1 /*
2 * Implementation of the hash table type.
3 *
4 * Author : Stephen Smalley, <sds@epoch.ncsc.mil>
5 */
6 #include <linux/kernel.h>
7 #include <linux/slab.h>
8 #include <linux/errno.h>
9 #include "hashtab.h"
10
11 struct hashtab *hashtab_create(u32 (*hash_value)(struct hashtab *h, const void *key),
12 int (*keycmp)(struct hashtab *h, const void *key1, const void *key2),
13 u32 size)
14 {
15 struct hashtab *p;
16 u32 i;
17
18 p = kzalloc(sizeof(*p), GFP_KERNEL);
19 if (p == NULL)
20 return p;
21
22 p->size = size;
23 p->nel = 0;
24 p->hash_value = hash_value;
25 p->keycmp = keycmp;
26 p->htable = kmalloc(sizeof(*(p->htable)) * size, GFP_KERNEL);
27 if (p->htable == NULL) {
28 kfree(p);
29 return NULL;
30 }
31
32 for (i = 0; i < size; i++)
33 p->htable[i] = NULL;
34
35 return p;
36 }
37
38 int hashtab_insert(struct hashtab *h, void *key, void *datum)
39 {
40 u32 hvalue;
41 struct hashtab_node *prev, *cur, *newnode;
42
43 if (!h || h->nel == HASHTAB_MAX_NODES)
44 return -EINVAL;
45
46 hvalue = h->hash_value(h, key);
47 prev = NULL;
48 cur = h->htable[hvalue];
49 while (cur && h->keycmp(h, key, cur->key) > 0) {
50 prev = cur;
51 cur = cur->next;
52 }
53
54 if (cur && (h->keycmp(h, key, cur->key) == 0))
55 return -EEXIST;
56
57 newnode = kzalloc(sizeof(*newnode), GFP_KERNEL);
58 if (newnode == NULL)
59 return -ENOMEM;
60 newnode->key = key;
61 newnode->datum = datum;
62 if (prev) {
63 newnode->next = prev->next;
64 prev->next = newnode;
65 } else {
66 newnode->next = h->htable[hvalue];
67 h->htable[hvalue] = newnode;
68 }
69
70 h->nel++;
71 return 0;
72 }
73
74 void *hashtab_search(struct hashtab *h, const void *key)
75 {
76 u32 hvalue;
77 struct hashtab_node *cur;
78
79 if (!h)
80 return NULL;
81
82 hvalue = h->hash_value(h, key);
83 cur = h->htable[hvalue];
84 while (cur != NULL && h->keycmp(h, key, cur->key) > 0)
85 cur = cur->next;
86
87 if (cur == NULL || (h->keycmp(h, key, cur->key) != 0))
88 return NULL;
89
90 return cur->datum;
91 }
92
93 void hashtab_destroy(struct hashtab *h)
94 {
95 u32 i;
96 struct hashtab_node *cur, *temp;
97
98 if (!h)
99 return;
100
101 for (i = 0; i < h->size; i++) {
102 cur = h->htable[i];
103 while (cur != NULL) {
104 temp = cur;
105 cur = cur->next;
106 kfree(temp);
107 }
108 h->htable[i] = NULL;
109 }
110
111 kfree(h->htable);
112 h->htable = NULL;
113
114 kfree(h);
115 }
116
117 int hashtab_map(struct hashtab *h,
118 int (*apply)(void *k, void *d, void *args),
119 void *args)
120 {
121 u32 i;
122 int ret;
123 struct hashtab_node *cur;
124
125 if (!h)
126 return 0;
127
128 for (i = 0; i < h->size; i++) {
129 cur = h->htable[i];
130 while (cur != NULL) {
131 ret = apply(cur->key, cur->datum, args);
132 if (ret)
133 return ret;
134 cur = cur->next;
135 }
136 }
137 return 0;
138 }
139
140
141 void hashtab_stat(struct hashtab *h, struct hashtab_info *info)
142 {
143 u32 i, chain_len, slots_used, max_chain_len;
144 struct hashtab_node *cur;
145
146 slots_used = 0;
147 max_chain_len = 0;
148 for (slots_used = max_chain_len = i = 0; i < h->size; i++) {
149 cur = h->htable[i];
150 if (cur) {
151 slots_used++;
152 chain_len = 0;
153 while (cur) {
154 chain_len++;
155 cur = cur->next;
156 }
157
158 if (chain_len > max_chain_len)
159 max_chain_len = chain_len;
160 }
161 }
162
163 info->slots_used = slots_used;
164 info->max_chain_len = max_chain_len;
165 }
166
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