hashtab.h
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/*
* A hash table (hashtab) maintains associations between
* key values and datum values. The type of the key values
* and the type of the datum values is arbitrary. The
* functions for hash computation and key comparison are
* provided by the creator of the table.
*
* Author : Stephen Smalley, <sds@epoch.ncsc.mil>
*/
#ifndef _SS_HASHTAB_H_
#define _SS_HASHTAB_H_
#define HASHTAB_MAX_NODES 0xffffffff
struct hashtab_node {
void *key;
void *datum;
struct hashtab_node *next;
};
struct hashtab {
struct hashtab_node **htable; /* hash table */
u32 size; /* number of slots in hash table */
u32 nel; /* number of elements in hash table */
u32 (*hash_value)(struct hashtab *h, const void *key);
/* hash function */
int (*keycmp)(struct hashtab *h, const void *key1, const void *key2);
/* key comparison function */
};
struct hashtab_info {
u32 slots_used;
u32 max_chain_len;
};
/*
* Creates a new hash table with the specified characteristics.
*
* Returns NULL if insufficent space is available or
* the new hash table otherwise.
*/
struct hashtab *hashtab_create(u32 (*hash_value)(struct hashtab *h, const void *key),
int (*keycmp)(struct hashtab *h, const void *key1, const void *key2),
u32 size);
/*
* Inserts the specified (key, datum) pair into the specified hash table.
*
* Returns -ENOMEM on memory allocation error,
* -EEXIST if there is already an entry with the same key,
* -EINVAL for general errors or
0 otherwise.
*/
int hashtab_insert(struct hashtab *h, void *k, void *d);
/*
* Searches for the entry with the specified key in the hash table.
*
* Returns NULL if no entry has the specified key or
* the datum of the entry otherwise.
*/
void *hashtab_search(struct hashtab *h, const void *k);
/*
* Destroys the specified hash table.
*/
void hashtab_destroy(struct hashtab *h);
/*
* Applies the specified apply function to (key,datum,args)
* for each entry in the specified hash table.
*
* The order in which the function is applied to the entries
* is dependent upon the internal structure of the hash table.
*
* If apply returns a non-zero status, then hashtab_map will cease
* iterating through the hash table and will propagate the error
* return to its caller.
*/
int hashtab_map(struct hashtab *h,
int (*apply)(void *k, void *d, void *args),
void *args);
/* Fill info with some hash table statistics */
void hashtab_stat(struct hashtab *h, struct hashtab_info *info);
#endif /* _SS_HASHTAB_H */