dix: drop DeviceIntRec's activeGrab struct

Obsolete since 4bc2761ad5. This struct
existed so copying a passive grab could be simply done by
  activeGrab = *grab

and thus have a copy of the GrabPtr we'd get from various sources but still
be able to check device->grab for NULL.

Since 4bc2761 activeGrab is a pointer itself and points to the same memory
as grabinfo->grab, leaving us with the potential of dangling pointers if
either calls FreeGrab() and doesn't reset the other one.

There is no reader of activeGrab anyway, so simply removing it is
sufficient.

Note: field is merely renamed to keep the ABI. Should be removed in the
future.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>

dix/devices.c

@@ -281,7 +281,6 @@ AddInputDevice(ClientPtr client, DeviceProc deviceProc, Bool autoStart)
     dev->deviceGrab.grabTime = currentTime;
     dev->deviceGrab.ActivateGrab = ActivateKeyboardGrab;
     dev->deviceGrab.DeactivateGrab = DeactivateKeyboardGrab;
-    dev->deviceGrab.activeGrab = AllocGrab();
     dev->deviceGrab.sync.event = calloc(1, sizeof(DeviceEvent));
 
     XkbSetExtension(dev, ProcessKeyboardEvent);
@@ -977,7 +976,8 @@ CloseDevice(DeviceIntPtr dev)
         }
     }
 
-    FreeGrab(dev->deviceGrab.activeGrab);
+    if (dev->deviceGrab.grab)
+        FreeGrab(dev->deviceGrab.grab);
     free(dev->deviceGrab.sync.event);
     free(dev->config_info);     /* Allocated in xf86ActivateDevice. */
     free(dev->last.scroll);

dix/events.c

@@ -1490,8 +1490,9 @@ ActivatePointerGrab(DeviceIntPtr mouse, GrabPtr grab,
         grabinfo->grabTime = time;
     if (grab->cursor)
         grab->cursor->refcnt++;
-    CopyGrab(grabinfo->activeGrab, grab);
-    grabinfo->grab = grabinfo->activeGrab;
+    BUG_WARN(grabinfo->grab != NULL);
+    grabinfo->grab = AllocGrab();
+    CopyGrab(grabinfo->grab, grab);
     grabinfo->fromPassiveGrab = isPassive;
     grabinfo->implicitGrab = autoGrab & ImplicitGrabMask;
     PostNewCursor(mouse);
@@ -1554,6 +1555,8 @@ DeactivatePointerGrab(DeviceIntPtr mouse)
         ReattachToOldMaster(mouse);
 
     ComputeFreezes();
+
+    FreeGrab(grab);
 }
 
 /**
@@ -1591,8 +1594,9 @@ ActivateKeyboardGrab(DeviceIntPtr keybd, GrabPtr grab, TimeStamp time,
         grabinfo->grabTime = syncEvents.time;
     else
         grabinfo->grabTime = time;
-    CopyGrab(grabinfo->activeGrab, grab);
-    grabinfo->grab = grabinfo->activeGrab;
+    BUG_WARN(grabinfo->grab != NULL);
+    grabinfo->grab = AllocGrab();
+    CopyGrab(grabinfo->grab, grab);
     grabinfo->fromPassiveGrab = passive;
     grabinfo->implicitGrab = passive & ImplicitGrabMask;
     CheckGrabForSyncs(keybd, (Bool) grab->keyboardMode,
@@ -1638,6 +1642,8 @@ DeactivateKeyboardGrab(DeviceIntPtr keybd)
         ReattachToOldMaster(keybd);
 
     ComputeFreezes();
+
+    FreeGrab(grab);
 }
 
 void

include/inputstr.h

@@ -485,7 +485,7 @@ typedef struct _GrabInfoRec {
     TimeStamp grabTime;
     Bool fromPassiveGrab;       /* true if from passive grab */
     Bool implicitGrab;          /* implicit from ButtonPress */
-    GrabPtr activeGrab;
+    GrabPtr unused;             /* Kept for ABI stability, remove soon */
     GrabPtr grab;
     CARD8 activatingKey;
     void (*ActivateGrab) (DeviceIntPtr /*device */ ,