DLL-Template-MinGW

• x64 DLL Template
• C++
• Cross compile with MinGW

Usage

• Cross compile the dll (Linux)

make

• Test the dll (Windows, python3)

python3 runDll.py

• On success, 2 MessageBox should pop
  • dynamic-link-library-best-practices, MSDOC
  • Because on first time load, DllMain is called. The test() function is called in the python script manually

DLL Loading

• dllmain, Windows App Development, MSDN

• The DllMain is optional, if exists, it is called "When the system starts or terminates a process or thread, it calls the entry-point function for each loaded DLL using the first thread of the process"; it is also called when "LoadLibrary" and "FreeLibrary" are called.

• TL;DR, the DLL Loading flow: DLLOptionalHeader."Entry Point" (DllMainCRTStartup(optional) -> ... -> DLLMain) -> finish setup

• Normally, the "AddressOfEntryPoint" (@"PE\0\0"+0x28 == 4("PE\0\0") + 20(COFF Header) + 16(OptionalHeader->AddressOfEntryPoint)) of the dll should be called by us, with "DLL_PROCESS_ATTACH", for once during the setup

• The default _DllMainCRTStartup handles C runtime library initialization etc.

• Use the C Run-Time, MSDN

• DLLs and Visual C++ run-time library behavior, Default DLL entry point DllMainCRTStartup, MSDN

// BOOL APIENTRY DllEntryPoint (
// HINSTANCE hInst,		/* [IN] Library instance handle. */
// DWORD reason,		/* [IN] Reason this function is being called. */
// LPVOID reserved      // [IN] NULL for dynamic loads, non-NULL for static loads
// );

DllEntryPoint(dllInMemBaseAddr, DLL_PROCESS_ATTACH, NULL);