Fix EventLog test CanReadAndWriteMessages (#89586)

* Fix EventLog bug discovered by the CanReadAndWriteMessages test where we were not trimming the null characters from the strings received from the P/Invokes.

Author: carlossanlop

src/libraries/System.Diagnostics.EventLog/src/System/Diagnostics/Reader/NativeWrapper.cs

@@ -967,7 +967,13 @@ public static string EvtFormatMessageRenderName(EventLogHandle pmHandle, EventLo
                 EventLogException.Throw(error);
             }
 
-            int len = bufferNeeded - 1; // buffer includes null terminator
+
+            // buffer may include null terminators
+            int len = bufferNeeded;
+            while (len > 0 && buffer[len - 1] == '\0')
+            {
+                len--;
+            }
             if (len <= 0)
                 return string.Empty;
 

src/libraries/System.Diagnostics.EventLog/tests/EventLogMessagesTests.cs

@@ -4,7 +4,6 @@
 using System.Diagnostics.Eventing.Reader;
 using System.IO;
 using System.Reflection;
-using System.Runtime.InteropServices;
 using Microsoft.Win32.SafeHandles;
 using Xunit;
 
@@ -50,10 +49,7 @@ public unsafe void CanFormatMessage(uint messageId)
             }
         }
 
-        public static bool HasAssemblyFilesIsElevatedAndSupportsEventLogs => PlatformDetection.HasAssemblyFiles && Helpers.IsElevatedAndSupportsEventLogs;
-
-        [ConditionalFact(nameof(HasAssemblyFilesIsElevatedAndSupportsEventLogs))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/88224", typeof(PlatformDetection), nameof(PlatformDetection.IsWindows10Version22000OrGreater))]
+        [ConditionalFact(typeof(Helpers), nameof(Helpers.HasAssemblyFilesIsElevatedAndSupportsEventLogs))]
         public void CanReadAndWriteMessages()
         {
             string messageDllPath = Path.Combine(Path.GetDirectoryName(typeof(EventLog).Assembly.Location), "System.Diagnostics.EventLog.Messages.dll");

src/libraries/System.Diagnostics.EventLog/tests/Helpers.cs

@@ -1,7 +1,6 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
-using System.ComponentModel;
 using System.Diagnostics.Eventing.Reader;
 using System.Threading;
 using Xunit;
@@ -13,6 +12,7 @@ namespace System.Diagnostics.Tests
 {
     internal class Helpers
     {
+        public static bool HasAssemblyFilesIsElevatedAndSupportsEventLogs => PlatformDetection.HasAssemblyFiles && IsElevatedAndSupportsEventLogs;
         public static bool NotElevatedAndSupportsEventLogs { get => !AdminHelpers.IsProcessElevated() && SupportsEventLogs; }
         public static bool IsElevatedAndSupportsEventLogs { get => AdminHelpers.IsProcessElevated() && SupportsEventLogs; }
         public static bool SupportsEventLogs { get => PlatformDetection.IsNotWindowsNanoNorServerCore && PlatformDetection.IsNotWindowsIoTCore; }

src/libraries/System.Diagnostics.EventLog/tests/System.Diagnostics.EventLog.Tests.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <TargetFrameworks>$(NetCoreAppCurrent)-windows;$(NetFrameworkMinimum)</TargetFrameworks>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>