numeric.c: check signs before division

* numeric.c (ruby_num_interval_step_size): check signs and get rid
  of implementation dependent behavior of negative division.
  [ruby-core:61106] [Bug #9570]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@45187 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 11 insertions, 0 deletions

diff --git a/numeric.c b/numeric.c
index 838ec43c29..99a1c7d60e 100644
--- a/numeric.c
+++ b/numeric.c
@@ -1808,10 +1808,21 @@ ruby_num_interval_step_size(VALUE from, VALUE to, VALUE step, int excl)
 	long delta, diff, result;
 
 	diff = FIX2LONG(step);
+	if (!diff) rb_num_zerodiv();
 	delta = FIX2LONG(to) - FIX2LONG(from);
 	if (excl) {
 	    delta += (diff > 0 ? -1 : +1);
 	}
+	if (delta) {
+	    if (diff < 0) {
+		if (delta > 0) return INT2FIX(0);
+		diff = -diff;
+		delta = -delta;
+	    }
+	    else {
+		if (delta < 0) return INT2FIX(0);
+	    }
+	}
 	result = delta / diff;
 	return LONG2FIX(result >= 0 ? result + 1 : 0);
     }