tiny exe to detect uefi/legacy boot

uefi-x64.exe

uefi.cpp

/* 
  Orignal Detect UEFI/Legacy https://github.com/xcat2/xcat-core/blob/master/xCAT-server/share/xcat/netboot/windows/detectefi.cpp
  Reduce binary size method https://www.jianshu.com/p/6b675c99fb49
  Other ways to detect UEFI/Legacy http://bbs.c3.wuyou.net/forum.php?mod=viewthread&tid=413675
*/

#include <windows.h>
#include <stdio.h>
#pragma comment(lib,"kernel32.lib")
#pragma comment(lib,"ucrt.lib")

#pragma comment(linker, "/align:16")
#pragma comment(linker, "/subsystem:console")
#pragma comment(linker, "/ENTRY:main")

void main()
{
  GetFirmwareEnvironmentVariableA("","{00000000-0000-0000-0000-000000000000}",NULL,0);
  if (GetLastError() == ERROR_INVALID_FUNCTION) { // This.. is.. LEGACY BIOOOOOOOOS....
    printf("Legacy");
	ExitProcess(1);
  } else {
    printf("UEFI");
    ExitProcess(0);
  }
}

uefi.exe