Embedding DLLs in a compiled executable

Question

Is it possible to embed a pre-existing DLL into a compiled C# executable (so that you only have one file to distribute)? If it is possible, how would one go about doing it?

Normally, I'm cool with just leaving the DLLs outside and having the setup program handle everything, but there have been a couple of people at work who have asked me this and I honestly don't know.

Answer 1

I highly recommend to use Costura.Fody - by far the best and easiest way to embed resources in your assembly. It's available as NuGet package.

Install-Package Costura.Fody

After adding it to the project, it will automatically embed all references that are copied to the output directory into your main assembly. You might want to clean the embedded files by adding a target to your project:

Install-CleanReferencesTarget

You'll also be able to specify whether to include the pdb's, exclude certain assemblies, or extracting the assemblies on the fly. As far as I know, also unmanaged assemblies are supported.

Update

Currently, some people are trying to add support for DNX.

Update 2

For the lastest Fody version, you will need to have MSBuild 16 (so Visual Studio 2019). Fody version 4.2.1 will do MSBuild 15. (reference: Fody is only supported on MSBuild 16 and above. Current version: 15)

Answer 2

Just right-click your project in Visual Studio, choose Project Properties -> Resources -> Add Resource -> Add Existing File… And include the code below to your App.xaml.cs or equivalent.

public App()
{
    AppDomain.CurrentDomain.AssemblyResolve +=new ResolveEventHandler(CurrentDomain_AssemblyResolve);
}

System.Reflection.Assembly CurrentDomain_AssemblyResolve(object sender, ResolveEventArgs args)
{
    string dllName = args.Name.Contains(',') ? args.Name.Substring(0, args.Name.IndexOf(',')) : args.Name.Replace(".dll","");

    dllName = dllName.Replace(".", "_");

    if (dllName.EndsWith("_resources")) return null;

    System.Resources.ResourceManager rm = new System.Resources.ResourceManager(GetType().Namespace + ".Properties.Resources", System.Reflection.Assembly.GetExecutingAssembly());

    byte[] bytes = (byte[])rm.GetObject(dllName);

    return System.Reflection.Assembly.Load(bytes);
}

Here's my original blog post: http://codeblog.larsholm.net/2011/06/embed-dlls-easily-in-a-net-assembly/

Answer 3

If they're actually managed assemblies, you can use ILMerge. For native DLLs, you'll have a bit more work to do.

See also: How can a C++ windows dll be merged into a C# application exe?

Answer 4

Yes, it is possible to merge .NET executables with libraries. There are multiple tools available to get the job done:

• ILMerge is a utility that can be used to merge multiple .NET assemblies into a single assembly.
• Mono mkbundle, packages an exe and all assemblies with libmono into a single binary package.
• IL-Repack is a FLOSS alterantive to ILMerge, with some additional features.

In addition this can be combined with the Mono Linker, which does remove unused code and therefor makes the resulting assembly smaller.

Another possibility is to use .NETZ, which does not only allow compressing of an assembly, but also can pack the dlls straight into the exe. The difference to the above mentioned solutions is that .NETZ does not merge them, they stay separate assemblies but are packed into one package.

.NETZ is a open source tool that compresses and packs the Microsoft .NET Framework executable (EXE, DLL) files in order to make them smaller.

Answer 5

ILMerge can combine assemblies to one single assembly provided the assembly has only managed code. You can use the commandline app, or add reference to the exe and programmatically merge. For a GUI version there is Eazfuscator, and also .Netz both of which are free. Paid apps include BoxedApp and SmartAssembly.

If you have to merge assemblies with unmanaged code, I would suggest SmartAssembly. I never had hiccups with SmartAssembly but with all others. Here, it can embed the required dependencies as resources to your main exe.

You can do all this manually not needing to worry if assembly is managed or in mixed mode by embedding dll to your resources and then relying on AppDomain's Assembly ResolveHandler. This is a one stop solution by adopting the worst case, ie assemblies with unmanaged code.

static void Main()
{
    AppDomain.CurrentDomain.AssemblyResolve += (sender, args) =>
    {
        string assemblyName = new AssemblyName(args.Name).Name;
        if (assemblyName.EndsWith(".resources"))
            return null;

        string dllName = assemblyName + ".dll";
        string dllFullPath = Path.Combine(GetMyApplicationSpecificPath(), dllName);

        using (Stream s = Assembly.GetEntryAssembly().GetManifestResourceStream(typeof(Program).Namespace + ".Resources." + dllName))
        {
            byte[] data = new byte[stream.Length];
            s.Read(data, 0, data.Length);

            //or just byte[] data = new BinaryReader(s).ReadBytes((int)s.Length);

            File.WriteAllBytes(dllFullPath, data);
        }

        return Assembly.LoadFrom(dllFullPath);
    };
}

The key here is to write the bytes to a file and load from its location. To avoid chicken and egg problem, you have to ensure you declare the handler before accessing assembly and that you do not access the assembly members (or instantiate anything that has to deal with the assembly) inside the loading (assembly resolving) part. Also take care to ensure GetMyApplicationSpecificPath() is not any temp directory since temp files could be attempted to get erased by other programs or by yourself (not that it will get deleted while your program is accessing the dll, but at least its a nuisance. AppData is good location). Also note that you have to write the bytes each time, you cant load from location just 'cos the dll already resides there.

For managed dlls, you need not write bytes, but directly load from the location of the dll, or just read the bytes and load the assembly from memory. Like this or so:

    using (Stream s = Assembly.GetEntryAssembly().GetManifestResourceStream(typeof(Program).Namespace + ".Resources." + dllName))
    {
        byte[] data = new byte[stream.Length];
        s.Read(data, 0, data.Length);
        return Assembly.Load(data);
    }

    //or just

    return Assembly.LoadFrom(dllFullPath); //if location is known.

If the assembly is fully unmanaged, you can see this link or this as to how to load such dlls.

Answer 6

The excerpt by Jeffrey Richter is very good. In short, add the library's as embedded resources and add a callback before anything else. Here is a version of the code (found in the comments of his page) that I put at the start of Main method for a console app (just make sure that any calls that use the library's are in a different method to Main).

AppDomain.CurrentDomain.AssemblyResolve += (sender, bargs) =>
        {
            String dllName = new AssemblyName(bargs.Name).Name + ".dll";
            var assem = Assembly.GetExecutingAssembly();
            String resourceName = assem.GetManifestResourceNames().FirstOrDefault(rn => rn.EndsWith(dllName));
            if (resourceName == null) return null; // Not found, maybe another handler will find it
            using (var stream = assem.GetManifestResourceStream(resourceName))
            {
                Byte[] assemblyData = new Byte[stream.Length];
                stream.Read(assemblyData, 0, assemblyData.Length);
                return Assembly.Load(assemblyData);
            }
        };

Answer 7

To expand on @Bobby's asnwer above. You can edit your .csproj to use IL-Repack to automatically package all files into a single assembly when you build.

1. Install the nuget ILRepack.MSBuild.Task package with Install-Package ILRepack.MSBuild.Task
2. Edit the AfterBuild section of your .csproj

Here is a simple sample that merges ExampleAssemblyToMerge.dll into your project output.

<!-- ILRepack -->
<Target Name="AfterBuild" Condition="'$(Configuration)' == 'Release'">

   <ItemGroup>
    <InputAssemblies Include="$(OutputPath)\$(AssemblyName).exe" />
    <InputAssemblies Include="$(OutputPath)\ExampleAssemblyToMerge.dll" />
   </ItemGroup>

   <ILRepack 
    Parallel="true"
    Internalize="true"
    InputAssemblies="@(InputAssemblies)"
    TargetKind="Exe"
    OutputFile="$(OutputPath)\$(AssemblyName).exe"
   />
</Target>

Answer 8

.NET Core 3.0 natively supports compiling to a single .exe

The feature is enabled by the usage of the following property in your project file (.csproj):

    <PropertyGroup>
        <PublishSingleFile>true</PublishSingleFile>
    </PropertyGroup>

This is done without any external tool.

See my answer for this question for further details.

Answer 9

You could add the DLLs as embedded resources, and then have your program unpack them into the application directory on startup (after checking to see if they're there already).

Setup files are so easy to make, though, that I don't think this would be worth it.

EDIT: This technique would be easy with .NET assemblies. With non-.NET DLLs it would be a lot more work (you'd have to figure out where to unpack the files and register them and so on).

Answer 10

Another product that can handle this elegantly is SmartAssembly, at SmartAssembly.com. This product will, in addition to merging all dependencies into a single DLL, (optionally) obfuscate your code, remove extra meta-data to reduce the resulting file size, and can also actually optimize the IL to increase runtime performance.

There is also some kind of global exception handling/reporting feature it adds to your software (if desired) that could be useful. I believe it also has a command-line API so you can make it part of your build process.

Answer 11

Neither the ILMerge approach nor Lars Holm Jensen's handling the AssemblyResolve event will work for a plugin host. Say executable H loads assembly P dynamically and accesses it via interface IP defined in an separate assembly. To embed IP into H one shall need a little modification to Lars's code:

Dictionary<string, Assembly> loaded = new Dictionary<string,Assembly>();
AppDomain.CurrentDomain.AssemblyResolve += (sender, args) =>
{   Assembly resAssembly;
    string dllName = args.Name.Contains(",") ? args.Name.Substring(0, args.Name.IndexOf(',')) : args.Name.Replace(".dll","");
    dllName = dllName.Replace(".", "_");
    if ( !loaded.ContainsKey( dllName ) )
    {   if (dllName.EndsWith("_resources")) return null;
        System.Resources.ResourceManager rm = new System.Resources.ResourceManager(GetType().Namespace + ".Properties.Resources", System.Reflection.Assembly.GetExecutingAssembly());
        byte[] bytes = (byte[])rm.GetObject(dllName);
        resAssembly = System.Reflection.Assembly.Load(bytes);
        loaded.Add(dllName, resAssembly);
    }
    else
    {   resAssembly = loaded[dllName];  }
    return resAssembly;
};  

The trick to handle repeated attempts to resolve the same assembly and return the existing one instead of creating a new instance.

EDIT: Lest it spoil .NET's serialization, make sure to return null for all assemblies not embedded in yours, thereby defaulting to the standard behaviour. You can get a list of these libraries by:

static HashSet<string> IncludedAssemblies = new HashSet<string>();
string[] resources = System.Reflection.Assembly.GetExecutingAssembly().GetManifestResourceNames();
for(int i = 0; i < resources.Length; i++)
{   IncludedAssemblies.Add(resources[i]);  }

and just return null if the passed assembly does not belong to IncludedAssemblies .

Answer 12

The following method DO NOT use external tools and AUTOMATICALLY include all needed DLL (no manual action required, everything done at compilation)

I read a lot of answer here saying to use ILMerge, ILRepack or Jeffrey Ritcher method but none of that worked with WPF applications nor was easy to use.

When you have a lot of DLL it can be hard to manually include the one you need in your exe. The best method i found was explained by Wegged here on StackOverflow

Copy pasted his answer here for clarity (all credit to Wegged)

---

1) Add this to your .csproj file:

<Target Name="AfterResolveReferences">
  <ItemGroup>
    <EmbeddedResource Include="@(ReferenceCopyLocalPaths)" Condition="'%(ReferenceCopyLocalPaths.Extension)' == '.dll'">
      <LogicalName>%(ReferenceCopyLocalPaths.DestinationSubDirectory)%(ReferenceCopyLocalPaths.Filename)%(ReferenceCopyLocalPaths.Extension)</LogicalName>
    </EmbeddedResource>
  </ItemGroup>
</Target>

2) Make your Main Program.cs look like this:

[STAThreadAttribute]
public static void Main()
{
    AppDomain.CurrentDomain.AssemblyResolve += OnResolveAssembly;
    App.Main();
}

3) Add the OnResolveAssembly method:

private static Assembly OnResolveAssembly(object sender, ResolveEventArgs args)
{
    Assembly executingAssembly = Assembly.GetExecutingAssembly();
    AssemblyName assemblyName = new AssemblyName(args.Name);

    var path = assemblyName.Name + ".dll";
    if (assemblyName.CultureInfo.Equals(CultureInfo.InvariantCulture) == false) path = String.Format(@"{0}\{1}", assemblyName.CultureInfo, path);

    using (Stream stream = executingAssembly.GetManifestResourceStream(path))
    {
        if (stream == null) return null;

        var assemblyRawBytes = new byte[stream.Length];
        stream.Read(assemblyRawBytes, 0, assemblyRawBytes.Length);
        return Assembly.Load(assemblyRawBytes);
    }
}

Answer 13

It may sound simplistic, but WinRar gives the option to compress a bunch of files to a self-extracting executable.
It has lots of configurable options: final icon, extract files to given path, file to execute after extraction, custom logo/texts for popup shown during extraction, no popup window at all, license agreement text, etc.
May be useful in some cases.

Answer 14

I use the csc.exe compiler called from a .vbs script.

In your xyz.cs script, add the following lines after the directives (my example is for the Renci SSH):

using System;
using Renci;//FOR THE SSH
using System.Net;//FOR THE ADDRESS TRANSLATION
using System.Reflection;//FOR THE Assembly

//+ref>"C:\Program Files (x86)\Microsoft\ILMerge\Renci.SshNet.dll"
//+res>"C:\Program Files (x86)\Microsoft\ILMerge\Renci.SshNet.dll"
//+ico>"C:\Program Files (x86)\Microsoft CAPICOM 2.1.0.2 SDK\Samples\c_sharp\xmldsig\resources\Traffic.ico"

The ref, res and ico tags will be picked up by the .vbs script below to form the csc command.

Then add the assembly resolver caller in the Main:

public static void Main(string[] args)
{
    AppDomain.CurrentDomain.AssemblyResolve += new ResolveEventHandler(CurrentDomain_AssemblyResolve);
    .

...and add the resolver itself somewhere in the class:

    static Assembly CurrentDomain_AssemblyResolve(object sender, ResolveEventArgs args)
    {
        String resourceName = new AssemblyName(args.Name).Name + ".dll";

        using (var stream = Assembly.GetExecutingAssembly().GetManifestResourceStream(resourceName))
        {
            Byte[] assemblyData = new Byte[stream.Length];
            stream.Read(assemblyData, 0, assemblyData.Length);
            return Assembly.Load(assemblyData);
        }

    }

I name the vbs script to match the .cs filename (e.g. ssh.vbs looks for ssh.cs); this makes running the script numerous times a lot easier, but if you aren't an idiot like me then a generic script could pick up the target .cs file from a drag-and-drop:

    Dim name_,oShell,fso
    Set oShell = CreateObject("Shell.Application")
    Set fso = CreateObject("Scripting.fileSystemObject")

    'TAKE THE VBS SCRIPT NAME AS THE TARGET FILE NAME
    '################################################
    name_ = Split(wscript.ScriptName, ".")(0)

    'GET THE EXTERNAL DLL's AND ICON NAMES FROM THE .CS FILE
    '#######################################################
    Const OPEN_FILE_FOR_READING = 1
    Set objInputFile = fso.OpenTextFile(name_ & ".cs", 1)

    'READ EVERYTHING INTO AN ARRAY
    '#############################
    inputData = Split(objInputFile.ReadAll, vbNewline)

    For each strData In inputData

        if left(strData,7)="//+ref>" then 
            csc_references = csc_references & " /reference:" &         trim(replace(strData,"//+ref>","")) & " "
        end if

        if left(strData,7)="//+res>" then 
            csc_resources = csc_resources & " /resource:" & trim(replace(strData,"//+res>","")) & " "
        end if

        if left(strData,7)="//+ico>" then 
            csc_icon = " /win32icon:" & trim(replace(strData,"//+ico>","")) & " "
        end if
    Next

    objInputFile.Close


    'COMPILE THE FILE
    '################
    oShell.ShellExecute "c:\windows\microsoft.net\framework\v3.5\csc.exe", "/warn:1 /target:exe " & csc_references & csc_resources & csc_icon & " " & name_ & ".cs", "", "runas", 2


    WScript.Quit(0)

Answer 15

It's possible but not all that easy, to create a hybrid native/managed assembly in C#. Were you using C++ instead it'd be a lot easier, as the Visual C++ compiler can create hybrid assemblies as easily as anything else.

Unless you have a strict requirement to produce a hybrid assembly, I'd agree with MusiGenesis that this isn't really worth the trouble to do with C#. If you need to do it, perhaps look at moving to C++/CLI instead.

Answer 16

Generally you would need some form of post build tool to perform an assembly merge like you are describing. There is a free tool called Eazfuscator (eazfuscator.blogspot.com/) which is designed for bytecode mangling that also handles assembly merging. You can add this into a post build command line with Visual Studio to merge your assemblies, but your mileage will vary due to issues that will arise in any non trival assembly merging scenarios.

You could also check to see if the build make untility NANT has the ability to merge assemblies after building, but I am not familiar enough with NANT myself to say whether the functionality is built in or not.

There are also many many Visual Studio plugins that will perform assembly merging as part of building the application.

Alternatively if you don't need this to be done automatically, there are a number of tools like ILMerge that will merge .net assemblies into a single file.

The biggest issue I've had with merging assemblies is if they use any similar namespaces. Or worse, reference different versions of the same dll (my problems were generally with the NUnit dll files).