fmt: fix crash of %b on huge negative int64
The buffer had 64 bytes but needs one more for the sign.
Fixes #3510.
R=golang-dev, dave, dsymonds
CC=golang-dev
https://golang.org/cl/6011057
diff --git a/src/pkg/fmt/fmt_test.go b/src/pkg/fmt/fmt_test.go
index 758fc50..de03429 100644
--- a/src/pkg/fmt/fmt_test.go
+++ b/src/pkg/fmt/fmt_test.go
@@ -461,6 +461,9 @@
// zero reflect.Value, which formats as <nil>.
// This test is just to check that it shows the two NaNs at all.
{"%v", map[float64]int{math.NaN(): 1, math.NaN(): 2}, "map[NaN:<nil> NaN:<nil>]"},
+
+ // Used to crash because nByte didn't allow for a sign.
+ {"%b", int64(-1 << 63), "-1000000000000000000000000000000000000000000000000000000000000000"},
}
func TestSprintf(t *testing.T) {
diff --git a/src/pkg/fmt/format.go b/src/pkg/fmt/format.go
index 2186f33..caf900d 100644
--- a/src/pkg/fmt/format.go
+++ b/src/pkg/fmt/format.go
@@ -10,7 +10,7 @@
)
const (
- nByte = 64
+ nByte = 65 // %b of an int64, plus a sign.
ldigits = "0123456789abcdef"
udigits = "0123456789ABCDEF"
