Content-Length header always zero

Question

I set a header in the following way:

header('Content-Length: ' . filesize($strPath));

On my PC with ZendServer it works fine and I can download a file with the correct file size. On the production server, a Solaris with Apache and compiled PHP, I get a file with the file size equal to zero, so an empty file.

Is there a config parameter? Something that can prevent to set 'Content-Length: 1222'?

Thanks.

The code:

<?php
error_reporting(E_ALL);
ini_set('display_errors', '1');

require 'includes/prepend.inc.php';
require __ADMIN_DIR__.'/AdminInfo.php';
$intFile = QApplication::QueryString('fileID');
if($intFile == '') die('Error: missing ID');
$objFile = File::Load($intFile);
$blnRight = false;
$objAdminInfo = new AdminInfo();
if($objAdminInfo->isAdmin()) {
    $blnRight = true;
}
else {
    $objSecMan = new SecurityManager(
        'file:'.$objFile->FileID, 
        $objAdminInfo->getUserID()
    );
    $blnRight = $objSecMan->processResource('view');
}

// if the user can modify and or publish, can even view the file
if(!$blnRight) {
    $blnRight = $objSecMan->processResource('modify');

    if(!$blnRight) {
        $blnRight = $objSecMan->processResource('publish');
    }       
}

//$strPath = __UPLOADS__.DIRECTORY_SEPARATOR.$objFile->FileID;
$strPath = 'subdept.csv';

if (file_exists($strPath) && $blnRight) {
    header('Content-Description: File Transfer');
    header('Content-Type: application/octet-stream');
    header('Content-Disposition: attachment; filename='.$strPath);//$objFile->Filename);
    header('Content-Transfer-Encoding: binary');
    header('Expires: 0');
    header('Cache-Control: must-revalidate, post-check=0, pre-check=0');
    header('Pragma: public');
    header('Content-Length: ' . filesize($strPath));
    ob_clean();
    flush();
    readfile($strPath);
    exit;
}
else {
    die('Restricted access');
}   
?>

When I comment the code before $strPath it works, so it must be something in the bloody framework. I would like to throw the whole CMS away.

Answer 1

Check for transfer-encoding header. If the transfer encoding is chunked, then the Content-Length field will not be set

Possible causes, is that ZendServer does not do chunked encoding, whereas Apache does

See the following links for details

http://en.wikipedia.org/wiki/Chunked_transfer_encoding

http://www.w3.org/Protocols/rfc2616/rfc2616-sec3.html

Answer 2

Make sure that the file really exists under the specified path (is_file checks both the existance and if the file is a regular file) and is readable (is_readable) before sending it to the client. filesize returns false if an error occured. So that might be the cause of your 0 value or empty value for Content-Length.

And, as Ferdinand Beyer already mentioned, make sure that your script is portable and can handle different environments.

Answer 3

Are you sure the file exists on the production server? Maybe it's a case sensitivity issue (e.g, "File" and "file" are the same on Windows, but different on UNIX)? Does the user running Apache/PHP have read access?

Answer 4

Do you get any errors if you enable errors?

error_reporting(E_ALL);
ini_set('display_errors', '1');

Answer 5

A problem may be that Apache is gzipping your download, taking care of correcting the Content-Length, or in your case, removing that header and adding

Content-Encoding: chunked

You can add a .htaccess RewriteRule to disable gzip:

RewriteRule . - [E=no-gzip:1]