Bestem mime-type fra MySQL-kolonnen

HVIS din vært stadig bruger php 5.2 og ikke har adgang til filinfo-funktionerne, kan du teste filens header-signatur (magiske tal) for at bestemme mime-typen

function mimetype($data)
{
    //File signatures with their associated mime type
    $Types = array(
    "474946383761"=>"image/gif",                        //GIF87a type gif
    "474946383961"=>"image/gif",                        //GIF89a type gif
    "89504E470D0A1A0A"=>"image/png",
    "FFD8FFE0"=>"image/jpeg",                           //JFIF jpeg
    "FFD8FFE1"=>"image/jpeg",                           //EXIF jpeg
    "FFD8FFE8"=>"image/jpeg",                           //SPIFF jpeg
    "25504446"=>"application/pdf",
    "377ABCAF271C"=>"application/zip",                  //7-Zip zip file
    "504B0304"=>"application/zip",                      //PK Zip file ( could also match other file types like docx, jar, etc )
    );

    $Signature = substr($data,0,60); //get first 60 bytes shouldnt need more then that to determine signature
    $Signature = array_shift(unpack("H*",$Signature)); //String representation of the hex values

    foreach($Types as $MagicNumber => $Mime)
    {
        if( stripos($Signature,$MagicNumber) === 0 )
            return $Mime;  
    }

    //Return octet-stream (binary content type) if no signature is found
    return "application/octet-stream"; 
}

BEMÆRK: Nogle signaturer kan matche partialer af andre, f.eks. matcher PK Zip-filsignaturen de første 4 bytes af java archive (.jar) filsignatur, ekstra sætninger ville være nødvendige i foreach loop for at bestemme den korrekte signatur for mime type , men for din situation burde dette gøre det.

En opdateret liste over filsignaturer kan findes på http://www.garykessler.net/library /file_sigs.html hvis nogen har brug for flere filsignaturtyper.