crashtest: crash on layout of novell622972-2.html

Change-Id: I49be59a9b9cdda8f80b6579f393be0a99f231833

sw/source/core/inc/flowfrm.hxx

@@ -62,6 +62,7 @@ class SwFlowFrm
     friend inline void TableSplitRecalcUnlock( SwFlowFrm * );
     // #i44049#
     friend class SwObjectFormatterTxtFrm;
+    friend class JoinLockGuard;
 
     // TblSel is allowed to reset the follow-bit
     friend inline void UnsetFollow( SwFlowFrm *pFlow );
@@ -234,6 +235,39 @@ inline bool SwFlowFrm::IsFwdMoveAllowed()
 {
     return m_rThis.GetIndPrev() != 0;
 }
+
+//use this to protect a SwLayoutFrm for a given scope from getting merged with
+//its neighbour and thus deleted
+class JoinLockGuard
+{
+private:
+    SwFlowFrm *m_pFlow;
+    bool m_bOldJoinLocked;
+public:
+    //JoinLock pParent for the lifetime of the Cut/Paste call, etc. to avoid
+    //SwSectionFrm::MergeNext removing the pParent we're trying to reparent
+    //into
+    JoinLockGuard(SwLayoutFrm* pFrm)
+    {
+        m_pFlow = SwFlowFrm::CastFlowFrm(pFrm);
+        if (m_pFlow)
+        {
+            m_bOldJoinLocked = m_pFlow->IsJoinLocked();
+            m_pFlow->LockJoin();
+        }
+        else
+        {
+            m_bOldJoinLocked = false;
+        }
+    }
+
+    ~JoinLockGuard()
+    {
+        if (m_pFlow && !m_bOldJoinLocked)
+            m_pFlow->UnlockJoin();
+    }
+};
+
 #endif
 
 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */

sw/source/core/layout/flowfrm.cxx

@@ -574,23 +574,18 @@ void SwFlowFrm::MoveSubTree( SwLayoutFrm* pParent, SwFrm* pSibling )
 
     SwPageFrm *pOldPage = m_rThis.FindPageFrm();
 
-    //JoinLock pParent for the lifetime of the Cut/Paste call to avoid
-    //SwSectionFrm::MergeNext removing the pParent we're trying to reparent
-    //into
-    bool bOldJoinLocked(false);
-    SwFlowFrm *pParentFlow = SwFlowFrm::CastFlowFrm(pParent);
-    if (pParentFlow)
+    SwLayoutFrm *pOldParent;
+    bool bInvaLay;
+
     {
-        bOldJoinLocked = pParentFlow->IsJoinLocked();
-        pParentFlow->LockJoin();
+        //JoinLock pParent for the lifetime of the Cut/Paste call to avoid
+        //SwSectionFrm::MergeNext removing the pParent we're trying to reparent
+        //into
+        JoinLockGuard aJoinGuard(pParent);
+        pOldParent = CutTree( &m_rThis );
+        bInvaLay = PasteTree( &m_rThis, pParent, pSibling, pOldParent );
     }
 
-    SwLayoutFrm *pOldParent = CutTree( &m_rThis );
-    const bool bInvaLay = PasteTree( &m_rThis, pParent, pSibling, pOldParent );
-
-    if (pParentFlow && !bOldJoinLocked)
-        pParentFlow->UnlockJoin();
-
     // If, by cutting & pasting, an empty SectionFrm came into existence, it should
     // disappear automatically.
     SwSectionFrm *pSct;

sw/source/core/layout/layact.cxx

@@ -1239,7 +1239,13 @@ bool SwLayAction::FormatLayout( SwLayoutFrm *pLay, bool bAddRect )
             aOldRect = static_cast<SwPageFrm*>(pLay)->GetBoundRect();
         }
 
-        pLay->Calc();
+        {
+            //JoinLock pParent for the lifetime of the Calc call to avoid
+            //SwSectionFrm::MergeNext removing the pLay we're trying to Format
+            JoinLockGuard aJoinGuard(pLay);
+            pLay->Calc();
+        }
+
         if ( aOldFrame != pLay->Frm() )
             bChanged = true;