1 /* $OpenBSD: 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.
27 struct _ohash_record {
32 #define DELETED ((const char *)h)
33 #define NONE (h->size)
35 /* Don't bother changing the hash table if the change is small enough. */
36 #define MINSIZE (1UL << 4)
39 static void ohash_resize(struct ohash *);
42 /* This handles the common case of variable length keys, where the
43 * key is stored at the end of the record.
46 ohash_create_entry(struct ohash_info *i, const char *start, const char **end)
51 *end = start + strlen(start);
52 p = (i->alloc)(i->key_offset + (*end - start) + 1, i->data);
54 memcpy(p+i->key_offset, start, *end-start);
55 p[i->key_offset + (*end - start)] = '\0';
60 /* hash_delete only frees the hash structure. Use hash_first/hash_next
61 * to free entries as well. */
63 ohash_delete(struct ohash *h)
65 (h->info.free)(h->t, h->info.data);
72 ohash_resize(struct ohash *h)
74 struct _ohash_record *n;
79 if (4 * h->deleted < h->total) {
80 if (h->size >= (UINT_MAX >> 1U))
84 } else if (3 * h->deleted > 2 * h->total)
92 STAT_HASH_SIZE += ns - h->size;
95 n = (h->info.calloc)(ns, sizeof(struct _ohash_record), h->info.data);
99 for (j = 0; j < h->size; j++) {
100 if (h->t[j].p != NULL && h->t[j].p != DELETED) {
102 incr = ((h->t[j].hv % (ns - 2)) & ~1) + 1;
103 while (n[i].p != NULL) {
108 n[i].hv = h->t[j].hv;
112 (h->info.free)(h->t, h->info.data);
115 h->total -= h->deleted;
120 ohash_remove(struct ohash *h, unsigned int i)
122 void *result = (void *)h->t[i].p;
124 if (result == NULL || result == DELETED)
132 if (h->deleted >= MINDELETED && 4 * h->deleted > h->total)
138 ohash_find(struct ohash *h, unsigned int i)
140 if (h->t[i].p == DELETED)
143 return (void *)h->t[i].p;
147 ohash_insert(struct ohash *h, unsigned int i, void *p)
152 if (h->t[i].p == DELETED) {
157 /* Arbitrary resize boundary. Tweak if not efficient enough. */
158 if (++h->total * 4 > h->size * 3)
165 ohash_entries(struct ohash *h)
167 return h->total - h->deleted;
171 ohash_first(struct ohash *h, unsigned int *pos)
174 return ohash_next(h, pos);
178 ohash_next(struct ohash *h, unsigned int *pos)
180 for (; *pos < h->size; (*pos)++)
181 if (h->t[*pos].p != DELETED && h->t[*pos].p != NULL)
182 return (void *)h->t[(*pos)++].p;
187 ohash_init(struct ohash *h, unsigned int size, struct ohash_info *info)
189 h->size = 1UL << size;
190 if (h->size < MINSIZE)
193 STAT_HASH_CREATION++;
194 STAT_HASH_SIZE += h->size;
196 /* Copy info so that caller may free it. */
197 h->info.key_offset = info->key_offset;
198 h->info.calloc = info->calloc;
199 h->info.free = info->free;
200 h->info.alloc = info->alloc;
201 h->info.data = info->data;
202 h->t = (h->info.calloc)(h->size, sizeof(struct _ohash_record),
204 h->total = h->deleted = 0;
208 ohash_interval(const char *s, const char **e)
219 k = ((k << 2) | (k >> 30)) ^ *s++;
224 ohash_lookup_interval(struct ohash *h, const char *start, const char *end,
227 unsigned int i, incr;
235 incr = ((hv % (h->size-2)) & ~1) + 1;
236 while (h->t[i].p != NULL) {
240 if (h->t[i].p == DELETED) {
243 } else if (h->t[i].hv == hv &&
244 strncmp(h->t[i].p+h->info.key_offset, start,
246 (h->t[i].p+h->info.key_offset)[end-start] == '\0') {
249 h->t[empty].p = h->t[i].p;
254 STAT_HASH_POSITIVE++;
264 /* Found an empty position. */
272 ohash_lookup_memory(struct ohash *h, const char *k, size_t size, uint32_t hv)
274 unsigned int i, incr;
282 incr = ((hv % (h->size-2)) & ~1) + 1;
283 while (h->t[i].p != NULL) {
287 if (h->t[i].p == DELETED) {
290 } else if (h->t[i].hv == hv &&
291 memcmp(h->t[i].p+h->info.key_offset, k, size) == 0) {
294 h->t[empty].p = h->t[i].p;
299 STAT_HASH_POSITIVE++;
308 /* Found an empty position. */
316 ohash_qlookup(struct ohash *h, const char *s)
318 const char *e = NULL;
319 return ohash_qlookupi(h, s, &e);
323 ohash_qlookupi(struct ohash *h, const char *s, const char **e)
327 hv = ohash_interval(s, e);
328 return ohash_lookup_interval(h, s, *e, hv);