[whatwg] [mimesniff] Sniffing archives

Gordon P. Hemsley gphemsley at gmail.com
Wed Nov 28 09:18:49 PST 2012

The mimesniff spec currently includes signatures for ZIP, gzip, and
RAR archive formats. However, no major browser seems to support them
natively (they all prompt for download), and it's not clear whether
the type detection is a product of the browser code or the OS, or
whether it is used beyond choosing an appropriate file extension for
the download.

Are there any valid usecases for explicitly sniffing archive formats
instead of letting them default to application/octet-stream like other
binary files would? Note that Henri Sivonen has previously raised the
issue that ZIP-based formats (like office suite documents), for
example, would be misleadingly sniffed as ZIP files, and there is no
easy way around that.

Gordon P. Hemsley
me at gphemsley.org

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