Re-introduce the waiting loop for input grabbing

We actually “need” to wait a little for input to be released before
locking for cases where slock is spawned from other graphical
applications using keybindings.
This undoes the misbehaviour I introduced in c2f9757, sorry for the mess.

1 files changed, 38 insertions, 22 deletions

diff --git a/slock.c b/slock.c
index 4980325..97c7489 100644
--- a/slock.c
+++ b/slock.c
@@ -223,6 +223,7 @@ unlockscreen(Display *dpy, Lock *lock)
                 return;
 
         XUngrabPointer(dpy, CurrentTime);
+        XUngrabKeyboard(dpy, CurrentTime);
         XFreeColors(dpy, DefaultColormap(dpy, lock->screen), lock->colors, NUMCOLS, 0);
         XFreePixmap(dpy, lock->pmap);
         XDestroyWindow(dpy, lock->win);
@@ -241,7 +242,7 @@ static Lock *
 lockscreen(Display *dpy, int screen)
 {
         char curs[] = {0, 0, 0, 0, 0, 0, 0, 0};
-        int i;
+        int i, ptgrab, kbgrab;
         Lock *lock;
         XColor color, dummy;
         XSetWindowAttributes wa;
@@ -268,30 +269,45 @@ lockscreen(Display *dpy, int screen)
         invisible = XCreatePixmapCursor(dpy, lock->pmap, lock->pmap, &color, &color, 0, 0);
         XDefineCursor(dpy, lock->win, invisible);
 
-        /* Try to grab mouse pointer *and* keyboard, else fail the lock */
-        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);
-                running = 0;
-                unlockscreen(dpy, lock);
-                return NULL;
-        }
+        /* Try to grab mouse pointer *and* keyboard for 600ms, else fail the lock */
+        for (i = 6, ptgrab = kbgrab = -1; i; --i) {
+                if (ptgrab != GrabSuccess) {
+                        ptgrab = XGrabPointer(dpy, lock->root, False,
+                                 ButtonPressMask | ButtonReleaseMask |
+                                 PointerMotionMask, GrabModeAsync,
+                                 GrabModeAsync, None, invisible, CurrentTime);
+                }
+                if (kbgrab != GrabSuccess) {
+                        kbgrab = XGrabKeyboard(dpy, lock->root, True,
+                                 GrabModeAsync, GrabModeAsync, CurrentTime);
+                }
 
-        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;
-        }
+                /* input is grabbed: we can lock the screen */
+                if (ptgrab == GrabSuccess && kbgrab == GrabSuccess) {
+                        XMapRaised(dpy, lock->win);
+                        if (rr)
+                                XRRSelectInput(dpy, lock->win, RRScreenChangeNotifyMask);
+
+                        XSelectInput(dpy, lock->root, SubstructureNotifyMask);
+                        return lock;
+                }
 
-        XMapRaised(dpy, lock->win);
-        if (rr)
-                XRRSelectInput(dpy, lock->win, RRScreenChangeNotifyMask);
+                /* retry on AlreadyGrabbed but fail on other errors */
+                if ((ptgrab != AlreadyGrabbed && ptgrab != GrabSuccess) ||
+                    (kbgrab != AlreadyGrabbed && kbgrab != GrabSuccess))
+                        break;
 
-        XSelectInput(dpy, lock->root, SubstructureNotifyMask);
-        return lock;
+                usleep(100000);
+        }
+
+        /* we couldn't grab all input: fail out */
+        if (ptgrab != GrabSuccess)
+                fprintf(stderr, "slock: unable to grab mouse pointer for screen %d\n", screen);
+        if (kbgrab != GrabSuccess)
+                fprintf(stderr, "slock: unable to grab keyboard for screen %d\n", screen);
+        running = 0;
+        unlockscreen(dpy, lock);
+        return NULL;
 }
 
 static void