fdo#70345 Reuse XStream for Windows platform create a new one for others.

Change-Id: I911c24b82b55445c6f95e14be29759e2fe3d9dfd
Reviewed-on: https://gerrit.libreoffice.org/6580Reviewed-by: Michael Stahl <mstahl@redhat.com>
Tested-by: Michael Stahl <mstahl@redhat.com>

sfx2/source/doc/docfile.cxx

@@ -604,13 +604,26 @@ SvStream* SfxMedium::GetOutStream()
 
         if ( pImp->pTempFile )
         {
-            // don't try to re-use XOutStream from xStream if that exists;
+            // On windows we try to re-use XOutStream from xStream if that exists;
+            // because opening new SvFileStream in this situation may fail with ERROR_SHARING_VIOLATION
+            #ifdef WNT
+            if (pImp->xStream.is())
+            {
+                assert(pImp->xStream->getOutputStream().is()); // need that...
+                pImp->m_pOutStream = utl::UcbStreamHelper::CreateStream(
+                        pImp->xStream, false);
+            }
+            else
+            {
+                pImp->m_pOutStream = new SvFileStream(
+                        pImp->m_aName, STREAM_STD_READWRITE);
+            }
+            // On Unix don't try to re-use XOutStream from xStream if that exists;
             // it causes fdo#59022 (fails opening files via SMB on Linux)
-            // OTOH opening new SvFileStream in this situation may fail on
-            // Windows with ERROR_SHARING_VIOLATION... but that is apparently
-            // not a problem in practice currently
+            #else
             pImp->m_pOutStream = new SvFileStream(
                         pImp->m_aName, STREAM_STD_READWRITE);
+            #endif
             CloseStorage();
         }
     }