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
15 struct hashtab_node {
16 void *key;
17 void *datum;
18 struct hashtab_node *next;
19 };
20
21 struct 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
31 struct 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 */
42 struct 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 */
54 int 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 */
62 void *hashtab_search(struct hashtab *h, const void *k);
63
64 /*
65 * Destroys the specified hash table.
66 */
67 void 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 */
80 int 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 */
85 void hashtab_stat(struct hashtab *h, struct hashtab_info *info);
86
87 #endif /* _SS_HASHTAB_H */
88
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