usr.bin/make/lst.lib/lstRemove.c

   1 /*      $NetBSD: lstRemove.c,v 1.14 2008/12/13 15:19:29 dsl Exp $       */
   2
   3 /*
   4  * Copyright (c) 1988, 1989, 1990, 1993
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * This code is derived from software contributed to Berkeley by
   8  * Adam de Boor.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  * 3. Neither the name of the University nor the names of its contributors
  19  *    may be used to endorse or promote products derived from this software
  20  *    without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  */
  34
  35 #ifndef MAKE_NATIVE
  36 static char rcsid[] = "$NetBSD: lstRemove.c,v 1.14 2008/12/13 15:19:29 dsl Exp $";
  37 #else
  38 #include <sys/cdefs.h>
  39 #ifndef lint
  40 #if 0
  41 static char sccsid[] = "@(#)lstRemove.c 8.1 (Berkeley) 6/6/93";
  42 #else
  43 __RCSID("$NetBSD: lstRemove.c,v 1.14 2008/12/13 15:19:29 dsl Exp $");
  44 #endif
  45 #endif /* not lint */
  46 #endif
  47
  48 /*-
  49  * LstRemove.c --
  50  *      Remove an element from a list
  51  */
  52
  53 #include        "lstInt.h"
  54
  55 /*-
  56  *-----------------------------------------------------------------------
  57  * Lst_Remove --
  58  *      Remove the given node from the given list.
  59  *
  60  * Results:
  61  *      SUCCESS or FAILURE.
  62  *
  63  * Side Effects:
  64  *      The list's firstPtr will be set to NULL if ln is the last
  65  *      node on the list. firsPtr and lastPtr will be altered if ln is
  66  *      either the first or last node, respectively, on the list.
  67  *
  68  *-----------------------------------------------------------------------
  69  */
  70 ReturnStatus
  71 Lst_Remove(Lst l, LstNode ln)
  72 {
  73     List        list = l;
  74     ListNode    lNode = ln;
  75
  76     if (!LstValid (l) ||
  77         !LstNodeValid (ln, l)) {
  78             return (FAILURE);
  79     }
  80
  81     /*
  82      * unlink it from the list
  83      */
  84     if (lNode->nextPtr != NULL) {
  85         lNode->nextPtr->prevPtr = lNode->prevPtr;
  86     }
  87     if (lNode->prevPtr != NULL) {
  88         lNode->prevPtr->nextPtr = lNode->nextPtr;
  89     }
  90
  91     /*
  92      * if either the firstPtr or lastPtr of the list point to this node,
  93      * adjust them accordingly
  94      */
  95     if (list->firstPtr == lNode) {
  96         list->firstPtr = lNode->nextPtr;
  97     }
  98     if (list->lastPtr == lNode) {
  99         list->lastPtr = lNode->prevPtr;
 100     }
 101
 102     /*
 103      * Sequential access stuff. If the node we're removing is the current
 104      * node in the list, reset the current node to the previous one. If the
 105      * previous one was non-existent (prevPtr == NULL), we set the
 106      * end to be Unknown, since it is.
 107      */
 108     if (list->isOpen && (list->curPtr == lNode)) {
 109         list->curPtr = list->prevPtr;
 110         if (list->curPtr == NULL) {
 111             list->atEnd = Unknown;
 112         }
 113     }
 114
 115     /*
 116      * the only way firstPtr can still point to ln is if ln is the last
 117      * node on the list (the list is circular, so lNode->nextptr == lNode in
 118      * this case). The list is, therefore, empty and is marked as such
 119      */
 120     if (list->firstPtr == lNode) {
 121         list->firstPtr = NULL;
 122     }
 123
 124     /*
 125      * note that the datum is unmolested. The caller must free it as
 126      * necessary and as expected.
 127      */
 128     if (lNode->useCount == 0) {
 129         free(ln);
 130     } else {
 131         lNode->flags |= LN_DELETED;
 132     }
 133
 134     return (SUCCESS);
 135 }
 136