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

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Implementation of the hash table type.
   4 *
   5 * Author : Stephen Smalley, <sds@tycho.nsa.gov>
   6 */
   7#include <linux/kernel.h>
   8#include <linux/slab.h>
   9#include <linux/errno.h>
  10#include <linux/sched.h>
  11#include "hashtab.h"
  12
  13struct hashtab *hashtab_create(u32 (*hash_value)(struct hashtab *h, const void *key),
  14                               int (*keycmp)(struct hashtab *h, const void *key1, const void *key2),
  15                               u32 size)
  16{
  17        struct hashtab *p;
  18        u32 i;
  19
  20        p = kzalloc(sizeof(*p), GFP_KERNEL);
  21        if (!p)
  22                return p;
  23
  24        p->size = size;
  25        p->nel = 0;
  26        p->hash_value = hash_value;
  27        p->keycmp = keycmp;
  28        p->htable = kmalloc_array(size, sizeof(*p->htable), GFP_KERNEL);
  29        if (!p->htable) {
  30                kfree(p);
  31                return NULL;
  32        }
  33
  34        for (i = 0; i < size; i++)
  35                p->htable[i] = NULL;
  36
  37        return p;
  38}
  39
  40int hashtab_insert(struct hashtab *h, void *key, void *datum)
  41{
  42        u32 hvalue;
  43        struct hashtab_node *prev, *cur, *newnode;
  44
  45        cond_resched();
  46
  47        if (!h || h->nel == HASHTAB_MAX_NODES)
  48                return -EINVAL;
  49
  50        hvalue = h->hash_value(h, key);
  51        prev = NULL;
  52        cur = h->htable[hvalue];
  53        while (cur && h->keycmp(h, key, cur->key) > 0) {
  54                prev = cur;
  55                cur = cur->next;
  56        }
  57
  58        if (cur && (h->keycmp(h, key, cur->key) == 0))
  59                return -EEXIST;
  60
  61        newnode = kzalloc(sizeof(*newnode), GFP_KERNEL);
  62        if (!newnode)
  63                return -ENOMEM;
  64        newnode->key = key;
  65        newnode->datum = datum;
  66        if (prev) {
  67                newnode->next = prev->next;
  68                prev->next = newnode;
  69        } else {
  70                newnode->next = h->htable[hvalue];
  71                h->htable[hvalue] = newnode;
  72        }
  73
  74        h->nel++;
  75        return 0;
  76}
  77
  78void *hashtab_search(struct hashtab *h, const void *key)
  79{
  80        u32 hvalue;
  81        struct hashtab_node *cur;
  82
  83        if (!h)
  84                return NULL;
  85
  86        hvalue = h->hash_value(h, key);
  87        cur = h->htable[hvalue];
  88        while (cur && h->keycmp(h, key, cur->key) > 0)
  89                cur = cur->next;
  90
  91        if (!cur || (h->keycmp(h, key, cur->key) != 0))
  92                return NULL;
  93
  94        return cur->datum;
  95}
  96
  97void hashtab_destroy(struct hashtab *h)
  98{
  99        u32 i;
 100        struct hashtab_node *cur, *temp;
 101
 102        if (!h)
 103                return;
 104
 105        for (i = 0; i < h->size; i++) {
 106                cur = h->htable[i];
 107                while (cur) {
 108                        temp = cur;
 109                        cur = cur->next;
 110                        kfree(temp);
 111                }
 112                h->htable[i] = NULL;
 113        }
 114
 115        kfree(h->htable);
 116        h->htable = NULL;
 117
 118        kfree(h);
 119}
 120
 121int hashtab_map(struct hashtab *h,
 122                int (*apply)(void *k, void *d, void *args),
 123                void *args)
 124{
 125        u32 i;
 126        int ret;
 127        struct hashtab_node *cur;
 128
 129        if (!h)
 130                return 0;
 131
 132        for (i = 0; i < h->size; i++) {
 133                cur = h->htable[i];
 134                while (cur) {
 135                        ret = apply(cur->key, cur->datum, args);
 136                        if (ret)
 137                                return ret;
 138                        cur = cur->next;
 139                }
 140        }
 141        return 0;
 142}
 143
 144
 145void hashtab_stat(struct hashtab *h, struct hashtab_info *info)
 146{
 147        u32 i, chain_len, slots_used, max_chain_len;
 148        struct hashtab_node *cur;
 149
 150        slots_used = 0;
 151        max_chain_len = 0;
 152        for (slots_used = max_chain_len = i = 0; i < h->size; i++) {
 153                cur = h->htable[i];
 154                if (cur) {
 155                        slots_used++;
 156                        chain_len = 0;
 157                        while (cur) {
 158                                chain_len++;
 159                                cur = cur->next;
 160                        }
 161
 162                        if (chain_len > max_chain_len)
 163                                max_chain_len = chain_len;
 164                }
 165        }
 166
 167        info->slots_used = slots_used;
 168        info->max_chain_len = max_chain_len;
 169}
 170