Re: using libmagic in Emacs?

[Chong Yidong <cyd@stupidchicken.com>]

Richard Stallman <rms@gnu.org> writes:

>     PLEASE do not base Emacs infrastructure on external programs, unless
>     they come with Emacs.  `file' is not available on every platform, and
>
> libmagic isn't either.
>
>     even on those it is, the quality and extent of its database is unclear
>     and so cannot be relied upon.
>
> On systems that have libmagic, isn't it the case that file uses libmagic?
>
>     I really don't understand why linking against a simple free library is
>     an issue, but if it is, we should find a different solution using some
>     database internal to Emacs, as we did until now.
>
> It shouldn't be a big deal.  Only a few specialized places should want
> to run `file' on a file.

No one has yet explained why we shouldn't deal with such failures by
simply fixing Emacs' file detection, instead of relying on libmagic or
file.  Given that libmagic/file isn't always going to be present, and
there's no intention of removing our file detection code, why not make
sure the latter works?  Are there any situations we are inherently
incapable of detecting, and why?