Post character limit(24998) after switch to PHP5

[Idealist]

Ever since switching from PHP 4 to 5 new posts and edits that aren't done via quick edit end up blank if they're more than 24998 characters. I've had to place a limit on post size via the "Maximum Characters Per Post" setting, so users won't lose edits or new posts.

Here's a bit of info about the forum/server:
CENTOS Enterprise 4.4 i686
Apache 1.3.39
PHP 5.2.4
MySQL 4.0.27
vB 3.5.4 with security patches

There've been no errors reported by PHP or in the server's error_log. I've tried on a test instance of vB without any plugins and the same happens. Any ideas?

[Marco van Herwaarden]

Please enable Public PHPInfo in your vBuletin Options and provide a link to your board.

[Idealist]

<a href="http://sleepywood.net/forum/" target="_blank">http://sleepywood.net/forum/</a>

You'll see APC enabled, but the test forum had it disabled and still had the problem.

[Marco van Herwaarden]

Try increasing the 'post_max_size' in your PHP config. Other then that, i don't see anything obvious.

[Paul M]

25,000 chars is rather a lot, I would have though that limiting posts to (a lot) less than that would be sensible anyway.

[Idealist]

PHP would've logged an error if it exceeded post_max_size.

I thought 20k was enough after I noticed the blanking, but then the users got antsy about it. Think I'll look at what handles the quick edits compared to normal edits and see if I can fix this myself.

I'll post about it on success.

--------------- Added 1192684620 at 1192684620 ---------------

Found it! It failed at:

function strip_empty_bbcode($text)
{
return preg_replace('#(^.*|.*)(\[(php|html|noparse)\].*\[/\\3])(.*|.*$)#siUe', "\$this->strip_empty_bbcode_callback('\\1', '\\2', '\\4')", $text);
}

strip_empty_bbcode ended up causing the script to hit the pcre.backtrack_limit and/or pcre.recursion_limit (http://php.net/pcre#pcre.configuration) settings yet not logging an error.

I suggest having the option to set these in the vB AdminCP, or just correlate the setting to the "Maximum Characters Per Post" setting. The quickest solution is an:
ini_set('pcre.backtrack_limit', '-1');
ini_set('pcre.recursion_limit', '-1');
At the top of class_dm.php.

[Marco van Herwaarden]

Very nice find, how did you find this if it was not logged?

[Marco van Herwaarden]

I had a short chat with one of our developers on this subject, and it is known that this can happen in PHP 5.2, and a workaround has been added since 3.5.8 & 3.6.5.

My advice is to upgrade to a newer vBulletin version.

[Idealist]

Very nice find, how did you find this if it was not logged?

error_log()'ing at each point the message was changed. Took a moderate amount of time, I hoped it'd be quicker and dreaded it'd being longer.

I had a short chat with one of our developers on this subject, and it is known that this can happen in PHP 5.2, and a workaround has been added since 3.5.8 & 3.6.5.

My advice is to upgrade to a newer vBulletin version.My forum is very customized, the work I did finding this is less than checking each bit of customization. But a fine suggestion for others with this problem that don't want to screw with php.ini settings.