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Say you want a PHP script that will make the browser to download a file instead of opening it. This is useful for common filetypes that would normally be displayed in a browser, like .html, images, PDFs and .doc files.
You can find a lot of scripts that do this on the web but one thing most of them don’t handle is download resuming and multi-thread downloading. If you don’t need that feature, feel free to use a simpler script. Personally I’ve found that a function that handles download resuming works more reliably across various browsers (what actually happened : a simpler script didn’t work with Opera + my weird Internet connection, so I found another script and decided to make broad generalizations about download resuming :p).
Note – most of the code below isn’t mine. I found it somewhere on the web and adjusted it for my needs; unfortunately I’ve lost the URL of the original page. If you know where it came from, let me know and I’ll add a link to this post.
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');
