From 3d9d59f9a9775de684060dd048ac09045e0bfcc3 Mon Sep 17 00:00:00 2001
From: Kevin Bost <kitokeboo@gmail.com>
Date: Thu, 2 Oct 2025 21:24:01 -0700
Subject: [PATCH] Automatically detecting runtime when not specified.

---
 .../Commands/WindowsPackCommandRunner.cs      |  1 +
 .../Msi/MsiBuilder.cs                         | 24 ++++++++++++++++---
 2 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/src/vpk/Velopack.Packaging.Windows/Commands/WindowsPackCommandRunner.cs b/src/vpk/Velopack.Packaging.Windows/Commands/WindowsPackCommandRunner.cs
index a96598f6..59891707 100644
--- a/src/vpk/Velopack.Packaging.Windows/Commands/WindowsPackCommandRunner.cs
+++ b/src/vpk/Velopack.Packaging.Windows/Commands/WindowsPackCommandRunner.cs
@@ -339,6 +339,7 @@ public class WindowsPackCommandRunner : PackageBuilder<WindowsPackOptions>
     private void CompileWixTemplateToMsi(Action<int> progress, DirectoryInfo portableDirectory, string msiFilePath)
     {
         var templateData = MsiBuilder.ConvertOptionsToTemplateData(
+            MainExePath,
             portableDirectory,
             GetShortcuts(),
             GetRuntimeDependencies(),
diff --git a/src/vpk/Velopack.Packaging.Windows/Msi/MsiBuilder.cs b/src/vpk/Velopack.Packaging.Windows/Msi/MsiBuilder.cs
index d1b297fe..b8403b79 100644
--- a/src/vpk/Velopack.Packaging.Windows/Msi/MsiBuilder.cs
+++ b/src/vpk/Velopack.Packaging.Windows/Msi/MsiBuilder.cs
@@ -4,6 +4,7 @@ using System.Runtime.Versioning;
 using System.Text;
 using System.Text.RegularExpressions;
 using System.Xml;
+using AsmResolver.PE;
 using HandlebarsDotNet;
 using Markdig;
 using Microsoft.Extensions.Logging;
@@ -105,7 +106,7 @@ public static class MsiBuilder
         return rv;
     }
 
-    public static MsiTemplateData ConvertOptionsToTemplateData(DirectoryInfo portableDir, ShortcutLocation shortcuts,
+    public static MsiTemplateData ConvertOptionsToTemplateData(string mainExePath, DirectoryInfo portableDir, ShortcutLocation shortcuts,
         string runtimeDeps, WindowsPackOptions options)
     {
         // WiX Identifiers may contain ASCII characters A-Z, a-z, digits, underscores (_), or
@@ -120,6 +121,12 @@ public static class MsiBuilder
             msiVersion = $"{parsedVersion.Major}.{parsedVersion.Minor}.{parsedVersion.Patch}.0";
         }
 
+        RuntimeCpu runtimeCpu = options.TargetRuntime.Architecture;
+        if (runtimeCpu == RuntimeCpu.Unknown) {
+            runtimeCpu = GetMachineForBinary(mainExePath);
+            options.TargetRuntime.Architecture = runtimeCpu;
+        }
+
         return new MsiTemplateData() {
             WixId = wixId,
             AppId = options.PackId,
@@ -128,8 +135,8 @@ public static class MsiBuilder
             AppMsiVersion = msiVersion,
             AppVersion = parsedVersion.ToFullString(),
             SourceDirectoryPath = portableDir.FullName,
-            Is64Bit = options.TargetRuntime.Architecture is not RuntimeCpu.x86 and not RuntimeCpu.Unknown,
-            IsArm64 = options.TargetRuntime.Architecture is RuntimeCpu.arm64,
+            Is64Bit = runtimeCpu is RuntimeCpu.x64,
+            IsArm64 = runtimeCpu is RuntimeCpu.arm64,
             InstallForAllUsers = options.InstLocation.HasFlag(InstallLocation.PerMachine),
             InstallForCurrentUser = options.InstLocation.HasFlag(InstallLocation.PerUser),
             UpgradeCodeGuid = GuidUtil.CreateGuidFromHash($"{options.PackId}:UpgradeCode").ToString(),
@@ -148,6 +155,17 @@ public static class MsiBuilder
             WelcomeMessage = GetPlainTextMessage(options.InstWelcome),
             LicenseRtfFilePath = GetLicenseRtfPath(options.InstLicense, portableDir.Parent),
         };
+
+        static RuntimeCpu GetMachineForBinary(string path)
+        {
+            var image = PEImage.FromFile(path);
+            
+            if (image.MachineType.HasFlag(AsmResolver.PE.File.Headers.MachineType.Amd64))
+                return RuntimeCpu.x64;
+            if (image.MachineType.HasFlag(AsmResolver.PE.File.Headers.MachineType.Arm64))
+                return RuntimeCpu.arm64;
+            return RuntimeCpu.x86;
+        }
     }
 
     [SupportedOSPlatform("windows")]