xlockkbd.c


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#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <X11/Xlib.h>
#include <X11/keysym.h>

static void die(const char *s)
{
	fprintf(stderr, "xlockkbd: %s\n", s);
	exit(1);
}

static bool grab_kbd(Display *d, int screen)
{
	return (XGrabKeyboard(d, RootWindow(d, screen), True, GrabModeAsync,
			GrabModeAsync, CurrentTime)
		== GrabSuccess);
}

static void wait_for_key(Display *d)
{
	XEvent ev;
	while (!XNextEvent(d, &ev)) {
		if (ev.type == KeyPress &&
				XLookupKeysym(&ev.xkey, 0) == XK_Escape)
			break;
	}
}

int main()
{
	Display *d = XOpenDisplay(NULL);
	if (!d)
		die("cannot open display");

	for (int i = 0; i < ScreenCount(d); ++i) {
		if (!grab_kbd(d, i))
			die("failed to grab keyboard");
	}

	wait_for_key(d);
	return 0;
}