This extension has been deprecated as the PECL extension
Fileinfo
provides the same functionality (and more) in a much cleaner way.
The functions in this module try to guess the content type
and encoding of a file by looking for certain
magic byte sequences at specific
positions within the file. While this is not a bullet proof
approach the heuristics used do a very good job.
This extension is derived from Apache mod_mime_magic,
which is itself based on the file
command maintained by Ian F. Darwin. See the source code for
further historic and copyright information.