Re: [gentoo-user] repair damaged pdf?

[Florian Philipp <lists@binarywings.net>]

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Am 14.04.2011 23:08, schrieb Liviu Andronic:
> Dear all
> What is your experience with corrupted PDF files? Do you know any tool
> that can attempt to repair damaged PDF files? Does it make any sense
> to edit a PDF file in hex mode?
> 
> I have a damaged PDF that cannot be opened with any of the about 10
> tools that I've just tried.
> liv@liv-laptop:/tmp$ pdf2ps Class\ 1.pdf
>    **** Warning: File has a corrupted %%EOF marker, or garbage after %%EOF.
>    **** Warning:  An error occurred while reading an XREF table.
>    **** The file has been damaged.  This may have been caused
>    **** by a problem while converting or transfering the file.
>    **** Ghostscript will attempt to recover the data.
> Error: /typecheck in --run--
> Operand stack:
>    --nostringval--   --nostringval--   1
> Execution stack:
>    %interp_exit   .runexec2   --nostringval--   --nostringval--
> --nostringval--   2   %stopped_push   --nostringval--
> --nostringval--   --nostringval--   false   1   %stopped_push   1878
> 1   3   %oparray_pop   1877   1   3   %oparray_pop   1861   1   3
> %oparray_pop   --nostringval--   --nostringval--   --nostringval--
> --nostringval--   --nostringval--   --nostringval--
> Dictionary stack:
>    --dict:1155/1684(ro)(G)--   --dict:1/20(G)--   --dict:75/200(L)--
> --dict:75/200(L)--   --dict:108/127(ro)(G)--   --dict:288/300(ro)(G)--
>   --dict:20/25(L)--   --dict:1/10(L)--
> Current allocation mode is local
> GPL Ghostscript 8.71: Unrecoverable error, exit code 1
> 
> liv@liv-laptop:/tmp$ pdftops Class\ 1.pdf
> Error: PDF file is damaged - attempting to reconstruct xref table...
> Error: Top-level pages object is wrong type (null)
> Error: Couldn't read page catalog
> 
> Any ideas how I could try to repair it? (It's not sensitive and it's
> small, so I could post it.) I tried pdftk, but it also fails.
> liv@liv-laptop:/tmp$ pdftk Class\ 1.pdf output Class\ 11.pdf
> java.lang.NullPointerException
>    at com.lowagie.text.pdf.PdfReader$PageRefs.iteratePages(itext-2.1.7.jar.so)
>    at com.lowagie.text.pdf.PdfReader$PageRefs.readPages(itext-2.1.7.jar.so)
>    at com.lowagie.text.pdf.PdfReader$PageRefs.<init>(itext-2.1.7.jar.so)
>    at com.lowagie.text.pdf.PdfReader$PageRefs.<init>(itext-2.1.7.jar.so)
>    at com.lowagie.text.pdf.PdfReader.readPages(itext-2.1.7.jar.so)
>    at com.lowagie.text.pdf.PdfReader.readPdf(itext-2.1.7.jar.so)
>    at com.lowagie.text.pdf.PdfReader.<init>(itext-2.1.7.jar.so)
>    at com.lowagie.text.pdf.PdfReader.<init>(itext-2.1.7.jar.so)
> Error: Unexpected Exception in open_reader()
> Error: Failed to open PDF file:
>    Class 1.pdf
> Errors encountered.  No output created.
> Done.  Input errors, so no output created.
> 
> Regards
> Liviu
> 
> 

Well, you could try app-text/qpdf from the benf overlay. It has an
option to suppress recovery of damaged files so it looks like it at
least tries to repair them per default.

If you don't want to install layman and overlays, you can send me the
file off-list and I take a look.

One good thing about PDF is that its structure is stored uncompressed
(AFAIK it only compresses text and binary data with zlib since version
1.2). This means that it might be at least partially recoverable.

Regards,
Florian Philipp


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