From cb2f0c288d4b7acfa37d7a9c8bc1024c3f332b5f Mon Sep 17 00:00:00 2001
From: Matt McCutchen <matt@mattmccutchen.net>
Date: Thu, 17 Jul 2008 07:44:27 -0400
Subject: [PATCH] - Fix a sign-checking bug in the BigInteger(..., Sign)
 constructors. - Add some tests of constructors, including one for the
 aforementioned bug. - Improve some comments.

---
 BigInteger.cc | 16 +++++++++++++++-
 testsuite.cc  | 26 ++++++++++++++++++++++++++
 2 files changed, 41 insertions(+), 1 deletion(-)

diff --git a/BigInteger.cc b/BigInteger.cc
index 56f30ab..3b23aa1 100644
--- a/BigInteger.cc
+++ b/BigInteger.cc
@@ -13,11 +13,18 @@ void BigInteger::operator =(const BigInteger &x) {
 BigInteger::BigInteger(const Blk *b, Index blen, Sign s) : mag(b, blen) {
 	switch (s) {
 	case zero:
+		if (!mag.isZero())
+			throw "BigInteger::BigInteger(const Blk *, Index, Sign): Cannot use a sign of zero with a nonzero magnitude";
+		sign = zero;
+		break;
 	case positive:
 	case negative:
+		// If the magnitude is zero, force the sign to zero.
 		sign = mag.isZero() ? zero : s;
 		break;
 	default:
+		/* g++ seems to be optimizing out this case on the assumption
+		 * that the sign is a valid member of the enumeration.  Oh well. */
 		throw "BigInteger::BigInteger(const Blk *, Index, Sign): Invalid sign";
 	}
 }
@@ -25,12 +32,19 @@ BigInteger::BigInteger(const Blk *b, Index blen, Sign s) : mag(b, blen) {
 BigInteger::BigInteger(const BigUnsigned &x, Sign s) : mag(x) {
 	switch (s) {
 	case zero:
+		if (!mag.isZero())
+			throw "BigInteger::BigInteger(const BigUnsigned &, Sign): Cannot use a sign of zero with a nonzero magnitude";
+		sign = zero;
+		break;
 	case positive:
 	case negative:
+		// If the magnitude is zero, force the sign to zero.
 		sign = mag.isZero() ? zero : s;
 		break;
 	default:
-		throw "BigInteger::BigInteger(Blk *, Index, Sign): Invalid sign";
+		/* g++ seems to be optimizing out this case on the assumption
+		 * that the sign is a valid member of the enumeration.  Oh well. */
+		throw "BigInteger::BigInteger(const BigUnsigned &, Sign): Invalid sign";
 	}
 }
 
diff --git a/testsuite.cc b/testsuite.cc
index 8d31eda..7817e9a 100644
--- a/testsuite.cc
+++ b/testsuite.cc
@@ -60,6 +60,32 @@ TEST(10); //10
 TEST(check(BigUnsigned())); //0
 TEST(check(BigInteger())); //0
 
+// === Block-array constructors ===
+
+BigUnsigned::Blk myBlocks[3];
+myBlocks[0] = 3;
+myBlocks[1] = 4;
+myBlocks[2] = 0;
+BigUnsigned bu(myBlocks, 3);
+TEST(check(bu)); //17179869187
+TEST(check(BigInteger(myBlocks, 3))); //17179869187
+TEST(check(BigInteger(bu         ))); //17179869187
+
+// For nonzero magnitude, reject zero and invalid signs.
+TEST(check(BigInteger(myBlocks, 3, BigInteger::positive))); //17179869187
+TEST(check(BigInteger(myBlocks, 3, BigInteger::negative))); //-17179869187
+TEST(check(BigInteger(myBlocks, 3, BigInteger::zero    ))); //error
+TEST(check(BigInteger(bu,          BigInteger::positive))); //17179869187
+TEST(check(BigInteger(bu,          BigInteger::negative))); //-17179869187
+TEST(check(BigInteger(bu,          BigInteger::zero    ))); //error
+
+// For zero magnitude, force the sign to zero without error.
+BigUnsigned::Blk myZeroBlocks[1];
+myZeroBlocks[0] = 0;
+TEST(check(BigInteger(myZeroBlocks, 1, BigInteger::positive))); //0
+TEST(check(BigInteger(myZeroBlocks, 1, BigInteger::negative))); //0
+TEST(check(BigInteger(myZeroBlocks, 1, BigInteger::zero    ))); //0
+
 // === BigUnsigned conversion limits ===
 
 TEST(BigUnsigned(0).toUnsignedLong()); //0
-- 
2.34.1