Dynamic code execution on WinRT in Windows 8 (either C++ or .NET/C#)?

Question

Does WinRT under windows 8 metro allow you to dynamically load and execute code? For example, is it possible to download a dll into memory or to isolated storage and run code from it? Could code that JIT compiles a scripting language to native assembly language (eg third party browsers) be able to do the same in WinRT, or is it prohibited as an "unsafe" operation?

Is the answer to this question different for "managed" code running in WinRT? For example, in managed code, could you download an assembly from the internet and have it be discoverable in MEF or otherwise be able to load it at runtime? Can you use Reflection.Emit in some form? In C++, can you run assembly code generated at runtime by your application, or dynamically load a DLL at runtime (presumably some form of WinRT DLL)?

Answer 1

In general, you cannot load and execute new code in a Metro style app. What you can access is what you ship with the app.

LoadLibrary and GetProcAddress are missing so C++ can't dynamically load code.
Likewise, C# cannot because there is no Assembly.Load.
JavaScript can, but only in the web container and not in the fuller trust portions of the code.

The reason for all this is that the store's security/malware protection would be moot if an app could just load and run arbitrary code.

Answer 2

Actually, Metro style apps CAN dynamically load and execute code. There are some restrictions; Metro and Desktop apps work a bit differently in key ways.

The mechanisms vary a bit, depending on the caller (LoadPackagedLibrary() Assembly.Load(), etc). One key difference between Metro and Desktop - Metro apps can only dynamically load what's in your app's package graph (your package and s) and system code (that could be otherwise loaded statically).

See my post for some more details http://social.msdn.microsoft.com/Forums/en-US/wingameswithdirectx/thread/d1ebe727-2d10-430e-96af-46964dda8225

Answer 3

Does WinRT under windows 8 metro allow you to dynamically load and execute code?

No.

For example, is it possible to download a dll into memory or to isolated storage and run code from it?

No.

Could code that JIT compiles a scripting language to native assembly language (eg third party browsers) be able to do the same in WinRT, or is it prohibited as an "unsafe" operation?

It would be prohibited.

Is the answer to this question different for "managed" code running in WinRT?

No.

For example, in managed code, could you download an assembly from the internet and have it be discoverable in MEF or otherwise be able to load it at runtime?

No.

Can you use Reflection.Emit in some form?

No.

In C++, can you run assembly code generated at runtime by your application, or dynamically load a DLL at runtime (presumably some form of WinRT DLL)?

No.

Everything you described would allow the safety guarantees of WinRT to be circumvented.

Answer 4

Windows 10 adds the codeGeneration capability for this purpose. This allows the functions VirtualAllocFromApp and VirtualProtectFromApp to be used in WinRT apps as VirtualAlloc and VirtualProtect would be used in Win32.

Answer 5

You question is a bit unclear... so some general pointers:

• .NET app using among other things WinRT (but NOT the new UI model!)
  In this case everything is possible that you today (perhaps not OLEDB) but Reflection etc.

• .NET app built for Metro UI
  AFAIK this is not possible (see http://blogs.microsoft.co.il/blogs/sasha/archive/2011/09/17/metro-net-framework-profile-windows-tailored.aspx and http://tirania.org/blog/ ) at least as long as you want to sell via Windows Store... outside of this scope (Windows Store) there might some tricks to circumvent that restriction as already demonstrated by some... but I wouldn't count on that... MAYBE you can use some JavaScript ( eval etc.) to do something dynamic but I am not sure currently

Answer 6

为了使它更有趣，IE 10实际上确实在其js代码上执行JIT，因此API显然允许它。

Answer 7

You can create a Windows Runtime Component (Universal Windows) C++, You access the Component from c# code, inside the component you can call LoadPackagedLibrary, which has the restriction that it can only load DLL's that are packaged with your app. Otherwise it is same as LoadLibrary.

You cannot download and dynamically load, as ApplicationData and InstalledLocation are different locations. (LoadPackagedLibrary doesn not allow you to specify path). And you can only write to ApplicationData...

Answer 8

Example of dynamic assembly loading from AppX package directory (from MSDN Forums ):

private async Task<IEnumerable<Assembly>> GetAssemblyListAsync()
{
    var folder = Windows.ApplicationModel.Package.Current.InstalledLocation;

    List<Assembly> assemblies = new List<Assembly>();
    foreach (StorageFile file in await folder.GetFilesAsync())
    {
        if (file.FileType == ".dll" || file.FileType == ".exe")
        {
            var name = file.Name.Substring(0, file.Name.Length - file.FileType.Length);
            Assembly assembly = Assembly.Load(new AssemblyName() { Name = name });
            assemblies.Add(assembly);
        }
    }

    return assemblies;
}

The assemblies must be added to the application package. You can't download them from external source.

However, this approach does not work in .NET Native , because everything is merged into a single DLL. You should save a list of assembly names somewhere (in a simple file inside Assets) and call Assembly.Load for each item.

Example of dynamic assembly listing in debug mode and predefined array of assembly names in release mode (.NET Native tool chain).

#if DEBUG
using Windows.Storage;
#endif

    // ...

    IEnumerable<string> assemblyNames;

#if DEBUG
    assemblyNames = Windows.ApplicationModel.Package.Current.InstalledLocation.GetFilesAsync().AsTask().Result
        .Where(file => file.FileType == ".dll" && file.Name.Contains("Business"))
        .Select(file => file.Name.Substring(0, file.Name.Length - file.FileType.Length));
#else
    assemblyNames = new[] { "California.Business", "Colorado.Business" };
#endif

    foreach (var name in assemblyNames)
    {
        var assembly = Assembly.Load(new AssemblyName() { Name = name });

        // Load required types.
        // ...

    }

Answer 9

雅可能，检查Windows 8中的谷歌Chrome应用程序，它们提供了一种在正常模式和Windows 8模式之间切换的方法，可以持久查看所查看的页面。