src/hash.c

/*
 * (C) 2006-2009 by Pablo Neira Ayuso <pablo@netfilter.org>
 * 
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 * Description: generic hash table implementation
 */

#include "hash.h"

#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <limits.h>

struct hashtable *
hashtable_create(int hashsize, int limit,
		 uint32_t (*hash)(const void *data,
		 		  const struct hashtable *table),
		 int (*compare)(const void *data1, const void *data2))
{
	int i;
	struct hashtable *h;
	int size = sizeof(struct hashtable)
		   + hashsize * sizeof(struct list_head);

	h = (struct hashtable *) calloc(size, 1);
	if (h == NULL) {
		errno = ENOMEM;
		return NULL;
	}

	for (i=0; i<hashsize; i++)
		INIT_LIST_HEAD(&h->members[i]);

	h->hashsize = hashsize;
	h->limit = limit;
	h->hash = hash;
	h->compare = compare;

	return h;
}

void hashtable_destroy(struct hashtable *h)
{
	free(h);
}

int hashtable_hash(const struct hashtable *table, const void *data)
{
	return table->hash(data, table);
}

struct hashtable_node *
hashtable_find(const struct hashtable *table, const void *data, int id)
{
	struct list_head *e;
	struct hashtable_node *n;

	list_for_each(e, &table->members[id]) {
		n = list_entry(e, struct hashtable_node, head);
		if (table->compare(n, data)) {
			return n;
		}
	}
	errno = ENOENT;
	return NULL;
}

int hashtable_add(struct hashtable *table, struct hashtable_node *n, int id)
{
	/* hash table is full */
	if (table->count >= table->limit) {
		errno = ENOSPC;
		return -1;
	}
	list_add(&n->head, &table->members[id]);
	table->count++;
	return 0;
}

void hashtable_del(struct hashtable *table, struct hashtable_node *n)
{
	list_del(&n->head);
	table->count--;
}

int hashtable_flush(struct hashtable *table)
{
	uint32_t i;
	struct list_head *e, *tmp;
	struct hashtable_node *n;

	for (i=0; i < table->hashsize; i++) {
		list_for_each_safe(e, tmp, &table->members[i]) {
			n = list_entry(e, struct hashtable_node, head);
			free(n);
		}
	}
	return 0;
}

int
hashtable_iterate_limit(struct hashtable *table, void *data,
			uint32_t from, uint32_t steps,
		        int (*iterate)(void *data1, void *n))
{
	uint32_t i;
	struct list_head *e, *tmp;
	struct hashtable_node *n;

	for (i=from; i < table->hashsize && i < from+steps; i++) {
		list_for_each_safe(e, tmp, &table->members[i]) {
			n = list_entry(e, struct hashtable_node, head);
			if (iterate(data, n) == -1)
				return -1;
		}
	}
	return i;
}

int hashtable_iterate(struct hashtable *table, void *data,
		      int (*iterate)(void *data1, void *n))
{
	return hashtable_iterate_limit(table, data, 0, UINT_MAX, iterate);
}

unsigned int hashtable_counter(const struct hashtable *table)
{
	return table->count;
}