c++ dll infinite loop without using a thread - c++

Question

is it possible to use an infinite loop in a dll function without using a thread?
here's some example code:
BOOL WINAPI DllMain(HMODULE hModule, DWORD dwReason, LPVOID lpReserved) {
switch (dwReason)
{
case DLL_PROCESS_ATTACH:
DisableThreadLibraryCalls(hModule);
GetModuleHandleExA(GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS | GET_MODULE_HANDLE_EX_FLAG_PIN, (LPCSTR)hModule, &hModule);
CreateThread(NULL, 0, (LPTHREAD_START_ROUTINE)myfunction, 0, NULL, 0); //my current method
myfunction(); //locks the program at runtime if i do it this way (just an example)
case DLL_THREAD_ATTACH:
break;
case DLL_THREAD_DETACH:
break;
case DLL_PROCESS_DETACH:
break;
}
return TRUE;
}
and here's an example of the function in the thread:
void myfunction() {
//begin the infinite loop after 5 seconds
Sleep(5000);
for (;;) //set no condition for breaking the loop
{
Sleep(500); //this keeps the cpu from spiking
//call my functions
function1();
function2();
function3();
function4();
}
}
this code works well. i just wonder if there are alternatives. for example: can the function be written into the memory of the process? or called at a later time, instead of DLL_PROCESS_ATTACH?

Answer 1

First issue
This is undefined behavior:
CreateThread(NULL, 0, (LPTHREAD_START_ROUTINE)myfunction, 0, NULL, 0);
The fact that you are casting the function signature of myFunction is likely to corrupt the stack.
Change your signature of myFunction as follows:
DWORD __stdcall myfunction(void*) {
You know you got it right when you can remove the suspicious cast from CreateThread:
CreateThread(NULL, 0, myfunction, 0, NULL, 0);
Second issue
You shouldn't be doing anything of significance in DLL_PROCESS_ATTACH to begin with. And according to Raymond, you definitely shouldn't be creating a thread.