root/security/selinux/ss/hashtab.c

DEFINITIONS

1. hashtab_create
2. hashtab_insert
3. hashtab_search
4. hashtab_destroy
5. hashtab_map
6. hashtab_stat

/*
 * Implementation of the hash table type.
 *
 * Author : Stephen Smalley, <sds@epoch.ncsc.mil>
 */
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/errno.h>
#include "hashtab.h"

struct hashtab *hashtab_create(u32 (*hash_value)(struct hashtab *h, const void *key),
                               int (*keycmp)(struct hashtab *h, const void *key1, const void *key2),
                               u32 size)
{
        struct hashtab *p;
        u32 i;

        p = kzalloc(sizeof(*p), GFP_KERNEL);
        if (p == NULL)
                return p;

        p->size = size;
        p->nel = 0;
        p->hash_value = hash_value;
        p->keycmp = keycmp;
        p->htable = kmalloc(sizeof(*(p->htable)) * size, GFP_KERNEL);
        if (p->htable == NULL) {
                kfree(p);
                return NULL;
        }

        for (i = 0; i < size; i++)
                p->htable[i] = NULL;

        return p;
}

int hashtab_insert(struct hashtab *h, void *key, void *datum)
{
        u32 hvalue;
        struct hashtab_node *prev, *cur, *newnode;

        if (!h || h->nel == HASHTAB_MAX_NODES)
                return -EINVAL;

        hvalue = h->hash_value(h, key);
        prev = NULL;
        cur = h->htable[hvalue];
        while (cur && h->keycmp(h, key, cur->key) > 0) {
                prev = cur;
                cur = cur->next;
        }

        if (cur && (h->keycmp(h, key, cur->key) == 0))
                return -EEXIST;

        newnode = kzalloc(sizeof(*newnode), GFP_KERNEL);
        if (newnode == NULL)
                return -ENOMEM;
        newnode->key = key;
        newnode->datum = datum;
        if (prev) {
                newnode->next = prev->next;
                prev->next = newnode;
        } else {
                newnode->next = h->htable[hvalue];
                h->htable[hvalue] = newnode;
        }

        h->nel++;
        return 0;
}

void *hashtab_search(struct hashtab *h, const void *key)
{
        u32 hvalue;
        struct hashtab_node *cur;

        if (!h)
                return NULL;

        hvalue = h->hash_value(h, key);
        cur = h->htable[hvalue];
        while (cur && h->keycmp(h, key, cur->key) > 0)
                cur = cur->next;

        if (cur == NULL || (h->keycmp(h, key, cur->key) != 0))
                return NULL;

        return cur->datum;
}

void hashtab_destroy(struct hashtab *h)
{
        u32 i;
        struct hashtab_node *cur, *temp;

        if (!h)
                return;

        for (i = 0; i < h->size; i++) {
                cur = h->htable[i];
                while (cur) {
                        temp = cur;
                        cur = cur->next;
                        kfree(temp);
                }
                h->htable[i] = NULL;
        }

        kfree(h->htable);
        h->htable = NULL;

        kfree(h);
}

int hashtab_map(struct hashtab *h,
                int (*apply)(void *k, void *d, void *args),
                void *args)
{
        u32 i;
        int ret;
        struct hashtab_node *cur;

        if (!h)
                return 0;

        for (i = 0; i < h->size; i++) {
                cur = h->htable[i];
                while (cur) {
                        ret = apply(cur->key, cur->datum, args);
                        if (ret)
                                return ret;
                        cur = cur->next;
                }
        }
        return 0;
}


void hashtab_stat(struct hashtab *h, struct hashtab_info *info)
{
        u32 i, chain_len, slots_used, max_chain_len;
        struct hashtab_node *cur;

        slots_used = 0;
        max_chain_len = 0;
        for (slots_used = max_chain_len = i = 0; i < h->size; i++) {
                cur = h->htable[i];
                if (cur) {
                        slots_used++;
                        chain_len = 0;
                        while (cur) {
                                chain_len++;
                                cur = cur->next;
                        }

                        if (chain_len > max_chain_len)
                                max_chain_len = chain_len;
                }
        }

        info->slots_used = slots_used;
        info->max_chain_len = max_chain_len;
}