breakhack/hashtable/hashtable.c

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <limits.h>
#include "hashtable.h"

static void*
ec_malloc(unsigned int size)
{
	void *ptr = malloc(size);
	if (ptr == NULL) {
		fprintf(stderr, "[!!] Failed to allocate hashtable\n");
		exit(-1);
	}

	return ptr;
}


Hashtable*
ht_create(unsigned int size)
{
	Hashtable *table;
	unsigned int i;

	if (size < 1)
		return NULL;

	table = ec_malloc(sizeof(Hashtable));
	table->size = size;
	table->entries = ec_malloc(sizeof(Entry) * size);

	for (i = 0; i < size; ++i) {
		table->entries[i] = NULL;
	}

	return table;
}

static unsigned int
hash(Hashtable *table, const char *key)
{
	unsigned long int hashval = 0;
	int i = 0;

	while (hashval < ULONG_MAX && i < strlen(key)) {
		hashval = hashval << 8;
		hashval += key[i++];
	}

	return hashval % table->size;
}

static Entry*
entry_create(const char *key, void *value)
{
	Entry *entry;

	entry = ec_malloc(sizeof(Entry));
	entry->key = strdup(key);
	entry->value = value;
	entry->next = NULL;

	return entry;
}

void
ht_set(Hashtable *table, const char *key, void *val)
{
	int hashkey = 0;
	Entry *newEntry;
	Entry *next;
	Entry *last;

	hashkey = hash(table, key);

	next = table->entries[hashkey];

	/* Find a position */
	while (next != NULL
	       && next->key != NULL
	       && strcmp(key, next->key) > 0)
	{
		last = next;
		next = next->next;
	}

	if (next && next->key && strcmp(key, next->key) == 0) {
		/* Collision */
		free(next->value);
		next->value = val;
	} else {
		/* New entry */
		newEntry = entry_create(key, val);

		if (next == table->entries[hashkey]) {
			table->entries[hashkey] = newEntry;
			newEntry->next = next;
		} else if(next == NULL) {
			last->next = newEntry;
		} else {
			newEntry->next = next;
			last->next = newEntry;
		}
	}
}

void*
ht_get(Hashtable *table, const char *key)
{
	int hashkey = 0;
	Entry *entry;

	hashkey = hash(table, key);

	entry = table->entries[hashkey];

	while (entry && entry->key && strcmp(entry->key, key) > 0) {
		entry = entry->next;
	}

	if (!entry || !entry->key || strcmp(entry->key, key) != 0) {
		return NULL;
	}
	return entry->value;
}

void
ht_destroy(Hashtable *table)
{
	ht_destroy_custom(table, free);
}

void
ht_destroy_custom(Hashtable *table, void (*destroy_value)(void *value))
{
	Entry *entry, *next;
	unsigned int i;

	if (table == NULL) {
		return;
	}

	for (i = 0; i < table->size; ++i) {
		entry = table->entries[i];
		if (entry == NULL)
			continue;
		while (entry) {
			next = entry->next;
			destroy_value(entry->value);
			entry->value = NULL;
			free(entry->key);
			free(entry);
			entry = next;
		}
	}
	free(table->entries);
	free(table);
}