util/types: fix floatStrToIntStr, handle large exponent corner case. (p…

…ingcap#2199)
YQGL · Dec 8, 2016 · 7e61f16 · 7e61f16
1 parent b134396
commit 7e61f16
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Showing 2 changed files with 14 additions and 1 deletion.
diff --git a/util/types/convert.go b/util/types/convert.go
@@ -204,6 +204,10 @@ func floatStrToIntStr(validFloat string) (string, error) {
 		if err != nil {
 			return validFloat, errors.Trace(err)
 		}
+		if exp > 0 && intCnt > (math.MaxInt64-exp) {
+			// (exp + incCnt) overflows MaxInt64.
+			return validFloat, errors.Trace(ErrOverflow)
+		}
 		intCnt += exp
 	}
 	if intCnt <= 0 {
@@ -216,7 +220,12 @@ func floatStrToIntStr(validFloat string) (string, error) {
 	if intCnt <= len(digits) {
 		validInt = string(digits[:intCnt])
 	} else {
-		validInt = string(digits) + strings.Repeat("0", intCnt-len(digits))
+		extraZeroCount := intCnt - len(digits)
+		if extraZeroCount > 20 {
+			// Return overflow to avoid allocating too much memory.
+			return validFloat, errors.Trace(ErrOverflow)
+		}
+		validInt = string(digits) + strings.Repeat("0", extraZeroCount)
 	}
 	return validInt, nil
 }

diff --git a/util/types/convert_test.go b/util/types/convert_test.go
@@ -644,4 +644,8 @@ func (s *testTypeConvertSuite) TestGetValidFloat(c *C) {
 		_, err := strconv.ParseFloat(prefix, 64)
 		c.Assert(err, IsNil)
 	}
+	_, err := floatStrToIntStr("1e9223372036854775807")
+	c.Assert(terror.ErrorEqual(err, ErrOverflow), IsTrue)
+	_, err = floatStrToIntStr("1e21")
+	c.Assert(terror.ErrorEqual(err, ErrOverflow), IsTrue)
 }