Calling function from address doesn't work

Question

I can't understand why if i call the CreateFileA function using the address the program crash.

This snipet should call the CreateFileA using it's address retrieved from the GetProcAddress call. Of course in this simple example i could just call it normally, but i need to retrieve each address manually (Even LoadLibraryA and GetProcAddress but for the sake of brevity i didn't in this example)

What am i doing wrong? Why if i use CreateFileA instead of (*CreateFileAAddr) on the last line it works even if they are pointing to the same thing?

#include <windows.h>

typedef HMODULE(*_LoadLibraryA)(LPCSTR);
typedef FARPROC(*_GetProcAddress)(HMODULE, LPCSTR);
typedef HANDLE(*_CreateFileA)(LPCSTR, DWORD, DWORD, LPSECURITY_ATTRIBUTES, DWORD, DWORD, HANDLE);

int main() {
    _LoadLibraryA LoadLibraryAAddr = (_LoadLibraryA)&LoadLibraryA;
    _GetProcAddress GetProcAddressAddr = (_GetProcAddress)&GetProcAddress;

    HMODULE kernel32Handle = (*LoadLibraryAAddr)("Kernel32.dll");
    if (kernel32Handle == NULL) return -1;
    _CreateFileA CreateFileAAddr = (_CreateFileA)((*GetProcAddressAddr)(kernel32Handle, "CreateFileA"));
    if ((unsigned long)CreateFileAAddr != (unsigned long)&CreateFileA) return -1; //Just to check if the address is correct for Debug
    (*CreateFileAAddr)("123.txt", GENERIC_WRITE, 0, NULL, OPEN_ALWAYS, OPEN_ALWAYS, NULL);
    return 0;
}

Answer 1

As per my comment, Windows API functions and pointer types to said functions need to be annotated with __stdcall (or WINAPI ), which will change their calling convention to the one expected by the API (more information on the stdcall calling convention here ).

typedef HMODULE(__stdcall *_LoadLibraryA)(LPCSTR);
typedef FARPROC(__stdcall *_GetProcAddress)(HMODULE, LPCSTR);
typedef HANDLE(__stdcall *_CreateFileA)(LPCSTR, DWORD, DWORD, LPSECURITY_ATTRIBUTES, DWORD, DWORD, HANDLE);

Also side note: the * must be placed after the __stdcall , for some reason; otherwise the annotation will do nothing.