On Mon, Nov 29, 2010 at 01:14:58AM -0500, Roger Burrows wrote:
> Hi Michal,

Hi,

> I thought it would be a good thing for me to understand a little bit about 
> the  
> file structure of PDFs.  So I started by writing a simple program to display 
> the file structure of a PDF, based on section 7.5 of the PDF 1.7 manual.  I 
> looked at a lot of PDFs, as well as the one delinearized by PDFEDIT, and I 
> see 
> one thing that is definitely different: the cross-reference table of the 
> delinearized PDF has no object zero.
> 
> In section 7.5.4 of the PDF 1.7 reference manual on page 41, it says:
> The cross-reference table (comprising the original cross-reference section 
> and 
> all update sections) shall contain one entry for each object number from 0 to 
> the maximum object number defined in the file, even if one or more of the 
> object numbers in this range do not actually occur in the file.
> 
> So (with great hesitation because I am ignorant of the remaining 700+ pages 
> of 
> the manual), it seems to me that the problem with reading the delinearized 
> output may be because there is no entry for object zero.

You can check that easily. Just edit the delinearized document and
replace:
xref
-1 263
+0 264
+0000000000 65535 f \n

Make sure that you do not edit anything before xref keyword and that
that the added entry has exactly 20B (if you are using DOS EOL - \r\n then you
have to skip the space after `f').

I have another suspicion that the problem might be related to UNIX vs.
DOS EOL. This shouldn't be a problem because the specification is rather
clear on the EOL but who knows. If the first test with the object 0
doesn't pass then I would try to update each entry to use DOS EOL.

Let's see

> 
> Hope this helps,
> Roger Burrows

Thanks!
-- 
Michal Hocko

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