Embedded OLE PDF-Object bigger than the original in DOCX

Question

The problem I have is, that when I create a docx-document with an embedded (ole) File of type .pdf the generated binary file in the /embeddings folder is larger than the original document.

I have inserted a document with size 52076 Bytes. If I rename the .docx to zip and open it the oleObject1.bin has 55296 Bytes

Now when I want to extract the file with Apache POI the file is there but corrupted.

Any ideas? (I first thought that it is maybe compressed?)

Thx

Answer 1

Ok I found the issue:

for docx for example there are some data-blocks before the file (RootEntry, ObjInfo, Contents,..). With an hex-editor you will see that the file starts somewhere behind. I fixed my extractor by looking which type the directory is - for pdf you have to look into the CONTENTS directory-entry:

private void writeBinaryPackagePart(PackagePart part, File targetfolder, String extension, String fileName) throws IOException {
        if (StringUtils.isEmpty(fileName)) {
            fileName = generateUniqueId(OleExtractorUtils.OfficeType.BINARY).concat(".").concat(extension);
        }
        InputStream inputStream = FileMagic.prepareToCheckMagic(part.getInputStream());
        try {
            if (FileMagic.valueOf(inputStream) == FileMagic.OLE2) {
                try (NPOIFSFileSystem npoifsFileSystem = new NPOIFSFileSystem(inputStream)) {
                    if (isOle10Native(npoifsFileSystem.getRoot())) {
                        byte[] dataBuffer = Ole10Native.createFromEmbeddedOleObject(npoifsFileSystem.getRoot()).getDataBuffer();
                        writeOle10NativeObject(dataBuffer, fileName, targetfolder);
                    }
                    else if (npoifsFileSystem.getRoot().getEntryNames().contains("CONTENTS"))
                        try (DocumentInputStream contents = npoifsFileSystem.createDocumentInputStream("CONTENTS")) {
                            writeOle10NativeObject(IOUtils.toByteArray(contents), fileName, targetfolder);
                        }
                }
            }
        }
        catch (Exception e) {
            LOGGER.warn("Cannot create Ole10Native from Object {}! Writing the following binary: {}", part.getPartName(), fileName);
            ServiceUtil.moveUploadedFileToExistingTempFolder(inputStream, fileName, targetfolder);
            inputStream.close();
        }
    }

private boolean isOle10Native(DirectoryNode directoryNode) {
    String ole10Native = Ole10Native.OLE10_NATIVE;
    Iterator<Entry> entries = directoryNode.getEntries();
    while(entries.hasNext()) {
        Entry entry = entries.next();
        if (entry.getName().contains(ole10Native)) {
            return true;
        }
    }
    return false;
}