Bug #4835

ReadLine causes memory exhaustion

Details

Submitted	2005-07-14 20:42 UTC
From	chris dot stone at gmail dot com
Assigned	mike
Status	Closed
Package	File
PHP Version	5.0.4
OS	RHEL4
Roadmaps	(Not assigned)

Comments

[2005-07-14 20:42 UTC] chris dot stone at gmail dot com

Description:
------------
File::readLine() doesn't work.

Reproduce code:
---------------
$foo = File::readLine('bar');

Expected result:
----------------
it works?

Actual result:
--------------
it doesn't work

[2005-07-20 07:35 UTC] chris dot stone at gmail dot com

From bug 4865 (hope this is enough info)

Description:
------------
Using File::readLine with PHP5 is totally broken, I don't know how else to describe it. When I load the test page below absolutely nothing happens at all. No errors, no page refresh, nothing. It's like PHP is breaking or something??

Reproduce code:
---------------
<?php

require_once 'File.php';

var_dump(File::readLine('foo.txt'));

foo.txt contains:
This is a file test.
With two lines in it.

Expected result:
----------------
var_dump of "This is a file test."

Actual result:
--------------
Complete breakage, page doesn't even start, for example, if you have another page already loaded and try to load file.php, the old page just remains on the screen.

[2005-07-20 09:27 UTC] chris dot stone at gmail dot com

I modified my example program to this:

<?php

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

require 'File.php';
var_dump(File::readLine('foo.txt'));

And as I said, absolutely nothing happens. No headers are sent, no errors are shown, no page is loaded, no output is printed. The previous page I have loaded does not even go away. It basically just dies and does nothing.

Is there a file where errors are logged?

[2005-07-20 09:28 UTC] chris dot stone at gmail dot com

Oh forgot to mention version info:

$ pear info file
About File-1.2.0

[2005-07-20 09:38 UTC] chris dot stone at gmail dot com

If I try to browse to the example.php file from a new window (no previous page loaded), I do get some headers on the output:

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html><head><title></title></head><body></body></html>

but that is all it prints.

[2005-07-20 09:47 UTC] chris dot stone at gmail dot com

I'm not sure if this will help you, but I also tried it on my local server at home using Fedora Core 4 which also uses PHP 5.0.4 and I get the same results. You can see the results at:

http://xulchris.dyndns.org/example.php

Please let me know if you need me to modify the example script at all. If I change readLine to readAll, the script runs correctly.

[2005-07-20 10:12 UTC] chris dot stone at gmail dot com

Apache is giving me an error message:

[client 209.78.16.118] PHP Fatal error: Allowed memory size of 8388608 bytes ex
hausted (tried to allocate 8192001 bytes) in /usr/share/pear/File.php on line 32
6
Allowed memory size of 8388608 bytes exhausted (tried to allocate 256 bytes)

hope this helps.

[2005-07-20 10:21 UTC] chris dot stone at gmail dot com

The following patch fixes the problem:

--- File.php.orig 2005-07-20 03:20:15.000000000 -0700
+++ File.php 2005-07-20 03:20:34.000000000 -0700
@@ -323,7 +323,7 @@
return false;
}

- return rtrim(fgets($fp, FILE_MAX_LINE_READSIZE), "\r\n");
+ return rtrim(fgets($fp, FILE_DEFAULT_READSIZE), "\r\n");
}

/**

[2005-07-20 15:31 UTC] chris dot stone at gmail dot com

Yes, this will work, but it seems that this is a work-around to the real problem. It seems as if PHP is not detecting EOL or EOF characters. I've reviewed the code in File.php, and nothing seems incorrect. The length parameter to fgets should not allocate 8M of RAM on a simple two line file thats < 1k. fgets() is supposed to return the smallest of string to EOL, EOF or length. I think I should try to recreate this problem using standard PHP calls such as fopen and fgets and file a bug report with PHP or RedHat. Please let me know if you have any insight on what might be going wrong. Thanks for the help, I'm glad we atleast have a working work-around to the problem! :)

[2005-07-21 01:56 UTC] chris dot stone at gmail dot com

<?php
define('FILE_MAX_LINE_READSIZE', 8192000, true);
define('FILE_MODE_READ', 'rb', true);
$fp = @fopen('foo.txt', FILE_MODE_READ);
var_dump(rtrim(fgets($fp, FILE_MAX_LINE_READSIZE), "\r\n"));
?>

Okay I tried using standard PHP calls (see above), and it works just fine when I do it this way. For some reason, the fgets() call is not working under the File class. :/

Any ideas?

[2005-07-21 02:57 UTC] chris dot stone at gmail dot com

<?php

require 'PEAR.php';

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

define('FILE_MAX_LINE_READSIZE', 8192000, true);
define('FILE_MODE_READ', 'rb', true);

class MyFile
{
function myReadLine($filename, $lock = false)
{
$fp = @fopen($filename, FILE_MODE_READ);
var_dump(rtrim(fgets($fp, FILE_MAX_LINE_READSIZE), "\r\n"));
}
}

MyFile::MyReadLine('foo.txt');

Okay, I've reduced the error down to the simplest code possible to reproduce the error. This code will cause the following error:

Fatal error: Allowed memory size of 8388608 bytes exhausted (tried to allocate 8192 bytes) in /var/www/html/example2.php on line 16

However, if I comment out the require 'PEAR.php'; line, the code will work!