engines/ccgost/gosthash.c: simplify and avoid SEGV.

 */

int hash_block(gost_hash_ctx *ctx,const byte *block, size_t length)

	{

	const byte *curptr=block;

	const byte *barrier=block+(length-32);/* Last byte we can safely hash*/

	if (ctx->left)

		{

		/*There are some bytes from previous step*/

			{

			return 1;

			}	

		curptr=block+add_bytes;

		block+=add_bytes;

		length-=add_bytes;

		hash_step(ctx->cipher_ctx,ctx->H,ctx->remainder);

		add_blocks(32,ctx->S,ctx->remainder);

		ctx->len+=32;

		ctx->left=0;

		}

	while (curptr<=barrier)

	while (length>=32)

		{	

		hash_step(ctx->cipher_ctx,ctx->H,curptr);

		hash_step(ctx->cipher_ctx,ctx->H,block);

		add_blocks(32,ctx->S,curptr);

		add_blocks(32,ctx->S,block);

		ctx->len+=32;

		curptr+=32;

		block+=32;

		length-=32;

		}	

	if (curptr!=block+length)

	if (length)

		{

		ctx->left=block+length-curptr;

		memcpy(ctx->remainder,curptr,ctx->left);

		memcpy(ctx->remainder,block,ctx->left=length);

		}	

	return 1;	

	}