PHP readfile() corrupts file

Question

In my function I'm downloading a file that saves downloads to a log file. Whenever I try to download an Excel file I uploaded, Excel states that it is corrupted. My local copy works fine. Here is my download.php:

<?php
include_once 'includes/db_connect.php';
include_once 'includes/functions.php';

sec_session_start();
ob_start();
?>

<?php if (login_check($mysqli) == true) :?>
<?php
$logFile = "download.log";
$directory = "./downloads/";
date_default_timezone_set('America/New_York');

$filename = $_GET['file'];
$path = "$directory$filename";
if(file_exists($path) AND substr_count($filename,"/") == "0") {
  if (isset($logFile)) {
    $downloadLogRecord = $filename." || ".$_SESSION['name']." || ".$_SESSION['username']." || ".$_SERVER['REMOTE_ADDR']." || ".date('Y-m-d H:i:s')."\r\n";
    @file_put_contents($logFile,$downloadLogRecord,FILE_APPEND|LOCK_EX);
  }
  header("Content-type: application/octet-stream"); 
  header("Content-Disposition: attachment; filename=$filename"); 
  header("Content-Length: ".filesize($path));
  readfile("$path");
}
?>
<?php else : ?>
  <p>
    <span class="error">You are not authorized to access this page.</span> Please <a href="index.php">login</a>.
  </p>
<?php endif; ?>

How can I fix this?

Your ob_start will buffer output; but unless you flush the buffer at some point, then your whitespace between `?>` and ` — Mark Baker, Mar 05 '14 at 23:47

score 16 · Accepted Answer · answered Mar 05 '14 at 23:58

16

Figured it out. I simply added ob_get_clean(); before readfile(); and ob_end_flush(); after it.

answered Mar 05 '14 at 23:58

Konstantin Keller

473
6
16

1

Thank you! Of all offered solutions this was the one that got my problem solved in which the server side script would deliver a corrupt file while deliverd from localhost my script worked fine. You created great relieve after hours of desperately searching for unnnecessary linebreaks and trying numerous stackoverflow answers! Really THANK YOU – Max Apr 01 '16 at 13:15
1

I'm late to the party, but just like @Max said - this solved my issue as well! :) – prk Sep 20 '17 at 08:55
This doesn't solve my problem, for my case I have a ".xltx" file. I think this extension is not accepted by http or https – NASSIM ADRAO Jan 04 '22 at 11:46

score 13 · Answer 2 · answered Aug 12 '15 at 20:44

13

Keep in mind you can have nested output buffers, and this will corrupt your download as well (cheers to Vladamir for figuring this out). So to clear the output buffer completely (instead of just running ob_end_clean();) run this before you read your file:

while (ob_get_level()) {
    ob_end_clean();
}

This will clear out your entire buffer and you won't have any extra characters to mess up your download.

answered Aug 12 '15 at 20:44

Maximus

1,417
15
19

2

I spent hours looking for the reason my zip archive was downloading as corrupt. God bless you sir :) – Matt Kaye Jun 02 '16 at 01:52
You are most welcome. Feel free to upvote it so other's will see it more easily. – Maximus Jun 02 '16 at 16:19
1

hours spent here as well, an upvote is all i can do to thank you – Fanckush Sep 07 '16 at 14:58

AamirR · Answer 3 · 2017-09-27T20:28:14.590

I also had the same situation: In my function I was downloading a PDF file, and the file always downloads corrupted, I spent hours giggling around, nothing helped, finally:

I had to add die(); or exit(); as the last line, because I was using a MVC Framework, and MVC was causing to render view after action was finished.

Bottom line: make sure you do not have any code executed after the last line readfile(FILE_NAME)

score 0 · Answer 4 · answered Oct 07 '22 at 08:24

I had the same problem in Laravel, I tried these solutions but didn't work. I used return readfile($doc) which was causing the problem .This is my working code:

header("Cache-Control: public");
header("Content-Description: File Transfer");
header("Content-Disposition: attachment; filename=" . basename($doc));
header("Content-Type: " . $file_extension);
//return readfile($doc);
readfile($doc);

I got the corrupted file error only for excel and others were working fine. But when i removed return from return readfile($doc); excel also worked fine.

PHP readfile() corrupts file

4 Answers4