Fix integer overflow handling in parseUintBuf() (#789)

* Add more tests for parseUintBuf()

* Fix integer overflow handling in parseUintBuf()

bytesconv.go

@@ -185,11 +185,12 @@ func parseUintBuf(b []byte) (int, int, error) {
 			}
 			return v, i, nil
 		}
+		vNew := 10*v + int(k)
 		// Test for overflow.
-		if v*10 < v {
+		if vNew < v {
 			return -1, i, errTooLongInt
 		}
-		v = 10*v + int(k)
+		v = vNew
 	}
 	return v, n, nil
 }

bytesconv_32_test.go

@@ -38,10 +38,22 @@ func TestReadHexIntSuccess(t *testing.T) {
 	testReadHexIntSuccess(t, "1234ZZZ", 0x1234)
 }
 
+func TestParseUintError32(t *testing.T) {
+	t.Parallel()
+
+	// Overflow by last digit: 2 ** 32 / 2 * 10 ** n
+	testParseUintError(t, "2147483648")
+	testParseUintError(t, "21474836480")
+	testParseUintError(t, "214748364800")
+}
+
 func TestParseUintSuccess(t *testing.T) {
 	t.Parallel()
 
 	testParseUintSuccess(t, "0", 0)
 	testParseUintSuccess(t, "123", 123)
 	testParseUintSuccess(t, "123456789", 123456789)
+
+	// Max supported value: 2 ** 32 / 2 - 1
+	testParseUintSuccess(t, "2147483647", 2147483647)
 }

bytesconv_64_test.go

@@ -39,6 +39,15 @@ func TestReadHexIntSuccess(t *testing.T) {
 	testReadHexIntSuccess(t, "7ffffffffffffff", 0x7ffffffffffffff)
 }
 
+func TestParseUintError64(t *testing.T) {
+	t.Parallel()
+
+	// Overflow by last digit: 2 ** 64 / 2 * 10 ** n
+	testParseUintError(t, "9223372036854775808")
+	testParseUintError(t, "92233720368547758080")
+	testParseUintError(t, "922337203685477580800")
+}
+
 func TestParseUintSuccess(t *testing.T) {
 	t.Parallel()
 
@@ -46,5 +55,7 @@ func TestParseUintSuccess(t *testing.T) {
 	testParseUintSuccess(t, "123", 123)
 	testParseUintSuccess(t, "1234567890", 1234567890)
 	testParseUintSuccess(t, "123456789012345678", 123456789012345678)
+
+	// Max supported value: 2 ** 64 / 2 - 1
 	testParseUintSuccess(t, "9223372036854775807", 9223372036854775807)
 }