[ruby/openssl] BN.abs and BN uplus

Adds standard math abs fuction and revises uplus to return a duplicated object due to BN mutability

https://github.com/ruby/openssl/commit/0321b1e945

ext/openssl/ossl_bn.c

@@ -936,7 +936,17 @@ ossl_bn_copy(VALUE self, VALUE other)
 static VALUE
 ossl_bn_uplus(VALUE self)
 {
-    return self;
+    VALUE obj;
+    BIGNUM *bn1, *bn2;
+
+    GetBN(self, bn1);
+    obj = NewBN(cBN);
+    bn2 = BN_dup(bn1);
+    if (!bn2)
+	ossl_raise(eBNError, "BN_dup");
+    SetBN(obj, bn2);
+
+    return obj;
 }
 
 /*
@@ -960,6 +970,24 @@ ossl_bn_uminus(VALUE self)
     return obj;
 }
 
+/*
+ * call-seq:
+ *   bn.abs -> aBN
+ */
+static VALUE
+ossl_bn_abs(VALUE self)
+{
+    BIGNUM *bn1;
+
+    GetBN(self, bn1);
+    if (BN_is_negative(bn1)) {
+        return ossl_bn_uminus(self);
+    }
+    else {
+        return ossl_bn_uplus(self);
+    }
+}
+
 #define BIGNUM_CMP(func)				\
     static VALUE					\
     ossl_bn_##func(VALUE self, VALUE other)		\
@@ -1176,6 +1204,7 @@ Init_ossl_bn(void)
 
     rb_define_method(cBN, "+@", ossl_bn_uplus, 0);
     rb_define_method(cBN, "-@", ossl_bn_uminus, 0);
+    rb_define_method(cBN, "abs", ossl_bn_abs, 0);
 
     rb_define_method(cBN, "+", ossl_bn_add, 1);
     rb_define_method(cBN, "-", ossl_bn_sub, 1);

test/openssl/test_bn.rb

@@ -130,6 +130,27 @@ class OpenSSL::TestBN < OpenSSL::TestCase
     assert_equal(-999, +@e2)
     assert_equal(-999, -@e1)
     assert_equal(+999, -@e2)
+
+    # These methods create new BN instances due to BN mutability
+    # Ensure that the instance isn't the same
+    e1_plus = +@e1
+    e1_minus = -@e1
+    assert_equal(false, @e1.equal?(e1_plus))
+    assert_equal(true, @e1 == e1_plus)
+    assert_equal(false, @e1.equal?(e1_minus))
+  end
+
+  def test_abs
+    assert_equal(@e1, @e2.abs)
+    assert_equal(@e3, @e4.abs)
+    assert_not_equal(@e2, @e2.abs)
+    assert_not_equal(@e4, @e4.abs)
+    assert_equal(false, @e2.abs.negative?)
+    assert_equal(false, @e4.abs.negative?)
+    assert_equal(true, (-@e1.abs).negative?)
+    assert_equal(true, (-@e2.abs).negative?)
+    assert_equal(true, (-@e3.abs).negative?)
+    assert_equal(true, (-@e4.abs).negative?)
   end
 
   def test_mod