head, member)          \
 210    for (pos = NULL, pos = container_of((start), pos, member);           \
 211         &pos->member != (head);                                         \
 212         pos = container_of(pos->member.prev, pos, member))
 213
 214 #define list_for_each_entry(type, pos, head, member)                    \
 215    for (type *pos = LIST_ENTRY(type, (head)->next, member);             \
 216         &pos->member != (head);                                         \
 217         pos = LIST_ENTRY(type, pos->member.next, member))
 218
 219 #define list_for_each_entry_safe(type, pos, head, member)               \
 220    for (type *pos = LIST_ENTRY(type, (head)->next, member),             \
 221              *__next = LIST_ENTRY(type, pos->member.next, member);      \
 222         &pos->member != (head);                                         \
 223         pos = __next,                                                   \
 224         __next = LIST_ENTRY(type, __next->member.next, member))
 225
 226 #define list_for_each_entry_rev(type, pos, head, member)                \
 227    for (type *pos = LIST_ENTRY(type, (head)->prev, member);             \
 228         &pos->member != (head);                                         \
 229         pos = LIST_ENTRY(type, pos->member.prev, member))
 230
 231 #define list_for_each_entry_safe_rev(type, pos, head, member)           \
 232    for (type *pos = LIST_ENTRY(type, (head)->prev, member),             \
 233              *__prev = LIST_ENTRY(type, pos->member.prev, member);      \
 234         &pos->member != (head);                                         \
 235         pos = __prev,                                                   \
 236         __prev = LIST_ENTRY(type, __prev->member.prev, member))
 237
 238 #define list_for_each_entry_from(type, pos, start, head, member)        \
 239    for (type *pos = LIST_ENTRY(type, (start), member);                  \
 240         &pos->member != (head);                                         \
 241         pos = LIST_ENTRY(type, pos->member.next, member))
 242
 243 #define list_for_each_entry_from_rev(type, pos, start, head, member)    \
 244    for (type *pos = LIST_ENTRY(type, (start), member);                  \
 245         &pos->member != (head);                                         \
 246         pos = LIST_ENTRY(type, pos->member.prev, member))
 247
 248 #endif /*_UTIL_LIST_H_*/