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Diffstat (limited to 'lst.lib/lstRemove.c')
| -rw-r--r-- | lst.lib/lstRemove.c | 136 |
1 files changed, 136 insertions, 0 deletions
diff --git a/lst.lib/lstRemove.c b/lst.lib/lstRemove.c new file mode 100644 index 0000000..54d7b33 --- /dev/null +++ b/lst.lib/lstRemove.c @@ -0,0 +1,136 @@ +/* $NetBSD: lstRemove.c,v 1.14 2008/12/13 15:19:29 dsl Exp $ */ + +/* + * Copyright (c) 1988, 1989, 1990, 1993 + * The Regents of the University of California. All rights reserved. + * + * This code is derived from software contributed to Berkeley by + * Adam de Boor. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. Neither the name of the University nor the names of its contributors + * may be used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ + +#ifndef MAKE_NATIVE +static char rcsid[] = "$NetBSD: lstRemove.c,v 1.14 2008/12/13 15:19:29 dsl Exp $"; +#else +#include <sys/cdefs.h> +#ifndef lint +#if 0 +static char sccsid[] = "@(#)lstRemove.c 8.1 (Berkeley) 6/6/93"; +#else +__RCSID("$NetBSD: lstRemove.c,v 1.14 2008/12/13 15:19:29 dsl Exp $"); +#endif +#endif /* not lint */ +#endif + +/*- + * LstRemove.c -- + * Remove an element from a list + */ + +#include "lstInt.h" + +/*- + *----------------------------------------------------------------------- + * Lst_Remove -- + * Remove the given node from the given list. + * + * Results: + * SUCCESS or FAILURE. + * + * Side Effects: + * The list's firstPtr will be set to NULL if ln is the last + * node on the list. firsPtr and lastPtr will be altered if ln is + * either the first or last node, respectively, on the list. + * + *----------------------------------------------------------------------- + */ +ReturnStatus +Lst_Remove(Lst l, LstNode ln) +{ + List list = l; + ListNode lNode = ln; + + if (!LstValid (l) || + !LstNodeValid (ln, l)) { + return (FAILURE); + } + + /* + * unlink it from the list + */ + if (lNode->nextPtr != NULL) { + lNode->nextPtr->prevPtr = lNode->prevPtr; + } + if (lNode->prevPtr != NULL) { + lNode->prevPtr->nextPtr = lNode->nextPtr; + } + + /* + * if either the firstPtr or lastPtr of the list point to this node, + * adjust them accordingly + */ + if (list->firstPtr == lNode) { + list->firstPtr = lNode->nextPtr; + } + if (list->lastPtr == lNode) { + list->lastPtr = lNode->prevPtr; + } + + /* + * Sequential access stuff. If the node we're removing is the current + * node in the list, reset the current node to the previous one. If the + * previous one was non-existent (prevPtr == NULL), we set the + * end to be Unknown, since it is. + */ + if (list->isOpen && (list->curPtr == lNode)) { + list->curPtr = list->prevPtr; + if (list->curPtr == NULL) { + list->atEnd = Unknown; + } + } + + /* + * the only way firstPtr can still point to ln is if ln is the last + * node on the list (the list is circular, so lNode->nextptr == lNode in + * this case). The list is, therefore, empty and is marked as such + */ + if (list->firstPtr == lNode) { + list->firstPtr = NULL; + } + + /* + * note that the datum is unmolested. The caller must free it as + * necessary and as expected. + */ + if (lNode->useCount == 0) { + free(ln); + } else { + lNode->flags |= LN_DELETED; + } + + return (SUCCESS); +} + |