/* * 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 */