CTRL_BREAK_EVENT to a GUI application will compromise parent process - c++

Question

I created a console application with code beneath.
Those code will just start a child process of the explorer.exe then send a CTRL_BREAK_EVENT to it which is expected to be a NO-OP since the child explorer process is not a console application. Then using TerminateProcess to kill the child process which had no effect either but it's ok too.
The problem is, after those steps, the whole console event system for this parent process is broken - I cannot shutdown this console application by clicking X on the console window nor by pressing CTRL-C.
#include <Windows.h>
#include <iostream>
int main() {
const LPWSTR exe = const_cast<LPTSTR>(TEXT("C:\\Windows\\explorer.exe"));
STARTUPINFO si;
PROCESS_INFORMATION pi;
ZeroMemory(&si, sizeof(si));
ZeroMemory(&pi, sizeof(pi));
si.cb = sizeof(si);
CreateProcess(exe,
exe,
NULL,
NULL,
FALSE,
CREATE_NEW_PROCESS_GROUP,
NULL,
NULL,
&si,
&pi);
Sleep(1000);
GenerateConsoleCtrlEvent(CTRL_BREAK_EVENT, pi.dwProcessId);
Sleep(1000);
TerminateProcess(pi.hProcess, 0);
Sleep(1000);
while (true) {
Sleep(1000);
std::cout << "Hello World!\n";
}
}
I do this because I'm making an application hosting platform that people can upload and run applications on a private cloud. We don't know what kinds of EXEs users will upload. If user uploads a console application that relying on CTRL_BREAK_EVENT for a graceful exit, we want to make it possible, so we try CTRL_BREAK_EVENT first. If the program doesn't shutdown in time after a while (for example a GUI program) we will kill it, just like the code above did. We don't want it to break the whole console control event system if we do this on a GUI application since we rely on it to manage lifecycles other services which run as children processes.
By the way, if we created the process with creation flag "DETACHED_PROCESS", the breaking of console control event system will break too even the EXE is a console application.
Any idea to workaround this?
Many thanks!

Answer 1

This is a workaround to prevent this issue from occuring which I use currently in our production, for anyone who is facing the same issue.
Use QueryFullProcessImageName to find the PE image file path of the child process.
Find the subsystem of this PE image. https://learn.microsoft.com/en-us/windows/win32/debug/pe-format
If the subsystem is GUI, don't use GenerateConsoleCtrlEvent on it.
If you are not familiar with PE format and don't want to read the doc, just do this:
Read at 0x3c as UINT16 of the PE file to find the offset of PE header.
Read UINT8 at PE_HEADER + 0x18 + 0x44, and 0x02 means a GUI application.
I would like to not mark this as an answer since I'm hoping some more elegant way.