Quartz: Fix Potential Race

[Robert Shearman]

Fixes nasty race that could cause subtle memory corruption or hard to 
reproduce crashes due to This->pConnectedTo potentially being destroyed 
by another thread disconnecting the pin.

Changelog:
Fix potential race in IPinImpl_ConnectedTo

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Index: wine/dlls/quartz/pin.c
===================================================================
RCS file: /home/wine/wine/dlls/quartz/pin.c,v
retrieving revision 1.3
diff -u -r1.3 pin.c
--- wine/dlls/quartz/pin.c	18 Nov 2003 20:47:48 -0000	1.3
+++ wine/dlls/quartz/pin.c	14 Aug 2004 14:01:48 -0000
@@ -247,19 +247,25 @@
 
 HRESULT WINAPI IPinImpl_ConnectedTo(IPin * iface, IPin ** ppPin)
 {
+    HRESULT hr;
     ICOM_THIS(IPinImpl, iface);
 
 /*  TRACE("(%p)\n", ppPin);*/
 
-    *ppPin = This->pConnectedTo;
-
-    if (*ppPin)
+    EnterCriticalSection(This->pCritSec);
     {
-        IPin_AddRef(*ppPin);
-        return S_OK;
+        if (This->pConnectedTo)
+        {
+            *ppPin = This->pConnectedTo;
+            IPin_AddRef(*ppPin);
+            hr = S_OK;
+        }
+        else
+            hr = VFW_E_NOT_CONNECTED;
     }
-    else
-        return VFW_E_NOT_CONNECTED;
+    LeaveCriticalSection(This->pCritSec);
+
+    return hr;
 }
 
 HRESULT WINAPI IPinImpl_ConnectionMediaType(IPin * iface, AM_MEDIA_TYPE * pmt)