Exit as soon as possible on input grabbing error

We want to know at once if slock failed or not to lock the screen, not
seing a black screen for a whole second (or two) and then die.
Thanks to ^7heo for reporting this.

1 files changed, 20 insertions, 24 deletions

diff --git a/slock.c b/slock.c
index 210d5c8..dd32374 100644
--- a/slock.c
+++ b/slock.c
@@ -222,7 +222,6 @@ static Lock *
 lockscreen(Display *dpy, int screen)
 {
         char curs[] = {0, 0, 0, 0, 0, 0, 0, 0};
-        unsigned int len;
         int i;
         Lock *lock;
         XColor color, dummy;
@@ -249,34 +248,31 @@ lockscreen(Display *dpy, int screen)
         lock->pmap = XCreateBitmapFromData(dpy, lock->win, curs, 8, 8);
         invisible = XCreatePixmapCursor(dpy, lock->pmap, lock->pmap, &color, &color, 0, 0);
         XDefineCursor(dpy, lock->win, invisible);
-        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 (!len) {
+        if (XGrabPointer(dpy, lock->root, False, ButtonPressMask |
+            ButtonReleaseMask | PointerMotionMask, GrabModeAsync, GrabModeAsync,
+            None, invisible, CurrentTime) != GrabSuccess) {
                 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) {
-                                /* everything fine, we grabbed both inputs */
-                                XSelectInput(dpy, lock->root, SubstructureNotifyMask);
-                                return lock;
-                        }
-                        usleep(1000);
-                }
+                running = 0;
+                unlockscreen(dpy, lock);
+                return NULL;
+        }
+
+        if (XGrabKeyboard(dpy, lock->root, True, GrabModeAsync, GrabModeAsync,
+            CurrentTime) != GrabSuccess) {
                 fprintf(stderr, "slock: unable to grab keyboard for screen %d\n", screen);
+                running = 0;
+                unlockscreen(dpy, lock);
+                return NULL;
         }
-        /* grabbing one of the inputs failed */
-        running = 0;
-        unlockscreen(dpy, lock);
-        return NULL;
+
+        XMapRaised(dpy, lock->win);
+        if (rr)
+                XRRSelectInput(dpy, lock->win, RRScreenChangeNotifyMask);
+
+        XSelectInput(dpy, lock->root, SubstructureNotifyMask);
+        return lock;
 }
 
 static void