Fixing datetime arithmetic overflow/underflow.

src/Microsoft.Health.Fhir.Core.UnitTests/Extensions/DateTimeSafeExtensionsTests.cs

@@ -0,0 +1,152 @@
+// -------------------------------------------------------------------------------------------------
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License (MIT). See LICENSE in the repo root for license information.
+// -------------------------------------------------------------------------------------------------
+
+using System;
+using Microsoft.Health.Fhir.Core.Extensions;
+using Microsoft.Health.Fhir.Tests.Common;
+using Microsoft.Health.Test.Utilities;
+using Xunit;
+
+namespace Microsoft.Health.Fhir.Core.UnitTests.Extensions
+{
+    [Trait(Traits.OwningTeam, OwningTeam.Fhir)]
+    [Trait(Traits.Category, Categories.Search)]
+    public class DateTimeSafeExtensionsTests
+    {
+        // SafeAddTicks - DateTime
+
+        [Fact]
+        public void GivenNormalDateTime_WhenSafeAddTicksCalled_ThenReturnsExpectedResult()
+        {
+            var dt = new DateTime(2024, 6, 15, 12, 0, 0, DateTimeKind.Utc);
+            DateTime result = dt.SafeAddTicks(TimeSpan.TicksPerMillisecond);
+            Assert.Equal(dt.AddTicks(TimeSpan.TicksPerMillisecond), result);
+        }
+
+        [Fact]
+        public void GivenDateTimeNearMaxValue_WhenSafeAddTicksPositive_ThenClampsToMaxValue()
+        {
+            var dt = DateTime.MaxValue.AddTicks(-100);
+            DateTime result = dt.SafeAddTicks(TimeSpan.TicksPerMillisecond);
+            Assert.Equal(DateTime.MaxValue, result);
+        }
+
+        [Fact]
+        public void GivenDateTimeMaxValue_WhenSafeAddTicksPositive_ThenClampsToMaxValue()
+        {
+            DateTime result = DateTime.MaxValue.SafeAddTicks(1);
+            Assert.Equal(DateTime.MaxValue, result);
+        }
+
+        [Fact]
+        public void GivenDateTimeNearMinValue_WhenSafeAddTicksNegative_ThenClampsToMinValue()
+        {
+            var dt = DateTime.MinValue.AddTicks(100);
+            DateTime result = dt.SafeAddTicks(-TimeSpan.TicksPerMillisecond);
+            Assert.Equal(DateTime.MinValue, result);
+        }
+
+        [Fact]
+        public void GivenDateTimeMinValue_WhenSafeAddTicksNegative_ThenClampsToMinValue()
+        {
+            DateTime result = DateTime.MinValue.SafeAddTicks(-1);
+            Assert.Equal(DateTime.MinValue, result);
+        }
+
+        [Fact]
+        public void GivenDateTime_WhenSafeAddTicksZero_ThenReturnsOriginal()
+        {
+            var dt = new DateTime(2024, 1, 1, 0, 0, 0, DateTimeKind.Utc);
+            DateTime result = dt.SafeAddTicks(0);
+            Assert.Equal(dt, result);
+        }
+
+        [Fact]
+        public void GivenAnyDateTime_WhenSafeAddTicksLongMinValue_ThenClampsToMinValue()
+        {
+            var dt = new DateTime(2024, 1, 1, 0, 0, 0, DateTimeKind.Utc);
+            DateTime result = dt.SafeAddTicks(long.MinValue);
+            Assert.Equal(DateTime.MinValue, result);
+        }
+
+        // SafeAddTicks - DateTimeOffset
+
+        [Fact]
+        public void GivenNormalDateTimeOffset_WhenSafeAddTicksCalled_ThenReturnsExpectedResult()
+        {
+            var dto = new DateTimeOffset(2024, 6, 15, 12, 0, 0, TimeSpan.Zero);
+            DateTimeOffset result = dto.SafeAddTicks(TimeSpan.TicksPerMillisecond);
+            Assert.Equal(dto.AddTicks(TimeSpan.TicksPerMillisecond), result);
+        }
+
+        [Fact]
+        public void GivenDateTimeOffsetNearMaxValue_WhenSafeAddTicksPositive_ThenClampsToMaxValue()
+        {
+            var dto = DateTimeOffset.MaxValue.AddTicks(-100);
+            DateTimeOffset result = dto.SafeAddTicks(TimeSpan.TicksPerMillisecond);
+            Assert.Equal(DateTimeOffset.MaxValue, result);
+        }
+
+        [Fact]
+        public void GivenDateTimeOffsetNearMinValue_WhenSafeAddTicksNegative_ThenClampsToMinValue()
+        {
+            var dto = DateTimeOffset.MinValue.AddTicks(100);
+            DateTimeOffset result = dto.SafeAddTicks(-TimeSpan.TicksPerMillisecond);
+            Assert.Equal(DateTimeOffset.MinValue, result);
+        }
+
+        // SafeAddDays - DateTime
+
+        [Fact]
+        public void GivenNormalDateTime_WhenSafeAddDaysCalled_ThenReturnsExpectedResult()
+        {
+            var dt = new DateTime(2024, 6, 15, 0, 0, 0, DateTimeKind.Utc);
+            DateTime result = dt.SafeAddDays(1);
+            Assert.Equal(dt.AddDays(1), result);
+        }
+
+        [Fact]
+        public void GivenDateTimeNearMaxValue_WhenSafeAddDaysPositive_ThenClampsToMaxValue()
+        {
+            var dt = DateTime.MaxValue.AddDays(-0.5);
+            DateTime result = dt.SafeAddDays(1);
+            Assert.Equal(DateTime.MaxValue, result);
+        }
+
+        [Fact]
+        public void GivenDateTimeNearMinValue_WhenSafeAddDaysNegative_ThenClampsToMinValue()
+        {
+            var dt = DateTime.MinValue.AddDays(0.5);
+            DateTime result = dt.SafeAddDays(-1);
+            Assert.Equal(DateTime.MinValue, result);
+        }
+
+        // SafeAddDays - DateTimeOffset
+
+        [Fact]
+        public void GivenNormalDateTimeOffset_WhenSafeAddDaysCalled_ThenReturnsExpectedResult()
+        {
+            var dto = new DateTimeOffset(2024, 6, 15, 0, 0, 0, TimeSpan.Zero);
+            DateTimeOffset result = dto.SafeAddDays(1);
+            Assert.Equal(dto.AddDays(1), result);
+        }
+
+        [Fact]
+        public void GivenDateTimeOffsetNearMaxValue_WhenSafeAddDaysPositive_ThenClampsToMaxValue()
+        {
+            var dto = DateTimeOffset.MaxValue.AddDays(-0.5);
+            DateTimeOffset result = dto.SafeAddDays(1);
+            Assert.Equal(DateTimeOffset.MaxValue, result);
+        }
+
+        [Fact]
+        public void GivenDateTimeOffsetNearMinValue_WhenSafeAddDaysNegative_ThenClampsToMinValue()
+        {
+            var dto = DateTimeOffset.MinValue.AddDays(0.5);
+            DateTimeOffset result = dto.SafeAddDays(-1);
+            Assert.Equal(DateTimeOffset.MinValue, result);
+        }
+    }
+}

src/Microsoft.Health.Fhir.Core/Extensions/DateTimeSafeExtensions.cs

@@ -0,0 +1,87 @@
+// -------------------------------------------------------------------------------------------------
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License (MIT). See LICENSE in the repo root for license information.
+// -------------------------------------------------------------------------------------------------
+
+using System;
+
+namespace Microsoft.Health.Fhir.Core.Extensions
+{
+    /// <summary>
+    /// Extension methods for <see cref="DateTime"/> and <see cref="DateTimeOffset"/> that clamp
+    /// results to <see cref="DateTime.MinValue"/>/<see cref="DateTime.MaxValue"/> instead of
+    /// throwing on overflow.
+    /// </summary>
+    public static class DateTimeSafeExtensions
+    {
+        /// <summary>
+        /// Adds the specified number of ticks to a <see cref="DateTime"/>, clamping the result
+        /// to <see cref="DateTime.MinValue"/> or <see cref="DateTime.MaxValue"/> on overflow.
+        /// </summary>
+        public static DateTime SafeAddTicks(this DateTime value, long ticks)
+        {
+            if (ticks == long.MinValue)
+            {
+                // Can't negate long.MinValue; adding it always underflows within DateTime's range.
+                return DateTime.MinValue;
+            }
+
+            if (ticks > 0 && value.Ticks > DateTime.MaxValue.Ticks - ticks)
+            {
+                return DateTime.MaxValue;
+            }
+
+            if (ticks < 0 && value.Ticks < DateTime.MinValue.Ticks - ticks)
+            {
+                return DateTime.MinValue;
+            }
+
+            return value.AddTicks(ticks);
+        }
+
+        /// <summary>
+        /// Adds the specified number of ticks to a <see cref="DateTimeOffset"/>, clamping the result
+        /// to <see cref="DateTimeOffset.MinValue"/> or <see cref="DateTimeOffset.MaxValue"/> on overflow.
+        /// </summary>
+        public static DateTimeOffset SafeAddTicks(this DateTimeOffset value, long ticks)
+        {
+            if (ticks == long.MinValue)
+            {
+                // Can't negate long.MinValue; adding it always underflows within DateTimeOffset's range.
+                return DateTimeOffset.MinValue;
+            }
+
+            if (ticks > 0 && value.Ticks > DateTimeOffset.MaxValue.Ticks - ticks)
+            {
+                return DateTimeOffset.MaxValue;
+            }
+
+            if (ticks < 0 && value.Ticks < DateTimeOffset.MinValue.Ticks - ticks)
+            {
+                return DateTimeOffset.MinValue;
+            }
+
+            return value.AddTicks(ticks);
+        }
+
+        /// <summary>
+        /// Adds the specified number of days to a <see cref="DateTime"/>, clamping the result
+        /// to <see cref="DateTime.MinValue"/> or <see cref="DateTime.MaxValue"/> on overflow.
+        /// </summary>
+        public static DateTime SafeAddDays(this DateTime value, int days)
+        {
+            long ticks = days * TimeSpan.TicksPerDay;
+            return value.SafeAddTicks(ticks);
+        }
+
+        /// <summary>
+        /// Adds the specified number of days to a <see cref="DateTimeOffset"/>, clamping the result
+        /// to <see cref="DateTimeOffset.MinValue"/> or <see cref="DateTimeOffset.MaxValue"/> on overflow.
+        /// </summary>
+        public static DateTimeOffset SafeAddDays(this DateTimeOffset value, int days)
+        {
+            long ticks = days * TimeSpan.TicksPerDay;
+            return value.SafeAddTicks(ticks);
+        }
+    }
+}

src/Microsoft.Health.Fhir.Core/Features/Search/Expressions/Parsers/SearchValueExpressionBuilderHelper.cs

@@ -102,8 +102,8 @@ void ISearchValueVisitor.Visit(DateTimeSearchValue dateTime)
 
                     var differenceTicks = (long)((Clock.UtcNow.Ticks - Math.Max(startTicks, endTicks)) * ApproximateMultiplier);
 
-                    var approximateStart = dateTime.Start.AddTicks(-differenceTicks);
-                    var approximateEnd = dateTime.End.AddTicks(differenceTicks);
+                    var approximateStart = dateTime.Start.SafeAddTicks(-differenceTicks);
+                    var approximateEnd = dateTime.End.SafeAddTicks(differenceTicks);
 
                     // Spec (ap): the search range overlaps the target range. Emit overlap directly
                     // (Start <= approxEnd AND End >= approxStart) rather than the eq-shaped containment.

src/Microsoft.Health.Fhir.SqlServer/Features/Search/Expressions/Visitors/DateTimeBoundedRangeRewriter.cs

@@ -4,6 +4,7 @@
 // -------------------------------------------------------------------------------------------------
 
 using System;
+using Microsoft.Health.Fhir.Core.Extensions;
 using Microsoft.Health.Fhir.Core.Features.Search.Expressions;
 using Microsoft.Health.Fhir.ValueSets;
 
@@ -41,7 +42,7 @@ expression.Expressions[0] is BinaryExpression isLong &&
                 return Expression.And(
                     Expression.Equals(SqlFieldName.DateTimeIsLongerThanADay, left.ComponentIndex, false),
                     new BinaryExpression(left.BinaryOperator, FieldName.DateTimeEnd, left.ComponentIndex, left.Value),
-                    new BinaryExpression(left.BinaryOperator, FieldName.DateTimeStart, left.ComponentIndex, ((DateTimeOffset)left.Value).AddTicks(-TimeSpan.TicksPerDay)),
+                    new BinaryExpression(left.BinaryOperator, FieldName.DateTimeStart, left.ComponentIndex, ((DateTimeOffset)left.Value).SafeAddTicks(-TimeSpan.TicksPerDay)),
                     new BinaryExpression(right.BinaryOperator, FieldName.DateTimeStart, right.ComponentIndex, right.Value));
             }
 

src/Microsoft.Health.Fhir.SqlServer/Features/Search/Expressions/Visitors/LastUpdatedToResourceSurrogateIdRewriter.cs

@@ -5,6 +5,7 @@
 
 using System;
 using Microsoft.Health.Core.Extensions;
+using Microsoft.Health.Fhir.Core.Extensions;
 using Microsoft.Health.Fhir.Core.Features.Search;
 using Microsoft.Health.Fhir.Core.Features.Search.Expressions;
 using Microsoft.Health.Fhir.SqlServer.Features.Storage;
@@ -56,7 +57,7 @@ public override Expression VisitBinary(BinaryExpression expression, object conte
                     return Expression.GreaterThanOrEqual(
                         SqlFieldName.ResourceSurrogateId,
                         null,
-                        new DateTimeOffset(truncated.AddTicks(TimeSpan.TicksPerMillisecond)).ToSurrogateId());
+                        new DateTimeOffset(truncated.SafeAddTicks(TimeSpan.TicksPerMillisecond)).ToSurrogateId());
                 case BinaryOperator.GreaterThanOrEqual:
                     if (original == truncated)
                     {
@@ -81,7 +82,7 @@ public override Expression VisitBinary(BinaryExpression expression, object conte
                     return Expression.LessThan(
                         SqlFieldName.ResourceSurrogateId,
                         null,
-                        new DateTimeOffset(truncated.AddTicks(TimeSpan.TicksPerMillisecond)).ToSurrogateId());
+                        new DateTimeOffset(truncated.SafeAddTicks(TimeSpan.TicksPerMillisecond)).ToSurrogateId());
                 case BinaryOperator.NotEqual:
                 case BinaryOperator.Equal: // expecting eq to have been rewritten as a range
                 default:

src/Microsoft.Health.Fhir.SqlServer/Features/Search/Expressions/Visitors/ScalarTemporalEqualityRewriter.cs

@@ -5,6 +5,7 @@
 
 using System;
 using System.Collections.Generic;
+using Microsoft.Health.Fhir.Core.Extensions;
 using Microsoft.Health.Fhir.Core.Features.Search.Expressions;
 using Microsoft.Health.Fhir.Core.Models;
 using Microsoft.Health.Fhir.SqlServer.Features.Search.Expressions;
@@ -133,7 +134,7 @@ private static Precision ClassifyPrecision(DateTimeOffset start, DateTimeOffset
                 return Precision.NotRewritable;
             }
 
-            if (end == start.AddDays(1).AddTicks(-1))
+            if (end == start.SafeAddTicks(TimeSpan.TicksPerDay - 1))
             {
                 return Precision.ExactDay;
             }