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, struct list_head *next)
  41 {
  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 {
  58         __list_add(newitem, head, head->next);
  59 }
  60
  61 /**
  62  * list_add_tail - add a new entry
  63  * @newitem: new entry to be added
  64  * @head: list head to add it before
  65  *
  66  * Insert a new entry before the specified head.
  67  * This is useful for implementing queues.
  68  */
  69 static inline void list_add_tail(struct list_head *newitem,
  70                                  struct list_head *head)
  71 {
  72         __list_add(newitem, head->prev, head);
  73 }
  74
  75 /*
  76  * Delete a list entry by making the prev/next entries
  77  * point to each other.
  78  *
  79  * This is only for internal list manipulation where we know
  80  * the prev/next entries already!
  81  */
  82 static inline void __list_del(struct list_head *prev, struct list_head *next)
  83 {
  84         next->prev = prev;
  85         prev->next = next;
  86 }
  87
  88 /**
  89  * list_del - deletes entry from list.
  90  * @entry: the element to delete from the list.
  91  * Note: list_empty on entry does not return true after this, the entry is
  92  * in an undefined state.
  93  */
  94 static inline void list_del(struct list_head *entry)
  95 {
  96         __list_del(entry->prev, entry->next);
  97         entry->next = LIST_POISON1;
  98         entry->prev = LIST_POISON2;
  99 }
 100
 101 /**
 102  * list_del_init - deletes entry from list and reinitialize it.
 103  * @entry: the element to delete from the list.
 104  */
 105 static inline void list_del_init(struct list_head *entry)
 106 {
 107         __list_del(entry->prev, entry->next);
 108         INIT_LIST_HEAD(entry);
 109 }
 110
 111 /**
 112  * list_move - delete from one list and add as another's head
 113  * @list: the entry to move
 114  * @head: the head that will precede our entry
 115  */
 116 static inline void list_move(struct list_head *list, struct list_head *head)
 117 {
 118         __list_del(list->prev, list->next);
 119         list_add(list, head);
 120 }
 121
 122 /**
 123  * list_move_tail - delete from one list and add as another's tail
 124  * @list: the entry to move
 125  * @head: the head that will follow our entry
 126  */
 127 static inline void list_move_tail(struct list_head *list,
 128                                   struct list_head *head)
 129 {
 130         __list_del(list->prev, list->next);
 131         list_add_tail(list, head);
 132 }
 133
 134 /**
 135  * list_empty - tests whether a list is empty
 136  * @head: the list to test.
 137  */
 138 static inline int list_empty(const struct list_head *head)
 139 {
 140         return head->next == head;
 141 }
 142
 143 /**
 144  * list_empty_careful - tests whether a list is
 145  * empty _and_ checks that no other CPU might be
 146  * in the process of still modifying either member
 147  *
 148  * NOTE: using list_empty_careful() without synchronization
 149  * can only be safe if the only activity that can happen
 150  * to the list entry is list_del_init(). Eg. it cannot be used
 151  * if another CPU could re-list_add() it.
 152  *
 153  * @head: the list to test.
 154  */
 155 static inline int list_empty_careful(const struct list_head *head)
 156 {
 157         struct list_head *next = head->next;
 158         return (next == head) && (next == head->prev);
 159 }
 160
 161 static inline void __list_splice(struct list_head *list, struct list_head *head)
 162 {
 163         struct list_head *first = list->next;
 164         struct list_head *last = list->prev;
 165         struct list_head *at = head->next;
 166
 167         first->prev = head;
 168         head->next = first;
 169
 170         last->next = at;
 171         at->prev = last;
 172 }
 173
 174 /**
 175  * list_splice - join two lists
 176  * @list: the new list to add.
 177  * @head: the place to add it in the first list.
 178  */
 179 static inline void list_splice(struct list_head *list, struct list_head *head)
 180 {
 181         if (!list_empty(list))
 182                 __list_splice(list, head);
 183 }
 184
 185 /**
 186  * list_splice_init - join two lists and reinitialise the emptied list.
 187  * @list: the new list to add.
 188  * @head: the place to add it in the first list.
 189  *
 190  * The list at @list is reinitialised
 191  */
 192 static inline void list_splice_init(struct list_head *list,
 193                                     struct list_head *head)
 194 {
 195         if (!list_empty(list)) {
 196                 __list_splice(list, head);
 197                 INIT_LIST_HEAD(list);
 198         }
 199 }
 200
 201 #define _offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
 202 #define container_of(ptr, type, member) ({                      \
 203         const typeof( ((type *)0)->member ) *__mptr = (ptr);    \
 204         (type *)( (char *)__mptr - _offsetof(type,member) );})
 205
 206 /**
 207  * list_entry - get the struct for this entry
 208  * @ptr:        the &struct list_head pointer.
 209  * @type:       the type of the struct this is embedded in.
 210  * @member:     the name of the list_struct within the struct.
 211  */
 212 #define list_entry(ptr, type, member) \
 213         container_of(ptr, type, member)
 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 #define list_for_each(pos, head) \
 221         for (pos = (head)->next; pos != (head); \
 222                 pos = pos->next)
 223
 224 /**
 225  * __list_for_each      -       iterate over a list
 226  * @pos:        the &struct list_head to use as a loop counter.
 227  * @head:       the head for your list.
 228  *
 229  * This variant differs from list_for_each() in that it's the
 230  * simplest possible list iteration code, no prefetching is done.
 231  * Use this for code that knows the list to be very short (empty
 232  * or 1 entry) most of the time.
 233  */
 234 #define __list_for_each(pos, head) \
 235         for (pos = (head)->next; pos != (head); pos = pos->next)
 236
 237 /**
 238  * list_for_each_prev   -       iterate over a list backwards
 239  * @pos:        the &struct list_head to use as a loop counter.
 240  * @head:       the head for your list.
 241  */
 242 #define list_for_each_prev(pos, head) \
 243         for (pos = (head)->prev; pos != (head); \
 244                 pos = pos->prev)
 245
 246 /**
 247  * list_for_each_safe   -       iterate over a list safe against removal of list entry
 248  * @pos:        the &struct list_head to use as a loop counter.
 249  * @n:          another &struct list_head to use as temporary storage
 250  * @head:       the head for your list.
 251  */
 252 #define list_for_each_safe(pos, n, head) \
 253         for (pos = (head)->next, n = pos->next; pos != (head); \
 254                 pos = n, n = pos->next)
 255
 256 /**
 257  * list_for_each_entry  -       iterate over list of given type
 258  * @pos:        the type * to use as a loop counter.
 259  * @head:       the head for your list.
 260  * @member:     the name of the list_struct within the struct.
 261  */
 262 #define list_for_each_entry(pos, head, member)                          \
 263         for (pos = list_entry((head)->next, typeof(*pos), member);      \
 264              &pos->member != (head);    \
 265              pos = list_entry(pos->member.next, typeof(*pos), member))
 266
 267 /**
 268  * list_for_each_entry_reverse - iterate backwards over list of given type.
 269  * @pos:        the type * to use as a loop counter.
 270  * @head:       the head for your list.
 271  * @member:     the name of the list_struct within the struct.
 272  */
 273 #define list_for_each_entry_reverse(pos, head, member)                  \
 274         for (pos = list_entry((head)->prev, typeof(*pos), member);      \
 275              &pos->member != (head);    \
 276              pos = list_entry(pos->member.prev, typeof(*pos), member))
 277
 278 /**
 279  * list_prepare_entry - prepare a pos entry for use as a start point in
 280  *                      list_for_each_entry_continue
 281  * @pos:        the type * to use as a start point
 282  * @head:       the head of the list
 283  * @member:     the name of the list_struct within the struct.
 284  */
 285 #define list_prepare_entry(pos, head, member) \
 286         ((pos) ? : list_entry(head, typeof(*pos), member))
 287
 288 /**
 289  * list_for_each_entry_continue -       iterate over list of given type
 290  *                      continuing after existing point
 291  * @pos:        the type * to use as a loop counter.
 292  * @head:       the head for your list.
 293  * @member:     the name of the list_struct within the struct.
 294  */
 295 #define list_for_each_entry_continue(pos, head, member)                 \
 296         for (pos = list_entry(pos->member.next, typeof(*pos), member);  \
 297              &pos->member != (head);    \
 298              pos = list_entry(pos->member.next, typeof(*pos), member))
 299
 300 /**
 301  * list_for_each_entry_safe - iterate over list of given type safe against removal of list entry
 302  * @pos:        the type * to use as a loop counter.
 303  * @n:          another type * to use as temporary storage
 304  * @head:       the head for your list.
 305  * @member:     the name of the list_struct within the struct.
 306  */
 307 #define list_for_each_entry_safe(pos, n, head, member)                  \
 308         for (pos = list_entry((head)->next, typeof(*pos), member),      \
 309                 n = list_entry(pos->member.next, typeof(*pos), member); \
 310              &pos->member != (head);                                    \
 311              pos = n, n = list_entry(n->member.next, typeof(*n), member))
 312
 313 #endif