Commit ce84456d authored by Richard Levitte's avatar Richard Levitte
Browse files

Math::BigInt does floored divs, BN_div does truncated div, compensate 



According to documentation, perl's Math::BigInt does floored division,
i.e. the bdiv function does 1 / -4 = -1.  OpenSSL's BN_div, as well as
bc, do truncated division, i.e. 1 / -4 = 0.

We need to compensate for that difference in test/recipes/bc.pl to
make sure to verify the bntest results under its own conditions, by
dividing the absolute values of the given numbers and fixup the
result's negativity afterwards.

Closes RT#4485

Reviewed-by: default avatarViktor Dukhovni <viktor@openssl.org>
parent c828cd7c

test/recipes/bc.pl

+9 −0
Original line number Diff line number Diff line
@@ -46,7 +46,16 @@ sub __multiplier { 
	if ($operator eq "*") {

	    $operand1->bmul($operand2);

	} elsif ($operator eq "/") {

	    # Math::BigInt->bdiv() is documented to do floored division,

	    # i.e. 1 / -4 = -1, while bc and OpenSSL BN_div do truncated

	    # division, i.e. 1 / -4 = 0.  We need to make the operation

	    # work like OpenSSL's BN_div to be able to verify.

	    my $neg = ($operand1->is_neg()

		       ? !$operand2->is_neg() : $operand2->is_neg());

	    $operand1->babs();

	    $operand2->babs();

	    $operand1->bdiv($operand2);

	    if ($neg) { $operand1->bneg(); }

	} elsif ($operator eq "%") {

	    # Here's a bit of a quirk...

	    # With OpenSSL's BN, as well as bc, the result of -10 % 3 is -1