Single MSI to install correct 32 or 64 bit c# application

Question

I have a C# application which is built for both x86 (32 bit) and x64 (64 bit) platforms. My build system currently outputs two MSI installers, one for each platform. In case

Answer 1

You could work around the problem. Pack the 2 installers under third deployment project. Create a custom action that checks the running OS version, then make the installer call the right installer.

Something like this:

[RunInstaller(true)]
public partial class MyInstaller: Installer
{
    String installerPath;

    public MyInstaller()
    {
        InitializeComponent();       
        if (Is64Bit())//running as 64-bit
        {
            installerPath= @"installfolder\my64bitsetup.exe";
        }
        else
        {
            installerPath= @"installfolder\my32bitsetup.exe";
        }
    }

    [SecurityPermission(SecurityAction.Demand)]
    public override void Install(IDictionary stateSaver)
    {
        base.Install(stateSaver);
    }

    [SecurityPermission(SecurityAction.Demand)]
    public override void Commit(IDictionary savedState)
    {
        base.Commit(savedState);
        MyInstall();
    }

    [SecurityPermission(SecurityAction.Demand)]
    public override void Rollback(IDictionary savedState)
    {
        base.Rollback(savedState);
    }

    [SecurityPermission(SecurityAction.Demand)]
    public override void Uninstall(IDictionary savedState)
    {
        base.Uninstall(savedState);
        base.Commit(savedState);
    }

    private void MyInstall()
    {
         ProcessStartInfo procStartInfo = new ProcessStartInfo("cmd.exe", "/c " + installerPath);
        RunProcess(procStartInfo);
    }

    private void RunProcess(ProcessStartInfo procStartInfo)
    {
        Process proc = new Process();
        proc.StartInfo = procStartInfo;
        proc.Start();
        proc.WaitForExit();
    }

[DllImport("kernel32.dll", SetLastError = true, CallingConvention = CallingConvention.Winapi)]
[return: MarshalAs(UnmanagedType.Bool)]
public static extern bool IsWow64Process([In] IntPtr hProcess, [Out] out bool lpSystemInfo);

private bool Is64Bit()
{
    return (IntPtr.Size == 8 || (IntPtr.Size == 4 && Is32BitProcessOn64BitProcessor()));
}

private bool Is32BitProcessOn64BitProcessor()
{
    bool retVal;
    IsWow64Process(Process.GetCurrentProcess().Handle, out retVal);
    return retVal;
}

Ok, that was long...

Anyway, in the Commit you can be sure that the installers are already unpacked, just make sure you have the right path. (You can change the cmd command from /c to /k for testings, that will keep the command prompt window alive for you to see the messages)

You can read some more about custom actions, the installation path can be passed by arguments.

Answer 2

No, this is not possible. See Heath Stewart's Different Packages are Required for Different Processor Architectures post. The only way to handle this with MSI is with a bootstrap along the lines of what you describe. If you just needed to put a file or key or two in a 64-bit location, it's possible (but not recommended) to do that in a custom action, but changing the target installation location and using built-in MSI file support won't work.