Loading...
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/*
2 * A hash table (hashtab) maintains associations between
3 * key values and datum values. The type of the key values
4 * and the type of the datum values is arbitrary. The
5 * functions for hash computation and key comparison are
6 * provided by the creator of the table.
7 *
8 * Author : Stephen Smalley, <sds@epoch.ncsc.mil>
9 */
10#ifndef _SS_HASHTAB_H_
11#define _SS_HASHTAB_H_
12
13#define HASHTAB_MAX_NODES 0xffffffff
14
15struct hashtab_node {
16 void *key;
17 void *datum;
18 struct hashtab_node *next;
19};
20
21struct hashtab {
22 struct hashtab_node **htable; /* hash table */
23 u32 size; /* number of slots in hash table */
24 u32 nel; /* number of elements in hash table */
25 u32 (*hash_value)(struct hashtab *h, const void *key);
26 /* hash function */
27 int (*keycmp)(struct hashtab *h, const void *key1, const void *key2);
28 /* key comparison function */
29};
30
31struct hashtab_info {
32 u32 slots_used;
33 u32 max_chain_len;
34};
35
36/*
37 * Creates a new hash table with the specified characteristics.
38 *
39 * Returns NULL if insufficent space is available or
40 * the new hash table otherwise.
41 */
42struct hashtab *hashtab_create(u32 (*hash_value)(struct hashtab *h, const void *key),
43 int (*keycmp)(struct hashtab *h, const void *key1, const void *key2),
44 u32 size);
45
46/*
47 * Inserts the specified (key, datum) pair into the specified hash table.
48 *
49 * Returns -ENOMEM on memory allocation error,
50 * -EEXIST if there is already an entry with the same key,
51 * -EINVAL for general errors or
52 0 otherwise.
53 */
54int hashtab_insert(struct hashtab *h, void *k, void *d);
55
56/*
57 * Searches for the entry with the specified key in the hash table.
58 *
59 * Returns NULL if no entry has the specified key or
60 * the datum of the entry otherwise.
61 */
62void *hashtab_search(struct hashtab *h, const void *k);
63
64/*
65 * Destroys the specified hash table.
66 */
67void hashtab_destroy(struct hashtab *h);
68
69/*
70 * Applies the specified apply function to (key,datum,args)
71 * for each entry in the specified hash table.
72 *
73 * The order in which the function is applied to the entries
74 * is dependent upon the internal structure of the hash table.
75 *
76 * If apply returns a non-zero status, then hashtab_map will cease
77 * iterating through the hash table and will propagate the error
78 * return to its caller.
79 */
80int hashtab_map(struct hashtab *h,
81 int (*apply)(void *k, void *d, void *args),
82 void *args);
83
84/* Fill info with some hash table statistics */
85void hashtab_stat(struct hashtab *h, struct hashtab_info *info);
86
87#endif /* _SS_HASHTAB_H */