1 /* $NetBSD: hcreate.c,v 1.13 2022/03/13 01:44:37 kre 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,v 1.2 2000/06/14 15:57:33 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 defined(LIBC_SCCS) && !defined(lint)
46 __RCSID("$NetBSD: hcreate.c,v 1.13 2022/03/13 01:44:37 kre Exp $");
47 #endif /* LIBC_SCCS and not lint */
48
49 #if !defined(lint)
50 __COPYRIGHT("@(#) Copyright (c) 2001\
51 Christopher G. Demetriou. All rights reserved.");
52 #endif /* not lint */
53
54 #include "namespace.h"
55 #include <assert.h>
56 #include <errno.h>
57 #include <inttypes.h>
58 #include <search.h>
59 #include <stdlib.h>
60 #include <string.h>
61 #include <sys/queue.h>
62
63 /*
64 * DO NOT MAKE THIS STRUCTURE LARGER THAN 32 BYTES (4 ptrs on 64-bit
65 * ptr machine) without adjusting MAX_BUCKETS_LG2 below.
66 */
67 struct internal_entry {
68 SLIST_ENTRY(internal_entry) link;
69 ENTRY ent;
70 };
71 SLIST_HEAD(internal_head, internal_entry);
72
73 #define MIN_BUCKETS_LG2 4
74 #define MIN_BUCKETS (1 << MIN_BUCKETS_LG2)
75
76 /*
77 * max * sizeof internal_entry must fit into size_t.
78 * assumes internal_entry is <= 32 (2^5) bytes.
79 */
80 #define MAX_BUCKETS_LG2 (sizeof (size_t) * 8 - 1 - 5)
81 #define MAX_BUCKETS ((size_t)1 << MAX_BUCKETS_LG2)
82
83 /* Default hash function, from db/hash/hash_func.c */
84 extern u_int32_t (*__default_hash)(const void *, size_t);
85
86 static struct hsearch_data htable;
87
88 int
hcreate(size_t nel)89 hcreate(size_t nel)
90 {
91 _DIAGASSERT(htable.table == NULL);
92
93 /* Make sure this isn't called when a table already exists. */
94 if (htable.table != NULL) {
95 errno = EINVAL;
96 return 0;
97 }
98 return hcreate_r(nel, &htable);
99 }
100
101 int
hcreate_r(size_t nel,struct hsearch_data * head)102 hcreate_r(size_t nel, struct hsearch_data *head)
103 {
104 struct internal_head *table;
105 size_t idx;
106 unsigned int p2;
107
108 /* If nel is too small, make it min sized. */
109 if (nel < MIN_BUCKETS)
110 nel = MIN_BUCKETS;
111
112 /* If it's too large, cap it. */
113 if (nel > MAX_BUCKETS)
114 nel = MAX_BUCKETS;
115
116 /* If it's is not a power of two in size, round up. */
117 if ((nel & (nel - 1)) != 0) {
118 for (p2 = 0; nel != 0; p2++)
119 nel >>= 1;
120 _DIAGASSERT(p2 <= MAX_BUCKETS_LG2);
121 nel = 1 << p2;
122 }
123
124 /* Allocate the table. */
125 head->size = nel;
126 head->filled = 0;
127 table = NULL;
128 errno = reallocarr(&table, nel, sizeof(*table));
129 if (errno)
130 return 0;
131 head->table = (void *)table;
132
133 /* Initialize it. */
134 for (idx = 0; idx < nel; idx++)
135 SLIST_INIT(&table[idx]);
136
137 return 1;
138 }
139
140 void
hdestroy1(void (* freekey)(void *),void (* freedata)(void *))141 hdestroy1(void (*freekey)(void *), void (*freedata)(void *))
142 {
143 _DIAGASSERT(htable.table != NULL);
144 hdestroy1_r(&htable, freekey, freedata);
145 }
146
147 void
hdestroy(void)148 hdestroy(void)
149 {
150 hdestroy1(NULL, NULL);
151 }
152
153 void
hdestroy1_r(struct hsearch_data * head,void (* freekey)(void *),void (* freedata)(void *))154 hdestroy1_r(struct hsearch_data *head, void (*freekey)(void *),
155 void (*freedata)(void *))
156 {
157 struct internal_entry *ie;
158 size_t idx;
159 void *p;
160 struct internal_head *table;
161
162 if (head == NULL)
163 return;
164
165 p = head->table;
166 head->table = NULL;
167 table = p;
168
169 for (idx = 0; idx < head->size; idx++) {
170 while (!SLIST_EMPTY(&table[idx])) {
171 ie = SLIST_FIRST(&table[idx]);
172 SLIST_REMOVE_HEAD(&table[idx], link);
173 if (freekey)
174 (*freekey)(ie->ent.key);
175 if (freedata)
176 (*freedata)(ie->ent.data);
177 free(ie);
178 }
179 }
180 free(table);
181 }
182
183 void
hdestroy_r(struct hsearch_data * head)184 hdestroy_r(struct hsearch_data *head)
185 {
186 hdestroy1_r(head, NULL, NULL);
187 }
188
189 ENTRY *
hsearch(ENTRY item,ACTION action)190 hsearch(ENTRY item, ACTION action)
191 {
192 ENTRY *ep;
193 _DIAGASSERT(htable.table != NULL);
194 (void)hsearch_r(item, action, &ep, &htable);
195 return ep;
196 }
197
198 int
hsearch_r(ENTRY item,ACTION action,ENTRY ** itemp,struct hsearch_data * head)199 hsearch_r(ENTRY item, ACTION action, ENTRY **itemp, struct hsearch_data *head)
200 {
201 struct internal_head *table, *chain;
202 struct internal_entry *ie;
203 uint32_t hashval;
204 size_t len;
205 void *p;
206
207 _DIAGASSERT(item.key != NULL);
208 _DIAGASSERT(action == ENTER || action == FIND);
209
210 p = head->table;
211 table = p;
212
213 len = strlen(item.key);
214 hashval = (*__default_hash)(item.key, len);
215
216 chain = &table[hashval & (head->size - 1)];
217 ie = SLIST_FIRST(chain);
218 while (ie != NULL) {
219 if (strcmp(ie->ent.key, item.key) == 0)
220 break;
221 ie = SLIST_NEXT(ie, link);
222 }
223
224 if (ie != NULL) {
225 *itemp = &ie->ent;
226 return 1;
227 } else if (action == FIND) {
228 *itemp = NULL;
229 errno = ESRCH;
230 return 1;
231 }
232
233 ie = malloc(sizeof *ie);
234 if (ie == NULL)
235 return 0;
236 ie->ent.key = item.key;
237 ie->ent.data = item.data;
238
239 SLIST_INSERT_HEAD(chain, ie, link);
240 *itemp = &ie->ent;
241 head->filled++;
242 return 1;
243 }
244