Php download script outputs corrupted file

Question

I was building a file download Class for my CMS in PHP, at a time I noticed it outputs files in a different Encoding format. I tried with readfile, file_get_contents,fread but a

Answer 1

The problem lies in the Content-Disposition header. This header is not really part of the HTTP protocol, see RFC 2616, 15.5 Content-Disposition Issues

Content-Disposition is not part of the HTTP standard, but since it is widely implemented, we are documenting its use and risks for implementors.

And later in section 19.5.1 Content-Disposition

The Content-Disposition response-header field has been proposed as a means for the origin server to suggest a default filename if the user requests that the content is saved to a file.
...
An example is

Content-Disposition: attachment; filename="fname.ext"

If this header is used in a response with the application/octet- stream content-type, the implied suggestion is that the user agent should not display the response, but directly enter a `save response as...' dialog.

Leaving out this header shows the contents of the sent file.

I have tested this with Firefox only, so other web browsers might behave different.

Answer 2

Try running an ob_start() as the first thing in your script, write stuff, edit your headers and then ob_flush() and ob_clean() whenever you want your content to be sent to the user's browser.

This is worked for me..

if (file_exists($file)) {
    header('Content-Description: File Transfer');
    header('Content-Type: application/octet-stream');
    header('Content-Disposition: attachment; filename='.basename($file));
    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($file));
    ob_clean();
    flush();
    readfile($file);
    exit;
}

Hope this helps..