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 static u_int32_t
  52 hash(const void *keyarg, size_t len)
  53 {
  54         const u_char *key;
  55         size_t loop;
  56         u_int32_t h;
  57
  58 #define HASHC   h = *key++ + 65599 * h
  59
  60         h = 0;
  61         key = keyarg;
  62         if (len > 0) {
  63                 loop = (len + 8 - 1) >> 3;
  64
  65                 switch (len & (8 - 1)) {
  66                 case 0:
  67                         do {
  68                                 HASHC;
  69                                 /* FALLTHROUGH */
  70                 case 7:
  71                                 HASHC;
  72                                 /* FALLTHROUGH */
  73                 case 6:
  74                                 HASHC;
  75                                 /* FALLTHROUGH */
  76                 case 5:
  77                                 HASHC;
  78                                 /* FALLTHROUGH */
  79                 case 4:
  80                                 HASHC;
  81                                 /* FALLTHROUGH */
  82                 case 3:
  83                                 HASHC;
  84                                 /* FALLTHROUGH */
  85                 case 2:
  86                                 HASHC;
  87                                 /* FALLTHROUGH */
  88                 case 1:
  89                                 HASHC;
  90                         } while (--loop);
  91                 }
  92         }
  93         return (h);
  94 }
  95
  96 /*
  97  * Generate a hash value for a given key (character string).
  98  * We mask off all but the lower 8 bits since our table array
  99  * can only hole 256 elements.
 100  */
 101 static u_int32_t
 102 hashkey(char *key)
 103 {
 104
 105         if (key == NULL)
 106                 return (-1);
 107         return(hash((void *)key, strlen(key)) & HASH_MASK);
 108 }
 109
 110 /* Find an entry in the hash table (may be hanging off a linked list). */
 111 struct grouplist *
 112 lookup(struct member_entry *table[], char *key)
 113 {
 114         struct member_entry *cur;
 115
 116         cur = table[hashkey(key)];
 117
 118         while (cur) {
 119                 if (!strcmp(cur->key, key))
 120                         return(cur->groups);
 121                 cur = cur->next;
 122         }
 123
 124         return(NULL);
 125 }
 126
 127 struct grouplist dummy = { 99999, NULL };
 128
 129 /*
 130  * Store an group member entry and/or update its grouplist.
 131  */
 132 void
 133 mstore(struct member_entry *table[], char *key, int gid, int dup)
 134 {
 135         struct member_entry *cur, *new;
 136         struct grouplist *tmp = NULL;
 137         u_int32_t i;
 138
 139         i = hashkey(key);
 140         cur = table[i];
 141
 142         if (!dup) {
 143                 tmp = (struct grouplist *)malloc(sizeof(struct grouplist));
 144                 tmp->groupid = gid;
 145                 tmp->next = NULL;
 146         }
 147
 148                 /* Check if all we have to do is insert a new groupname. */
 149         while (cur) {
 150                 if (!dup && !strcmp(cur->key, key)) {
 151                         tmp->next = cur->groups;
 152                         cur->groups = tmp;
 153                         return;
 154                 }
 155                 cur = cur->next;
 156         }
 157
 158         /* Didn't find a match -- add the whole mess to the table. */
 159         new = (struct member_entry *)malloc(sizeof(struct member_entry));
 160         new->key = strdup(key);
 161         if (!dup)
 162                 new->groups = tmp;
 163         else
 164                 new->groups = (struct grouplist *)&dummy;
 165         new->next = table[i];
 166         table[i] = new;
 167
 168         return;
 169 }