hash.c revision 22989 
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 *	$Id$
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#ifndef lint
42static const char rcsid[] = "$Id$";
43#endif
44
45
46/*
47 * This hash function is stolen directly from the
48 * Berkeley DB package. It already exists inside libc, but
49 * it's declared static which prevents us from calling it
50 * from here.
51 */
52/*
53 * OZ's original sdbm hash
54 */
55u_int32_t
56hash(keyarg, len)
57	const void *keyarg;
58	register size_t len;
59{
60	register const u_char *key;
61	register size_t loop;
62	register u_int32_t h;
63
64#define HASHC   h = *key++ + 65599 * h
65
66	h = 0;
67	key = keyarg;
68	if (len > 0) {
69		loop = (len + 8 - 1) >> 3;
70
71		switch (len & (8 - 1)) {
72		case 0:
73			do {
74				HASHC;
75				/* FALLTHROUGH */
76		case 7:
77				HASHC;
78				/* FALLTHROUGH */
79		case 6:
80				HASHC;
81				/* FALLTHROUGH */
82		case 5:
83				HASHC;
84				/* FALLTHROUGH */
85		case 4:
86				HASHC;
87				/* FALLTHROUGH */
88		case 3:
89				HASHC;
90				/* FALLTHROUGH */
91		case 2:
92				HASHC;
93				/* FALLTHROUGH */
94		case 1:
95				HASHC;
96			} while (--loop);
97		}
98	}
99	return (h);
100}
101
102/*
103 * Generate a hash value for a given key (character string).
104 * We mask off all but the lower 8 bits since our table array
105 * can only hole 256 elements.
106 */
107u_int32_t hashkey(key)
108	char *key;
109{
110
111	if (key == NULL)
112		return (-1);
113	return(hash((void *)key, strlen(key)) & HASH_MASK);
114}
115
116/* Find an entry in the hash table (may be hanging off a linked list). */
117struct grouplist *lookup(table, key)
118	struct member_entry *table[];
119	char *key;
120{
121	struct member_entry *cur;
122
123	cur = table[hashkey(key)];
124
125	while (cur) {
126		if (!strcmp(cur->key, key))
127			return(cur->groups);
128		cur = cur->next;
129	}
130
131	return(NULL);
132}
133
134struct grouplist dummy = { 99999, NULL };
135
136/*
137 * Store an group member entry and/or update its grouplist.
138 */
139void mstore (table, key, gid, dup)
140	struct member_entry *table[];
141	char *key;
142	int gid;
143	int dup;
144{
145	struct member_entry *cur, *new;
146	struct grouplist *tmp;
147	u_int32_t i;
148
149	i = hashkey(key);
150	cur = table[i];
151
152	if (!dup) {
153		tmp = (struct grouplist *)malloc(sizeof(struct grouplist));
154		tmp->groupid = gid;
155		tmp->next = NULL;
156	}
157
158		/* Check if all we have to do is insert a new groupname. */
159	while (cur) {
160		if (!dup && !strcmp(cur->key, key)) {
161			tmp->next = cur->groups;
162			cur->groups = tmp;
163			return;
164		}
165		cur = cur->next;
166	}
167
168	/* Didn't find a match -- add the whole mess to the table. */
169	new = (struct member_entry *)malloc(sizeof(struct member_entry));
170	new->key = strdup(key);
171	if (!dup)
172		new->groups = tmp;
173	else
174		new->groups = (struct grouplist *)&dummy;
175	new->next = table[i];
176	table[i] = new;
177
178	return;
179}
180