libexec/mknetid/hash.c

   1 /*
   2  * Copyright (c) 1995
   3  *      Bill Paul <wpaul@ctr.columbia.edu>.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by Bill Paul.
  16  * 4. Neither the name of the author nor the names of any co-contributors
  17  *    may be used to endorse or promote products derived from this software
  18  *    without specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY Bill Paul AND CONTRIBUTORS ``AS IS'' AND
  21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23  * ARE DISCLAIMED.  IN NO EVENT SHALL Bill Paul OR CONTRIBUTORS BE LIABLE
  24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  *
  32  * $FreeBSD: src/libexec/mknetid/hash.c,v 1.5 1999/08/28 00:09:40 peter Exp $
  33  * $DragonFly: src/libexec/mknetid/hash.c,v 1.2 2003/06/17 04:27:07 dillon Exp $
  34  */
  35
  36 #include <stdio.h>
  37 #include <stdlib.h>
  38 #include <string.h>
  39 #include <sys/types.h>
  40 #include "hash.h"
  41
  42 /*
  43  * This hash function is stolen directly from the
  44  * Berkeley DB package. It already exists inside libc, but
  45  * it's declared static which prevents us from calling it
  46  * from here.
  47  */
  48 /*
  49  * OZ's original sdbm hash
  50  */
  51 u_int32_t
  52 hash(keyarg, len)
  53         const void *keyarg;
  54         register size_t len;
  55 {
  56         register const u_char *key;
  57         register size_t loop;
  58         register u_int32_t h;
  59
  60 #define HASHC   h = *key++ + 65599 * h
  61
  62         h = 0;
  63         key = keyarg;
  64         if (len > 0) {
  65                 loop = (len + 8 - 1) >> 3;
  66
  67                 switch (len & (8 - 1)) {
  68                 case 0:
  69                         do {
  70                                 HASHC;
  71                                 /* FALLTHROUGH */
  72                 case 7:
  73                                 HASHC;
  74                                 /* FALLTHROUGH */
  75                 case 6:
  76                                 HASHC;
  77                                 /* FALLTHROUGH */
  78                 case 5:
  79                                 HASHC;
  80                                 /* FALLTHROUGH */
  81                 case 4:
  82                                 HASHC;
  83                                 /* FALLTHROUGH */
  84                 case 3:
  85                                 HASHC;
  86                                 /* FALLTHROUGH */
  87                 case 2:
  88                                 HASHC;
  89                                 /* FALLTHROUGH */
  90                 case 1:
  91                                 HASHC;
  92                         } while (--loop);
  93                 }
  94         }
  95         return (h);
  96 }
  97
  98 /*
  99  * Generate a hash value for a given key (character string).
 100  * We mask off all but the lower 8 bits since our table array
 101  * can only hole 256 elements.
 102  */
 103 u_int32_t hashkey(key)
 104         char *key;
 105 {
 106
 107         if (key == NULL)
 108                 return (-1);
 109         return(hash((void *)key, strlen(key)) & HASH_MASK);
 110 }
 111
 112 /* Find an entry in the hash table (may be hanging off a linked list). */
 113 struct grouplist *lookup(table, key)
 114         struct member_entry *table[];
 115         char *key;
 116 {
 117         struct member_entry *cur;
 118
 119         cur = table[hashkey(key)];
 120
 121         while (cur) {
 122                 if (!strcmp(cur->key, key))
 123                         return(cur->groups);
 124                 cur = cur->next;
 125         }
 126
 127         return(NULL);
 128 }
 129
 130 struct grouplist dummy = { 99999, NULL };
 131
 132 /*
 133  * Store an group member entry and/or update its grouplist.
 134  */
 135 void mstore (table, key, gid, dup)
 136         struct member_entry *table[];
 137         char *key;
 138         int gid;
 139         int dup;
 140 {
 141         struct member_entry *cur, *new;
 142         struct grouplist *tmp;
 143         u_int32_t i;
 144
 145         i = hashkey(key);
 146         cur = table[i];
 147
 148         if (!dup) {
 149                 tmp = (struct grouplist *)malloc(sizeof(struct grouplist));
 150                 tmp->groupid = gid;
 151                 tmp->next = NULL;
 152         }
 153
 154                 /* Check if all we have to do is insert a new groupname. */
 155         while (cur) {
 156                 if (!dup && !strcmp(cur->key, key)) {
 157                         tmp->next = cur->groups;
 158                         cur->groups = tmp;
 159                         return;
 160                 }
 161                 cur = cur->next;
 162         }
 163
 164         /* Didn't find a match -- add the whole mess to the table. */
 165         new = (struct member_entry *)malloc(sizeof(struct member_entry));
 166         new->key = strdup(key);
 167         if (!dup)
 168                 new->groups = tmp;
 169         else
 170                 new->groups = (struct grouplist *)&dummy;
 171         new->next = table[i];
 172         table[i] = new;
 173
 174         return;
 175 }