1 /*
   2  * Copyright (c) 1999, 2018, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 /** ------------------------------------------------------------------------
  26         This file contains routines for manipulating generic lists.
  27         Lists are implemented with a "harness".  In other words, each
  28         node in the list consists of two pointers, one to the data item
  29         and one to the next node in the list.  The head of the list is
  30         the same struct as each node, but the "item" ptr is used to point
  31         to the current member of the list (used by the first_in_list and
  32         next_in_list functions).
  33 
  34  This file is available under and governed by the GNU General Public
  35  License version 2 only, as published by the Free Software Foundation.
  36  However, the following notice accompanied the original version of this
  37  file:
  38 
  39 Copyright 1994 Hewlett-Packard Co.
  40 Copyright 1996, 1998  The Open Group
  41 
  42 Permission to use, copy, modify, distribute, and sell this software and its
  43 documentation for any purpose is hereby granted without fee, provided that
  44 the above copyright notice appear in all copies and that both that
  45 copyright notice and this permission notice appear in supporting
  46 documentation.
  47 
  48 The above copyright notice and this permission notice shall be included
  49 in all copies or substantial portions of the Software.
  50 
  51 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  52 OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  53 MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
  54 IN NO EVENT SHALL THE OPEN GROUP BE LIABLE FOR ANY CLAIM, DAMAGES OR
  55 OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  56 ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  57 OTHER DEALINGS IN THE SOFTWARE.
  58 
  59 Except as contained in this notice, the name of The Open Group shall
  60 not be used in advertising or otherwise to promote the sale, use or
  61 other dealings in this Software without prior written authorization
  62 from The Open Group.
  63 
  64   ----------------------------------------------------------------------- **/




  65 
  66 #include <stdio.h>
  67 #include <stdlib.h>
  68 
  69 #include "list.h"
  70 
  71 
  72 /** ------------------------------------------------------------------------
  73         Sets the pointers of the specified list to NULL.
  74     --------------------------------------------------------------------- **/
  75 void zero_list(list_ptr lp)
  76 {
  77     lp->next = NULL;
  78     lp->ptr.item = NULL;
  79 }
  80 
  81 
  82 /** ------------------------------------------------------------------------
  83         Adds item to the list pointed to by lp.  Finds the end of the
  84         list, then mallocs a new list node onto the end of the list.
  85         The item pointer in the new node is set to "item" passed in,
  86         and the next pointer in the new node is set to NULL.
  87         Returns 1 if successful, 0 if the malloc failed.
  88     -------------------------------------------------------------------- **/
  89 int add_to_list(list_ptr lp, void *item)
  90 {
  91     while (lp->next) {
  92         lp = lp->next;
  93     }
  94     if ((lp->next = (list_ptr) malloc( sizeof( list_item))) == NULL) {
  95 
  96         return 0;
  97     }
  98     lp->next->ptr.item = item;
  99     lp->next->next = NULL;
 100 
 101     return 1;
 102 }
 103 
 104 
 105 /** ------------------------------------------------------------------------
 106         Creates a new list and sets its pointers to NULL.
 107         Returns a pointer to the new list.
 108     -------------------------------------------------------------------- **/
 109 list_ptr new_list (void)
 110 {
 111     list_ptr lp;
 112 
 113     if ((lp = (list_ptr) malloc( sizeof( list_item)))) {
 114         lp->next = NULL;
 115         lp->ptr.item = NULL;
 116     }
 117 
 118     return lp;
 119 }
 120 
 121 
 122 /** ------------------------------------------------------------------------
 123         Creates a new list head, pointing to the same list as the one
 124         passed in.  If start_at_curr is TRUE, the new list's first item
 125         is the "current" item (as set by calls to first/next_in_list()).
 126         If start_at_curr is FALSE, the first item in the new list is the
 127         same as the first item in the old list.  In either case, the
 128         curr pointer in the new list is the same as in the old list.
 129         Returns a pointer to the new list head.
 130     -------------------------------------------------------------------- **/
 131 list_ptr dup_list_head(list_ptr lp, int start_at_curr)
 132 {
 133     list_ptr new_listp;
 134 
 135     if ((new_listp = (list_ptr) malloc( sizeof( list_item))) == NULL) {
 136 
 137         return (list_ptr)NULL;
 138     }
 139     new_listp->next = start_at_curr ? lp->ptr.curr : lp->next;
 140     new_listp->ptr.curr = lp->ptr.curr;
 141 
 142     return new_listp;
 143 }
 144 
 145 
 146 /** ------------------------------------------------------------------------
 147         Returns the number of items in the list.
 148     -------------------------------------------------------------------- **/
 149 unsigned int list_length(list_ptr lp)
 150 {
 151     unsigned int count = 0;
 152 
 153     while (lp->next) {
 154         count++;
 155         lp = lp->next;
 156     }
 157 
 158     return count;
 159 }
 160 
 161 
 162 /** ------------------------------------------------------------------------
 163         Scans thru list, looking for a node whose ptr.item is equal to
 164         the "item" passed in.  "Equal" here means the same address - no
 165         attempt is made to match equivalent values stored in different
 166         locations.  If a match is found, that node is deleted from the
 167         list.  Storage for the node is freed, but not for the item itself.
 168         Returns a pointer to the item, so the caller can free it if it
 169         so desires.  If a match is not found, returns NULL.
 170     -------------------------------------------------------------------- **/
 171 void *delete_from_list(list_ptr lp, void *item)
 172 {
 173     list_ptr new_next;
 174 
 175     while (lp->next) {
 176         if (lp->next->ptr.item == item) {
 177             new_next = lp->next->next;
 178             free (lp->next);
 179             lp->next = new_next;
 180 
 181             return item;
 182         }
 183         lp = lp->next;
 184     }
 185 
 186     return NULL;
 187 }
 188 
 189 
 190 /** ------------------------------------------------------------------------
 191         Deletes each node in the list *except the head*.  This allows
 192         the deletion of lists where the head is not malloced or created
 193         with new_list().  If free_items is true, each item pointed to
 194         from the node is freed, in addition to the node itself.
 195     -------------------------------------------------------------------- **/
 196 void delete_list(list_ptr lp, int free_items)
 197 {
 198     list_ptr del_node;
 199     void *item;
 200 
 201     while (lp->next) {
 202         del_node = lp->next;
 203         item = del_node->ptr.item;
 204         lp->next = del_node->next;
 205         free (del_node);
 206         if (free_items) {
 207             free( item);
 208         }
 209     }
 210 }
 211 
 212 void delete_list_destroying(list_ptr lp, void destructor(void *item))
 213 {
 214     list_ptr del_node;
 215     void *item;
 216 
 217     while (lp->next) {
 218         del_node = lp->next;
 219         item = del_node->ptr.item;
 220         lp->next = del_node->next;
 221         free( del_node);
 222         if (destructor) {
 223             destructor( item);
 224         }
 225     }
 226 }
 227 
 228 
 229 /** ------------------------------------------------------------------------
 230         Returns a ptr to the first *item* (not list node) in the list.
 231         Sets the list head node's curr ptr to the first node in the list.
 232         Returns NULL if the list is empty.
 233     -------------------------------------------------------------------- **/
 234 void * first_in_list(list_ptr lp)
 235 {
 236     if (! lp) {
 237 
 238         return NULL;
 239     }
 240     lp->ptr.curr = lp->next;
 241 
 242     return lp->ptr.curr ? lp->ptr.curr->ptr.item : NULL;
 243 }
 244 
 245 /** ------------------------------------------------------------------------
 246         Returns a ptr to the next *item* (not list node) in the list.
 247         Sets the list head node's curr ptr to the next node in the list.
 248         first_in_list must have been called prior.
 249         Returns NULL if no next item.
 250     -------------------------------------------------------------------- **/
 251 void * next_in_list(list_ptr lp)
 252 {
 253     if (! lp) {
 254 
 255         return NULL;
 256     }
 257     if (lp->ptr.curr) {
 258         lp->ptr.curr = lp->ptr.curr->next;
 259     }
 260 
 261     return lp->ptr.curr ? lp->ptr.curr->ptr.item : NULL;
 262 }
 263 
 264 int list_is_empty(list_ptr lp)
 265 {
 266     return (lp == NULL || lp->next == NULL);
 267 }
 268 
--- EOF ---