internal/number: possible out of range error avoiding

Case when r.Increment > 0 and r.IncrementScale == len(scales) in *Decimal.ConvertFloat method is taken into account. It led to unexpected out of range panic. fixes golang/go#42147 Change-Id: Ic26e67010b766bdbd322a3853489f6d1ecb0dcfc Reviewed-on: https://go-review.googlesource.com/c/text/+/265021 Reviewed-by: Marcel van Lohuizen <[email protected]> Trust: Russ Cox <[email protected]>
golang · Nov 25, 2020 · 305da72 · 305da72
1 parent 72ead5f
commit 305da72
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Showing 2 changed files with 6 additions and 1 deletion.
diff --git a/internal/number/decimal.go b/internal/number/decimal.go
@@ -379,7 +379,7 @@ func (d *Decimal) ConvertFloat(r RoundingContext, x float64, size int) {
 	if r.Increment > 0 {
 		scale := int(r.IncrementScale)
 		mult := 1.0
-		if scale > len(scales) {
+		if scale >= len(scales) {
 			mult = math.Pow(10, float64(scale))
 		} else {
 			mult = scales[scale]

diff --git a/internal/number/decimal_test.go b/internal/number/decimal_test.go
@@ -248,6 +248,10 @@ func TestConvert(t *testing.T) {
 	inc0_05 := RoundingContext{Increment: 5, IncrementScale: 2}
 	inc0_05.SetScale(2)
 	inc50 := RoundingContext{Increment: 50}
+	incScaleEqualToScalesLen := RoundingContext{Increment: 1, IncrementScale: 0}
+	if len(scales) <= math.MaxUint8 {
+		incScaleEqualToScalesLen.IncrementScale = uint8(len(scales))
+	}
 	prec3 := RoundingContext{}
 	prec3.SetPrecision(3)
 	roundShift := RoundingContext{DigitShift: 2, MaxFractionDigits: 2}
@@ -309,6 +313,7 @@ func TestConvert(t *testing.T) {
 		{math.Inf(-1), inc50, "-Inf"},
 		{math.NaN(), inc50, "NaN"},
 		{"clearly not a number", scale2, "NaN"},
+		{0.0, incScaleEqualToScalesLen, "0"},
 	}
 	for _, tc := range testCases {
 		var d Decimal