1 /* $OpenBSD: src/lib/libutil/ohash.c,v 1.1 2014/06/02 18:52:03 deraadt Exp $ */
3 /* Copyright (c) 1999, 2004 Marc Espie <espie@openbsd.org>
5 * Permission to use, copy, modify, and distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
18 #include <sys/cdefs.h>
26 struct _ohash_record {
31 #define DELETED ((const char *)h)
32 #define NONE (h->size)
34 /* Don't bother changing the hash table if the change is small enough. */
35 #define MINSIZE (1UL << 4)
38 static void ohash_resize(struct ohash *);
41 /* This handles the common case of variable length keys, where the
42 * key is stored at the end of the record.
45 ohash_create_entry(struct ohash_info *i, const char *start, const char **end)
50 *end = start + strlen(start);
51 p = (i->alloc)(i->key_offset + (*end - start) + 1, i->data);
53 memcpy(p+i->key_offset, start, *end-start);
54 p[i->key_offset + (*end - start)] = '\0';
59 /* hash_delete only frees the hash structure. Use hash_first/hash_next
60 * to free entries as well. */
62 ohash_delete(struct ohash *h)
64 (h->info.free)(h->t, h->info.data);
71 ohash_resize(struct ohash *h)
73 struct _ohash_record *n;
78 if (4 * h->deleted < h->total) {
79 if (h->size >= (UINT_MAX >> 1U))
83 } else if (3 * h->deleted > 2 * h->total)
91 STAT_HASH_SIZE += ns - h->size;
94 n = (h->info.calloc)(ns, sizeof(struct _ohash_record), h->info.data);
98 for (j = 0; j < h->size; j++) {
99 if (h->t[j].p != NULL && h->t[j].p != DELETED) {
101 incr = ((h->t[j].hv % (ns - 2)) & ~1) + 1;
102 while (n[i].p != NULL) {
107 n[i].hv = h->t[j].hv;
111 (h->info.free)(h->t, h->info.data);
114 h->total -= h->deleted;
119 ohash_remove(struct ohash *h, unsigned int i)
121 void *result = (void *)h->t[i].p;
123 if (result == NULL || result == DELETED)
131 if (h->deleted >= MINDELETED && 4 * h->deleted > h->total)
137 ohash_find(struct ohash *h, unsigned int i)
139 if (h->t[i].p == DELETED)
142 return (void *)h->t[i].p;
146 ohash_insert(struct ohash *h, unsigned int i, void *p)
151 if (h->t[i].p == DELETED) {
156 /* Arbitrary resize boundary. Tweak if not efficient enough. */
157 if (++h->total * 4 > h->size * 3)
164 ohash_entries(struct ohash *h)
166 return h->total - h->deleted;
170 ohash_first(struct ohash *h, unsigned int *pos)
173 return ohash_next(h, pos);
177 ohash_next(struct ohash *h, unsigned int *pos)
179 for (; *pos < h->size; (*pos)++)
180 if (h->t[*pos].p != DELETED && h->t[*pos].p != NULL)
181 return (void *)h->t[(*pos)++].p;
186 ohash_init(struct ohash *h, unsigned int size, struct ohash_info *info)
188 h->size = 1UL << size;
189 if (h->size < MINSIZE)
192 STAT_HASH_CREATION++;
193 STAT_HASH_SIZE += h->size;
195 /* Copy info so that caller may free it. */
196 h->info.key_offset = info->key_offset;
197 h->info.calloc = info->calloc;
198 h->info.free = info->free;
199 h->info.alloc = info->alloc;
200 h->info.data = info->data;
201 h->t = (h->info.calloc)(h->size, sizeof(struct _ohash_record),
203 h->total = h->deleted = 0;
207 ohash_interval(const char *s, const char **e)
218 k = ((k << 2) | (k >> 30)) ^ *s++;
223 ohash_lookup_interval(struct ohash *h, const char *start, const char *end,
226 unsigned int i, incr;
234 incr = ((hv % (h->size-2)) & ~1) + 1;
235 while (h->t[i].p != NULL) {
239 if (h->t[i].p == DELETED) {
242 } else if (h->t[i].hv == hv &&
243 strncmp(h->t[i].p+h->info.key_offset, start,
245 (h->t[i].p+h->info.key_offset)[end-start] == '\0') {
248 h->t[empty].p = h->t[i].p;
253 STAT_HASH_POSITIVE++;
263 /* Found an empty position. */
271 ohash_lookup_memory(struct ohash *h, const char *k, size_t size, uint32_t hv)
273 unsigned int i, incr;
281 incr = ((hv % (h->size-2)) & ~1) + 1;
282 while (h->t[i].p != NULL) {
286 if (h->t[i].p == DELETED) {
289 } else if (h->t[i].hv == hv &&
290 memcmp(h->t[i].p+h->info.key_offset, k, size) == 0) {
293 h->t[empty].p = h->t[i].p;
298 STAT_HASH_POSITIVE++;
307 /* Found an empty position. */
315 ohash_qlookup(struct ohash *h, const char *s)
317 const char *e = NULL;
318 return ohash_qlookupi(h, s, &e);
322 ohash_qlookupi(struct ohash *h, const char *s, const char **e)
326 hv = ohash_interval(s, e);
327 return ohash_lookup_interval(h, s, *e, hv);