determining whether a MIME type is binary or text-based

Question

Is there a library which allows determining whether a given content type is binary or text-based?

Obviously text/* is always textual, but for things like application/json, image/svg+xml or even application/x-latex it's rather tricky without inspecting the actual data.

Answer 1

I don't know of a definitive list of binary and non-binary MIME types, but for the Common MIME types I think the following does pretty well.

def is_binary(mime_type, subtype):
    if mime_type == "text":
        return False
    if mime_type != "application":
        return True
    return subtype not in ["json", "ld+json", "x-httpd-php", "x-sh", "x-csh", "xhtml+xml", "xml"]

Answer 2

There's a wrapper for libmagic for python -- pymagic. Thats the easiest method to accomplish what you want. Keep in mind that magic is only as good as the fingerprint. You can have false-positives if something 'looks' like another file format, but most cases pymagic will give you what you need.

One thing to watch out for would be the 'simple solution' of checking to see if any of the characters are 'outside' the printable ASCII range, as you will likely encounter unicode which will look like binary (and in fact, be binary) even though it's just textual content.