[jira] [Commented] (TIKA-2986) Edge case (?) in file type detection

["Nick Burch (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/TIKA-2986?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16976670#comment-16976670 ] 

Nick Burch commented on TIKA-2986:
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I seem to recall that we allow the filename only to win for things like octet-stream, to give our best-guess even on truncated files, or files of a subtype that we don't know about

> Edge case (?) in file type detection
> ------------------------------------
>
>                 Key: TIKA-2986
>                 URL: https://issues.apache.org/jira/browse/TIKA-2986
>             Project: Tika
>          Issue Type: Improvement
>            Reporter: Tim Allison
>            Priority: Trivial
>
> I recently came across a file that was identified as an Acrobat fdf file.  The particular file was some kind of binary file with a ".fdf" extension, but not an Acrobat fdf.  
> Our current MimeTypes algorithm runs magic first, and then it tries to use the file extension.  If the file extension suggests a child mime type of what was found via magic, that is used.  The problem with this file was that the magic {{%FDF-}} was not found, so from the magic step, it was {{application/octet}}, and then the file extension, which was ".fdf", was selected because {{application/vnd.fdf}} is a child of {{application/octet}}.
> If feels like we might want to add a rule that if a mime definition has a defined magic and that magic is not found, we should not then fall back to the file extension. Or, is there a better way to prevent this from happening? Or, is this just an edge case that we should ignore?



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