[plug] MIME Types by file contents

[Onno Benschop]

On Fri, 2004-07-02 at 22:55, Bernd Felsche wrote:
> Using "file -bi ~/* | sort -u"

Note of caution. I once had the same problem, but in PHP. My solution
was also to use the file command, but it wasn't working in Solaris. Then
I found out that there are multiple version of file.

On the way I learnt roughly how the magic file works and I confess that
it is a pure work of evil. Basically it is a huge list of patterns, so
the code can build a switch() that ends up looking like this:

if byte[4]=aa and byte[6]=b0 and byte[42]=11 then return bob/type
if byte[22]=be and byte[11]=00 and byte[12]=00 then return music/type
etc.

(Of course there is pattern matching in there also, but it's all based
on certain character orders.) So, if you carefully craft legitimate
data, that matches one of those things, then it will be mis-identified.

All I'm saying is that while I also used file as a solution, it's evil,
bad, subject to breaking and cause for palpitations.

Onno Benschop 

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