Force File Download with PHP

Here is the code taken from

function output_file($file, $name, $mime_type='')
{
/*
This function takes a path to a file to output ($file),
the filename that the browser will see ($name) and
the MIME type of the file ($mime_type, optional).

If you want to do something on download abort/finish,
register_shutdown_function('function_name');
*/
if(!is_readable($file)) die('File not found or inaccessible!');

$size = filesize($file);
$name = rawurldecode($name);

/* Figure out the MIME type (if not specified) */
$known_mime_types=array(
 "pdf" => "application/pdf",
 "txt" => "text/plain",
 "html" => "text/html",
 "htm" => "text/html",
 "exe" => "application/octet-stream",
 "zip" => "application/zip",
 "doc" => "application/msword",
 "xls" => "application/vnd.ms-excel",
 "ppt" => "application/vnd.ms-powerpoint",
 "gif" => "image/gif",
 "png" => "image/png",
 "jpeg"=> "image/jpg",
 "jpg" =>  "image/jpg",
 "php" => "text/plain"
);

if($mime_type==''){
  $file_extension = strtolower(substr(strrchr($file,"."),1));
  if(array_key_exists($file_extension, $known_mime_types)){
  $mime_type=$known_mime_types[$file_extension];
  } else {
  $mime_type="application/force-download";
  };
};

@ob_end_clean(); //turn off output buffering to decrease cpu usage

// required for IE, otherwise Content-Disposition may be ignored
if(ini_get('zlib.output_compression'))
 ini_set('zlib.output_compression', 'Off');

header('Content-Type: ' . $mime_type);
header('Content-Disposition: attachment; filename="'.$name.'"');
header("Content-Transfer-Encoding: binary");
header('Accept-Ranges: bytes');

/* The three lines below basically make the
   download non-cacheable */
header("Cache-control: private");
header('Pragma: private');
header("Expires: Mon, 26 Jul 1997 05:00:00 GMT");

// multipart-download and download resuming support
if(isset($_SERVER['HTTP_RANGE']))
{
 list($a, $range) = explode("=",$_SERVER['HTTP_RANGE'],2);
 list($range) = explode(",",$range,2);
 list($range, $range_end) = explode("-", $range);
 $range=intval($range);
 if(!$range_end) {
  $range_end=$size-1;
 } else {
  $range_end=intval($range_end);
 }

 $new_length = $range_end-$range+1;
 header("HTTP/1.1 206 Partial Content");
 header("Content-Length: $new_length");
 header("Content-Range: bytes $range-$range_end/$size");
} else {
 $new_length=$size;
 header("Content-Length: ".$size);
}

/* output the file itself */
$chunksize = 1*(1024*1024); //you may want to change this
$bytes_send = 0;
if ($file = fopen($file, 'r'))
{
 if(isset($_SERVER['HTTP_RANGE']))
 fseek($file, $range);

 while(!feof($file) &&
  (!connection_aborted()) &&
  ($bytes_send<$new_length)
       )
 {
  $buffer = fread($file, $chunksize);
  print($buffer); //echo($buffer); // is also possible
  flush();
  $bytes_send += strlen($buffer);
 }
fclose($file);
} else die('Error - can not open file.');

die();
} 

/*********************************************
   Example of use
**********************************************/ 

/*
Make sure script execution doesn't time out.
Set maximum execution time in seconds (0 means no limit).
*/
set_time_limit(0); 
$file_path='that_one_file.txt';
output_file($file_path, 'some file.txt', 'text/plain');