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
  16 struct hashtab_node {
  17         void *key;
  18         void *datum;
  19         struct hashtab_node *next;
  20 };
  21
  22 struct 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
  32 struct 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  */
  43 struct 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  */
  55 int 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  */
  63 void *hashtab_search(struct hashtab *h, const void *k);
  64
  65 /*
  66  * Destroys the specified hash table.
  67  */
  68 void 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  */
  81 int 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 */
  86 void hashtab_stat(struct hashtab *h, struct hashtab_info *info);
  87
  88 /* Use kmem_cache for hashtab_node */
  89 void hashtab_cache_init(void);
  90 void hashtab_cache_destroy(void);
  91
  92 #endif  /* _SS_HASHTAB_H */