list.h

/**************************************************************************
 *
 * Copyright 2006 VMware, Inc., Bismarck, ND. USA.
 * All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sub license, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
 * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
 * USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 * The above copyright notice and this permission notice (including the
 * next paragraph) shall be included in all copies or substantial portions
 * of the Software.
 *
 **************************************************************************/

/**
 * \file
 * List macros heavily inspired by the Linux kernel
 * list handling. No list looping yet.
 *
 * Is not threadsafe, so common operations need to
 * be protected using an external mutex.
 */

#ifndef _UTIL_LIST_H_
#define _UTIL_LIST_H_


#include <stdbool.h>
#include <stddef.h>
#include <assert.h>
#include "c99_compat.h"

#ifdef DEBUG
#  define list_assert(cond, msg)  assert(cond && msg)
#else
#  define list_assert(cond, msg)  (void)(0 && (cond))
#endif

struct list_head
{
    struct list_head *prev;
    struct list_head *next;
};

static inline void list_inithead(struct list_head *item)
{
    item->prev = item;
    item->next = item;
}

static inline void list_add(struct list_head *item, struct list_head *list)
{
    item->prev = list;
    item->next = list->next;
    list->next->prev = item;
    list->next = item;
}

static inline void list_addtail(struct list_head *item, struct list_head *list)
{
    item->next = list;
    item->prev = list->prev;
    list->prev->next = item;
    list->prev = item;
}

static inline bool list_is_empty(const struct list_head *list);

static inline void list_replace(struct list_head *from, struct list_head *to)
{
    if (list_is_empty(from)) {
        list_inithead(to);
    } else {
        to->prev = from->prev;
        to->next = from->next;
        from->next->prev = to;
        from->prev->next = to;
    }
}

static inline void list_del(struct list_head *item)
{
    item->prev->next = item->next;
    item->next->prev = item->prev;
    item->prev = item->next = NULL;
}

static inline void list_delinit(struct list_head *item)
{
    item->prev->next = item->next;
    item->next->prev = item->prev;
    item->next = item;
    item->prev = item;
}

static inline bool list_is_empty(const struct list_head *list)
{
   return list->next == list;
}

static inline bool list_is_linked(const struct list_head *list)
{
   /* both must be NULL or both must be not NULL */
   assert((list->prev != NULL) == (list->next != NULL));

   return list->next != NULL;
}

/**
 * Returns whether the list has exactly one element.
 */
static inline bool list_is_singular(const struct list_head *list)
{
   return list_is_linked(list) && !list_is_empty(list) && list->next->next == list;
}

static inline unsigned list_length(const struct list_head *list)
{
   struct list_head *node;
   unsigned length = 0;
   for (node = list->next; node != list; node = node->next)
      length++;
   return length;
}

static inline void list_splice(struct list_head *src, struct list_head *dst)
{
   if (list_is_empty(src))
      return;

   src->next->prev = dst;
   src->prev->next = dst->next;
   dst->next->prev = src->prev;
   dst->next = src->next;
}

static inline void list_splicetail(struct list_head *src, struct list_head *dst)
{
   if (list_is_empty(src))
      return;

   src->prev->next = dst;
   src->next->prev = dst->prev;
   dst->prev->next = src->next;
   dst->prev = src->prev;
}

static inline void list_validate(const struct list_head *list)
{
   struct list_head *node;
   assert(list_is_linked(list));
   assert(list->next->prev == list && list->prev->next == list);
   for (node = list->next; node != list; node = node->next)
      assert(node->next->prev == node && node->prev->next == node);
}

#define LIST_ENTRY(__type, __item, __field)   \
    ((__type *)(((char *)(__item)) - offsetof(__type, __field)))

/**
 * Cast from a pointer to a member of a struct back to the containing struct.
 *
 * 'sample' MUST be initialized, or else the result is undefined!
 */
#define list_container_of(ptr, sample, member)				\
    (void *)((char *)(ptr)						\
	     - ((char *)&(sample)->member - (char *)(sample)))

#define list_first_entry(ptr, type, member) \
        LIST_ENTRY(type, (ptr)->next, member)

#define list_last_entry(ptr, type, member) \
        LIST_ENTRY(type, (ptr)->prev, member)


#define LIST_FOR_EACH_ENTRY(pos, head, member)				\
   for (pos = NULL, pos = list_container_of((head)->next, pos, member);	\
	&pos->member != (head);						\
	pos = list_container_of(pos->member.next, pos, member))

#define LIST_FOR_EACH_ENTRY_SAFE(pos, storage, head, member)	\
   for (pos = NULL, pos = list_container_of((head)->next, pos, member),	\
	storage = list_container_of(pos->member.next, pos, member);	\
	&pos->member != (head);						\
	pos = storage, storage = list_container_of(storage->member.next, storage, member))

#define LIST_FOR_EACH_ENTRY_SAFE_REV(pos, storage, head, member)	\
   for (pos = NULL, pos = list_container_of((head)->prev, pos, member),	\
	storage = list_container_of(pos->member.prev, pos, member);		\
	&pos->member != (head);						\
	pos = storage, storage = list_container_of(storage->member.prev, storage, member))

#define LIST_FOR_EACH_ENTRY_FROM(pos, start, head, member)		\
   for (pos = NULL, pos = list_container_of((start), pos, member);		\
	&pos->member != (head);						\
	pos = list_container_of(pos->member.next, pos, member))

#define LIST_FOR_EACH_ENTRY_FROM_REV(pos, start, head, member)		\
   for (pos = NULL, pos = list_container_of((start), pos, member);		\
	&pos->member != (head);						\
	pos = list_container_of(pos->member.prev, pos, member))

#define list_for_each_entry(type, pos, head, member)                    \
   for (type *pos = LIST_ENTRY(type, (head)->next, member),             \
	     *__next = LIST_ENTRY(type, pos->member.next, member);      \
	&pos->member != (head);                                         \
	pos = LIST_ENTRY(type, pos->member.next, member),               \
	list_assert(pos == __next, "use _safe iterator"),               \
	__next = LIST_ENTRY(type, __next->member.next, member))

#define list_for_each_entry_safe(type, pos, head, member)               \
   for (type *pos = LIST_ENTRY(type, (head)->next, member),             \
	     *__next = LIST_ENTRY(type, pos->member.next, member);      \
	&pos->member != (head);                                         \
	pos = __next,                                                   \
	__next = LIST_ENTRY(type, __next->member.next, member))

#define list_for_each_entry_rev(type, pos, head, member)                \
   for (type *pos = LIST_ENTRY(type, (head)->prev, member),             \
	     *__prev = LIST_ENTRY(type, pos->member.prev, member);      \
	&pos->member != (head);                                         \
	pos = LIST_ENTRY(type, pos->member.prev, member),               \
	list_assert(pos == __prev, "use _safe iterator"),               \
	__prev = LIST_ENTRY(type, __prev->member.prev, member))

#define list_for_each_entry_safe_rev(type, pos, head, member)           \
   for (type *pos = LIST_ENTRY(type, (head)->prev, member),             \
	     *__prev = LIST_ENTRY(type, pos->member.prev, member);      \
	&pos->member != (head);                                         \
	pos = __prev,                                                   \
        __prev = LIST_ENTRY(type, __prev->member.prev, member))

#define list_for_each_entry_from(type, pos, start, head, member)        \
   for (type *pos = LIST_ENTRY(type, (start), member);                  \
	&pos->member != (head);                                         \
	pos = LIST_ENTRY(type, pos->member.next, member))

#define list_for_each_entry_from_safe(type, pos, start, head, member)   \
   for (type *pos = LIST_ENTRY(type, (start), member),                  \
	     *__next = LIST_ENTRY(type, pos->member.next, member);      \
	&pos->member != (head);                                         \
	pos = __next,                                                   \
	__next = LIST_ENTRY(type, __next->member.next, member))

#define list_for_each_entry_from_rev(type, pos, start, head, member)    \
   for (type *pos = LIST_ENTRY(type, (start), member);                  \
	&pos->member != (head);                                         \
	pos = LIST_ENTRY(type, pos->member.prev, member))

#define list_pair_for_each_entry(type, pos1, pos2, head1, head2, member) \
   for (type *pos1 = LIST_ENTRY(type, (head1)->next, member),           \
             *pos2 = LIST_ENTRY(type, (head2)->next, member);           \
        &pos1->member != (head1) && &pos2->member != (head2);           \
	pos1 = LIST_ENTRY(type, pos1->member.next, member),               \
	pos2 = LIST_ENTRY(type, pos2->member.next, member))

#endif /*_UTIL_LIST_H_*/