tdf#151470 svtools: prevent storing broken graphic of embedded objects

Updating the preview of the embedded PDF object in the bugdoc leads to
Acrobat generating a new preview, we throw away the old one, write the
new one to the document, and next time the document is opened, we can't
parse it, so the preview is lost for the user.

The reason for this seems to be that sometimes Acrobat generates a
broken WMF: the first 4 bytes is 0x0002 (DISKMETAFILE from the
MetafileType enum), but the next 4 bytes is 0x6f43, which means that the
header size is 56966 bytes long, but the whole preview is 29291, so this
WMF looks broken.

Fix the problem by adding error handling before we insert the WMF we get
from Acrobat as a graphic stream to the document storage: don't update
the graphic stream if the data is something that can't be handled by
VCL's graphic filters. svt::EmbeddedObjectRef::GetReplacement() has a
similar error handling, which is why the preview only gets broken on
document reload.

No testcase, this only happens on Windows and only in case a problematic
handler for PDF is installed, which is hard to test from 'make check'.

Change-Id: I9e1ce979e58a155fa5e72e31cd9ea38258bb8b6a
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/141229
Reviewed-by: Miklos Vajna <vmiklos@collabora.com>
Tested-by: Jenkins

1 files changed, 34 insertions, 1 deletions

diff --git a/svtools/source/misc/embedhlp.cxx b/svtools/source/misc/embedhlp.cxx
index c3e13a551b44..053a30835d2d 100644
--- a/svtools/source/misc/embedhlp.cxx
+++ b/svtools/source/misc/embedhlp.cxx
@@ -680,7 +680,40 @@ std::unique_ptr<SvStream> EmbeddedObjectRef::GetGraphicStream( bool bUpdate ) co
             if(xStream.is())
             {
                 if (mpImpl->pContainer)
-                    mpImpl->pContainer->InsertGraphicStream(xStream,mpImpl->aPersistName,mpImpl->aMediaType);
+                {
+                    bool bInsertGraphicStream = true;
+                    uno::Reference<io::XSeekable> xSeekable(xStream, uno::UNO_QUERY);
+                    std::optional<sal_Int64> oPosition;
+                    if (xSeekable.is())
+                    {
+                        oPosition = xSeekable->getPosition();
+                    }
+                    if (bUpdate)
+                    {
+                        std::unique_ptr<SvStream> pResult = utl::UcbStreamHelper::CreateStream(xStream);
+                        if (pResult)
+                        {
+                            GraphicFilter& rGF = GraphicFilter::GetGraphicFilter();
+                            Graphic aGraphic;
+                            rGF.ImportGraphic(aGraphic, u"", *pResult);
+                            if (aGraphic.IsNone())
+                            {
+                                // The graphic is not something we can understand, don't overwrite a
+                                // potentially working previous graphic.
+                                SAL_WARN("svtools.misc", "EmbeddedObjectRef::GetGraphicStream: failed to parse xStream");
+                                bInsertGraphicStream = false;
+                            }
+                        }
+                    }
+                    if (xSeekable.is() && oPosition.has_value())
+                    {
+                        xSeekable->seek(*oPosition);
+                    }
+                    if (bInsertGraphicStream)
+                    {
+                        mpImpl->pContainer->InsertGraphicStream(xStream,mpImpl->aPersistName,mpImpl->aMediaType);
+                    }
+                }
 
                 std::unique_ptr<SvStream> pResult = ::utl::UcbStreamHelper::CreateStream( xStream );
                 if (pResult && bUpdate)