Function evlHash

src/jrd/SysFunction.cpp:5073–5129

dsc* evlHash(thread_db* tdbb, const SysFunction* function, const NestValueArray& args,
	impure_value* impure)
{
	fb_assert(args.getCount() >= 1);

	Request* request = tdbb->getRequest();

	const dsc* value = EVL_expr(tdbb, request, args[0]);
	if (request->req_flags & req_null)	// return NULL if value is NULL
		return NULL;

	AutoPtr<HashContext> hashContext;
	MemoryPool& pool = *request->req_pool;

	if (args.getCount() >= 2)
	{
		const dsc* algorithmDesc = EVL_expr(tdbb, request, args[1]);
		if (request->req_flags & req_null)	// return NULL if algorithm is NULL
			return NULL;

		const HashAlgorithmDescriptor* d = getHashAlgorithmDesc(tdbb, function, algorithmDesc);
		hashContext.reset(d->create(pool));
	}
	else
	{
		hashContext.reset(FB_NEW_POOL(pool) WeakHashContext());
		impure->vlu_misc.vlu_int64 = 0;
	}

	if (value->isBlob())
	{
		UCHAR buffer[BUFFER_LARGE];
		blb* blob = blb::open(tdbb, tdbb->getRequest()->req_transaction,
			reinterpret_cast<bid*>(value->dsc_address));

		while (!(blob->blb_flags & BLB_eof))
		{
			const ULONG length = blob->BLB_get_data(tdbb, buffer, sizeof(buffer), false);
			hashContext->update(buffer, length);
		}

		blob->BLB_close(tdbb);
	}
	else
	{
		UCHAR* address;
		MoveBuffer buffer;
		const ULONG length = MOV_make_string2(tdbb, value, value->getTextType(), &address, buffer, false);
		hashContext->update(address, length);
	}

	dsc result;
	hashContext->finish(result);
	EVL_make_value(tdbb, &result, impure);

	return &impure->vlu_desc;
}