#include <X11/Xlib-xcb.h>
#include <stdio.h>

static int nullHandler(Display *dpy, XErrorEvent *err)
{
	puts("Got error");
	return 0;
}

int main()
{
	XInitThreads();

	Display *dpy = XOpenDisplay(NULL);
	xcb_connection_t *c = XGetXCBConnection(dpy);
	uint32_t random_id = xcb_generate_id(c);

	XSetEventQueueOwner(dpy, XCBOwnsEventQueue);
	XSetErrorHandler(nullHandler);

	while (True) {
		/* First, let's make sure that Xlib has no idea what the current
		 * sequence number is.
		 */
		for (int i = 0; i < (2<<16)+(2<<14); i++) {
			xcb_no_operation(c);
		}
		puts("Done with the NoOperation requests");

		/* Finally, let's break Xlib */

		/* Xlib makes sure that it will handle the error (if any) for
		 * this request: append_pending_request() in xcb_io.c
		 */
		XCreateWindow(dpy, random_id, 0, 0, 10, 10, 0, 24, InputOutput, CopyFromParent, 0, NULL);

		/* _XReply() now handles the previous pending request and gets
		 * the error. While calling the error handler, it will deadlock.
		 */
		XCreateWindow(dpy, random_id, 0, 0, 10, 10, 0, 24, InputOutput, CopyFromParent, 0, NULL);

		puts("Oh shit, it survived?!");
	}
}