force-download problem and somthin after dl

xenoda9uy

I have a problem about force-downloading,

the download process goes fine, it's more of the encoding part (in my assumption).

here is th code:

	header('Content-Description: File Transfer');
	header("Content-Type: application/force-download");
	header("Content-Transfer-Encoding: Binary");
	header("Content-Length: ".filesize($file));
	header("Content-Disposition: attachment; filename=".basename($file)."");
	if ( readfile($file) !== false ) {

	logActivity("Some log stuff");

	if ( $_GET['remove_after_download']==true || $_GET['remove_after_download']=="true" ) {
		unlink( $file );
	}

}

basically, after the script, i get a file that is different from the original file -- it has an additional "\n" character at the beginning of the file. And this character became very detrimental to some of the files that i want them to download. Does anyone ever hit this kind of problem? Or anyone know whhere the "\n" came from?

2) This could be related to the above question. Is it possible execute any php scripts after the method call readfile? Because as you see in the code, I was trying to log the activity, and remove the file after download. Apparently, none of them happened... anyone know why?

Weedpacket

There aren't any trailing newlines in your script? They'd be output too. (Which also answers your second question: processing does continue after a readfile()).

(Incidentally, the correct MIME type is application/octet-stream. Also, you don't need to check that $_GET['remove_after_download']==true, unless the remove_after_download field might contain something other than true that also means "remove after download". Form-posted variables are all strings - and any nonempty string is equivalent to true.)

xenoda9uy

Thanks for answer my question!

There aren't any trailing newlines in your script? They'd be output too. (Which also answers your second question: processing does continue after a readfile()).

Im sure if I understand your question correctly. Do you mean that whehter I have output any other character after the readline() method call? Because I have nothing output'ed before readfile is called in the download page. The only other place where I could have output something is in logActivity, which happens after readfile. So there shouldn't be any newlines at the beginning of the downloaded file.

Im really confused. Thanks for help!

Weedpacket

Sorry; for some reason I misread your post as saying that the stray \n was at the end.
Are you using output buffering (either with ob_start(), etc., or set in php.ini)?

xenoda9uy

nope, im not use ob_start(). as a matter of fact, im not too familiar with ob_start() in the use of downloading files. i mean is it even possible?

Weedpacket

I was asking because if there was a stray empty line being output somewhere earlier in the code, output buffering would explain why there weren't any error messages when the headers were generated.

xenoda9uy

Hmmm, I got the script working using ob_start()....

i basically trim'ed the buffer and then output'ed.

However, the newline is still puzzling me. Because I have nothing, absolutely nothing output'ed before the headers.

Thanks for your help!

Weedpacket

I don't see anywhere either. The only place I can see where it might possibly happen is if $file ends with a newline and basename() doesn't trim it (I've never tried such a stunt). But then I wouldn't expect the readfile() to work - and if it did, I wouldn't expect the unlink() to fail.