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hash.c
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hash.c
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/*
* Part of Very Secure FTPd
* Licence: GPL v2
* Author: Chris Evans
* hash.c
*
* Routines to handle simple hash table lookups and modifications.
*/
#include "hash.h"
#include "sysutil.h"
#include "utility.h"
struct hash_node
{
void* p_key;
void* p_value;
struct hash_node* p_prev;
struct hash_node* p_next;
};
struct hash
{
unsigned int buckets;
unsigned int key_size;
unsigned int value_size;
hashfunc_t hash_func;
struct hash_node** p_nodes;
};
/* Internal functions */
struct hash_node** hash_get_bucket(struct hash* p_hash, void* p_key);
struct hash_node* hash_get_node_by_key(struct hash* p_hash, void* p_key);
struct hash*
hash_alloc(unsigned int buckets, unsigned int key_size,
unsigned int value_size, hashfunc_t hash_func)
{
unsigned int size;
struct hash* p_hash = vsf_sysutil_malloc(sizeof(*p_hash));
p_hash->buckets = buckets;
p_hash->key_size = key_size;
p_hash->value_size = value_size;
p_hash->hash_func = hash_func;
size = (unsigned int) sizeof(struct hash_node*) * buckets;
p_hash->p_nodes = vsf_sysutil_malloc(size);
vsf_sysutil_memclr(p_hash->p_nodes, size);
return p_hash;
}
void*
hash_lookup_entry(struct hash* p_hash, void* p_key)
{
struct hash_node* p_node = hash_get_node_by_key(p_hash, p_key);
if (!p_node)
{
return p_node;
}
return p_node->p_value;
}
void
hash_add_entry(struct hash* p_hash, void* p_key, void* p_value)
{
struct hash_node** p_bucket;
struct hash_node* p_new_node;
if (hash_lookup_entry(p_hash, p_key))
{
bug("duplicate hash key");
}
p_bucket = hash_get_bucket(p_hash, p_key);
p_new_node = vsf_sysutil_malloc(sizeof(*p_new_node));
p_new_node->p_prev = 0;
p_new_node->p_next = 0;
p_new_node->p_key = vsf_sysutil_malloc(p_hash->key_size);
vsf_sysutil_memcpy(p_new_node->p_key, p_key, p_hash->key_size);
p_new_node->p_value = vsf_sysutil_malloc(p_hash->value_size);
vsf_sysutil_memcpy(p_new_node->p_value, p_value, p_hash->value_size);
if (!*p_bucket)
{
*p_bucket = p_new_node;
}
else
{
p_new_node->p_next = *p_bucket;
(*p_bucket)->p_prev = p_new_node;
*p_bucket = p_new_node;
}
}
void
hash_free_entry(struct hash* p_hash, void* p_key)
{
struct hash_node* p_node = hash_get_node_by_key(p_hash, p_key);
if (!p_node)
{
bug("hash node not found");
}
vsf_sysutil_free(p_node->p_key);
vsf_sysutil_free(p_node->p_value);
if (p_node->p_prev)
{
p_node->p_prev->p_next = p_node->p_next;
}
else
{
struct hash_node** p_bucket = hash_get_bucket(p_hash, p_key);
*p_bucket = p_node->p_next;
}
if (p_node->p_next)
{
p_node->p_next->p_prev = p_node->p_prev;
}
vsf_sysutil_free(p_node);
}
struct hash_node**
hash_get_bucket(struct hash* p_hash, void* p_key)
{
unsigned int bucket = (*p_hash->hash_func)(p_hash->buckets, p_key);
if (bucket >= p_hash->buckets)
{
bug("bad bucket lookup");
}
return &(p_hash->p_nodes[bucket]);
}
struct hash_node*
hash_get_node_by_key(struct hash* p_hash, void* p_key)
{
struct hash_node** p_bucket = hash_get_bucket(p_hash, p_key);
struct hash_node* p_node = *p_bucket;
if (!p_node)
{
return p_node;
}
while (p_node != 0 &&
vsf_sysutil_memcmp(p_key, p_node->p_key, p_hash->key_size) != 0)
{
p_node = p_node->p_next;
}
return p_node;
}