libopkg/list.h

   1 /* list.h - the opkg package management system
   2
   3    Tick Chen <tick@openmoko.com>
   4
   5    Copyright (C) 2008 Openmoko Inc.
   6
   7    This program is free software; you can redistribute it and/or
   8    modify it under the terms of the GNU General Public License as
   9    published by the Free Software Foundation; either version 2, or (at
  10    your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful, but
  13    WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15    General Public License for more details.
  16
  17    This is modified from Linux Kernel.
  18 */
  19
  20 #ifndef _LINUX_LIST_H
  21 #define _LINUX_LIST_H
  22
  23 struct list_head {
  24     struct list_head *next, *prev;
  25 };
  26
  27 #define LIST_POISON1  ((struct list_head *) 0x00100100)
  28 #define LIST_POISON2  ((struct list_head *) 0x00200200)
  29
  30 #define LIST_HEAD_INIT(name) { &(name), &(name) }
  31
  32 #define LIST_HEAD(name) \
  33         struct list_head name = LIST_HEAD_INIT(name)
  34
  35 #define INIT_LIST_HEAD(ptr) do { \
  36         (ptr)->next = (ptr); (ptr)->prev = (ptr); \
  37 } while (0)
  38
  39 static inline void __list_add(struct list_head *newitem,
  40                               struct list_head *prev,
  41                               struct list_head *next) {
  42     next->prev = newitem;
  43     newitem->next = next;
  44     newitem->prev = prev;
  45     prev->next = newitem;
  46 }
  47
  48 /**
  49  * list_add - add a new entry
  50  * @newitem: new entry to be added
  51  * @head: list head to add it after
  52  *
  53  * Insert a new entry after the specified head.
  54  * This is good for implementing stacks.
  55  */
  56 static inline void list_add(struct list_head *newitem, struct list_head *head) {
  57     __list_add(newitem, head, head->next);
  58 }
  59
  60 /**
  61  * list_add_tail - add a new entry
  62  * @newitem: new entry to be added
  63  * @head: list head to add it before
  64  *
  65  * Insert a new entry before the specified head.
  66  * This is useful for implementing queues.
  67  */
  68 static inline void list_add_tail(struct list_head *newitem, struct list_head *head) {
  69     __list_add(newitem, head->prev, head);
  70 }
  71
  72
  73 /*
  74  * Delete a list entry by making the prev/next entries
  75  * point to each other.
  76  *
  77  * This is only for internal list manipulation where we know
  78  * the prev/next entries already!
  79  */
  80 static inline void __list_del(struct list_head * prev, struct list_head * next) {
  81     next->prev = prev;
  82     prev->next = next;
  83 }
  84
  85 /**
  86  * list_del - deletes entry from list.
  87  * @entry: the element to delete from the list.
  88  * Note: list_empty on entry does not return true after this, the entry is
  89  * in an undefined state.
  90  */
  91 static inline void list_del(struct list_head *entry) {
  92     __list_del(entry->prev, entry->next);
  93     entry->next = LIST_POISON1;
  94     entry->prev = LIST_POISON2;
  95 }
  96
  97 /**
  98  * list_del_init - deletes entry from list and reinitialize it.
  99  * @entry: the element to delete from the list.
 100  */
 101 static inline void list_del_init(struct list_head *entry) {
 102     __list_del(entry->prev, entry->next);
 103     INIT_LIST_HEAD(entry);
 104 }
 105
 106 /**
 107  * list_move - delete from one list and add as another's head
 108  * @list: the entry to move
 109  * @head: the head that will precede our entry
 110  */
 111 static inline void list_move(struct list_head *list, struct list_head *head) {
 112     __list_del(list->prev, list->next);
 113     list_add(list, head);
 114 }
 115
 116 /**
 117  * list_move_tail - delete from one list and add as another's tail
 118  * @list: the entry to move
 119  * @head: the head that will follow our entry
 120  */
 121 static inline void list_move_tail(struct list_head *list,
 122                                   struct list_head *head) {
 123     __list_del(list->prev, list->next);
 124     list_add_tail(list, head);
 125 }
 126
 127 /**
 128  * list_empty - tests whether a list is empty
 129  * @head: the list to test.
 130  */
 131 static inline int list_empty(const struct list_head *head) {
 132     return head->next == head;
 133 }
 134
 135 /**
 136  * list_empty_careful - tests whether a list is
 137  * empty _and_ checks that no other CPU might be
 138  * in the process of still modifying either member
 139  *
 140  * NOTE: using list_empty_careful() without synchronization
 141  * can only be safe if the only activity that can happen
 142  * to the list entry is list_del_init(). Eg. it cannot be used
 143  * if another CPU could re-list_add() it.
 144  *
 145  * @head: the list to test.
 146  */
 147 static inline int list_empty_careful(const struct list_head *head) {
 148     struct list_head *next = head->next;
 149     return (next == head) && (next == head->prev);
 150 }
 151
 152 static inline void __list_splice(struct list_head *list,
 153                                  struct list_head *head) {
 154     struct list_head *first = list->next;
 155     struct list_head *last = list->prev;
 156     struct list_head *at = head->next;
 157
 158     first->prev = head;
 159     head->next = first;
 160
 161     last->next = at;
 162     at->prev = last;
 163 }
 164
 165 /**
 166  * list_splice - join two lists
 167  * @list: the new list to add.
 168  * @head: the place to add it in the first list.
 169  */
 170 static inline void list_splice(struct list_head *list, struct list_head *head) {
 171     if (!list_empty(list))
 172         __list_splice(list, head);
 173 }
 174
 175 /**
 176  * list_splice_init - join two lists and reinitialise the emptied list.
 177  * @list: the new list to add.
 178  * @head: the place to add it in the first list.
 179  *
 180  * The list at @list is reinitialised
 181  */
 182 static inline void list_splice_init(struct list_head *list,
 183                                     struct list_head *head) {
 184     if (!list_empty(list)) {
 185         __list_splice(list, head);
 186         INIT_LIST_HEAD(list);
 187     }
 188 }
 189
 190
 191
 192 #define _offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
 193 #define container_of(ptr, type, member) ({                      \
 194         const typeof( ((type *)0)->member ) *__mptr = (ptr);    \
 195         (type *)( (char *)__mptr - _offsetof(type,member) );})
 196
 197 /**
 198  * list_entry - get the struct for this entry
 199  * @ptr:        the &struct list_head pointer.
 200  * @type:       the type of the struct this is embedded in.
 201  * @member:     the name of the list_struct within the struct.
 202  */
 203 #define list_entry(ptr, type, member) \
 204         container_of(ptr, type, member)
 205
 206 /**
 207  * list_for_each        -       iterate over a list
 208  * @pos:        the &struct list_head to use as a loop counter.
 209  * @head:       the head for your list.
 210  */
 211 #define list_for_each(pos, head) \
 212         for (pos = (head)->next; pos != (head); \
 213                 pos = pos->next)
 214
 215 /**
 216  * __list_for_each      -       iterate over a list
 217  * @pos:        the &struct list_head to use as a loop counter.
 218  * @head:       the head for your list.
 219  *
 220  * This variant differs from list_for_each() in that it's the
 221  * simplest possible list iteration code, no prefetching is done.
 222  * Use this for code that knows the list to be very short (empty
 223  * or 1 entry) most of the time.
 224  */
 225 #define __list_for_each(pos, head) \
 226         for (pos = (head)->next; pos != (head); pos = pos->next)
 227
 228 /**
 229  * list_for_each_prev   -       iterate over a list backwards
 230  * @pos:        the &struct list_head to use as a loop counter.
 231  * @head:       the head for your list.
 232  */
 233 #define list_for_each_prev(pos, head) \
 234         for (pos = (head)->prev; pos != (head); \
 235                 pos = pos->prev)
 236
 237 /**
 238  * list_for_each_safe   -       iterate over a list safe against removal of list entry
 239  * @pos:        the &struct list_head to use as a loop counter.
 240  * @n:          another &struct list_head to use as temporary storage
 241  * @head:       the head for your list.
 242  */
 243 #define list_for_each_safe(pos, n, head) \
 244         for (pos = (head)->next, n = pos->next; pos != (head); \
 245                 pos = n, n = pos->next)
 246
 247 /**
 248  * list_for_each_entry  -       iterate over list of given type
 249  * @pos:        the type * to use as a loop counter.
 250  * @head:       the head for your list.
 251  * @member:     the name of the list_struct within the struct.
 252  */
 253 #define list_for_each_entry(pos, head, member)                          \
 254         for (pos = list_entry((head)->next, typeof(*pos), member);      \
 255              &pos->member != (head);    \
 256              pos = list_entry(pos->member.next, typeof(*pos), member))
 257
 258 /**
 259  * list_for_each_entry_reverse - iterate backwards over list of given type.
 260  * @pos:        the type * to use as a loop counter.
 261  * @head:       the head for your list.
 262  * @member:     the name of the list_struct within the struct.
 263  */
 264 #define list_for_each_entry_reverse(pos, head, member)                  \
 265         for (pos = list_entry((head)->prev, typeof(*pos), member);      \
 266              &pos->member != (head);    \
 267              pos = list_entry(pos->member.prev, typeof(*pos), member))
 268
 269 /**
 270  * list_prepare_entry - prepare a pos entry for use as a start point in
 271  *                      list_for_each_entry_continue
 272  * @pos:        the type * to use as a start point
 273  * @head:       the head of the list
 274  * @member:     the name of the list_struct within the struct.
 275  */
 276 #define list_prepare_entry(pos, head, member) \
 277         ((pos) ? : list_entry(head, typeof(*pos), member))
 278
 279 /**
 280  * list_for_each_entry_continue -       iterate over list of given type
 281  *                      continuing after existing point
 282  * @pos:        the type * to use as a loop counter.
 283  * @head:       the head for your list.
 284  * @member:     the name of the list_struct within the struct.
 285  */
 286 #define list_for_each_entry_continue(pos, head, member)                 \
 287         for (pos = list_entry(pos->member.next, typeof(*pos), member);  \
 288              &pos->member != (head);    \
 289              pos = list_entry(pos->member.next, typeof(*pos), member))
 290
 291 /**
 292  * list_for_each_entry_safe - iterate over list of given type safe against removal of list entry
 293  * @pos:        the type * to use as a loop counter.
 294  * @n:          another type * to use as temporary storage
 295  * @head:       the head for your list.
 296  * @member:     the name of the list_struct within the struct.
 297  */
 298 #define list_for_each_entry_safe(pos, n, head, member)                  \
 299         for (pos = list_entry((head)->next, typeof(*pos), member),      \
 300                 n = list_entry(pos->member.next, typeof(*pos), member); \
 301              &pos->member != (head);                                    \
 302              pos = n, n = list_entry(n->member.next, typeof(*n), member))
 303
 304 #endif