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.

(cherry picked from commit fb4dc0f1786e0a036fc224393e91a3f1fdbff1b3)

Change-Id: I4dd34ebe6ad892a14cdcfb82acc82d9edf790fb3

1 files changed, 9 insertions, 0 deletions

diff --git a/sw/source/filter/html/htmlreqifreader.cxx b/sw/source/filter/html/htmlreqifreader.cxx
index 005dd2788640..6488f32ad578 100644
--- a/sw/source/filter/html/htmlreqifreader.cxx
+++ b/sw/source/filter/html/htmlreqifreader.cxx
@@ -142,6 +142,15 @@ bool ParseOLE2Presentation(SvStream& rOle2, sal_uInt32& nWidth, sal_uInt32& nHei
     // Read Data.
     if (nSize > xOle2Presentation->remainingSize())
         return false;
+
+    if (nSize <= 64)
+    {
+        SAL_WARN("sw.html",
+                 "ParseOLE2Presentation: ignoring potentially broken small preview: size is "
+                     << nSize);
+        return false;
+    }
+
     std::vector<char> aBuffer(nSize);
     xOle2Presentation->ReadBytes(aBuffer.data(), aBuffer.size());
     rPresentationData.WriteBytes(aBuffer.data(), aBuffer.size());