input: change CHECKEVENT macro to verify_internal_event function

The macro is sufficient if called during a development cycle, but not
sufficient information when triggered by a user (e.g.
https://bugzilla.redhat.com/show_bug.cgi?id=688693).

Expand what this does to print the event content and a backtrace, so at
least we know where we're coming from. Only the first 32 bytes are printed
since if something goes wrong, the event we have is almost certainly an
xEvent or xError, both restricted to 32 bytes.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Daniel Stone <daniel@fooishbar.org>

Xi/exevents.c

@@ -77,6 +77,7 @@ SOFTWARE.
 #include "xiquerydevice.h" /* For List*Info */
 #include "eventconvert.h"
 #include "eventstr.h"
+#include "inpututils.h"
 
 #include <X11/extensions/XKBproto.h>
 #include "xkbsrv.h"
@@ -920,7 +921,7 @@ ProcessOtherEvent(InternalEvent *ev, DeviceIntPtr device)
     DeviceIntPtr mouse = NULL, kbd = NULL;
     DeviceEvent *event = &ev->device_event;
 
-    CHECKEVENT(ev);
+    verify_internal_event(ev);
 
     if (ev->any.type == ET_RawKeyPress ||
         ev->any.type == ET_RawKeyRelease ||

dix/events.c

@@ -2377,7 +2377,7 @@ DeliverDeviceEvents(WindowPtr pWin, InternalEvent *event, GrabPtr grab,
     xEvent *xE = NULL, *core = NULL;
     int rc, mask, count = 0;
 
-    CHECKEVENT(event);
+    verify_internal_event(event);
 
     while (pWin)
     {
@@ -2723,7 +2723,7 @@ CheckMotion(DeviceEvent *ev, DeviceIntPtr pDev)
     WindowPtr prevSpriteWin, newSpriteWin;
     SpritePtr pSprite = pDev->spriteInfo->sprite;
 
-    CHECKEVENT(ev);
+    verify_internal_event(ev);
 
     prevSpriteWin = pSprite->win;
 

dix/inpututils.c

@@ -36,6 +36,7 @@
 #include "xkbsrv.h"
 #include "xkbstr.h"
 #include "inpututils.h"
+#include "eventstr.h"
 
 /* Check if a button map change is okay with the device.
  * Returns -1 for BadValue, as it collides with MappingBusy. */
@@ -556,3 +557,30 @@ CountBits(const uint8_t *mask, int len)
 
     return ret;
 }
+
+/**
+ * Verifies sanity of the event. If the event is not an internal event,
+ * memdumps the first 32 bytes of event to the log, a backtrace, then kill
+ * the server.
+ */
+void verify_internal_event(const InternalEvent *ev)
+{
+    if (ev && ev->any.header != ET_Internal)
+    {
+        int i;
+        unsigned char *data = (unsigned char*)ev;
+
+        ErrorF("dix: invalid event type %d\n", ev->any.header);
+
+        for (i = 0; i < sizeof(xEvent); i++, data++)
+        {
+            ErrorF("%02hx ", *data);
+
+            if ((i % 8) == 7)
+                ErrorF("\n");
+        }
+
+        xorg_backtrace();
+        FatalError("Wrong event type %d. Aborting server\n", ev->any.header);
+    }
+}

include/eventstr.h

@@ -68,10 +68,6 @@ enum EventType {
     ET_Internal = 0xFF /* First byte */
 };
 
-#define CHECKEVENT(ev) if (ev && ((InternalEvent*)(ev))->any.header != 0xFF) \
-                          FatalError("Wrong event type %d.\n", \
-                                     ((InternalEvent*)(ev))->any.header);
-
 /**
  * Used for ALL input device events internal in the server until
  * copied into the matching protocol event.

include/inpututils.h

@@ -37,4 +37,6 @@ struct _ValuatorMask {
     int         valuators[MAX_VALUATORS]; /* valuator data */
 };
 
+extern void verify_internal_event(const InternalEvent *ev);
+
 #endif

mi/mieq.c

@@ -156,7 +156,7 @@ mieqEnqueue(DeviceIntPtr pDev, InternalEvent *e)
     pthread_mutex_lock(&miEventQueueMutex);
 #endif
 
-    CHECKEVENT(e);
+    verify_internal_event(e);
 
     /* avoid merging events from different devices */
     if (e->any.type == ET_Motion)
@@ -292,8 +292,8 @@ static void
 FixUpEventForMaster(DeviceIntPtr mdev, DeviceIntPtr sdev,
                     InternalEvent* original, InternalEvent *master)
 {
-    CHECKEVENT(original);
-    CHECKEVENT(master);
+    verify_internal_event(original);
+    verify_internal_event(master);
     /* Ensure chained button mappings, i.e. that the detail field is the
      * value of the mapped button on the SD, not the physical button */
     if (original->any.type == ET_ButtonPress ||
@@ -323,7 +323,7 @@ CopyGetMasterEvent(DeviceIntPtr sdev,
     int type = original->any.type;
     int mtype; /* which master type? */
 
-    CHECKEVENT(original);
+    verify_internal_event(original);
 
     /* ET_XQuartz has sdev == NULL */
     if (!sdev || IsMaster(sdev) || IsFloating(sdev))
@@ -376,7 +376,7 @@ mieqProcessDeviceEvent(DeviceIntPtr dev,
     DeviceIntPtr master;
     InternalEvent mevent; /* master event */
 
-    CHECKEVENT(event);
+    verify_internal_event(event);
 
     /* Custom event handler */
     handler = miEventQueue.handlers[event->any.type];