error messages on grab failure

diff --git a/slock.c b/slock.c
index d2c3729..df2d3c6 100644 (file)
--- a/slock.c
+++ b/slock.c
@@ -230,7 +230,7 @@ lockscreen(Display *dpy, int screen)
        XSetWindowAttributes wa;
        Cursor invisible;
 
-       if (dpy == NULL || screen < 0 || !(lock = malloc(sizeof(Lock))))
+       if (!running || dpy == NULL || screen < 0 || !(lock = malloc(sizeof(Lock))))
                return NULL;
 
        lock->screen = screen;
@@ -253,29 +253,31 @@ lockscreen(Display *dpy, int screen)
        XMapRaised(dpy, lock->win);
        if (rr)
                XRRSelectInput(dpy, lock->win, RRScreenChangeNotifyMask);
+
+       /* Try to grab mouse pointer *and* keyboard, else fail the lock */
        for (len = 1000; len; len--) {
                if (XGrabPointer(dpy, lock->root, False, ButtonPressMask | ButtonReleaseMask | PointerMotionMask,
                    GrabModeAsync, GrabModeAsync, None, invisible, CurrentTime) == GrabSuccess)
                        break;
                usleep(1000);
        }
-       if (running && len) {
+       if (!len) {
+               fprintf(stderr, "slock: unable to grab mouse pointer for screen %d\n", screen);
+       } else {
                for (len = 1000; len; len--) {
-                       if (XGrabKeyboard(dpy, lock->root, True, GrabModeAsync, GrabModeAsync, CurrentTime) == GrabSuccess)
-                               break;
+                       if (XGrabKeyboard(dpy, lock->root, True, GrabModeAsync, GrabModeAsync, CurrentTime) == GrabSuccess) {
+                               /* everything fine, we grabbed both inputs */
+                               XSelectInput(dpy, lock->root, SubstructureNotifyMask);
+                               return lock;
+                       }
                        usleep(1000);
                }
+               fprintf(stderr, "slock: unable to grab keyboard for screen %d\n", screen);
        }
-
-       running &= (len > 0);
-       if (!running) {
-               unlockscreen(dpy, lock);
-               lock = NULL;
-       } else {
-               XSelectInput(dpy, lock->root, SubstructureNotifyMask);
-       }
-
-       return lock;
+       /* grabbing one of the inputs failed */
+       running = 0;
+       unlockscreen(dpy, lock);
+       return NULL;
 }
 
 static void