Resolve Windows shortcuts (.lnk) to their target file when opening

src/LogExpert.UI.Tests/Services/FileOperationServiceTests.cs

@@ -205,7 +205,7 @@ public void AddFileTab_RaisesFileOpenedEvent ()
         // Assert
         Assert.That(receivedArgs, Is.Not.Null);
         Assert.That(receivedArgs!.LogWindow, Is.SameAs(_stubLogWindow));
-        Assert.That(receivedArgs.Request, Is.SameAs(request));
+        Assert.That(receivedArgs.Request, Is.EqualTo(request));
         Assert.That(receivedArgs.ResolvedFileName, Is.Not.Null.And.Not.Empty);
         Assert.That(receivedArgs.EncodingOptions, Is.Not.Null);
     }
@@ -657,6 +657,71 @@ public void LoadFilesWithOption_SingleFile_CallsAddFileTab ()
         Assert.That(_factoryCalls[0].Request.FileName, Is.EqualTo("test.log"));
     }
 
+    [Test]
+    public void LoadFilesWithOption_ShortcutToLxjFile_CallsProjectCallback ()
+    {
+        // The .lxj check has to run on the resolved name, or the shortcut gets opened as a raw log.
+        var (directory, shortcut, session) = CreateShortcutToSession();
+
+        try
+        {
+            var decision = _sut.LoadFilesWithOption(new[] { shortcut }, false);
+
+            Assert.That(decision, Is.EqualTo(MultiFileDecision.Cancel));
+            Assert.That(_projectCallbackCalls, Has.Count.EqualTo(1));
+            Assert.That(_projectCallbackCalls[0].FileName, Is.EqualTo(session));
+            Assert.That(_factoryCalls, Is.Empty, "Should not open the shortcut as a log");
+        }
+        finally
+        {
+            Directory.Delete(directory, true);
+        }
+    }
+
+    [Test]
+    public void AddFileTabs_ShortcutToLxjFile_CallsProjectCallback ()
+    {
+        var (directory, shortcut, session) = CreateShortcutToSession();
+
+        try
+        {
+            _sut.AddFileTabs(new[] { shortcut });
+
+            Assert.That(_projectCallbackCalls, Has.Count.EqualTo(1));
+            Assert.That(_projectCallbackCalls[0].FileName, Is.EqualTo(session));
+            Assert.That(_factoryCalls, Is.Empty, "Should not open the shortcut as a log");
+        }
+        finally
+        {
+            Directory.Delete(directory, true);
+        }
+    }
+
+    [Test]
+    public void AddFileTab_ShortcutToLogFile_OpensTarget ()
+    {
+        var directory = Path.Join(Path.GetTempPath(), "LogExpertTests", "ShortcutLog", Guid.NewGuid().ToString());
+        _ = Directory.CreateDirectory(directory);
+
+        try
+        {
+            var log = Path.Join(directory, "actual.log");
+            File.WriteAllText(log, "line1");
+
+            var shortcut = Path.Join(directory, "actual.lnk");
+            TestShortcuts.Create(shortcut, log);
+
+            _sut.AddFileTab(new FileTabRequest { FileName = shortcut });
+
+            Assert.That(_factoryCalls, Has.Count.EqualTo(1));
+            Assert.That(_factoryCalls[0].Request.FileName, Is.EqualTo(log), "the target file is opened, not the shortcut");
+        }
+        finally
+        {
+            Directory.Delete(directory, true);
+        }
+    }
+
     [Test]
     public void LoadFilesWithOption_SingleLxjFile_CallsProjectCallback ()
     {
@@ -1225,6 +1290,24 @@ public void LoadFiles_DelegatesToAddFileTabs ()
         Assert.That(_factoryCalls[1].Request.FileName, Is.EqualTo("b.log"));
     }
 
+    /// <summary>
+    /// Creates a temporary directory holding a session file and a shortcut to it, and returns the
+    /// three paths. The caller owns the directory and deletes it.
+    /// </summary>
+    private static (string Directory, string Shortcut, string Session) CreateShortcutToSession ()
+    {
+        var directory = Path.Join(Path.GetTempPath(), "LogExpertTests", "ShortcutSession", Guid.NewGuid().ToString());
+        _ = Directory.CreateDirectory(directory);
+
+        var session = Path.Join(directory, "project.lxj");
+        File.WriteAllText(session, "<Project></Project>");
+
+        var shortcut = Path.Join(directory, "session.lnk");
+        TestShortcuts.Create(shortcut, session);
+
+        return (directory, shortcut, session);
+    }
+
     /// <summary>
     /// Builds a second service on the shared config manager, standing in for another LogTabWindow
     /// of the same session with its own tab controller.

src/LogExpert.UI.Tests/Services/ShortcutResolverTests.cs

@@ -0,0 +1,178 @@
+using System.Runtime.Versioning;
+
+using LogExpert.UI.Services.FileOperationService;
+
+using NUnit.Framework;
+
+namespace LogExpert.UI.Tests.Services;
+
+[TestFixture]
+[SupportedOSPlatform("windows")]
+internal class ShortcutResolverTests
+{
+    [Test]
+    public void Resolve_ShortcutToLocalTarget_ReturnsTarget ()
+    {
+        var directory = CreateTempDirectory("ShortcutLocal");
+
+        try
+        {
+            var log = Path.Join(directory, "actual.log");
+            File.WriteAllText(log, "line1");
+
+            var shortcut = Path.Join(directory, "actual.lnk");
+            TestShortcuts.Create(shortcut, log);
+
+            Assert.That(ShortcutResolver.Resolve(shortcut), Is.EqualTo(log));
+        }
+        finally
+        {
+            Directory.Delete(directory, true);
+        }
+    }
+
+    [Test]
+    public void Resolve_ShortcutToUncTarget_ReturnsShortcutUnchanged ()
+    {
+        var directory = CreateTempDirectory("ShortcutUnc");
+
+        try
+        {
+            var shortcut = Path.Join(directory, "remote.lnk");
+            TestShortcuts.Create(shortcut, @"\\nonexistent-host\share\actual.log");
+
+            Assert.That(ShortcutResolver.Resolve(shortcut), Is.EqualTo(shortcut),
+                "a UNC target must not be probed: File.Exists would authenticate against the remote host");
+        }
+        finally
+        {
+            Directory.Delete(directory, true);
+        }
+    }
+
+    [Test]
+    public void Resolve_OversizedShortcutFile_ReturnsPathUnchanged ()
+    {
+        var directory = CreateTempDirectory("ShortcutOversized");
+
+        try
+        {
+            var shortcut = Path.Join(directory, "oversized.lnk");
+            File.WriteAllBytes(shortcut, new byte[ShortcutResolver.MAX_SHORTCUT_SIZE + 1]);
+
+            Assert.That(ShortcutResolver.Resolve(shortcut), Is.EqualTo(shortcut));
+        }
+        finally
+        {
+            Directory.Delete(directory, true);
+        }
+    }
+
+    // The shell resolves .lnk targets when saving, so a real chain cannot be produced with
+    // WScript.Shell; the follower is exercised with injected hops instead.
+    [Test]
+    public void FollowChain_ShortcutToShortcut_ReturnsFinalTarget ()
+    {
+        var targets = new Dictionary<string, string>
+        {
+            [@"C:\logs\first.lnk"] = @"C:\logs\second.lnk",
+            [@"C:\logs\second.lnk"] = @"C:\logs\actual.log"
+        };
+
+        Assert.That(ShortcutResolver.FollowChain(@"C:\logs\first.lnk", path => targets.GetValueOrDefault(path)),
+            Is.EqualTo(@"C:\logs\actual.log"));
+    }
+
+    [Test]
+    public void FollowChain_ChainAtLimit_ReturnsFinalTarget ()
+    {
+        var targets = CreateChain(ShortcutResolver.MAX_SHORTCUT_HOPS);
+
+        Assert.That(ShortcutResolver.FollowChain(@"C:\logs\link1.lnk", path => targets.GetValueOrDefault(path)),
+            Is.EqualTo(@"C:\logs\actual.log"));
+    }
+
+    [Test]
+    public void FollowChain_ChainBeyondLimit_StopsAfterMaxHops ()
+    {
+        var targets = CreateChain(ShortcutResolver.MAX_SHORTCUT_HOPS + 1);
+
+        Assert.That(ShortcutResolver.FollowChain(@"C:\logs\link1.lnk", path => targets.GetValueOrDefault(path)),
+            Is.EqualTo(@"C:\logs\link1.lnk"));
+    }
+
+    [Test]
+    public void FollowChain_CyclicChain_StopsAfterMaxHops ()
+    {
+        var targets = new Dictionary<string, string>
+        {
+            [@"C:\logs\first.lnk"] = @"C:\logs\second.lnk",
+            [@"C:\logs\second.lnk"] = @"C:\logs\first.lnk"
+        };
+
+        Assert.That(ShortcutResolver.FollowChain(@"C:\logs\first.lnk", path => targets.GetValueOrDefault(path)),
+            Is.EqualTo(@"C:\logs\first.lnk"));
+    }
+
+    [TestCase("//nonexistent-host/share/actual.log")]
+    [TestCase(@"\\?\UNC\nonexistent-host\share\actual.log")]
+    [TestCase(@"\\?\C:\Windows\system32\drivers\etc\hosts")]
+    [TestCase(@"\\.\C:\nonexistent\actual.log")]
+    [TestCase(@"\??\UNC\nonexistent-host\share\actual.log")]
+    public void SanitizeLocalTarget_DisguisedNonLocalTarget_IsRejected (string target)
+    {
+        Assert.That(ShortcutResolver.SanitizeLocalTarget(target, @"C:\logs"), Is.Null,
+            $"'{target}' must not be followed: probing it could reach the network");
+    }
+
+    [Test]
+    public void SanitizeLocalTarget_PlainLocalTarget_ReturnsFullPath ()
+    {
+        Assert.That(ShortcutResolver.SanitizeLocalTarget(@"C:\logs\actual.log", @"D:\other"),
+            Is.EqualTo(@"C:\logs\actual.log"));
+    }
+
+    [Test]
+    public void SanitizeLocalTarget_RelativeTarget_ResolvesAgainstShortcutDirectory ()
+    {
+        Assert.That(ShortcutResolver.SanitizeLocalTarget(@"sub\actual.log", @"C:\logs"),
+            Is.EqualTo(@"C:\logs\sub\actual.log"));
+    }
+
+    [Test]
+    public void SanitizeLocalTarget_EnvironmentVariableTarget_IsExpanded ()
+    {
+        Environment.SetEnvironmentVariable("LOGEXPERT_TEST_VAR", @"C:\logs", EnvironmentVariableTarget.Process);
+
+        try
+        {
+            Assert.That(ShortcutResolver.SanitizeLocalTarget(@"%LOGEXPERT_TEST_VAR%\actual.log", @"D:\other"),
+                Is.EqualTo(@"C:\logs\actual.log"));
+        }
+        finally
+        {
+            Environment.SetEnvironmentVariable("LOGEXPERT_TEST_VAR", null, EnvironmentVariableTarget.Process);
+        }
+    }
+
+    private static Dictionary<string, string> CreateChain (int linkCount)
+    {
+        var targets = new Dictionary<string, string>();
+
+        for (var i = 1; i <= linkCount; i++)
+        {
+            targets[$@"C:\logs\link{i}.lnk"] = i == linkCount
+                ? @"C:\logs\actual.log"
+                : $@"C:\logs\link{i + 1}.lnk";
+        }
+
+        return targets;
+    }
+
+    private static string CreateTempDirectory (string name)
+    {
+        var directory = Path.Join(Path.GetTempPath(), "LogExpertTests", name, Guid.NewGuid().ToString());
+        _ = Directory.CreateDirectory(directory);
+        return directory;
+    }
+}

src/LogExpert.UI.Tests/Services/TestShortcuts.cs

@@ -0,0 +1,35 @@
+using System.Runtime.InteropServices;
+using System.Runtime.Versioning;
+
+using NUnit.Framework;
+
+namespace LogExpert.UI.Tests.Services;
+
+[SupportedOSPlatform("windows")]
+internal static class TestShortcuts
+{
+    public static void Create (string shortcutPath, string targetPath)
+    {
+        var shellType = Type.GetTypeFromProgID("WScript.Shell");
+        Assert.That(shellType, Is.Not.Null, "WScript.Shell should be available on Windows test machines");
+
+        dynamic shell = Activator.CreateInstance(shellType)!;
+        object? shortcut = null;
+        try
+        {
+            dynamic link = shell.CreateShortcut(shortcutPath);
+            shortcut = link;
+            link.TargetPath = targetPath;
+            link.Save();
+        }
+        finally
+        {
+            if (shortcut != null)
+            {
+                Marshal.FinalReleaseComObject(shortcut);
+            }
+
+            Marshal.FinalReleaseComObject(shell);
+        }
+    }
+}