LXR linux/security/selinux/ss/hashtab.h

   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
  16struct hashtab_node {
  17        void *key;
  18        void *datum;
  19        struct hashtab_node *next;
  20};
  21
  22struct 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
  32struct 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 */
  43struct 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 */
  55int 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 */
  63void *hashtab_search(struct hashtab *h, const void *k);
  64
  65/*
  66 * Destroys the specified hash table.
  67 */
  68void 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 */
  81int 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 */
  86void hashtab_stat(struct hashtab *h, struct hashtab_info *info);
  87
  88#endif  /* _SS_HASHTAB_H */
  89