revnetgroup.tproj/hash.c

   1 /*
   2  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * "Portions Copyright (c) 1999 Apple Computer, Inc.  All Rights
   7  * Reserved.  This file contains Original Code and/or Modifications of
   8  * Original Code as defined in and that are subject to the Apple Public
   9  * Source License Version 1.0 (the 'License').  You may not use this file
  10  * except in compliance with the License.  Please obtain a copy of the
  11  * License at http://www.apple.com/publicsource and read it before using
  12  * this file.
  13  *
  14  * The Original Code and all software distributed under the License are
  15  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  16  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  17  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
  19  * License for the specific language governing rights and limitations
  20  * under the License."
  21  *
  22  * @APPLE_LICENSE_HEADER_END@
  23  */
  24 /* $OpenBSD: hash.c,v 1.1 1997/04/15 22:06:11 maja Exp $ */
  25 /*
  26  * Copyright (c) 1995
  27  *      Bill Paul <wpaul@ctr.columbia.edu>.  All rights reserved.
  28  *
  29  * Redistribution and use in source and binary forms, with or without
  30  * modification, are permitted provided that the following conditions
  31  * are met:
  32  * 1. Redistributions of source code must retain the above copyright
  33  *    notice, this list of conditions and the following disclaimer.
  34  * 2. Redistributions in binary form must reproduce the above copyright
  35  *    notice, this list of conditions and the following disclaimer in the
  36  *    documentation and/or other materials provided with the distribution.
  37  * 3. All advertising materials mentioning features or use of this software
  38  *    must display the following acknowledgement:
  39  *      This product includes software developed by Bill Paul.
  40  * 4. Neither the name of the author nor the names of any co-contributors
  41  *    may be used to endorse or promote products derived from this software
  42  *    without specific prior written permission.
  43  *
  44  * THIS SOFTWARE IS PROVIDED BY Bill Paul AND CONTRIBUTORS ``AS IS'' AND
  45  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  46  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  47  * ARE DISCLAIMED.  IN NO EVENT SHALL Bill Paul OR CONTRIBUTORS BE LIABLE
  48  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  49  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  50  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  51  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  52  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  53  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  54  * SUCH DAMAGE.
  55  *
  56  *      $FreeBSD: hash.c,v 1.4 1997/02/22 14:22:01 peter Exp $
  57  */
  58
  59 #include <stdio.h>
  60 #include <stdlib.h>
  61 #include <string.h>
  62 #include <sys/types.h>
  63 #include "hash.h"
  64
  65 #ifndef lint
  66 static const char rcsid[] = "$OpenBSD: hash.c,v 1.1 1997/04/15 22:06:11 maja Exp $";
  67 #endif
  68
  69 /*
  70  * This hash function is stolen directly from the
  71  * Berkeley DB package. It already exists inside libc, but
  72  * it's declared static which prevents us from calling it
  73  * from here.
  74  */
  75 /*
  76  * OZ's original sdbm hash
  77  */
  78 u_int32_t
  79 hash(keyarg, len)
  80         const void *keyarg;
  81         register size_t len;
  82 {
  83         register const u_char *key;
  84         register size_t loop;
  85         register u_int32_t h;
  86
  87 #define HASHC   h = *key++ + 65599 * h
  88
  89         h = 0;
  90         key = keyarg;
  91         if (len > 0) {
  92                 loop = (len + 8 - 1) >> 3;
  93
  94                 switch (len & (8 - 1)) {
  95                 case 0:
  96                         do {
  97                                 HASHC;
  98                                 /* FALLTHROUGH */
  99                 case 7:
 100                                 HASHC;
 101                                 /* FALLTHROUGH */
 102                 case 6:
 103                                 HASHC;
 104                                 /* FALLTHROUGH */
 105                 case 5:
 106                                 HASHC;
 107                                 /* FALLTHROUGH */
 108                 case 4:
 109                                 HASHC;
 110                                 /* FALLTHROUGH */
 111                 case 3:
 112                                 HASHC;
 113                                 /* FALLTHROUGH */
 114                 case 2:
 115                                 HASHC;
 116                                 /* FALLTHROUGH */
 117                 case 1:
 118                                 HASHC;
 119                         } while (--loop);
 120                 }
 121         }
 122         return (h);
 123 }
 124
 125 /*
 126  * Generate a hash value for a given key (character string).
 127  * We mask off all but the lower 8 bits since our table array
 128  * can only hold 256 elements.
 129  */
 130 u_int32_t hashkey(key)
 131         char *key;
 132 {
 133
 134         if (key == NULL)
 135                 return (-1);
 136         return(hash((void *)key, strlen(key)) & HASH_MASK);
 137 }
 138
 139 /* Find an entry in the hash table (may be hanging off a linked list). */
 140 char *lookup(table, key)
 141         struct group_entry *table[];
 142         char *key;
 143 {
 144         struct group_entry *cur;
 145
 146         cur = table[hashkey(key)];
 147
 148         while (cur) {
 149                 if (!strcmp(cur->key, key))
 150                         return(cur->data);
 151                 cur = cur->next;
 152         }
 153
 154         return(NULL);
 155 }
 156
 157 /*
 158  * Store an entry in the main netgroup hash table. Here's how this
 159  * works: the table can only be so big when we initialize it (TABLESIZE)
 160  * but the number of netgroups in the /etc/netgroup file could easily be
 161  * much larger than the table. Since our hash values are adjusted to
 162  * never be greater than TABLESIZE too, this means it won't be long before
 163  * we find ourselves with two keys that hash to the same value.
 164  *
 165  * One way to deal with this is to malloc(2) a second table and start
 166  * doing indirection, but this is a pain in the butt and it's not worth
 167  * going to all that trouble for a dinky little program like this. Instead,
 168  * we turn each table entry into a linked list and simply link keys
 169  * with the same hash value together at the same index location within
 170  * the table.
 171  *
 172  * That's a lot of comment for such a small piece of code, isn't it.
 173  */
 174 void store (table, key, data)
 175         struct group_entry *table[];
 176         char *key, *data;
 177 {
 178         struct group_entry *new;
 179         u_int32_t i;
 180
 181         i = hashkey(key);
 182
 183         new = (struct group_entry *)malloc(sizeof(struct group_entry));
 184         new->key = strdup(key);
 185         new->data = strdup(data);
 186         new->next = table[i];
 187         table[i] = new;
 188
 189         return;
 190 }
 191
 192 /*
 193  * Store a group member entry and/or update its grouplist. This is
 194  * a bit more complicated than the previous function since we have to
 195  * maintain not only the hash table of group members, each group member
 196  * structure also has a linked list of groups hung off it. If handed
 197  * a member name that we haven't encountered before, we have to do
 198  * two things: add that member to the table (possibly hanging them
 199  * off the end of a linked list, as above), and add a group name to
 200  * the member's grouplist list. If we're handed a name that already has
 201  * an entry in the table, then we just have to do one thing, which is
 202  * to update its grouplist.
 203  */
 204 void mstore (table, key, data, domain)
 205         struct member_entry *table[];
 206         char *key, *data, *domain;
 207 {
 208         struct member_entry *cur, *new;
 209         struct grouplist *tmp,*p;
 210         u_int32_t i;
 211
 212         i = hashkey(key);
 213         cur = table[i];
 214
 215         tmp = (struct grouplist *)malloc(sizeof(struct grouplist));
 216         tmp->groupname = strdup(data);
 217         tmp->next = NULL;
 218
 219         /* Check if all we have to do is insert a new groupname. */
 220         while (cur) {
 221                 if (!strcmp(cur->key, key) && !strcmp(cur->domain,domain)) {
 222                         p = cur->groups;
 223                         while(p) {
 224                                 if (!strcmp(p->groupname,data))
 225                                         return;
 226                                 p = p->next;
 227                         }
 228                         tmp->next = cur->groups;
 229                         cur->groups = tmp;
 230                         return;
 231                 }
 232                 cur = cur->next;
 233         }
 234
 235         /* Didn't find a match -- add the whole mess to the table. */
 236         new = (struct member_entry *)malloc(sizeof(struct member_entry));
 237         new->key = strdup(key);
 238         new->domain = strdup(domain);
 239         new->groups = tmp;
 240         new->next = table[i];
 241         table[i] = new;
 242
 243         return;
 244 }