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https://issues.apache.org/jira/browse/TIKA-2986?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16977615#comment-16977615
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Nick Burch commented on TIKA-2986:
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How do we know which ones are a _must_ though? Many we expect, but for some
formats we've had to guess, and some formats are actually more flexible than
the spec suggests... That's why I thought a different detector mode might be
cleaner / more obvious
> 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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