New program to report cursor position

Makefile

@@ -1,6 +1,8 @@
 CFLAGS = -Wall
 LDLIBS = -lX11
 
-all: xss xsswin
+all: xss xsswin xcursorpos
 
 xss: LDLIBS += -lXss
+
+.PHONY: all

README

@@ -7,6 +7,7 @@ xsswin makes a full-screen black window and runs some other program,
 passing along the window ID in the environment ($XSS_WINDOW) and
 possibly as an argument (XSS_WINDOW gets replaced with the id).
 
+xcursorpos prints out the x and y coordinates of the cursor.
 
 Examples
 --------
@@ -26,9 +27,12 @@ Run like xscreensaver (no locking):
     xss xsswin /usr/lib/xscreensaver/flurry -window-id XSS_WINDOW
 
 
-Shell script to run an xscreensaver hack and xtrlock at the same time:
+Shell script to run an xscreensaver hack and xtrlock at the same time,
+but prevent locking if the cursor is in the upper-left corner:
 
     #! /bin/sh
+    
+    xcursorpos | (read x y; [ $x -lt 20 -a $y -lt 20 ]) && exit 0
     xsswin /usr/lib/xscreensaver/qix -window-id XSS_WINDOW &
     pid=$!
     xtrlock

xcursorpos.c

@@ -0,0 +1,55 @@
+/* xcursorpos -- print current cursor coordinates
+ * Copyright (C) 2008  Neale Pickett <neale@woozle.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or (at
+ * your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <stdio.h>
+#include <X11/Xlib.h>
+#include "obj.h"
+
+int
+main(int argc, char *argv[])
+{
+  Display *display = NULL;
+
+  if (argc != 1) {
+    fprintf(stderr, "Usage: %s\n", argv[0]);
+    return 64;                  /* EX_USAGE */
+  }
+
+  try {
+    Window       root, win;
+    int          x, y, win_x, win_y;
+    unsigned int mask;
+
+    if (! (display = XOpenDisplay(NULL))) raise("cannot open display");
+    root = DefaultRootWindow(display);
+    if (! XQueryPointer(display, root, &root, &win, &x, &y, &win_x, &win_y, &mask)) {
+      raise("unable to query pointer");
+    }
+    printf("%d %d\n", x, y);
+  } while (0);
+
+  if (display) {
+    (void)XCloseDisplay(display);
+  }
+
+  except {
+    fprintf(stderr, "Error: %s\n", exception);
+    return 69;                  /* EX_UNAVAILABLE */
+  }
+
+  return 0;
+}