DllRegisterServer w/o regsvr32

I have a need to register some COM DLLs from a C# program. Every example I found on the web used regsvr32 to perform the registration. This didn't make much sense to me as all regsvr32 does is call DllRegisterServer() exported in the DLL. So I worked out how to do the same from C# using P/Inovke and System.Runtime.InteropServices.

And here it is for you to use. This is a small sample but it compiles and registers the DLLs that are listed on the command line. Be sure to compile with the /unsafe switch. Also, I have more error checking and reporting in my application which I removed from this sample. Enjoy!

   1:  using System;

   2:  using System.Runtime.InteropServices;

   3:   

   4:  public class RegisterDll

   5:  {

   6:      unsafe internal delegate UInt32 DllRegisterServer();

   7:      

   8:      public static void Main(string[] args)

   9:      {

  10:          foreach (string file in args)

  11:          {

  12:              Console.WriteLine("Registering {0}", file);

  13:              RegisterCOMDll(file);

  14:          }

  15:   

  16:          Console.WriteLine("Done!");

  17:      }

  18:   

  19:      private static void RegisterCOMDll(string file)

  20:      {

  21:          IntPtr library = LoadLibraryEx(file, IntPtr.Zero, 0);

  22:          if (library == IntPtr.Zero)

  23:          {

  24:              string msg = "Unable to load '" + file + "' error is " + Marshal.GetLastWin32Error().ToString();

  25:              throw new ApplicationException(msg);

  26:          }

  27:   

  28:          IntPtr proc = GetProcAddress(library, "DllRegisterServer");

  29:          if (proc == IntPtr.Zero)

  30:          {

  31:              int err = Marshal.GetLastWin32Error();

  32:              string msg = "Unable to load 'DllRegisterServer' from '" + file + "' error is " + err.ToString();

  33:              throw new ApplicationException(msg);

  34:          }

  35:   

  36:          DllRegisterServer drs = (DllRegisterServer)Marshal.GetDelegateForFunctionPointer(proc, typeof(DllRegisterServer));

  37:          UInt32 result = drs();

  38:          if (result != 0)

  39:          {

  40:              string msg = "Error " + result.ToString() + " returned from DllRegisterServer in " + file;

  41:              throw new ApplicationException(msg);

  42:          }

  43:   

  44:          FreeLibrary(library);

  45:      }

  46:   

  47:      [Flags]

  48:      public enum LoadLibraryFlags : uint

  49:      {

  50:          DONT_RESOLVE_DLL_REFERENCES = 0x00000001,

  51:          LOAD_IGNORE_CODE_AUTHZ_LEVEL = 0x00000010,

  52:          LOAD_LIBRARY_AS_DATAFILE = 0x00000002,

  53:          LOAD_WITH_ALTERED_SEARCH_PATH = 0x00000008,

  54:      }

  55:   

  56:      [DllImport("kernel32.dll", EntryPoint = "FreeLibrary", SetLastError = true)]

  57:      public static extern bool FreeLibrary(IntPtr hModule);

  58:   

  59:      [DllImport("kernel32.dll", EntryPoint = "LoadLibraryExW", CharSet = CharSet.Unicode, SetLastError = true)]

  60:      public static extern IntPtr LoadLibraryEx(

  61:          [MarshalAs(UnmanagedType.LPWStr)] string lpFileName,

  62:          IntPtr hFile,

  63:          [MarshalAs(UnmanagedType.U4)] LoadLibraryFlags dwFlags);

  64:   

  65:      [DllImport("kernel32.dll", CharSet = CharSet.Ansi, EntryPoint = "GetProcAddress", ExactSpelling = true, SetLastError = true)]

  66:      public static extern IntPtr GetProcAddress(IntPtr hModule, string lpProcName);

  67:  }