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1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * A hash table (hashtab) maintains associations between
4 * key values and datum values. The type of the key values
5 * and the type of the datum values is arbitrary. The
6 * functions for hash computation and key comparison are
7 * provided by the creator of the table.
8 *
9 * Author : Stephen Smalley, <sds@tycho.nsa.gov>
10 */
11#ifndef _SS_HASHTAB_H_
12#define _SS_HASHTAB_H_
13
14#include <linux/types.h>
15#include <linux/errno.h>
16#include <linux/sched.h>
17
18#define HASHTAB_MAX_NODES U32_MAX
19
20struct hashtab_key_params {
21 u32 (*hash)(const void *key); /* hash function */
22 int (*cmp)(const void *key1, const void *key2);
23 /* key comparison function */
24};
25
26struct hashtab_node {
27 void *key;
28 void *datum;
29 struct hashtab_node *next;
30};
31
32struct hashtab {
33 struct hashtab_node **htable; /* hash table */
34 u32 size; /* number of slots in hash table */
35 u32 nel; /* number of elements in hash table */
36};
37
38struct hashtab_info {
39 u32 slots_used;
40 u32 max_chain_len;
41};
42
43/*
44 * Initializes a new hash table with the specified characteristics.
45 *
46 * Returns -ENOMEM if insufficient space is available or 0 otherwise.
47 */
48int hashtab_init(struct hashtab *h, u32 nel_hint);
49
50int __hashtab_insert(struct hashtab *h, struct hashtab_node **dst,
51 void *key, void *datum);
52
53/*
54 * Inserts the specified (key, datum) pair into the specified hash table.
55 *
56 * Returns -ENOMEM on memory allocation error,
57 * -EEXIST if there is already an entry with the same key,
58 * -EINVAL for general errors or
59 0 otherwise.
60 */
61static inline int hashtab_insert(struct hashtab *h, void *key, void *datum,
62 struct hashtab_key_params key_params)
63{
64 u32 hvalue;
65 struct hashtab_node *prev, *cur;
66
67 cond_resched();
68
69 if (!h->size || h->nel == HASHTAB_MAX_NODES)
70 return -EINVAL;
71
72 hvalue = key_params.hash(key) & (h->size - 1);
73 prev = NULL;
74 cur = h->htable[hvalue];
75 while (cur) {
76 int cmp = key_params.cmp(key, cur->key);
77
78 if (cmp == 0)
79 return -EEXIST;
80 if (cmp < 0)
81 break;
82 prev = cur;
83 cur = cur->next;
84 }
85
86 return __hashtab_insert(h, prev ? &prev->next : &h->htable[hvalue],
87 key, datum);
88}
89
90/*
91 * Searches for the entry with the specified key in the hash table.
92 *
93 * Returns NULL if no entry has the specified key or
94 * the datum of the entry otherwise.
95 */
96static inline void *hashtab_search(struct hashtab *h, const void *key,
97 struct hashtab_key_params key_params)
98{
99 u32 hvalue;
100 struct hashtab_node *cur;
101
102 if (!h->size)
103 return NULL;
104
105 hvalue = key_params.hash(key) & (h->size - 1);
106 cur = h->htable[hvalue];
107 while (cur) {
108 int cmp = key_params.cmp(key, cur->key);
109
110 if (cmp == 0)
111 return cur->datum;
112 if (cmp < 0)
113 break;
114 cur = cur->next;
115 }
116 return NULL;
117}
118
119/*
120 * Destroys the specified hash table.
121 */
122void hashtab_destroy(struct hashtab *h);
123
124/*
125 * Applies the specified apply function to (key,datum,args)
126 * for each entry in the specified hash table.
127 *
128 * The order in which the function is applied to the entries
129 * is dependent upon the internal structure of the hash table.
130 *
131 * If apply returns a non-zero status, then hashtab_map will cease
132 * iterating through the hash table and will propagate the error
133 * return to its caller.
134 */
135int hashtab_map(struct hashtab *h,
136 int (*apply)(void *k, void *d, void *args),
137 void *args);
138
139int hashtab_duplicate(struct hashtab *new, struct hashtab *orig,
140 int (*copy)(struct hashtab_node *new,
141 struct hashtab_node *orig, void *args),
142 int (*destroy)(void *k, void *d, void *args),
143 void *args);
144
145/* Fill info with some hash table statistics */
146void hashtab_stat(struct hashtab *h, struct hashtab_info *info);
147
148#endif /* _SS_HASHTAB_H */
1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * A hash table (hashtab) maintains associations between
4 * key values and datum values. The type of the key values
5 * and the type of the datum values is arbitrary. The
6 * functions for hash computation and key comparison are
7 * provided by the creator of the table.
8 *
9 * Author : Stephen Smalley, <sds@tycho.nsa.gov>
10 */
11#ifndef _SS_HASHTAB_H_
12#define _SS_HASHTAB_H_
13
14#define HASHTAB_MAX_NODES 0xffffffff
15
16struct hashtab_node {
17 void *key;
18 void *datum;
19 struct hashtab_node *next;
20};
21
22struct hashtab {
23 struct hashtab_node **htable; /* hash table */
24 u32 size; /* number of slots in hash table */
25 u32 nel; /* number of elements in hash table */
26 u32 (*hash_value)(struct hashtab *h, const void *key);
27 /* hash function */
28 int (*keycmp)(struct hashtab *h, const void *key1, const void *key2);
29 /* key comparison function */
30};
31
32struct hashtab_info {
33 u32 slots_used;
34 u32 max_chain_len;
35};
36
37/*
38 * Creates a new hash table with the specified characteristics.
39 *
40 * Returns NULL if insufficent space is available or
41 * the new hash table otherwise.
42 */
43struct hashtab *hashtab_create(u32 (*hash_value)(struct hashtab *h, const void *key),
44 int (*keycmp)(struct hashtab *h, const void *key1, const void *key2),
45 u32 size);
46
47/*
48 * Inserts the specified (key, datum) pair into the specified hash table.
49 *
50 * Returns -ENOMEM on memory allocation error,
51 * -EEXIST if there is already an entry with the same key,
52 * -EINVAL for general errors or
53 0 otherwise.
54 */
55int hashtab_insert(struct hashtab *h, void *k, void *d);
56
57/*
58 * Searches for the entry with the specified key in the hash table.
59 *
60 * Returns NULL if no entry has the specified key or
61 * the datum of the entry otherwise.
62 */
63void *hashtab_search(struct hashtab *h, const void *k);
64
65/*
66 * Destroys the specified hash table.
67 */
68void hashtab_destroy(struct hashtab *h);
69
70/*
71 * Applies the specified apply function to (key,datum,args)
72 * for each entry in the specified hash table.
73 *
74 * The order in which the function is applied to the entries
75 * is dependent upon the internal structure of the hash table.
76 *
77 * If apply returns a non-zero status, then hashtab_map will cease
78 * iterating through the hash table and will propagate the error
79 * return to its caller.
80 */
81int hashtab_map(struct hashtab *h,
82 int (*apply)(void *k, void *d, void *args),
83 void *args);
84
85/* Fill info with some hash table statistics */
86void hashtab_stat(struct hashtab *h, struct hashtab_info *info);
87
88#endif /* _SS_HASHTAB_H */