PHP readfile returns zero length file

问题

This is weird.

I have a script which sends local zip files to the user via browser. The script has worked fine so far without any problems. Today my colleague notified me about the script is sending zero-length files.

Some background info:

Server settings has not been modified before the script went wrong
Different browsers tested (same on Chrome/Firefox)
Previous zip files (which worked fine before) are zero-length too
Script founds the files on the server
File size (when echoed for debugging) is correct
Tried to tweak server settings and script as adviced here with no success.

UPDATES:

is_readable() returns 1
file sizes may vary between 5Mb and 100Mb (not specific)
$zip_file holds the file path
$zip_name holds the zip name
file is really zero-length (opened in text-editor it doesn't contain a single byte)
error_reporting is On (E_ALL) shows nothing
without headers the browser displays the zip 'source' correctly
Safari says: '0 bytes of? cannot decode raw data' first useful(?) symptom

Snippet in question:

if (file_exists($zip_file)) {
    header('Content-type: application/zip');
    header('Content-disposition: filename="' . $zip_name . '"');
    header("Content-length: " . filesize($zip_file));
    readfile($zip_file);
    exit();
}

How can i debug this easily?

Thanks in advance, fabrik

回答1:

http://www.php.net/manual/en/function.readfile.php#102137 :

It should be noted that in the example:

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

$file should really be the full path to the file. Otherwise content length will not always be set, often resulting in the dreaded "0 byte file" problem.

回答2:

The biggest issue here I think is the way your sending the file, have you tried sending in within chunks:

if (file_exists($zip_file))
{
    header('Content-type: application/zip');
    header('Content-disposition: filename="' . $zip_name . '"');
    header("Content-length: " . filesize($zip_file));

    $resource = fopen($zip_file,'r');
    while(!feof($resource))
    {
         $chunk = fread($resource,4096);
         //....
         echo $chunk;
    }

    exit();
}

回答3:

Try to add attachment; and use a different browser.

header('Content-disposition: attachment; filename="' . $zip_name . '"');

回答4:

My. Lame. Fault. Sorry for everyone.

Just tweaked the code a week ago and added:

if (substr_count($_SERVER['HTTP_ACCEPT_ENCODING'], 'gzip')) {
    ob_start('ob_gzhandler');
} else {
    ob_start();
}

What caused this anomaly. :(

来源：https://stackoverflow.com/questions/5375143/php-readfile-returns-zero-length-file

标签

php

readfile