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C++ / CLI - How To Use Managed C++ DLL when Microsoft Visual C++ Redistributable is not installed?


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If your .NET application uses components written in Managed C++, you face the necessity to distribute Microsoft Visual C++ Redistributable with it. If one attempts to launch such application in a system that doesn’t have the corresponding Microsoft Visual C++ Redistributable installed, the user will get a warning “This application has failed to start because the application configuration is incorrect”. Why this happens, and can that be done without installing Microsoft Visual C++ Redistributable?

With the common approach, a DLL written in Managed C++ has a dependency from Microsoft Visual C++ Runtime, DLL files from which cannot be linked statically. The traditional solution is the inclusion of Microsoft Visual C++ Redistributable in the setup file.

With BoxedApp SDK, you can emulate the availability of Microsoft Visual C++ Runtime. Right after the application is launched, before using the components compiled in Managed C++, create the files, from which the Managed C++ DLL depends (how to find paths to dependencies):

using System;
using System.Collections.Generic;
using System.Windows.Forms;
using System.IO;
using System.Runtime.InteropServices;
using System.Reflection;

namespace WindowsApplication1
{
    static class Program
    {
        /// 
        /// The main entry point for the application.
        /// 
        [STAThread]
        static void Main()
        {
            BoxedAppSDK.NativeMethods.BoxedAppSDK_Init();

            string PathOfWinSxS = 
                Directory.GetParent(Environment.SystemDirectory).FullName + 
                @"\WinSxS";

            if (!Directory.Exists(PathOfWinSxS))
                // Win2k
                PathOfWinSxS = Application.StartupPath;

            Stream fromStream =
                Assembly.
                GetExecutingAssembly().
                GetManifestResourceStream("WindowsApplication1.res.msvcm80d.dll");

            CreateDLLInMemory(
                PathOfWinSxS + 
                @"\x86_Microsoft.VC80.DebugCRT_1fc8b3b9a1e18e3b_8.0.50727.42_x-ww_f75eb16c\msvcm80d.dll",
                fromStream);

            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);
            Application.Run(new Form1());

            BoxedAppSDK.NativeMethods.BoxedAppSDK_Exit();
        }

        [DllImport("kernel32.dll", SetLastError = true)]
        static extern bool CloseHandle(IntPtr hObject);

        static void CreateDLLInMemory(string strVirtualPath, Stream stream)
        {
            const int BufferSize = 1024;
            byte[] buffer = new byte[BufferSize];

            IntPtr hHandle =
                BoxedAppSDK.NativeMethods.BoxedAppSDK_CreateVirtualFile(
                strVirtualPath,
                BoxedAppSDK.NativeMethods.EFileAccess.GenericWrite,
                BoxedAppSDK.NativeMethods.EFileShare.Read,
                IntPtr.Zero,
                BoxedAppSDK.NativeMethods.ECreationDisposition.New,
                BoxedAppSDK.NativeMethods.EFileAttributes.Normal,
                IntPtr.Zero);
            CloseHandle(hHandle);

            int nReadBytes;

            using (FileStream VirtualFileStream = new FileStream(strVirtualPath, FileMode.Open))
            {
                while ((nReadBytes = stream.Read(buffer, 0, BufferSize)) > 0)
                    VirtualFileStream.Write(buffer, 0, nReadBytes);
            }
        }
    }
}

To find out, which exact DLL files does your Managed C++ DLL has dependencies from, use the depends.exe application from Visual Studio setup. Open your Managed C++ DLL in depends.exe, and you will easily find, which VC++ Runtime components it depends from:

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