Change pendtail to be only a single pointer to the last event in queue

I could not wrap my head around what pendtail was attempting to do
without serious effort and pen and paper. All it needs to be is a simple
pointer to the last event in the queue, or NULL if there are no events.

Signed-off-by: Chase Douglas <chase.douglas@canonical.com>

2 files changed, 19 insertions, 13 deletions

diff --git a/dix/events.c b/dix/events.c
index 256d9d585..6487a711e 100644
--- a/dix/events.c
+++ b/dix/events.c
@@ -1128,7 +1128,7 @@ NoticeEventTime(InternalEvent *ev)
 void
 EnqueueEvent(InternalEvent *ev, DeviceIntPtr device)
 {
-    QdEventPtr	tail = *syncEvents.pendtail;
+    QdEventPtr	tail = syncEvents.pendtail;
     QdEventPtr	qe;
     SpritePtr	pSprite = device->spriteInfo->sprite;
     int		eventlen;
@@ -1199,8 +1199,10 @@ EnqueueEvent(InternalEvent *ev, DeviceIntPtr device)
     qe->event = (InternalEvent *)(qe + 1);
     memcpy(qe->event, event, eventlen);
     if (tail)
-	syncEvents.pendtail = &tail->next;
-    *syncEvents.pendtail = qe;
+        tail->next = qe;
+    else
+        syncEvents.pending = qe;
+    syncEvents.pendtail = qe;
 }
 
 /**
@@ -1215,18 +1217,19 @@ EnqueueEvent(InternalEvent *ev, DeviceIntPtr device)
 static void
 PlayReleasedEvents(void)
 {
-    QdEventPtr *prev, qe;
+    QdEventPtr prev = NULL;
+    QdEventPtr qe = syncEvents.pending;
     DeviceIntPtr dev;
     DeviceIntPtr pDev;
 
-    prev = &syncEvents.pending;
-    while ( (qe = *prev) )
+    while (qe)
     {
 	if (!qe->device->deviceGrab.sync.frozen)
 	{
-	    *prev = qe->next;
+            if (syncEvents.pending == qe)
+                syncEvents.pending = qe->next;
             pDev = qe->device;
-	    if (*syncEvents.pendtail == *prev)
+            if (syncEvents.pendtail == qe)
 		syncEvents.pendtail = prev;
 	    if (qe->event->any.type == ET_Motion)
 		CheckVirtualMotion(pDev, qe, NullWindow);
@@ -1266,10 +1269,13 @@ PlayReleasedEvents(void)
 		break;
 	    /* Playing the event may have unfrozen another device. */
 	    /* So to play it safe, restart at the head of the queue */
-	    prev = &syncEvents.pending;
+            qe = syncEvents.pending;
+            prev = NULL;
 	}
-	else
-	    prev = &qe->next;
+	else {
+            prev = qe;
+            qe = qe->next;
+        }
     }
 }
 
@@ -5618,7 +5624,7 @@ InitEvents(void)
 	free(syncEvents.pending);
 	syncEvents.pending = next;
     }
-    syncEvents.pendtail = &syncEvents.pending;
+    syncEvents.pendtail = NULL;
     syncEvents.playingEvents = FALSE;
     syncEvents.time.months = 0;
     syncEvents.time.milliseconds = 0;	/* hardly matters */
diff --git a/include/inputstr.h b/include/inputstr.h
index 339529020..43372c3eb 100644
--- a/include/inputstr.h
+++ b/include/inputstr.h
@@ -649,7 +649,7 @@ typedef struct _QdEvent {
  */
 typedef struct _EventSyncInfo {
     QdEventPtr          pending, /**<  list of queued events */
-                        *pendtail; /**< last event in list */
+                        pendtail; /**< last event in list */
     /** The device to replay events for. Only set in AllowEvents(), in which
      * case it is set to the device specified in the request. */
     DeviceIntPtr        replayDev;      /* kludgy rock to put flag for */