Insert and extract a binary file in C# assembly at run time

Summary ⁓ Learn how you can insert a binary file in C# assembly and extract it at run time. This can be useful when you want to hide files that you don't want to be modified.

Problem

There is a binary file (I’ll use an Excel file) that you want to embed in any C# assembly. Later on, at runtime, you want to extract the file from the EXE and continue working on it. In this post, I will share the code and describe how you can do that. You can use the same technique for any other kind of binary file as well.

Solution

First up, the reason why you may choose to embed a resource directly into your EXE is to ensure that no one tampers your file on which your code is based. This post doesn’t talk about handling an Excel file. It mainly focuses on two parts… embedding any file directly in your EXE, and then extract it at runtime and execute it.

Create a new Windows Forms Project
Add an Existing file (I’ve added a file called File.xlsx) in the project
Right click on File.xlsx and select Properties
Change the Build Action –> Embedded Resource
Switch to the form where you want to extract and use this resource
Add the following to the top of the code behind...

   using System.Reflection;  
   using System.IO;

Add the following methods and call ExtractFromAssembly method

   private void ExtractFromAssembly()
   {
      string strPath = Application.LocalUserAppDataPath + "OutputFile.xlsx";  
      if (File.Exists(strPath)) File.Delete(strPath);  
      Assembly assembly = Assembly.GetExecutingAssembly();  
      //In the next line you should provide      NameSpace.FileName.Extension that you have embedded  
      var input = assembly.GetManifestResourceStream("Sample.File.xlsx");  
      var output = File.Open(strPath, FileMode.CreateNew);  
      CopyStream(input, output);  
      input.Dispose();  
      output.Dispose();  
      System.Diagnostics.Process.Start(strPath);  
   }
   private void CopyStream(Stream input, Stream output)
   {
      byte[] buffer = new byte[32768];
      while (true)
      {
         int read = input.Read(buffer, 0, buffer.Length);
         if (read <= 0)
         return;
         output.Write(buffer, 0, read);
      }
   }

Hope it helps.