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Posted to dev@tika.apache.org by "Matthew Buckett (JIRA)" <ji...@apache.org> on 2015/05/20 17:08:00 UTC
[jira] [Commented] (TIKA-1085) PDF header and mime detection
[ https://issues.apache.org/jira/browse/TIKA-1085?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14552457#comment-14552457 ]
Matthew Buckett commented on TIKA-1085:
---------------------------------------
The original generator of the files I originally saw in the wild was "iText 1.4.8 (by lowagie.com)", but it could be that the programmer that integrated the library made the mistake rather than the iText library itself.
> PDF header and mime detection
> -----------------------------
>
> Key: TIKA-1085
> URL: https://issues.apache.org/jira/browse/TIKA-1085
> Project: Tika
> Issue Type: Improvement
> Components: mime
> Affects Versions: 1.3
> Reporter: Marco Quaranta
> Priority: Minor
> Labels: detection, header, mime, pdf
> Attachments: hello-world-bom.pdf, hello-world.pdf, test.pdf
>
>
> I've found some PDF files Tika recognizes as application/octet-stream.
> These files differs from regularly identified PDF having a different header: the %PDF-N.n string isn't at the beginning (zero offset) of the file but in the first 1024 bytes.
> PDF reference states that "The first line of a PDF file shall be a header consisting of the 5 characters %PDF– followed by a version
> number of the form 1.N, where N is a digit between 0 and 7" (http://tinyurl.com/8vnzm3c "p. 7.5.2 File Header").
> Looking further at implementation notes by Adobe (http://tinyurl.com/cbqpb24 p. 3.4.1 File Header) I've discover that: "Acrobat viewers require only that the header appear somewhere within the first 1024 bytes of the file"
> What do you think about a PDF magic match with an offset 0:1024?
> <match value="%PDF-" type="string" offset="0:1024"/>
> Thank you,
> Marco
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