[jira] [Resolved] (PDFBOX-2679) Blank page rendered with wrong xref start objid

["Andreas Lehmkühler (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/PDFBOX-2679?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Andreas Lehmkühler resolved PDFBOX-2679.
----------------------------------------
    Resolution: Fixed

I've improved the checkXrefOffsets implementation. The old one just checked if the given object number could be found and the one is able to detect and repair shifted offsets within the xref table.

> Blank page rendered with wrong xref start objid
> -----------------------------------------------
>
>                 Key: PDFBOX-2679
>                 URL: https://issues.apache.org/jira/browse/PDFBOX-2679
>             Project: PDFBox
>          Issue Type: Bug
>          Components: Parsing
>    Affects Versions: 2.0.0
>            Reporter: Tilman Hausherr
>            Assignee: Andreas Lehmkühler
>             Fix For: 2.0.0
>
>         Attachments: PDFBOX-2679.patch
>
>
> From Kevin M. on the users mailing list:
> A confidential file doesn't display its image because the objid is unaccessible, due to a malformed xref table:
> {code}
> xref
> 1 7
> 0000000000 65535 f
> 0000000009 00000 n
> 0000358745 00000 n
> 0000358842 00000 n
> 0000359029 00000 n
> 0000359087 00000 n
> 0000359138 00000 n
> trailer 
> {code}
> The first number (1) means the number of the first object. So it would be 1. The second number(7) is the size of the table. The number 1 is incorrect, it should be 0, because "0000000000 65535 f" is the dummy object 0.
> From the pdf spec:
> {quote}The free entries in the cross-reference table form a linked list, with each free entry containing the object number of the next. The first entry in the table (object number 0) is always free and has a generation number of 65,535; it is the head of the linked list of free objects {quote}
> The error messages are:
> Can't find the object 7 0 (origin offset 359138) 
>  Missing XObject: Im1   (Im1 is the object at 7 0, and is the missing image)



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