fix(agent-installer): refuse an untrusted agent data folder

package/AgentWindowsManaged.Tests/AgentIdentityTests.cs

@@ -17,8 +17,11 @@
 using Property = WixSharp.Property;
 using Record = Microsoft.Deployment.WindowsInstaller.Record;
 
+using static DevolutionsAgent.Installer.Tests.InstallerSession;
+
 namespace DevolutionsAgent.Installer.Tests;
 
+[Collection(InstallerSession.Collection)]
 public sealed class AgentIdentityTests
 {
     // A well-formed token (crates/agent-identity/src/token.rs) whose bag names https://example.test/dvls.
@@ -410,12 +413,6 @@ string ErrorIn(string productLanguage)
         Assert.Equal(english, ErrorIn("1031"));
     }
 
-    /// <summary>
-    /// The installer's action that runs the custom action <paramref name="methodName"/>.
-    /// </summary>
-    private static ManagedAction ActionOf(string methodName) =>
-        Assert.Single(AgentActions.Actions.OfType<ManagedAction>(), a => a.MethodName == methodName);
-
     /// <summary>
     /// Runs the custom action that reads the enrollment token file, in a session of a package in
     /// <paramref name="folder"/> where <paramref name="properties"/> (<c>NAME=value</c>) are set.
@@ -454,62 +451,4 @@ private static (ActionResult Result, string Token, List<(InstallMessage Type, st
             MsiInstaller.SetExternalUI(previous, InstallLogModes.None);
         }
     }
-
-    /// <summary>
-    /// Evaluates <paramref name="condition"/> with the Windows Installer engine, in a session where
-    /// <paramref name="properties"/> (<c>NAME=value</c>) are set.
-    /// </summary>
-    private static bool EvaluateCondition(string condition, string[] properties) =>
-        WithSession(properties, session => session.EvaluateCondition(condition));
-
-    private static T WithSession<T>(string[] properties, Func<Session, T> action) =>
-        WithSession(AppContext.BaseDirectory, properties, action);
-
-    /// <summary>
-    /// Runs <paramref name="action"/> in a Windows Installer session of an empty package in <paramref name="folder"/>
-    /// where <paramref name="properties"/> (<c>NAME=value</c>) are set.
-    /// </summary>
-    private static T WithSession<T>(string folder, string[] properties, Func<Session, T> action)
-    {
-        string path = Path.Combine(folder, $"session-{Guid.NewGuid():N}.msi");
-
-        try
-        {
-            using (Database database = new(path, DatabaseOpenMode.CreateDirect))
-            {
-                database.Execute("CREATE TABLE `Property` (`Property` CHAR(72) NOT NULL, `Value` CHAR(0) NOT NULL LOCALIZABLE PRIMARY KEY `Property`)");
-                database.Execute($"INSERT INTO `Property` (`Property`, `Value`) VALUES ('ProductCode', '{Guid.NewGuid():B}')");
-                database.SummaryInfo.Template = "x64;1033";
-                database.SummaryInfo.RevisionNumber = Guid.NewGuid().ToString("B");
-                database.SummaryInfo.PageCount = 500;
-                database.Commit();
-            }
-
-            using Session session = MsiInstaller.OpenPackage(path, ignoreMachineState: true);
-
-            foreach (string property in properties)
-            {
-                string[] parts = property.Split(['='], 2);
-                session[parts[0]] = parts[1];
-            }
-
-            return action(session);
-        }
-        finally
-        {
-            System.IO.File.Delete(path);
-        }
-    }
-
-    /// <summary>
-    /// A new, empty folder under the temporary directory, deleted with its content on disposal.
-    /// </summary>
-    private sealed class TempFolder : IDisposable
-    {
-        public string Path { get; } = System.IO.Path.Combine(System.IO.Path.GetTempPath(), $"agent-identity-{Guid.NewGuid():N}");
-
-        public TempFolder() => Directory.CreateDirectory(Path);
-
-        public void Dispose() => Directory.Delete(Path, recursive: true);
-    }
 }

package/AgentWindowsManaged.Tests/InstallerSession.cs

@@ -0,0 +1,82 @@
+using System;
+using System.IO;
+using System.Linq;
+
+using DevolutionsAgent.Actions;
+
+using Microsoft.Deployment.WindowsInstaller;
+
+using WixSharp;
+
+using Xunit;
+
+using MsiInstaller = Microsoft.Deployment.WindowsInstaller.Installer;
+
+namespace DevolutionsAgent.Installer.Tests;
+
+/// <summary>
+/// The installer's actions, and Windows Installer sessions to evaluate them in.
+/// </summary>
+internal static class InstallerSession
+{
+    /// <summary>
+    /// The test collection of every test class that opens a session.
+    /// </summary>
+    /// <remarks>
+    /// Windows Installer opens one package at a time in a process, and xUnit runs the tests of one collection one at a
+    /// time.
+    /// </remarks>
+    public const string Collection = "Windows Installer session";
+
+    /// <summary>
+    /// The installer's action that runs the custom action <paramref name="methodName"/>.
+    /// </summary>
+    public static ManagedAction ActionOf(string methodName) =>
+        Assert.Single(AgentActions.Actions.OfType<ManagedAction>(), a => a.MethodName == methodName);
+
+    /// <summary>
+    /// Evaluates <paramref name="condition"/> with the Windows Installer engine, in a session where
+    /// <paramref name="properties"/> (<c>NAME=value</c>) are set.
+    /// </summary>
+    public static bool EvaluateCondition(string condition, string[] properties) =>
+        WithSession(properties, session => session.EvaluateCondition(condition));
+
+    public static T WithSession<T>(string[] properties, Func<Session, T> action) =>
+        WithSession(AppContext.BaseDirectory, properties, action);
+
+    /// <summary>
+    /// Runs <paramref name="action"/> in a Windows Installer session of an empty package in <paramref name="folder"/>
+    /// where <paramref name="properties"/> (<c>NAME=value</c>) are set.
+    /// </summary>
+    public static T WithSession<T>(string folder, string[] properties, Func<Session, T> action)
+    {
+        string path = Path.Combine(folder, $"session-{Guid.NewGuid():N}.msi");
+
+        try
+        {
+            using (Database database = new(path, DatabaseOpenMode.CreateDirect))
+            {
+                database.Execute("CREATE TABLE `Property` (`Property` CHAR(72) NOT NULL, `Value` CHAR(0) NOT NULL LOCALIZABLE PRIMARY KEY `Property`)");
+                database.Execute($"INSERT INTO `Property` (`Property`, `Value`) VALUES ('ProductCode', '{Guid.NewGuid():B}')");
+                database.SummaryInfo.Template = "x64;1033";
+                database.SummaryInfo.RevisionNumber = Guid.NewGuid().ToString("B");
+                database.SummaryInfo.PageCount = 500;
+                database.Commit();
+            }
+
+            using Session session = MsiInstaller.OpenPackage(path, ignoreMachineState: true);
+
+            foreach (string property in properties)
+            {
+                string[] parts = property.Split(['='], 2);
+                session[parts[0]] = parts[1];
+            }
+
+            return action(session);
+        }
+        finally
+        {
+            System.IO.File.Delete(path);
+        }
+    }
+}

package/AgentWindowsManaged.Tests/OutputLogger.cs

@@ -0,0 +1,15 @@
+using DevolutionsAgent.Actions;
+
+using Xunit.Abstractions;
+
+namespace DevolutionsAgent.Installer.Tests;
+
+/// <summary>
+/// Writes the log of the code under test to the test's output.
+/// </summary>
+internal sealed class OutputLogger(ITestOutputHelper output) : ILogger
+{
+    public void Log(string msg) => output.WriteLine(msg);
+
+    public void Log(string format, params object[] args) => output.WriteLine(format, args);
+}