From 73711533210a3ddc85e092eb06c1373277b65e99 Mon Sep 17 00:00:00 2001
From: Casey Marshall <casey.marshall@gmail.com>
Date: Mon, 13 Oct 2014 12:41:14 -0700
Subject: [PATCH] math/big: Fixes issue 8920

(*Rat).SetString checks for denominator.

LGTM=gri
R=golang-codereviews, gri
CC=golang-codereviews
https://golang.org/cl/159760043
---
 src/math/big/rat.go      | 3 +++
 src/math/big/rat_test.go | 1 +
 2 files changed, 4 insertions(+)

diff --git a/src/math/big/rat.go b/src/math/big/rat.go
index 0bcec30252..c5339fe443 100644
--- a/src/math/big/rat.go
+++ b/src/math/big/rat.go
@@ -552,6 +552,9 @@ func (z *Rat) SetString(s string) (*Rat, bool) {
 		if z.b.abs, _, err = z.b.abs.scan(strings.NewReader(s), 10); err != nil {
 			return nil, false
 		}
+		if len(z.b.abs) == 0 {
+			return nil, false
+		}
 		return z.norm(), true
 	}
 
diff --git a/src/math/big/rat_test.go b/src/math/big/rat_test.go
index 598eac8cc7..5dbbb3510f 100644
--- a/src/math/big/rat_test.go
+++ b/src/math/big/rat_test.go
@@ -89,6 +89,7 @@ var setStringTests = []struct {
 	{"53/70893980658822810696", "53/70893980658822810696", true},
 	{"106/141787961317645621392", "53/70893980658822810696", true},
 	{"204211327800791583.81095", "4084226556015831676219/20000", true},
+	{in: "1/0", ok: false},
 }
 
 func TestRatSetString(t *testing.T) {
-- 
2.50.0