/* $NetBSD: list.c,v 1.1.1.1 2008/12/22 00:17:54 haad Exp $ */ /* * Copyright (C) 2001-2004 Sistina Software, Inc. All rights reserved. * Copyright (C) 2004-2007 Red Hat, Inc. All rights reserved. * * This file is part of LVM2. * * This copyrighted material is made available to anyone wishing to use, * modify, copy, or redistribute it subject to the terms and conditions * of the GNU Lesser General Public License v.2.1. * * You should have received a copy of the GNU Lesser General Public License * along with this program; if not, write to the Free Software Foundation, * Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */ #include "lib.h" /* * Initialise a list before use. * The list head's next and previous pointers point back to itself. */ void dm_list_init(struct dm_list *head) { head->n = head->p = head; } /* * Insert an element before 'head'. * If 'head' is the list head, this adds an element to the end of the list. */ void dm_list_add(struct dm_list *head, struct dm_list *elem) { assert(head->n); elem->n = head; elem->p = head->p; head->p->n = elem; head->p = elem; } /* * Insert an element after 'head'. * If 'head' is the list head, this adds an element to the front of the list. */ void dm_list_add_h(struct dm_list *head, struct dm_list *elem) { assert(head->n); elem->n = head->n; elem->p = head; head->n->p = elem; head->n = elem; } /* * Delete an element from its list. * Note that this doesn't change the element itself - it may still be safe * to follow its pointers. */ void dm_list_del(struct dm_list *elem) { elem->n->p = elem->p; elem->p->n = elem->n; } /* * Remove an element from existing list and insert before 'head'. */ void dm_list_move(struct dm_list *head, struct dm_list *elem) { dm_list_del(elem); dm_list_add(head, elem); } /* * Is the list empty? */ int dm_list_empty(const struct dm_list *head) { return head->n == head; } /* * Is this the first element of the list? */ int dm_list_start(const struct dm_list *head, const struct dm_list *elem) { return elem->p == head; } /* * Is this the last element of the list? */ int dm_list_end(const struct dm_list *head, const struct dm_list *elem) { return elem->n == head; } /* * Return first element of the list or NULL if empty */ struct dm_list *dm_list_first(const struct dm_list *head) { return (dm_list_empty(head) ? NULL : head->n); } /* * Return last element of the list or NULL if empty */ struct dm_list *dm_list_last(const struct dm_list *head) { return (dm_list_empty(head) ? NULL : head->p); } /* * Return the previous element of the list, or NULL if we've reached the start. */ struct dm_list *dm_list_prev(const struct dm_list *head, const struct dm_list *elem) { return (dm_list_start(head, elem) ? NULL : elem->p); } /* * Return the next element of the list, or NULL if we've reached the end. */ struct dm_list *dm_list_next(const struct dm_list *head, const struct dm_list *elem) { return (dm_list_end(head, elem) ? NULL : elem->n); } /* * Return the number of elements in a list by walking it. */ unsigned int dm_list_size(const struct dm_list *head) { unsigned int s = 0; const struct dm_list *v; dm_list_iterate(v, head) s++; return s; }