Download of large files does not work - php

Question

Hey i have following code to download a large file but the download does stop everytime without finish the download
function download($file)
{
include('logger.php5');
$log = new Logging();
$log->lfile('download.log');
ini_set('max_execution_time', 86400);
//header('Location: '.$file);
$filesize = filesize($file);
$filename = pathinfo($file, PATHINFO_BASENAME);
$filext = pathinfo($file, PATHINFO_EXTENSION);
$mime = include('mime.php5');
$log->lwrite(ini_get('max_execution_time'));
$log->lwrite(sprintf('%s %s %s %s', $filename, $filext, $mime[$filext], human_filesize($filesize)));
$log->lclose();
#ob_end_clean();
session_write_close();
header("Content-Description: File Transfer");
header("Content-Type: ".$mime[$filext]);
header("Content-Disposition: ".
(!strpos($HTTP_USER_AGENT,"MSIE 5.5")?"attachment; ":"").
"filename=".$filename);
header("Content-Transfer-Encoding: binary");
header("Content-Length: ".$filesize);
header("Cache-Control: must-revalidate, post-check=0, pre-check=0");
header("Cache-Control: public");
header('Pragma: public');
header('Expires: 0');
$done = readfile_chunked($file);
}
function readfile_chunked($filename,$retbytes=true) {
$chunksize = 1*(1024*1024); // how many bytes per chunk
$buffer = '';
$cnt =0;
// $handle = fopen($filename, 'rb');
$handle = fopen($filename, 'rb');
if ($handle === false) {
return false;
}
while (!feof($handle)) {
$buffer = fread($handle, $chunksize);
echo $buffer;
ob_flush();
flush();
if ($retbytes) {
$cnt += strlen($buffer);
}
}
$status = fclose($handle);
if ($retbytes && $status) {
return $cnt; // return num. bytes delivered like readfile() does.
}
return $status;
}
Each time i call the script the download start up but stops after 400MB, the file itself is 778MB big.
Someone can see a problem with the code?
UPDATE
after try to log the return value of readfile_chunkedit feels like the script gets stoped not the download itself. Because i cant get a log entry after the readfile_chunked call.

Answer 1

It could be a problem with the filesize function in PHP. There are known bugs for big file size reading and as you're sending it with the file as an header I would suggest you to try the script without using this line:
header("Content-Length: ".$filesize);
Oh and maybe you can take a look at this line:
header("Content-Transfer-Encoding: binary");
I think the encoding should be checked for each file. Like this:
$finfo = finfo_open(FILEINFO_MIME);
//check to see if the mime-type starts with 'text'
return substr(finfo_file($finfo, $filename), 0, 4) == 'text';
If it's a textfile you should use ASCII ofcourse. Has nothing to do with the question but I think it's an useful addition to your script :)