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 derivated from Apache mod_mime_magic, which is itself based on the file command maintaind by Ian F. Darwin. See the source code for further historic and copyright information.
The extension needs a copy of the magic.mime as distributed with the file command. This file also part of most recent Linux distributions and usually stored in the /usr/share/misc directory.
The behaviour of these functions is affected by settings in php.ini.
Table 1. Mimetype configuration options