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/* SPDX-License-Identifier: GPL-2.0 */
/*
* 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@tycho.nsa.gov>
*/
#ifndef _SS_HASHTAB_H_
#define _SS_HASHTAB_H_
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/sched.h>
#define HASHTAB_MAX_NODES U32_MAX
struct hashtab_key_params {
u32 (*hash)(const void *key); /* hash function */
int (*cmp)(const void *key1, const void *key2);
/* key comparison function */
};
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 */
};
struct hashtab_info {
u32 slots_used;
u32 max_chain_len;
};
/*
* Initializes a new hash table with the specified characteristics.
*
* Returns -ENOMEM if insufficient space is available or 0 otherwise.
*/
int hashtab_init(struct hashtab *h, u32 nel_hint);
int __hashtab_insert(struct hashtab *h, struct hashtab_node **dst,
void *key, void *datum);
/*
* 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.
*/
static inline int hashtab_insert(struct hashtab *h, void *key, void *datum,
struct hashtab_key_params key_params)
{
u32 hvalue;
struct hashtab_node *prev, *cur;
cond_resched();
if (!h->size || h->nel == HASHTAB_MAX_NODES)
return -EINVAL;
hvalue = key_params.hash(key) & (h->size - 1);
prev = NULL;
cur = h->htable[hvalue];
while (cur) {
int cmp = key_params.cmp(key, cur->key);
if (cmp == 0)
return -EEXIST;
if (cmp < 0)
break;
prev = cur;
cur = cur->next;
}
return __hashtab_insert(h, prev ? &prev->next : &h->htable[hvalue],
key, datum);
}
/*
* 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.
*/
static inline void *hashtab_search(struct hashtab *h, const void *key,
struct hashtab_key_params key_params)
{
u32 hvalue;
struct hashtab_node *cur;
if (!h->size)
return NULL;
hvalue = key_params.hash(key) & (h->size - 1);
cur = h->htable[hvalue];
while (cur) {
int cmp = key_params.cmp(key, cur->key);
if (cmp == 0)
return cur->datum;
if (cmp < 0)
break;
cur = cur->next;
}
return NULL;
}
/*
* 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 */
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