[TIKA-2588] Tika detecting/parsing pptx with embedded Excel worksheet(s)...

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.17
• Fix Version/s: 1.18, 2.0.0
• Component/s: detector, parser

Environment

 

• Assignee: Tim Allison
• Reporter: Brian McColgan
• Created: 24/Feb/18 16:00
• Updated: 29/Oct/19 15:52
• Resolved: 26/Feb/18 20:26

Description

Hello tika-developers,

First, a big 'thank-you' for creating and maintaining Apache-Tika!  A really useful capability/service that can be used in so many different ways.  You folks are the true Debabelizer (h2g2.com).

On to issue-encountered: using Tika 1.17 to extract an embedded Excel object out of a pptx is causing issues.  Simple example attached to this Jira-issue (tikaSample.pptx) which if run against Tika 1.17 (with verbose/list-parsers/list-detectors) provides the output in (foo.out).  The deck contains a title slide, and a single-slide with embedded Excel object on it.

As noted to gagravarr on S-Overflow, I grabbed the unit-test data which you use in your parser/office JUnit suite (test_ppt_embedded_two_slides.pptx) and tried opening in Office/PPT 2016.  I selected (with mouse) the embedded sheet (had Alfresco logo in it) and pasted it into an empty Office/Excel 2016 workbook.  When I tried to interact with it, I had to double-click to make it active.  As a result, I ended up with two Excel instances on my Windows 10 desktop (the original object in 1, the Excel worksheet in another).  I have included a picture of the embedded Excel object pasted into the workbook... ).

followed by the worksheet opened inside the workbook (required double-click within the black-bordered area in the first pic above):

I managed to extract the embedded object using apache POI.  The logic sequence was something like the following:

1. Create an XMLSlideShow object, and pull the list of underlying slide entities.
2. Walk the list of XSLFSlide(s), searching for a matching slide (by name) - e.g. 'MFL'.
3. Examine PackagePart of XSLFSlide (matching name) and for content-type.
4. If pPart.content-type is 'application/vnd.openxmlformats-officedocument.oleObject' then - 'candidate FOUND'.
5. Build POIFS around the candidate FOUND, extract root of FileSystem.
6. Verify that root has entries for { 'Package', '\u0001Ole', and '\u0001CompObj' }.
7. Extract entry '\u0001CompObj', verify entry is a DocumentEntry and underlying bytes for DocumentNode match an 'Excel' signature.
8. If (step 7 is true) -> extract entry 'Package'.
9. The resulting entry represents the byte-stream of the embedded Excel entity.

I was able to instantiate this into a new workbook (as an example) using POI, and when I opened it, the worksheet was correctly embedded in that 'example.xlsx'.

I am not as familiar with Tika, so was a little less comfortable trying to walk it through.  I thought however, recreating this path would provide further insight for you.

Issue Links

• causes: TIKA-2617 Ignore NPOIFS IOOBE in PPT attachments