LXR linux/security/selinux/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 */
  88