kernel: Remove <sys/mplock2.h> from all files that do not need it.
[dragonfly.git] / libexec / revnetgroup / hash.c
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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.
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31 *
32 * $FreeBSD: src/libexec/revnetgroup/hash.c,v 1.6 1999/08/28 00:09:47 peter Exp $
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33 */
34
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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 */
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50static u_int32_t
51hash(const void *keyarg, size_t len)
984263bc 52{
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53 const u_char *key;
54 size_t loop;
55 u_int32_t h;
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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 hold 256 elements.
99 */
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100static u_int32_t
101hashkey(char *key)
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102{
103
104 if (key == NULL)
105 return (-1);
4e1af74f 106 return(hash(key, strlen(key)) & HASH_MASK);
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107}
108
109/* Find an entry in the hash table (may be hanging off a linked list). */
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110char *
111lookup(struct group_entry *table[], char *key)
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112{
113 struct group_entry *cur;
114
115 cur = table[hashkey(key)];
116
117 while (cur) {
118 if (!strcmp(cur->key, key))
119 return(cur->data);
120 cur = cur->next;
121 }
122
123 return(NULL);
124}
125
126/*
127 * Store an entry in the main netgroup hash table. Here's how this
128 * works: the table can only be so big when we initialize it (TABLESIZE)
129 * but the number of netgroups in the /etc/netgroup file could easily be
130 * much larger than the table. Since our hash values are adjusted to
131 * never be greater than TABLESIZE too, this means it won't be long before
132 * we find ourselves with two keys that hash to the same value.
133 *
134 * One way to deal with this is to malloc(2) a second table and start
135 * doing indirection, but this is a pain in the butt and it's not worth
136 * going to all that trouble for a dinky little program like this. Instead,
137 * we turn each table entry into a linked list and simply link keys
138 * with the same hash value together at the same index location within
139 * the table.
140 *
141 * That's a lot of comment for such a small piece of code, isn't it.
142 */
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143void
144store(struct group_entry *table[], char *key, char *data)
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145{
146 struct group_entry *new;
147 u_int32_t i;
148
149 i = hashkey(key);
150
151 new = (struct group_entry *)malloc(sizeof(struct group_entry));
152 new->key = strdup(key);
153 new->data = strdup(data);
154 new->next = table[i];
155 table[i] = new;
156
157 return;
158}
159
160/*
161 * Store a group member entry and/or update its grouplist. This is
162 * a bit more complicated than the previous function since we have to
163 * maintain not only the hash table of group members, each group member
164 * structure also has a linked list of groups hung off it. If handed
165 * a member name that we haven't encountered before, we have to do
166 * two things: add that member to the table (possibly hanging them
167 * off the end of a linked list, as above), and add a group name to
168 * the member's grouplist list. If we're handed a name that already has
169 * an entry in the table, then we just have to do one thing, which is
170 * to update its grouplist.
171 */
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172void
173mstore(struct member_entry *table[], char *key, char *data, char *domain)
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174{
175 struct member_entry *cur, *new;
176 struct grouplist *tmp;
177 u_int32_t i;
178
179 i = hashkey(key);
180 cur = table[i];
181
182 tmp = (struct grouplist *)malloc(sizeof(struct grouplist));
183 tmp->groupname = strdup(data);
184 tmp->next = NULL;
185
186 /* Check if all we have to do is insert a new groupname. */
187 while (cur) {
188 if (!strcmp(cur->key, key)) {
189 tmp->next = cur->groups;
190 cur->groups = tmp;
191 return;
192 }
193 cur = cur->next;
194 }
195
196 /* Didn't find a match -- add the whole mess to the table. */
197 new = (struct member_entry *)malloc(sizeof(struct member_entry));
198 new->key = strdup(key);
199 new->domain = domain ? strdup(domain) : "*";
200 new->groups = tmp;
201 new->next = table[i];
202 table[i] = new;
203
204 return;
205}