embeddedobj: fix lost native data when updating it via OLE fails

How to reproduce the problem:

1) Create an ODT file which has an OLE object, where the native data is
an OLE2 container, containing a Package stream, containing a DOCX file.

2) Install some external application on Windows which registers itself
as a handler for the DOCX CSLID [ this is where writing a testcase for
this bug is challenging ].

3) Open this document via Java, using URP. Load the document with
Hidden=true and OnMainThread=true.

4) Dispatch .uno:UpdateAll

5) Save the document using XStorable.store()

Expected result: the native data is there.

Actual result: the native data is sometimes missing (0 bytes). Typically
happens at least once if you perform the steps 4 times in a row.

The root cause is that GetUserClassID() Win32 API fails in some cases,
and re-trying a few times after a small sleep doesn't help.

Handle this error better by detecting this situation in
OleEmbeddedObject::SwitchOwnPersistence() and reusing the old native
data, similar to how svt::EmbeddedObjectRef::GetReplacement() updates
the preview image in a transactional way (only delete the old one when
we have a one one).

Finally, detect a broken OLE2 preview during reqif export, this way the
reqif export result's embedded object is editable in Word, while
\objdata was simply empty previously.

Change-Id: I4dd34ebe6ad892a14cdcfb82acc82d9edf790fb3
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/113814
Reviewed-by: Miklos Vajna <vmiklos@collabora.com>
Tested-by: Jenkins

2 files changed, 18 insertions, 0 deletions

diff --git a/embeddedobj/source/msole/olecomponent.cxx b/embeddedobj/source/msole/olecomponent.cxx
index 9fe827bb00d9..9843e4999f44 100644
--- a/embeddedobj/source/msole/olecomponent.cxx
+++ b/embeddedobj/source/msole/olecomponent.cxx
@@ -1299,7 +1299,10 @@ void OleComponent::StoreOwnTmpIfNecessary()
             GUID aCLSID;
             hr = m_pNativeImpl->m_pOleObject->GetUserClassID( &aCLSID );
             if ( FAILED( hr ) )
+            {
+                SAL_WARN("embeddedobj.ole", "OleComponent::StoreOwnTmpIfNecessary: GetUserClassID() failed");
                 throw io::IOException(); // TODO
+            }
 
             hr = WriteClassStg( m_pNativeImpl->m_pIStorage, aCLSID );
             if ( FAILED( hr ) )
diff --git a/embeddedobj/source/msole/olepersist.cxx b/embeddedobj/source/msole/olepersist.cxx
index 7f5002ec2772..fddf46d6e658 100644
--- a/embeddedobj/source/msole/olepersist.cxx
+++ b/embeddedobj/source/msole/olepersist.cxx
@@ -768,6 +768,21 @@ void OleEmbeddedObject::SwitchOwnPersistence( const uno::Reference< embed::XStor
     sal_Int32 nStreamMode = m_bReadOnly ? embed::ElementModes::READ : embed::ElementModes::READWRITE;
 
     uno::Reference< io::XStream > xNewOwnStream = xNewParentStorage->openStreamElement( aNewName, nStreamMode );
+
+    uno::Reference<io::XSeekable> xNewSeekable (xNewOwnStream, uno::UNO_QUERY);
+    if (xNewSeekable.is() && xNewSeekable->getLength() == 0)
+    {
+        uno::Reference<io::XSeekable> xOldSeekable(m_xObjectStream, uno::UNO_QUERY);
+        if (xOldSeekable.is() && xOldSeekable->getLength() > 0)
+        {
+            SAL_WARN("embeddedobj.ole", "OleEmbeddedObject::SwitchOwnPersistence: empty new stream, reusing old one");
+            uno::Reference<io::XInputStream> xInput = m_xObjectStream->getInputStream();
+            uno::Reference<io::XOutputStream> xOutput = xNewOwnStream->getOutputStream();
+            comphelper::OStorageHelper::CopyInputToOutput(xInput, xOutput);
+            xNewSeekable->seek(0);
+        }
+    }
+
     SAL_WARN_IF( !xNewOwnStream.is(), "embeddedobj.ole", "The method can not return empty reference!" );
 
     SwitchOwnPersistence( xNewParentStorage, xNewOwnStream, aNewName );