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
16 struct hashtab_node {
17 void *key;
18 void *datum;
19 struct hashtab_node *next;
20 };
21
22 struct 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
32 struct 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 */
43 struct 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 */
55 int 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 */
63 void *hashtab_search(struct hashtab *h, const void *k);
64
65 /*
66 * Destroys the specified hash table.
67 */
68 void 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 */
81 int 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 */
86 void hashtab_stat(struct hashtab *h, struct hashtab_info *info);
87
88 #endif /* _SS_HASHTAB_H */