What is the best way to determine whether or not a file is an image in PHP?

Question

I have a sever which people can upload files to. The problem is that some of the filenames are mangled (dont have any extension) and so I cannot immediately determine file type.

Answer 1

You can use the Fileinfo extension: http://www.php.net/manual/en/function.finfo-file.php

finfo_file() uses magic bytes and does not have to load the whole image into memory. The result is a string with the corresponding MIME type, e.g.:

• text/html
• image/gif
• application/vnd.ms-excel