Potential bug in map->spare usage (used both as struct bucket and stored item)

[HeavenlyAwe]

In the initialize function map->spare is initialized to have sizeof(hashmap) + 2 * bucketsz

But it is used both as struct bucket and as the items stored in the buckets in the setter and getter.

hashmap.c/hashmap.c

Lines 280 to 290 in 84d0d3b

	{
	memcpy(map->spare, bitem, map->elsize);
	memcpy(bitem, eitem, map->elsize);
	return map->spare;
	}
	if (bucket->dib < entry->dib) {
	memcpy(map->spare, bucket, map->bucketsz);
	memcpy(bucket, entry, map->bucketsz);
	memcpy(entry, map->spare, map->bucketsz);
	eitem = bucket_item(entry);
	}

hashmap.c/hashmap.c

Line 361 in 84d0d3b

memcpy(map->spare, bitem, map->elsize);

As long as elsize is smaller than bucketsz this shouldn't be a problem.

[tidwall]

This is by design. It's not a bug, nor even potentially a bug.

The spare field is large enough to hold a bucket or an item, and a bucket size is always larger than an item size.

hashmap.c/hashmap.c

Line 105 in 84d0d3b

size_t bucketsz = sizeof(struct bucket) + elsize;

[HeavenlyAwe]

Thanks for the explanation. I wasn't completely sure prior to this explanation.