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Identify hybrid-reference PDFs #19

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petervwyatt opened this issue Sep 7, 2022 · 4 comments
Open

Identify hybrid-reference PDFs #19

petervwyatt opened this issue Sep 7, 2022 · 4 comments
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enhancement New feature or request
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TestGrammar C++ PoC

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@petervwyatt
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TestGrammar (C++ PoC) currently only reports on traditional style xref tables or cross-reference streams. Should expand to also identify hybrid reference PDFs, even though they are relatively rare:

7.5.8.4 Compatibility with applications that do not support compressed reference streams

A hybrid-reference PDF file is readable by PDF processors designed only to support versions of PDF before PDF 1.5. Such a PDF file contains objects referenced by standard cross-reference tables in addition to objects in object streams that are referenced by cross-reference streams.
@petervwyatt petervwyatt self-assigned this Sep 7, 2022
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Thanks @tballison for the question that prompted this!

@petervwyatt
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Having trouble working out how to do this with all PDF SDKs...

@petervwyatt
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Can be identified by the presence of XRefStm key as per Table 19 (and Note below Table 15).

Fix for Issue #39 means that pdfium will now report:

...
       1:   Trailer (as XRefStream)
Info: unknown key 'XRefStm' is not defined in Arlington for XRefStream in PDF 1.7

PDFix does not report anything currently.

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Example hybrid PDF: https://www.ema.europa.eu/documents/product-information/rapamune-epar-product-information_en.pdf
(has other issues also, just to add to the fun 😁)

@petervwyatt petervwyatt added this to the TestGrammar C++ PoC milestone Aug 13, 2023
@petervwyatt petervwyatt added the enhancement New feature or request label Aug 7, 2024
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