From: Richard Levitte Date: Fri, 25 Mar 2016 23:07:50 +0000 (+0100) Subject: Math::BigInt does floored divs, BN_div does truncated div, compensate X-Git-Tag: OpenSSL_1_1_0-pre5~226 X-Git-Url: https://git.openssl.org/?p=openssl.git;a=commitdiff_plain;h=ce84456ddf4e57c18a84858755b8b90c183a270e 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: Viktor Dukhovni --- diff --git a/test/recipes/bc.pl b/test/recipes/bc.pl index 29a4a8a84a..f7d4dc681d 100644 --- a/test/recipes/bc.pl +++ b/test/recipes/bc.pl @@ -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