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

• Type: Improvement
• Status: Open
• Priority: Trivial
• Resolution: Unresolved
• Assignee: Unassigned
• Reporter: Tim Allison
• Created: 18/Nov/19 15:07
• Updated: 19/Nov/19 17:41

Description

One of my colleagues, Philip Southam, 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?

Issue Links

• is related to: TIKA-2988 Add mime for alternative fdf format