How can I detect the mime type with PHP when an actual file doesn’t exist?

Is there a way to detect the mime type of a file without actually having an actual file, for example when you’re generating the file and serving it as a download?

I’m currently using file extension sniffing from here: http://www.php.net/manual/en/function.mime-content-type.php#87856

I was just wondering if there was another way short of actually creating the file on the server and using FileInfo, mime_content_type(), or file

Answer

Try the Fileinfo finfo_buffer() function:

$filename = 'image.jpg';
$contents = file_get_contents($filename);

$finfo = finfo_open(FILEINFO_MIME_TYPE);
var_dump( finfo_buffer($finfo, $contents) ); // string(10) "image/jpeg"

You do say “short of actually creating the file,” so this seems to meet your requirements even though it uses Fileinfo.