How to dynamically load and unload your own DLL file?

Question

I have erroneous third-party DLL files that, after some runtime, start throwing access violation exceptions. When this happens, I want to reload this dll file. How to do it?

Answer 1

try it

[DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)] private static extern IntPtr LoadLibrary(string libname); [DllImport("kernel32.dll", CharSet = CharSet.Auto)] private static extern bool FreeLibrary(IntPtr hModule); //Load IntPtr Handle = LoadLibrary(fileName); if (Handle == IntPtr.Zero) { int errorCode = Marshal.GetLastWin32Error(); throw new Exception(string.Format("Failed to load library (ErrorCode: {0})",errorCode)); } //Free if(Handle != IntPtr.Zero) FreeLibrary(Handle); 

If you want to call functions first, you must create a delegeate that matches that function and then use WinApi GetProcAddress

 [DllImport("kernel32.dll", CharSet = CharSet.Ansi)] private static extern IntPtr GetProcAddress(IntPtr hModule, string lpProcName); IntPtr funcaddr = GetProcAddress(Handle,functionName); YourFunctionDelegate function = Marshal.GetDelegateForFunctionPointer(funcaddr,typeof(YourFunctionDelegate )) as YourFunctionDelegate ; function.Invoke(pass here your parameters); 

Answer 2

Create a workflow that communicates through COM or another IPC mechanism. Then, when the DLL dies, you can simply restart the workflow.

Answer 3

Download the dll, call it, and then unload it until it disappears.

I applied the following code from the VB.Net example here .

  [DllImport("powrprof.dll")] static extern bool IsPwrHibernateAllowed(); [DllImport("kernel32.dll")] static extern bool FreeLibrary(IntPtr hModule); [DllImport("kernel32.dll")] static extern bool LoadLibraryA(string hModule); [DllImport("kernel32.dll")] static extern bool GetModuleHandleExA(int dwFlags, string ModuleName, ref IntPtr phModule); static void Main(string[] args) { Console.WriteLine("Is Power Hibernate Allowed? " + DoIsPwrHibernateAllowed()); Console.WriteLine("Press any key to continue..."); Console.ReadKey(); } private static bool DoIsPwrHibernateAllowed() { LoadLibraryA("powrprof.dll"); var result = IsPwrHibernateAllowed(); var hMod = IntPtr.Zero; if (GetModuleHandleExA(0, "powrprof", ref hMod)) { while (FreeLibrary(hMod)) { } } return result; }