Thread: signals on windows

I replicated kill( pid, SIGTERM ), kill( pid, SIGSTOP ) & kill( SIGCONT ) using TerminateProcess, CreateToolhelp32Snapshot, SuspendThread & ResumeThread but struggling to find info on how to replicate kill( pid, SIGSEGV ), anyone have any ideas? And yes I know it's unlikely to have any actual use but if I'm going to replicate the kill function then I should do it properly and implement everything that it supports on linux

So far this is all I've been able to come up with:

Code:

#ifdef PAW_API_MSW
/*BOOL CALLBACK EnumThreadWndProc( HWND hwnd, LPARAM lParam );*/
BOOL CALLBACK term_window( HWND hwnd, LPARAM lParam )
	{ return PostMessageA( hwnd, WM_QUIT, EXIT_FAILURE, 0 ); }
BOOL CALLBACK segv_window( HWND hwnd, LPARAM lParam )
	{ return PostMessageA( hwnd, WM_QUIT, ERROR_INVALID_ACCESS, 0 ); }
RAWPAW_API pawd pawsigid( pawjd tid, PAWSIG sig )
{
	pawd err = 0;
	HANDLE thread = OpenThread( THREAD_ALL_ACCESS, FALSE, tid );
	if ( !thread )
		return -1;
	switch ( sig )
	{
	case PAWSIG_KILL: TerminateThread( thread, EXIT_SUCCESS ); break;
	case PAWSIG_TERM:
		err = -(EnumThreadWindows( tid, term_window, 0 ) != TRUE);
		break;
	case PAWSIG_STOP: SuspendThread( thread ); break;
	case PAWSIG_CONT: ResumeThread( thread ); break;
	default: err = -1;
	}
	CloseHandle( thread );
	return err;
}
static pawd pawsig_threads( DWORD pid, PAWSIG sig )
{
	HANDLE threads = CreateToolhelp32Snapshot( TH32CS_SNAPTHREAD, pid );
	THREADENTRY32 thread;
	BOOL valid = FALSE;

	if ( !threads )
		return -1;

	thread.dwSize = sizeof(THREADENTRY32);

	for
	(
		valid = Thread32First(threads, &thread)
		; valid == TRUE
		; pawsigid( thread.th32ThreadID, sig )
		, valid = Thread32Next(threads, &thread)
	);

	CloseHandle(threads);
	return 0;
}
RAWPAW_API pawd pawsigpid( pawjd pid, PAWSIG sig )
{
	pawd err = 0;
	HANDLE proc = NULL;
	switch ( sig )
	{
	case PAWSIG_KILL:
		proc = OpenProcess( PROCESS_TERMINATE, FALSE, pid );
		if ( !proc )
			return -1;
		TerminateProcess( proc, EXIT_SUCCESS );
		CloseHandle( proc );
		break;
	default:
		err = pawsig_threads(pid,sig);
	}
	return err;
}
#else
RAWPAW_API pawd pawsigid( pawjd tid, PAWSIG sig )
	{ return pthread_kill( tid, pawsignals[sig] ); }
RAWPAW_API pawd pawsigpid( pawjd pid, PAWSIG sig )
	{ return kill( pid, pawsignals[sig] ); }
#endif

Not even sure ERROR_INVALID_ACCESS is the right code to mimic SEGV

Originally Posted by aGerman

The return value for segfaults on Windows is -1073741819 (0xC0000005). You can reproduce it with this line of code

Code:

int main(void){ (void)(*(volatile char *)0 = 0); }

Run the program in a cmd prompt and execute echo %errorlevel% to get the return value.

You could pass this value to the second parameter of TerminateProcess().

Thank you Won't use it in TerminateProcess since it's supposed to be catchable last I checked, even in linux but if I find otherwise then yeah, I'll switch at that time

Originally Posted by adeyblue

I'm pretty sure there's a difference between PostMessage(WM_QUIT) and PostQuitMessage(), in that one is likely to be ignored and one will end the message loop.

Since you can't PostQuitMessage to a foreign thread, just post WM_CLOSE instead. You can't set the exit code of the thread with this, but you couldn't guarantee the app would respect the exit code you set anyway.

Also CreateToolhelp32Snapshot returns INVALID_HANDLE_VALUE when it fails, that value is not 0.


STATUS_ACCESS_VIOLATION is the define.

Right, I forgot windows was designed by idiots, sure they're smart programmers but when it comes to design they leave a LOT to be desired

Edit: Forgot to say thanks for the info on the other stuff, been so long since I did any real windows programming that I forgot they have 1001 ways to do the same thing with only 1 being the right way

Originally Posted by aGerman

Probably I would have used SendMessageTimeout() then However, I don't know if it works along with WM_QUIT as I didn't test.


D'oh. I looked it up in the HRESULTs instead of the list of NTSTATUS values

Probably does, seg faults typically trigger core dumps so the 2 combined would be rather natural