[PDFBOX-4541] Incorrect? handling of direct/indirect objects

• Type: Wish
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 2.0.14
• Component/s: Parsing, Writing
• Flags: Patch
• Assignee: Unassigned
• Reporter: Jonathan
• Created: 10/May/19 08:56
• Updated: 20/May/19 07:37

Description

We ran into some issues concerning blank pages in some of our resulting PDF documents. Investigation showed that some objects which were referenced were never actually written. We then noticed that these objects were never written because they missed the `isDirect` flag. We were able to mitigate this issue by adding

if (retval != null) {
    retval.setDirect(true);
}
return retval;

at the end of `BaseParser.parseDirObject()`.

While the pdfs were now displayed correctly, QPDFs check reported erroneous hint tables. The offsets there were calculated incorrectly because the objects were now written not only once, but, in fact, several times in places where they should have been merely referenced. We eventually resolved this issue by replacing the if-condiction

if (willEncrypt || incrementalUpdate || subValue instanceof COSDictionary || subValue == null)

in `COSWriter.visitFromArray(COSArray)` and `COSWriter.visitFromDictionay(COSDictionary)` with

if (willEncrypt || incrementalUpdate || subValue == null || !(subValue instanceof COSObject))