From c503a31ff3294d02bb38e276fc306d2bacd4db78 Mon Sep 17 00:00:00 2001
From: Roni Nevalainen <kitten@kittenz.dev>
Date: Thu, 23 Jul 2020 22:00:23 +0300
Subject: [PATCH] Replaced string.Compare

Replaced string.Compare in Microsoft.Extensions.Primitives.StringSegment
string.Compare caused issues in StringSegment.EndsWith when the Buffer
is only one character long.

Fix #39140
---
 .../src/StringSegment.cs                      | 27 ++++++-------
 .../tests/StringSegmentTest.cs                | 39 +++++++++++++++++++
 2 files changed, 51 insertions(+), 15 deletions(-)

diff --git a/src/libraries/Microsoft.Extensions.Primitives/src/StringSegment.cs b/src/libraries/Microsoft.Extensions.Primitives/src/StringSegment.cs
index 288b0e773b3172..a5ca79b0b0e7e0 100644
--- a/src/libraries/Microsoft.Extensions.Primitives/src/StringSegment.cs
+++ b/src/libraries/Microsoft.Extensions.Primitives/src/StringSegment.cs
@@ -310,15 +310,14 @@ public bool StartsWith(string text, StringComparison comparisonType)
                 ThrowHelper.ThrowArgumentNullException(ExceptionArgument.text);
             }
 
-            bool result = false;
-            int textLength = text.Length;
-
-            if (HasValue && Length >= textLength)
+            if (HasValue)
             {
-                result = string.Compare(Buffer, Offset, text, 0, textLength, comparisonType) == 0;
+                return this.AsSpan().StartsWith(text.AsSpan(), comparisonType);
+            }
+            else
+            {
+                return false;
             }
-
-            return result;
         }
 
         /// <summary>
@@ -338,16 +337,14 @@ public bool EndsWith(string text, StringComparison comparisonType)
                 ThrowHelper.ThrowArgumentNullException(ExceptionArgument.text);
             }
 
-            bool result = false;
-            int textLength = text.Length;
-            int comparisonLength = Offset + Length - textLength;
-
-            if (HasValue && comparisonLength > 0)
+            if (HasValue)
             {
-                result = string.Compare(Buffer, comparisonLength, text, 0, textLength, comparisonType) == 0;
+                return this.AsSpan().EndsWith(text.AsSpan(), comparisonType);
+            }
+            else
+            {
+                return false;
             }
-
-            return result;
         }
 
         /// <summary>
diff --git a/src/libraries/Microsoft.Extensions.Primitives/tests/StringSegmentTest.cs b/src/libraries/Microsoft.Extensions.Primitives/tests/StringSegmentTest.cs
index 3c7c941c338a2a..667bc958210608 100644
--- a/src/libraries/Microsoft.Extensions.Primitives/tests/StringSegmentTest.cs
+++ b/src/libraries/Microsoft.Extensions.Primitives/tests/StringSegmentTest.cs
@@ -258,6 +258,19 @@ public void StringSegment_EndsWith_Valid(string candidate, StringComparison comp
             Assert.Equal(expectedResult, result);
         }
 
+        [Fact]
+        public void StringSegment_EndsWith_Slash()
+        {
+            // Arrange
+            var segment = new StringSegment("/");
+
+            // Act
+            var result = segment.EndsWith("/", StringComparison.Ordinal);
+
+            // Assert
+            Assert.True(result);
+        }
+
         [Fact]
         public void StringSegment_EndsWith_Invalid()
         {
@@ -586,6 +599,32 @@ public void StringSegment_Equals_StringSegment_Valid(StringSegment candidate, St
             Assert.Equal(expectedResult, result);
         }
 
+        [Fact]
+        public void StringSegment_Equals_InvariantCultureIgnoreCase()
+        {
+            // Arrange
+            var segment = new StringSegment("xaex", 1, 2);
+
+            // Act
+            var result = segment.Equals("\u00C6", StringComparison.InvariantCultureIgnoreCase);
+
+            // Assert
+            Assert.True(result);
+        }
+
+        [Fact]
+        public void StringSegment_Equals_InvariantCultureIgnoreCase_StringSegment()
+        {
+            // Arrange
+            var segment = new StringSegment("xaex", 1, 2);
+
+            // Act
+            var result = segment.Equals(new StringSegment("\u00C6"), StringComparison.InvariantCultureIgnoreCase);
+
+            // Assert
+            Assert.True(result);
+        }
+
         [Fact]
         public void StringSegment_EqualsStringSegment_Invalid()
         {