libs/dbprim/ll_remove.c

   1 /*
   2 ** Copyright (C) 2002 by Kevin L. Mitchell <klmitch@mit.edu>
   3 **
   4 ** This library is free software; you can redistribute it and/or
   5 ** modify it under the terms of the GNU Library General Public
   6 ** License as published by the Free Software Foundation; either
   7 ** version 2 of the License, or (at your option) any later version.
   8 **
   9 ** This library is distributed in the hope that it will be useful,
  10 ** but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 ** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12 ** Library General Public License for more details.
  13 **
  14 ** You should have received a copy of the GNU Library General Public
  15 ** License along with this library; if not, write to the Free
  16 ** Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
  17 ** MA 02111-1307, USA
  18 **
  19 ** @(#)$Id: ll_remove.c,v 1.1 2003/03/07 02:36:11 klmitch Exp $
  20 */
  21 #include "dbprim.h"
  22 #include "dbprim_int.h"
  23
  24 RCSTAG("@(#)$Id: ll_remove.c,v 1.1 2003/03/07 02:36:11 klmitch Exp $");
  25
  26 /** \ingroup dbprim_link
  27  * \brief Remove an element from a linked list.
  28  *
  29  * This function removes a specified element from a linked list.
  30  *
  31  * \param list  A pointer to a #link_head_t.
  32  * \param elem  A pointer to the #link_elem_t describing the element
  33  *              to be removed.
  34  *
  35  * \retval DB_ERR_BADARGS       An argument was invalid.
  36  * \retval DB_ERR_UNUSED        \p elem is not in a linked list.
  37  * \retval DB_ERR_WRONGTABLE    \p elem is not in this linked list.
  38  */
  39 unsigned long
  40 ll_remove(link_head_t *list, link_elem_t *elem)
  41 {
  42   initialize_dbpr_error_table(); /* initialize error table */
  43
  44   if (!ll_verify(list) || !le_verify(elem)) /* First, verify the arguments */
  45     return DB_ERR_BADARGS;
  46
  47   if (!elem->le_head) /* is the element even being used? */
  48     return DB_ERR_UNUSED;
  49   if (list != elem->le_head) /* Verify that the element is in this list */
  50     return DB_ERR_WRONGTABLE;
  51
  52   list->lh_count--; /* OK, reduce the list count */
  53
  54   if (elem->le_next) /* Clip the list back together */
  55     elem->le_next->le_prev = elem->le_prev;
  56   if (elem->le_prev)
  57     elem->le_prev->le_next = elem->le_next;
  58   else
  59     list->lh_first = elem->le_next;
  60
  61   if (list->lh_last == elem) /* Make sure we know where the last element is */
  62     list->lh_last = elem->le_prev;
  63
  64   elem->le_next = 0; /* Clear the element out */
  65   elem->le_prev = 0;
  66   elem->le_head = 0;
  67
  68   return 0;
  69 }