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freebsd/lib/libopenbsd/ohash.c
Craig Rodrigues a36eca08bb Rename libohash to libopenbsd.
libopenbsd is an internal library which
to bring in compatibility stuff from OpenBSD.
This will allow us to bring in more
OpenBSD utilities into the FreeBSD base system.

We similarly use libnetbsd for bringing in stuff from NetBSD.

Reviewed by: bapt
Differential Revision: https://reviews.freebsd.org/D4078
2015-11-04 07:20:55 +00:00

331 lines
6.8 KiB
C

/* $OpenBSD: src/lib/libutil/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 <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#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);
}