From 12a2ca31bc121179260ec42b9326a9e53bd1eba9 Mon Sep 17 00:00:00 2001
From: Anton Kolesnyk <41349689+antkmsft@users.noreply.github.com>
Date: Mon, 13 Dec 2021 12:55:00 -0800
Subject: [PATCH] Fix DateTime::Parse validation for dates past year 9999 due
 to adjustments (#3177)

---
 sdk/core/azure-core/CHANGELOG.md              |  2 ++
 sdk/core/azure-core/src/datetime.cpp          |  2 +-
 sdk/core/azure-core/test/ut/datetime_test.cpp | 17 +++++++++++++++++
 3 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/sdk/core/azure-core/CHANGELOG.md b/sdk/core/azure-core/CHANGELOG.md
index 0925fa542..889a59f78 100644
--- a/sdk/core/azure-core/CHANGELOG.md
+++ b/sdk/core/azure-core/CHANGELOG.md
@@ -10,6 +10,8 @@
 
 ### Bugs Fixed
 
+- Fixed `Azure::DateTime::Parse()` validation if the result is going to exceed `9999-12-31T23:59:59.9999999` due to time zone, leap second, or fractional digits rounding up adjustments.
+
 ### Other Changes
 
 ## 1.3.1 (2021-11-05)
diff --git a/sdk/core/azure-core/src/datetime.cpp b/sdk/core/azure-core/src/datetime.cpp
index 58deaa7d4..4bfca2415 100644
--- a/sdk/core/azure-core/src/datetime.cpp
+++ b/sdk/core/azure-core/src/datetime.cpp
@@ -236,7 +236,7 @@ void ValidateDate(
           + (hour * OneHourIn100ns) + (minute * OneMinuteIn100ns) + (second * OneSecondIn100ns)
           + fracSec + (roundFracSecUp ? 1 : 0);
 
-      constexpr auto FracSecTo9999_12_31_23_59_59_9999999 = (31 * OneDayIn100ns)
+      constexpr auto FracSecTo9999_12_31_23_59_59_9999999 = (30 * OneDayIn100ns)
           + (23 * OneHourIn100ns) + (59 * OneMinuteIn100ns) + (59 * OneSecondIn100ns) + 9999999;
 
       if (fracSecSince9999_12_01 - fracSecTimeAdjustment > FracSecTo9999_12_31_23_59_59_9999999)
diff --git a/sdk/core/azure-core/test/ut/datetime_test.cpp b/sdk/core/azure-core/test/ut/datetime_test.cpp
index c577efee9..a962f52f8 100644
--- a/sdk/core/azure-core/test/ut/datetime_test.cpp
+++ b/sdk/core/azure-core/test/ut/datetime_test.cpp
@@ -802,3 +802,20 @@ TEST(DateTime, TimeRoundtrip)
   TestDateTimeRoundtrip<DateTime::TimeFractionFormat::AllDigits>("2021-02-05T10:00:00.0000000Z");
   TestDateTimeRoundtrip<DateTime::TimeFractionFormat::AllDigits>("2021-02-05T20:00:00.0000000Z");
 }
+
+TEST(DateTime, ParseRoundUpInvalidDate)
+{
+  EXPECT_THROW(
+      static_cast<void>(
+          DateTime::Parse("9999-12-31T23:59:00-00:01", DateTime::DateFormat::Rfc3339)),
+      std::invalid_argument);
+
+  EXPECT_THROW(
+      static_cast<void>(
+          DateTime::Parse("9999-12-31T23:59:59.99999995", DateTime::DateFormat::Rfc3339)),
+      std::invalid_argument);
+
+  EXPECT_THROW(
+      static_cast<void>(DateTime::Parse("9999-12-31T23:59:60", DateTime::DateFormat::Rfc3339)),
+      std::invalid_argument);
+}