1 /* $NetBSD: hcreate.c,v 1.2 2001/02/19 21:26:04 ross Exp $ */
2
3 /*
4 * Copyright (c) 2001 Christopher G. Demetriou
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. The name of the author may not be used to endorse or promote products
16 * derived from this software without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
19 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
20 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
21 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
22 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
23 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
24 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
25 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
27 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 *
29 * <<Id: LICENSE_GC,v 1.1 2001/10/01 23:24:05 cgd Exp>>
30 */
31
32 /*
33 * hcreate() / hsearch() / hdestroy()
34 *
35 * SysV/XPG4 hash table functions.
36 *
37 * Implementation done based on NetBSD manual page and Solaris manual page,
38 * plus my own personal experience about how they're supposed to work.
39 *
40 * I tried to look at Knuth (as cited by the Solaris manual page), but
41 * nobody had a copy in the office, so...
42 */
43
44 #include <sys/cdefs.h>
45 #if 0
46 #if defined(LIBC_SCCS) && !defined(lint)
47 __RCSID("$NetBSD: hcreate.c,v 1.2 2001/02/19 21:26:04 ross Exp $");
48 #endif /* LIBC_SCCS and not lint */
49 #endif
50
51 #include <sys/types.h>
52 #include <sys/queue.h>
53 #include <errno.h>
54 #include <search.h>
55 #include <stdlib.h>
56 #include <string.h>
57
58 /*
59 * DO NOT MAKE THIS STRUCTURE LARGER THAN 32 BYTES (4 ptrs on 64-bit
60 * ptr machine) without adjusting MAX_BUCKETS_LG2 below.
61 */
62 struct internal_entry {
63 SLIST_ENTRY(internal_entry) link;
64 ENTRY ent;
65 };
66 SLIST_HEAD(internal_head, internal_entry);
67
68 #define MIN_BUCKETS_LG2 4
69 #define MIN_BUCKETS (1 << MIN_BUCKETS_LG2)
70
71 /*
72 * max * sizeof internal_entry must fit into size_t.
73 * assumes internal_entry is <= 32 (2^5) bytes.
74 */
75 #define MAX_BUCKETS_LG2 (sizeof (size_t) * 8 - 1 - 5)
76 #define MAX_BUCKETS ((size_t)1 << MAX_BUCKETS_LG2)
77
78 /* Default hash function, from db/hash/hash_func.c */
79 extern __uint32_t (*__default_hash)(const void *, size_t);
80
81 int
hcreate_r(size_t nel,struct hsearch_data * htab)82 hcreate_r(size_t nel, struct hsearch_data *htab)
83 {
84 size_t idx;
85 unsigned int p2;
86
87 /* Make sure this this isn't called when a table already exists. */
88 if (htab->htable != NULL) {
89 errno = EINVAL;
90 return 0;
91 }
92
93 /* If nel is too small, make it min sized. */
94 if (nel < MIN_BUCKETS)
95 nel = MIN_BUCKETS;
96
97 /* If it's too large, cap it. */
98 if (nel > MAX_BUCKETS)
99 nel = MAX_BUCKETS;
100
101 /* If it's is not a power of two in size, round up. */
102 if ((nel & (nel - 1)) != 0) {
103 for (p2 = 0; nel != 0; p2++)
104 nel >>= 1;
105 nel = 1 << p2;
106 }
107
108 /* Allocate the table. */
109 htab->htablesize = nel;
110 htab->htable = malloc(htab->htablesize * sizeof htab->htable[0]);
111 if (htab->htable == NULL) {
112 errno = ENOMEM;
113 return 0;
114 }
115
116 /* Initialize it. */
117 for (idx = 0; idx < htab->htablesize; idx++)
118 SLIST_INIT(&(htab->htable[idx]));
119
120 return 1;
121 }
122
123 void
hdestroy_r(struct hsearch_data * htab)124 hdestroy_r(struct hsearch_data *htab)
125 {
126 struct internal_entry *ie;
127 size_t idx;
128
129 if (htab->htable == NULL)
130 return;
131
132 #if 0
133 for (idx = 0; idx < htab->htablesize; idx++) {
134 while (!SLIST_EMPTY(&(htab->htable[idx]))) {
135 ie = SLIST_FIRST(&(htab->htable[idx]));
136 SLIST_REMOVE_HEAD(&(htab->htable[idx]), link);
137 free(ie->ent.key);
138 free(ie);
139 }
140 }
141 #endif
142 free(htab->htable);
143 htab->htable = NULL;
144 }
145
146 int
hsearch_r(ENTRY item,ACTION action,ENTRY ** retval,struct hsearch_data * htab)147 hsearch_r(ENTRY item, ACTION action, ENTRY **retval, struct hsearch_data *htab)
148 {
149 struct internal_head *head;
150 struct internal_entry *ie;
151 __uint32_t hashval;
152 size_t len;
153
154 len = strlen(item.key);
155 hashval = (*__default_hash)(item.key, len);
156
157 head = &(htab->htable[hashval & (htab->htablesize - 1)]);
158 ie = SLIST_FIRST(head);
159 while (ie != NULL) {
160 if (strcmp(ie->ent.key, item.key) == 0)
161 break;
162 ie = SLIST_NEXT(ie, link);
163 }
164
165 if (ie != NULL)
166 {
167 *retval = &ie->ent;
168 return 1;
169 }
170 else if (action == FIND)
171 {
172 *retval = NULL;
173 return 0;
174 }
175
176 ie = malloc(sizeof *ie);
177 if (ie == NULL)
178 {
179 *retval = NULL;
180 return 0;
181 }
182 ie->ent.key = item.key;
183 ie->ent.data = item.data;
184
185 SLIST_INSERT_HEAD(head, ie, link);
186 *retval = &ie->ent;
187 return 1;
188 }
189