Question

In this small program, why does GetCurrentProcess() return -1?

int _tmain(int argc, _TCHAR* argv[]) {
    HANDLE h = GetCurrentProcess(); // ret -1 
    printf("0x%x\n",(DWORD)h); 
    return 0;
}

What’s wrong?

In Kernel32.GetCurrentProcess I see this:

OR EAX,FFFFFFFF  ; EAX - ?
RETN

Answer 1

That is correct, see this API reference for GetCurrentProcess.

The GetCurrentProcess function retrieves a pseudo-handle for the current process, which is currently defined as (HANDLE)-1. However, because you should not assume that the value will never change, the GetCurrentProcess function is provided as an alternative to hard-coding the constant into your code.