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  */
  34
  35 #include <stdio.h>
  36 #include <stdlib.h>
  37 #include <string.h>
  38 #include <sys/types.h>
  39 #include "hash.h"
  40
  41 /*
  42  * This hash function is stolen directly from the
  43  * Berkeley DB package. It already exists inside libc, but
  44  * it's declared static which prevents us from calling it
  45  * from here.
  46  */
  47 /*
  48  * OZ's original sdbm hash
  49  */
  50 static u_int32_t
  51 hash(const void *keyarg, size_t len)
  52 {
  53         const u_char *key;
  54         size_t loop;
  55         u_int32_t h;
  56
  57 #define HASHC   h = *key++ + 65599 * h
  58
  59         h = 0;
  60         key = keyarg;
  61         if (len > 0) {
  62                 loop = (len + 8 - 1) >> 3;
  63
  64                 switch (len & (8 - 1)) {
  65                 case 0:
  66                         do {
  67                                 HASHC;
  68                                 /* FALLTHROUGH */
  69                 case 7:
  70                                 HASHC;
  71                                 /* FALLTHROUGH */
  72                 case 6:
  73                                 HASHC;
  74                                 /* FALLTHROUGH */
  75                 case 5:
  76                                 HASHC;
  77                                 /* FALLTHROUGH */
  78                 case 4:
  79                                 HASHC;
  80                                 /* FALLTHROUGH */
  81                 case 3:
  82                                 HASHC;
  83                                 /* FALLTHROUGH */
  84                 case 2:
  85                                 HASHC;
  86                                 /* FALLTHROUGH */
  87                 case 1:
  88                                 HASHC;
  89                         } while (--loop);
  90                 }
  91         }
  92         return (h);
  93 }
  94
  95 /*
  96  * Generate a hash value for a given key (character string).
  97  * We mask off all but the lower 8 bits since our table array
  98  * can only hole 256 elements.
  99  */
 100 static u_int32_t
 101 hashkey(char *key)
 102 {
 103
 104         if (key == NULL)
 105                 return (-1);
 106         return(hash(key, strlen(key)) & HASH_MASK);
 107 }
 108
 109 /* Find an entry in the hash table (may be hanging off a linked list). */
 110 struct grouplist *
 111 lookup(struct member_entry *table[], char *key)
 112 {
 113         struct member_entry *cur;
 114
 115         cur = table[hashkey(key)];
 116
 117         while (cur) {
 118                 if (!strcmp(cur->key, key))
 119                         return(cur->groups);
 120                 cur = cur->next;
 121         }
 122
 123         return(NULL);
 124 }
 125
 126 struct grouplist dummy = { 99999, NULL };
 127
 128 /*
 129  * Store an group member entry and/or update its grouplist.
 130  */
 131 void
 132 mstore(struct member_entry *table[], char *key, int gid, int dup)
 133 {
 134         struct member_entry *cur, *new;
 135         struct grouplist *tmp = NULL;
 136         u_int32_t i;
 137
 138         i = hashkey(key);
 139         cur = table[i];
 140
 141         if (!dup) {
 142                 tmp = (struct grouplist *)malloc(sizeof(struct grouplist));
 143                 tmp->groupid = gid;
 144                 tmp->next = NULL;
 145         }
 146
 147                 /* Check if all we have to do is insert a new groupname. */
 148         while (cur) {
 149                 if (!dup && !strcmp(cur->key, key)) {
 150                         tmp->next = cur->groups;
 151                         cur->groups = tmp;
 152                         return;
 153                 }
 154                 cur = cur->next;
 155         }
 156
 157         /* Didn't find a match -- add the whole mess to the table. */
 158         new = (struct member_entry *)malloc(sizeof(struct member_entry));
 159         new->key = strdup(key);
 160         if (!dup)
 161                 new->groups = tmp;
 162         else
 163                 new->groups = (struct grouplist *)&dummy;
 164         new->next = table[i];
 165         table[i] = new;
 166
 167         return;
 168 }