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 #ifdef DEBUG
  47 #  define list_assert(cond, msg)  assert(cond && msg)
  48 #else
  49 #  define list_assert(cond, msg)  (void)(0 && (cond))
  50 #endif
  51
  52 struct list_head
  53 {
  54     struct list_head *prev;
  55     struct list_head *next;
  56 };
  57
  58 static inline void list_inithead(struct list_head *item)
  59 {
  60     item->prev = item;
  61     item->next = item;
  62 }
  63
  64 static inline void list_add(struct list_head *item, struct list_head *list)
  65 {
  66     item->prev = list;
  67     item->next = list->next;
  68     list->next->prev = item;
  69     list->next = item;
  70 }
  71
  72 static inline void list_addtail(struct list_head *item, struct list_head *list)
  73 {
  74     item->next = list;
  75     item->prev = list->prev;
  76     list->prev->next = item;
  77     list->prev = item;
  78 }
  79
  80 static inline bool list_empty(const struct list_head *list);
  81
  82 static inline void list_replace(struct list_head *from, struct list_head *to)
  83 {
  84     if (list_empty(from)) {
  85         list_inithead(to);
  86     } else {
  87         to->prev = from->prev;
  88         to->next = from->next;
  89         from->next->prev = to;
  90         from->prev->next = to;
  91     }
  92 }
  93
  94 static inline void list_del(struct list_head *item)
  95 {
  96     item->prev->next = item->next;
  97     item->next->prev = item->prev;
  98     item->prev = item->next = NULL;
  99 }
 100
 101 static inline void list_delinit(struct list_head *item)
 102 {
 103     item->prev->next = item->next;
 104     item->next->prev = item->prev;
 105     item->next = item;
 106     item->prev = item;
 107 }
 108
 109 static inline bool list_empty(const struct list_head *list)
 110 {
 111    return list->next == list;
 112 }
 113
 114 /**
 115  * Returns whether the list has exactly one element.
 116  */
 117 static inline bool list_is_singular(const struct list_head *list)
 118 {
 119    return list->next != NULL && list->next != list && list->next->next == list;
 120 }
 121
 122 static inline unsigned list_length(const struct list_head *list)
 123 {
 124    struct list_head *node;
 125    unsigned length = 0;
 126    for (node = list->next; node != list; node = node->next)
 127       length++;
 128    return length;
 129 }
 130
 131 static inline void list_splice(struct list_head *src, struct list_head *dst)
 132 {
 133    if (list_empty(src))
 134       return;
 135
 136    src->next->prev = dst;
 137    src->prev->next = dst->next;
 138    dst->next->prev = src->prev;
 139    dst->next = src->next;
 140 }
 141
 142 static inline void list_splicetail(struct list_head *src, struct list_head *dst)
 143 {
 144    if (list_empty(src))
 145       return;
 146
 147    src->prev->next = dst;
 148    src->next->prev = dst->prev;
 149    dst->prev->next = src->next;
 150    dst->prev = src->prev;
 151 }
 152
 153 static inline void list_validate(const struct list_head *list)
 154 {
 155    struct list_head *node;
 156    assert(list->next->prev == list && list->prev->next == list);
 157    for (node = list->next; node != list; node = node->next)
 158       assert(node->next->prev == node && node->prev->next == node);
 159 }
 160
 161 #define LIST_ENTRY(__type, __item, __field)   \
 162     ((__type *)(((char *)(__item)) - offsetof(__type, __field)))
 163
 164 #define LIST_IS_EMPTY(__list)                   \
 165     ((__list)->next == (__list))
 166
 167 /**
 168  * Cast from a pointer to a member of a struct back to the containing struct.
 169  *
 170  * 'sample' MUST be initialized, or else the result is undefined!
 171  */
 172 #ifndef container_of
 173 #define container_of(ptr, sample, member)                               \
 174     (void *)((char *)(ptr)                                              \
 175              - ((char *)&(sample)->member - (char *)(sample)))
 176 #endif
 177
 178 #define list_first_entry(ptr, type, member) \
 179         LIST_ENTRY(type, (ptr)->next, member)
 180
 181 #define list_last_entry(ptr, type, member) \
 182         LIST_ENTRY(type, (ptr)->prev, member)
 183
 184
 185 #define LIST_FOR_EACH_ENTRY(pos, head, member)                          \
 186    for (pos = NULL, pos = container_of((head)->next, pos, member);      \
 187         &pos->member != (head);                                         \
 188         pos = container_of(pos->member.next, pos, member))
 189
 190 #define LIST_FOR_EACH_ENTRY_SAFE(pos, storage, head, member)    \
 191    for (pos = NULL, pos = container_of((head)->next, pos, member),      \
 192         storage = container_of(pos->member.next, pos, member);  \
 193         &pos->member != (head);                                         \
 194         pos = storage, storage = container_of(storage->member.next, storage, member))
 195
 196 #define LIST_FOR_EACH_ENTRY_SAFE_REV(pos, storage, head, member)        \
 197    for (pos = NULL, pos = container_of((head)->prev, pos, member),      \
 198         storage = container_of(pos->member.prev, pos, member);          \
 199         &pos->member != (head);                                         \
 200         pos = storage, storage = container_of(storage->member.prev, storage, member))
 201
 202 #define LIST_FOR_EACH_ENTRY_FROM(pos, start, head, member)              \
 203    for (pos = NULL, pos = container_of((start), pos, member);           \
 204         &pos->member != (head);                                         \
 205         pos = container_of(pos->member.next, pos, member))
 206
 207 #define LIST_FOR_EACH_ENTRY_FROM_REV(pos, start, head, member)          \
 208    for (pos = NULL, pos = container_of((start), pos, member);           \
 209         &pos->member != (head);                                         \
 210         pos = container_of(pos->member.prev, pos, member))
 211
 212 #define list_for_each_entry(type, pos, head, member)                    \
 213    for (type *pos = LIST_ENTRY(type, (head)->next, member),             \
 214              *__next = LIST_ENTRY(type, pos->member.next, member);      \
 215         &pos->member != (head);                                         \
 216         pos = LIST_ENTRY(type, pos->member.next, member),               \
 217         list_assert(pos == __next, "use _safe iterator"),               \
 218         __next = LIST_ENTRY(type, __next->member.next, member))
 219
 220 #define list_for_each_entry_safe(type, pos, head, member)               \
 221    for (type *pos = LIST_ENTRY(type, (head)->next, member),             \
 222              *__next = LIST_ENTRY(type, pos->member.next, member);      \
 223         &pos->member != (head);                                         \
 224         pos = __next,                                                   \
 225         __next = LIST_ENTRY(type, __next->member.next, member))
 226
 227 #define list_for_each_entry_rev(type, pos, head, member)                \
 228    for (type *pos = LIST_ENTRY(type, (head)->prev, member),             \
 229              *__prev = LIST_ENTRY(type, pos->member.prev, member);      \
 230         &pos->member != (head);                                         \
 231         pos = LIST_ENTRY(type, pos->member.prev, member),               \
 232         list_assert(pos == __prev, "use _safe iterator"),               \
 233         __prev = LIST_ENTRY(type, __prev->member.prev, member))
 234
 235 #define list_for_each_entry_safe_rev(type, pos, head, member)           \
 236    for (type *pos = LIST_ENTRY(type, (head)->prev, member),             \
 237              *__prev = LIST_ENTRY(type, pos->member.prev, member);      \
 238         &pos->member != (head);                                         \
 239         pos = __prev,                                                   \
 240         __prev = LIST_ENTRY(type, __prev->member.prev, member))
 241
 242 #define list_for_each_entry_from(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.next, member))
 246
 247 #define list_for_each_entry_from_rev(type, pos, start, head, member)    \
 248    for (type *pos = LIST_ENTRY(type, (start), member);                  \
 249         &pos->member != (head);                                         \
 250         pos = LIST_ENTRY(type, pos->member.prev, member))
 251
 252 #endif /*_UTIL_LIST_H_*/