Attempt to fix issue #1558 "Crash when copying files/folders"

diff --git a/Src/Common/CMoveConstraint.cpp b/Src/Common/CMoveConstraint.cpp
index e549cfa..65f00cd 100644 (file)
--- a/Src/Common/CMoveConstraint.cpp
+++ b/Src/Common/CMoveConstraint.cpp
@@ -336,6 +336,8 @@ LRESULT CALLBACK
 CMoveConstraint::ConstraintWndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
 {
        void * data = GetProp(hwnd, _T("CMoveConstraintData"));
+       if (!data)
+               return DefWindowProc(hwnd, msg, wParam, lParam);
        CMoveConstraint * constraint = reinterpret_cast<CMoveConstraint *>(data);
 
        LRESULT lresult;
@@ -350,10 +352,19 @@ CMoveConstraint::SubclassWnd()
        void * data = reinterpret_cast<void *>(this);
        // this will return false if this window/wndproc combination has already
        // been established (subclassed)
-       m_bSubclassed = true;
        m_oldWndProc = reinterpret_cast<WNDPROC>(GetWindowLongPtr(m_hwndDlg, GWLP_WNDPROC));
-       SetWindowLongPtr(m_hwndDlg, GWLP_WNDPROC, (__int3264)(LONG_PTR)(CMoveConstraint::ConstraintWndProc));
-       SetProp(m_hwndDlg, _T("CMoveConstraintData"), data);
+       if (SetWindowLongPtr(m_hwndDlg, GWLP_WNDPROC, (__int3264)(LONG_PTR)(CMoveConstraint::ConstraintWndProc)) != 0)
+       {
+               if (SetProp(m_hwndDlg, _T("CMoveConstraintData"), data))
+               {
+                       m_bSubclassed = true;
+               }
+               else
+               {
+                       SetWindowLongPtr(m_hwndDlg, GWLP_WNDPROC, (__int3264)(LONG_PTR)(m_oldWndProc));
+                       m_oldWndProc = nullptr;
+               }
+       }
        return m_bSubclassed;
 }
 bool