How to Detect File Types Without Relying on Extensions

Determining whether a file is an mp3 or image format beyond examining its extension is a valuable task in programming. Here's a comprehensive solution that doesn't rely on extensions:

PHP >= 5.3:

$mimetype = finfo_fopen(fopen($filename, 'r'), FILEINFO_MIME_TYPE);

PHP

$mimetype = mime_content_type($filename);

Alternatives:

• exif_imagetype: Specifically checks for image mimetypes.
• getimagesize: Similar to exif_imagetype, but may have library dependency issues.

Proxy Method:

For a more generalized approach, consider wrapping these functions into a proxy method:

function getMimeType($filename)
{
    $mimetype = false;
    if (function_exists('finfo_fopen')) {
        // open with FileInfo
    } elseif (function_exists('getimagesize')) {
        // open with GD
    } elseif (function_exists('exif_imagetype')) {
        // open with EXIF
    } elseif (function_exists('mime_content_type')) {
        $mimetype = mime_content_type($filename);
    }
    return $mimetype;
}

By using this proxy method, you can easily determine the mimetype of a file based on the availability of different functions on your system.