1/*	$NetBSD: hash.c,v 1.1.1.2 2009/12/02 00:26:11 haad Exp $	*/
2
3/*
4 * Copyright (C) 2001-2004 Sistina Software, Inc. All rights reserved.
5 * Copyright (C) 2004-2007 Red Hat, Inc. All rights reserved.
6 *
7 * This file is part of the device-mapper userspace tools.
8 *
9 * This copyrighted material is made available to anyone wishing to use,
10 * modify, copy, or redistribute it subject to the terms and conditions
11 * of the GNU Lesser General Public License v.2.1.
12 *
13 * You should have received a copy of the GNU Lesser General Public License
14 * along with this program; if not, write to the Free Software Foundation,
15 * Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
16 */
17
18#include "dmlib.h"
19
20struct dm_hash_node {
21	struct dm_hash_node *next;
22	void *data;
23	unsigned keylen;
24	char key[0];
25};
26
27struct dm_hash_table {
28	unsigned num_nodes;
29	unsigned num_slots;
30	struct dm_hash_node **slots;
31};
32
33/* Permutation of the Integers 0 through 255 */
34static unsigned char _nums[] = {
35	1, 14, 110, 25, 97, 174, 132, 119, 138, 170, 125, 118, 27, 233, 140, 51,
36	87, 197, 177, 107, 234, 169, 56, 68, 30, 7, 173, 73, 188, 40, 36, 65,
37	49, 213, 104, 190, 57, 211, 148, 223, 48, 115, 15, 2, 67, 186, 210, 28,
38	12, 181, 103, 70, 22, 58, 75, 78, 183, 167, 238, 157, 124, 147, 172,
39	144,
40	176, 161, 141, 86, 60, 66, 128, 83, 156, 241, 79, 46, 168, 198, 41, 254,
41	178, 85, 253, 237, 250, 154, 133, 88, 35, 206, 95, 116, 252, 192, 54,
42	221,
43	102, 218, 255, 240, 82, 106, 158, 201, 61, 3, 89, 9, 42, 155, 159, 93,
44	166, 80, 50, 34, 175, 195, 100, 99, 26, 150, 16, 145, 4, 33, 8, 189,
45	121, 64, 77, 72, 208, 245, 130, 122, 143, 55, 105, 134, 29, 164, 185,
46	194,
47	193, 239, 101, 242, 5, 171, 126, 11, 74, 59, 137, 228, 108, 191, 232,
48	139,
49	6, 24, 81, 20, 127, 17, 91, 92, 251, 151, 225, 207, 21, 98, 113, 112,
50	84, 226, 18, 214, 199, 187, 13, 32, 94, 220, 224, 212, 247, 204, 196,
51	43,
52	249, 236, 45, 244, 111, 182, 153, 136, 129, 90, 217, 202, 19, 165, 231,
53	71,
54	230, 142, 96, 227, 62, 179, 246, 114, 162, 53, 160, 215, 205, 180, 47,
55	109,
56	44, 38, 31, 149, 135, 0, 216, 52, 63, 23, 37, 69, 39, 117, 146, 184,
57	163, 200, 222, 235, 248, 243, 219, 10, 152, 131, 123, 229, 203, 76, 120,
58	209
59};
60
61static struct dm_hash_node *_create_node(const char *str, unsigned len)
62{
63	struct dm_hash_node *n = dm_malloc(sizeof(*n) + len);
64
65	if (n) {
66		memcpy(n->key, str, len);
67		n->keylen = len;
68	}
69
70	return n;
71}
72
73static unsigned long _hash(const char *str, unsigned len)
74{
75	unsigned long h = 0, g;
76	unsigned i;
77
78	for (i = 0; i < len; i++) {
79		h <<= 4;
80		h += _nums[(unsigned char) *str++];
81		g = h & ((unsigned long) 0xf << 16u);
82		if (g) {
83			h ^= g >> 16u;
84			h ^= g >> 5u;
85		}
86	}
87
88	return h;
89}
90
91struct dm_hash_table *dm_hash_create(unsigned size_hint)
92{
93	size_t len;
94	unsigned new_size = 16u;
95	struct dm_hash_table *hc = dm_malloc(sizeof(*hc));
96
97	if (!hc) {
98		stack;
99		return 0;
100	}
101
102	memset(hc, 0, sizeof(*hc));
103
104	/* round size hint up to a power of two */
105	while (new_size < size_hint)
106		new_size = new_size << 1;
107
108	hc->num_slots = new_size;
109	len = sizeof(*(hc->slots)) * new_size;
110	if (!(hc->slots = dm_malloc(len))) {
111		stack;
112		goto bad;
113	}
114	memset(hc->slots, 0, len);
115	return hc;
116
117      bad:
118	dm_free(hc->slots);
119	dm_free(hc);
120	return 0;
121}
122
123static void _free_nodes(struct dm_hash_table *t)
124{
125	struct dm_hash_node *c, *n;
126	unsigned i;
127
128	for (i = 0; i < t->num_slots; i++)
129		for (c = t->slots[i]; c; c = n) {
130			n = c->next;
131			dm_free(c);
132		}
133}
134
135void dm_hash_destroy(struct dm_hash_table *t)
136{
137	_free_nodes(t);
138	dm_free(t->slots);
139	dm_free(t);
140}
141
142static struct dm_hash_node **_find(struct dm_hash_table *t, const char *key,
143				   uint32_t len)
144{
145	unsigned h = _hash(key, len) & (t->num_slots - 1);
146	struct dm_hash_node **c;
147
148	for (c = &t->slots[h]; *c; c = &((*c)->next)) {
149		if ((*c)->keylen != len)
150			continue;
151
152		if (!memcmp(key, (*c)->key, len))
153			break;
154	}
155
156	return c;
157}
158
159void *dm_hash_lookup_binary(struct dm_hash_table *t, const char *key,
160			 uint32_t len)
161{
162	struct dm_hash_node **c = _find(t, key, len);
163
164	return *c ? (*c)->data : 0;
165}
166
167int dm_hash_insert_binary(struct dm_hash_table *t, const char *key,
168			  uint32_t len, void *data)
169{
170	struct dm_hash_node **c = _find(t, key, len);
171
172	if (*c)
173		(*c)->data = data;
174	else {
175		struct dm_hash_node *n = _create_node(key, len);
176
177		if (!n)
178			return 0;
179
180		n->data = data;
181		n->next = 0;
182		*c = n;
183		t->num_nodes++;
184	}
185
186	return 1;
187}
188
189void dm_hash_remove_binary(struct dm_hash_table *t, const char *key,
190			uint32_t len)
191{
192	struct dm_hash_node **c = _find(t, key, len);
193
194	if (*c) {
195		struct dm_hash_node *old = *c;
196		*c = (*c)->next;
197		dm_free(old);
198		t->num_nodes--;
199	}
200}
201
202void *dm_hash_lookup(struct dm_hash_table *t, const char *key)
203{
204	return dm_hash_lookup_binary(t, key, strlen(key) + 1);
205}
206
207int dm_hash_insert(struct dm_hash_table *t, const char *key, void *data)
208{
209	return dm_hash_insert_binary(t, key, strlen(key) + 1, data);
210}
211
212void dm_hash_remove(struct dm_hash_table *t, const char *key)
213{
214	dm_hash_remove_binary(t, key, strlen(key) + 1);
215}
216
217unsigned dm_hash_get_num_entries(struct dm_hash_table *t)
218{
219	return t->num_nodes;
220}
221
222void dm_hash_iter(struct dm_hash_table *t, dm_hash_iterate_fn f)
223{
224	struct dm_hash_node *c, *n;
225	unsigned i;
226
227	for (i = 0; i < t->num_slots; i++)
228		for (c = t->slots[i]; c; c = n) {
229			n = c->next;
230			f(c->data);
231		}
232}
233
234void dm_hash_wipe(struct dm_hash_table *t)
235{
236	_free_nodes(t);
237	memset(t->slots, 0, sizeof(struct dm_hash_node *) * t->num_slots);
238	t->num_nodes = 0u;
239}
240
241char *dm_hash_get_key(struct dm_hash_table *t __attribute((unused)),
242		      struct dm_hash_node *n)
243{
244	return n->key;
245}
246
247void *dm_hash_get_data(struct dm_hash_table *t __attribute((unused)),
248		       struct dm_hash_node *n)
249{
250	return n->data;
251}
252
253static struct dm_hash_node *_next_slot(struct dm_hash_table *t, unsigned s)
254{
255	struct dm_hash_node *c = NULL;
256	unsigned i;
257
258	for (i = s; i < t->num_slots && !c; i++)
259		c = t->slots[i];
260
261	return c;
262}
263
264struct dm_hash_node *dm_hash_get_first(struct dm_hash_table *t)
265{
266	return _next_slot(t, 0);
267}
268
269struct dm_hash_node *dm_hash_get_next(struct dm_hash_table *t, struct dm_hash_node *n)
270{
271	unsigned h = _hash(n->key, n->keylen) & (t->num_slots - 1);
272
273	return n->next ? n->next : _next_slot(t, h + 1);
274}
275