Add range-check to DateTime.fromMillisecondsSinceEpoch on VM.

The current constructor allowed large numbers which overflows
when multiplied by 1000 to get microseconds, which then hid the
fact that the original value was out of range.

Now checks directly in the `fromMillisecondsSinceEpoch` constructor,
before multiplying by 1000.

Fixes #46966

BUG= http://dartbug.com/46966
TEST= Regression test added to date_time_test.dart

Change-Id: I4c6448666a49d51c285bd538e05e51a141b3b0b2
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/214641
Commit-Queue: Lasse R.H. Nielsen <lrn@google.com>
Reviewed-by: Nate Bosch <nbosch@google.com>

sdk/lib/_internal/vm/lib/date_patch.dart

@@ -39,7 +39,8 @@ class DateTime {
   DateTime.fromMillisecondsSinceEpoch(int millisecondsSinceEpoch,
       {bool isUtc: false})
       : this._withValue(
-            millisecondsSinceEpoch * Duration.microsecondsPerMillisecond,
+            _validateMilliseconds(millisecondsSinceEpoch) *
+                Duration.microsecondsPerMillisecond,
             isUtc: isUtc);
 
   @patch
@@ -58,6 +59,13 @@ class DateTime {
     if (isUtc == null) throw new ArgumentError();
   }
 
+  static int _validateMilliseconds(int millisecondsSinceEpoch) =>
+      RangeError.checkValueInInterval(
+          millisecondsSinceEpoch,
+          -_maxMillisecondsSinceEpoch,
+          _maxMillisecondsSinceEpoch,
+          "millisecondsSinceEpoch");
+
   @patch
   DateTime._now()
       : isUtc = false,

tests/corelib/date_time_test.dart

@@ -1188,6 +1188,34 @@ void testIsoString() {
   Expect.equals("-010000-01-01T23:49:59.989979Z", d.toIso8601String());
 }
 
+void testRegression46966() {
+  // See http://dartbug.com/46966
+  // The constructor allowed numbers larger than 100_000_000 days
+  // from epoch, contrary to documentation (and web behavior).
+
+  // Maximally allowed milliseconds on either side of epoch
+  // (±100 000 000 days).
+  var maxMilliseconds = 100000000 * 24 * 60 * 60 * 1000;
+  var maxDate = DateTime.fromMillisecondsSinceEpoch(maxMilliseconds);
+  var minDate = DateTime.fromMillisecondsSinceEpoch(-maxMilliseconds);
+
+  // Throws if greater.
+  Expect.throws(() => DateTime.fromMillisecondsSinceEpoch(maxMilliseconds + 1));
+  Expect.throws(
+      () => DateTime.fromMillisecondsSinceEpoch(-maxMilliseconds - 1));
+
+  // But also if much greater.
+  // The badMin value overflows 64-bits when multiplied by 1000.
+  var badMin = 0x20c49ba5e353f8;
+  Expect.throws(() => DateTime.fromMillisecondsSinceEpoch(badMin));
+  Expect.throws(() => DateTime.fromMillisecondsSinceEpoch(-badMin));
+  Expect.throws(() => DateTime.fromMillisecondsSinceEpoch(badMin + 1));
+  Expect.throws(() => DateTime.fromMillisecondsSinceEpoch(-badMin - 1));
+  var badMax = double.maxFinite.toInt(); // 2^63-1 on VM, max double on JS.
+  Expect.throws(() => DateTime.fromMillisecondsSinceEpoch(badMax));
+  Expect.throws(() => DateTime.fromMillisecondsSinceEpoch(-badMax - 1));
+}
+
 void main() {
   testNow();
   testMillisecondsSinceEpoch();
@@ -1203,4 +1231,5 @@ void main() {
   testWeekday();
   testToStrings();
   testIsoString();
+  testRegression46966();
 }

tests/corelib_2/date_time_test.dart

@@ -1190,6 +1190,34 @@ void testIsoString() {
   Expect.equals("-010000-01-01T23:49:59.989979Z", d.toIso8601String());
 }
 
+void testRegression46966() {
+  // See http://dartbug.com/46966
+  // The constructor allowed numbers larger than 100_000_000 days
+  // from epoch, contrary to documentation (and web behavior).
+
+  // Maximally allowed milliseconds on either side of epoch
+  // (±100 000 000 days).
+  var maxMilliseconds = 100000000 * 24 * 60 * 60 * 1000;
+  var maxDate = DateTime.fromMillisecondsSinceEpoch(maxMilliseconds);
+  var minDate = DateTime.fromMillisecondsSinceEpoch(-maxMilliseconds);
+
+  // Throws if greater.
+  Expect.throws(() => DateTime.fromMillisecondsSinceEpoch(maxMilliseconds + 1));
+  Expect.throws(
+      () => DateTime.fromMillisecondsSinceEpoch(-maxMilliseconds - 1));
+
+  // But also if much greater.
+  // The badMin value overflows 64-bits when multiplied by 1000.
+  var badMin = 0x20c49ba5e353f8;
+  Expect.throws(() => DateTime.fromMillisecondsSinceEpoch(badMin));
+  Expect.throws(() => DateTime.fromMillisecondsSinceEpoch(-badMin));
+  Expect.throws(() => DateTime.fromMillisecondsSinceEpoch(badMin + 1));
+  Expect.throws(() => DateTime.fromMillisecondsSinceEpoch(-badMin - 1));
+  var badMax = double.maxFinite.toInt(); // 2^63-1 on VM, max double on JS.
+  Expect.throws(() => DateTime.fromMillisecondsSinceEpoch(badMax));
+  Expect.throws(() => DateTime.fromMillisecondsSinceEpoch(-badMax - 1));
+}
+
 void main() {
   testNow();
   testMillisecondsSinceEpoch();
@@ -1205,4 +1233,5 @@ void main() {
   testWeekday();
   testToStrings();
   testIsoString();
+  testRegression46966();
 }