You must compile PHP with the configure switch --with-mime-magic to get support for mime-type functions. The extension needs a copy of the simplified magic file that is distributed with the Apache httpd.
Note: The configure option has been changed from --enable-mime-magic to --with-mime-magic since PHP 4.3.2
Note: This extension is not capable of handling the fully decorated magic file that generally comes with standard Linux distro's and is supposed to be used with recent versions of file command.
Note: Note to Win32 Users
In order to use this module on a Windows environment, you must set the path to the bundled magic.mime file in your php.ini.
Example #1 Setting the path to magic.mime
mime_magic.magicfile = "$PHP_INSTALL_DIR\magic.mime"
Remember to substitute the $PHP_INSTALL_DIR for your actual path to PHP in the above example. e.g. c:\php