RE: [PHP-DEV] Re: PHP 4.0 Bug #7080 Updated: Recursive Include()s crash system From: Andi Gutmans (andi <email protected>)
Date: 10/11/00

We have include_once().

Andi

At 02:22 PM 10/11/00 +0800, Mike Berry-Porter wrote:
>Potentially, couldn't this also occur in C/C++ itself? Even if they DO have
>a way of stopping this with inbuilt functionality, good programming practice
>usually dictates that they do something like having a #DEFINE statement that
>will only allow that include file being imported once. In C/C++ this would
>look like:
>
>#IFNDEF __MY_INC_FILE__
>#DEFINE __MY_INC_FILE__
>/* Have your code here */
>...
>#ENDIF __MY_INC_FILE__
>
>
>I would suggest you do something like this in PHP:
>
>///////////////////////////////////////////////////
>TESTINC.INC file:
><?php
>/* This is the TESTINC.INC file */
>
>/* Test if the include file exists */
>if(!$_DEFINE_TESTINC_INC_)
>{
> /* Set the define so we don't include this again */
> $_DEFINE_TESTINC_INC_ = TRUE;
>
> echo "Hit!!<BR>\n";
>} /* End of _DEFINE_TESTINC_INC_ */
>?>
>///////////////////////////////////////////////////
>
>
>///////////////////////////////////////////////////
>TESTINC.PHP file:
><?php
>/* This is the MAIN file TESTINC.PHP */
>
>/* Count the number of Hits! to see how many times
> this include file is included */
>for($i=0;$i<20;$i++)
>{
> echo "Count: $i<BR>\n";
> include("testinc.inc");
>}
>?>
>///////////////////////////////////////////////////
>
>NOTE: Variables set in the include file will exist even outside of it. This
>is how you stop it from happening again. Sure, the potential pitfall is
>still there (although as mentioned the resource limit in the php.ini file is
>useful). I would personally be against a recursive limit, but if you wanted
>to only include a file X amount of times why not have $_DEFINE_TESTINC_INC_
>simply increment itself each time you enter the include file and test if it
>reaches a certain maximum number? At least you have more control over it
>then...
>
>Mike Berry-Porter
>mikebp <email protected>
>
>
>-----Original Message-----
>From: Andi Gutmans [mailto:andi <email protected>]
>Sent: Wednesday, 11 October 2000 1:16 PM
>To: Harold Paulson; Bug Database
>Subject: Re: [PHP-DEV] Re: PHP 4.0 Bug #7080 Updated: Recusive
>Include()s crash system
>
>
>Under Windows PHP handles stack overflows. UNIX is an older operating
>system and doesn't give you anyway that I know of to really cope and
>recover from stack overflows.
>We have discussed putting a limit on recursive include()'s in the past but
>it would mean adding code and an arbitrary limit (which would be quite
>meaningless) to the execution function.
>
>Andi
>
>
>At 05:00 PM 10/10/00 -0700, Harold Paulson wrote:
> >Hi,
> >
> >I just wanted to follow up on this a bit..
> >
> >Your first point is quite correct. I have indeed set resource limits for
> >apache (and every other daemon I'm running). The limits that were set by
> >default on my box were infinite. Yes, it is my fault that I didn't know
> >this and fix it beforehand, but how often is it the case? How many of the
> >web servers out there are set up similarly? Most of them, I would
> >suspect, have this defect, since it's the default in at least FreeBSD and
> >RedHat. This is their problem, and I think they should fix it, but we
> >must admit that it is the status quo of the web today.
> >
> >
> >In reference to your second suggestion, include_once() is neat, I'll start
> >using it, but...I can't be the only sysadmin who isn't the sole developer
> >on his server?
> >
> >I think PHP would be a more stable tool if maybe it featured an
> >'include_limit' directive in php.ini, or somesuch. I can imagine
> >situations where a developer might want to include a file more than once,
> >but...more than a thousand times?
> >
> >Thanks for your time.
> >
> > - H
> >
> >
> >
> >On 10 Oct 2000, Bug Database wrote:
> >
> > > ID: 7080
> > > Updated by: stas
> > > Reported By: haroldp <email protected>
> > > Status: Closed
> > > Bug Type: Reproduceable crash
> > > Assigned To:
> > > Comments:
> > >
> > > First of all, you probably need to use resource limits. Second, you
> > have include_once for this - use it.
> > >
> > > Previous Comments:
> > >
>---------------------------------------------------------------------------
> > >
> > > [2000-10-07 20:36:26] haroldp <email protected>
> > > Include()ing a file that Include()s itself - ie, a recusive
> > > Include() - will completely crash a system. Not just the
> > > web server, it ran my box out of swap in a few seconds
> > > and required a power cycle.
> > >
> > > Could we get some sanity checking on this? I had a
> > > web designer's *typo* bring a ssytem to its knees.
> > >
> > >
> > >
> > >
>---------------------------------------------------------------------------
> > >
> > >
> > > Full Bug description available at: http://bugs.php.net/?id=7080
> > >
> > >
> >
> >
> >--
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>
>---
>Andi Gutmans <andi <email protected>>
>http://www.zend.com/
>
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---
Andi Gutmans <andi <email protected>>
http://www.zend.com/

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