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- /* $OpenBSD: ohash.c,v 1.1 2014/06/02 18:52:03 deraadt Exp $ */
-
- /* Copyright (c) 1999, 2004 Marc Espie <espie@openbsd.org>
- *
- * Permission to use, copy, modify, and distribute this software for any
- * purpose with or without fee is hereby granted, provided that the above
- * copyright notice and this permission notice appear in all copies.
- *
- * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
- * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
- * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
- * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
- * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
- * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
- * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
- */
-
- #include <stddef.h>
- #include <stdint.h>
- #include <stdlib.h>
- #include <string.h>
- #include <limits.h>
- #include "ohash.h"
-
- struct _ohash_record {
- uint32_t hv;
- const char *p;
- };
-
- #define DELETED ((const char *)h)
- #define NONE (h->size)
-
- /* Don't bother changing the hash table if the change is small enough. */
- #define MINSIZE (1UL << 4)
- #define MINDELETED 4
-
- static void ohash_resize(struct ohash *);
-
-
- /* This handles the common case of variable length keys, where the
- * key is stored at the end of the record.
- */
- void *
- ohash_create_entry(struct ohash_info *i, const char *start, const char **end)
- {
- char *p;
-
- if (!*end)
- *end = start + strlen(start);
- p = (i->alloc)(i->key_offset + (*end - start) + 1, i->data);
- if (p) {
- memcpy(p+i->key_offset, start, *end-start);
- p[i->key_offset + (*end - start)] = '\0';
- }
- return (void *)p;
- }
-
- /* hash_delete only frees the hash structure. Use hash_first/hash_next
- * to free entries as well. */
- void
- ohash_delete(struct ohash *h)
- {
- (h->info.free)(h->t, h->info.data);
- #ifndef NDEBUG
- h->t = NULL;
- #endif
- }
-
- static void
- ohash_resize(struct ohash *h)
- {
- struct _ohash_record *n;
- size_t ns;
- unsigned int j;
- unsigned int i, incr;
-
- if (4 * h->deleted < h->total) {
- if (h->size >= (UINT_MAX >> 1U))
- ns = UINT_MAX;
- else
- ns = h->size << 1U;
- } else if (3 * h->deleted > 2 * h->total)
- ns = h->size >> 1U;
- else
- ns = h->size;
- if (ns < MINSIZE)
- ns = MINSIZE;
- #ifdef STATS_HASH
- STAT_HASH_EXPAND++;
- STAT_HASH_SIZE += ns - h->size;
- #endif
-
- n = (h->info.calloc)(ns, sizeof(struct _ohash_record), h->info.data);
- if (!n)
- return;
-
- for (j = 0; j < h->size; j++) {
- if (h->t[j].p != NULL && h->t[j].p != DELETED) {
- i = h->t[j].hv % ns;
- incr = ((h->t[j].hv % (ns - 2)) & ~1) + 1;
- while (n[i].p != NULL) {
- i += incr;
- if (i >= ns)
- i -= ns;
- }
- n[i].hv = h->t[j].hv;
- n[i].p = h->t[j].p;
- }
- }
- (h->info.free)(h->t, h->info.data);
- h->t = n;
- h->size = ns;
- h->total -= h->deleted;
- h->deleted = 0;
- }
-
- void *
- ohash_remove(struct ohash *h, unsigned int i)
- {
- void *result = (void *)h->t[i].p;
-
- if (result == NULL || result == DELETED)
- return NULL;
-
- #ifdef STATS_HASH
- STAT_HASH_ENTRIES--;
- #endif
- h->t[i].p = DELETED;
- h->deleted++;
- if (h->deleted >= MINDELETED && 4 * h->deleted > h->total)
- ohash_resize(h);
- return result;
- }
-
- void *
- ohash_find(struct ohash *h, unsigned int i)
- {
- if (h->t[i].p == DELETED)
- return NULL;
- else
- return (void *)h->t[i].p;
- }
-
- void *
- ohash_insert(struct ohash *h, unsigned int i, void *p)
- {
- #ifdef STATS_HASH
- STAT_HASH_ENTRIES++;
- #endif
- if (h->t[i].p == DELETED) {
- h->deleted--;
- h->t[i].p = p;
- } else {
- h->t[i].p = p;
- /* Arbitrary resize boundary. Tweak if not efficient enough. */
- if (++h->total * 4 > h->size * 3)
- ohash_resize(h);
- }
- return p;
- }
-
- unsigned int
- ohash_entries(struct ohash *h)
- {
- return h->total - h->deleted;
- }
-
- void *
- ohash_first(struct ohash *h, unsigned int *pos)
- {
- *pos = 0;
- return ohash_next(h, pos);
- }
-
- void *
- ohash_next(struct ohash *h, unsigned int *pos)
- {
- for (; *pos < h->size; (*pos)++)
- if (h->t[*pos].p != DELETED && h->t[*pos].p != NULL)
- return (void *)h->t[(*pos)++].p;
- return NULL;
- }
-
- void
- ohash_init(struct ohash *h, unsigned int size, struct ohash_info *info)
- {
- h->size = 1UL << size;
- if (h->size < MINSIZE)
- h->size = MINSIZE;
- #ifdef STATS_HASH
- STAT_HASH_CREATION++;
- STAT_HASH_SIZE += h->size;
- #endif
- /* Copy info so that caller may free it. */
- h->info.key_offset = info->key_offset;
- h->info.calloc = info->calloc;
- h->info.free = info->free;
- h->info.alloc = info->alloc;
- h->info.data = info->data;
- h->t = (h->info.calloc)(h->size, sizeof(struct _ohash_record),
- h->info.data);
- h->total = h->deleted = 0;
- }
-
- uint32_t
- ohash_interval(const char *s, const char **e)
- {
- uint32_t k;
-
- if (!*e)
- *e = s + strlen(s);
- if (s == *e)
- k = 0;
- else
- k = *s++;
- while (s != *e)
- k = ((k << 2) | (k >> 30)) ^ *s++;
- return k;
- }
-
- unsigned int
- ohash_lookup_interval(struct ohash *h, const char *start, const char *end,
- uint32_t hv)
- {
- unsigned int i, incr;
- unsigned int empty;
-
- #ifdef STATS_HASH
- STAT_HASH_LOOKUP++;
- #endif
- empty = NONE;
- i = hv % h->size;
- incr = ((hv % (h->size-2)) & ~1) + 1;
- while (h->t[i].p != NULL) {
- #ifdef STATS_HASH
- STAT_HASH_LENGTH++;
- #endif
- if (h->t[i].p == DELETED) {
- if (empty == NONE)
- empty = i;
- } else if (h->t[i].hv == hv &&
- strncmp(h->t[i].p+h->info.key_offset, start,
- end - start) == 0 &&
- (h->t[i].p+h->info.key_offset)[end-start] == '\0') {
- if (empty != NONE) {
- h->t[empty].hv = hv;
- h->t[empty].p = h->t[i].p;
- h->t[i].p = DELETED;
- return empty;
- } else {
- #ifdef STATS_HASH
- STAT_HASH_POSITIVE++;
- #endif
- return i;
- }
- }
- i += incr;
- if (i >= h->size)
- i -= h->size;
- }
-
- /* Found an empty position. */
- if (empty != NONE)
- i = empty;
- h->t[i].hv = hv;
- return i;
- }
-
- unsigned int
- ohash_lookup_memory(struct ohash *h, const char *k, size_t size, uint32_t hv)
- {
- unsigned int i, incr;
- unsigned int empty;
-
- #ifdef STATS_HASH
- STAT_HASH_LOOKUP++;
- #endif
- empty = NONE;
- i = hv % h->size;
- incr = ((hv % (h->size-2)) & ~1) + 1;
- while (h->t[i].p != NULL) {
- #ifdef STATS_HASH
- STAT_HASH_LENGTH++;
- #endif
- if (h->t[i].p == DELETED) {
- if (empty == NONE)
- empty = i;
- } else if (h->t[i].hv == hv &&
- memcmp(h->t[i].p+h->info.key_offset, k, size) == 0) {
- if (empty != NONE) {
- h->t[empty].hv = hv;
- h->t[empty].p = h->t[i].p;
- h->t[i].p = DELETED;
- return empty;
- } else {
- #ifdef STATS_HASH
- STAT_HASH_POSITIVE++;
- #endif
- } return i;
- }
- i += incr;
- if (i >= h->size)
- i -= h->size;
- }
-
- /* Found an empty position. */
- if (empty != NONE)
- i = empty;
- h->t[i].hv = hv;
- return i;
- }
-
- unsigned int
- ohash_qlookup(struct ohash *h, const char *s)
- {
- const char *e = NULL;
- return ohash_qlookupi(h, s, &e);
- }
-
- unsigned int
- ohash_qlookupi(struct ohash *h, const char *s, const char **e)
- {
- uint32_t hv;
-
- hv = ohash_interval(s, e);
- return ohash_lookup_interval(h, s, *e, hv);
- }
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