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what is the reasonable thing to with a segfault in php?

php.internals

Per Jessen

22 years ago

Hi,

I've got a situation where a seemingly innocent statement produces a
segfault. I've tried reducing it to a single reproducable testcase, but
without success.  The problem is however solidly reproducable in the
context in which it occurs.
I'm *certain* it is caused by a mistake in *my* code, but I feel it isn't
exactly appropriate for php to segfault because of a user error?

Very briefly, this is an excerpt where the segfault occurs:

<h2><?php print $_SESSION['customers'][$customer]; ?></h2>
<?php

$q="<longish SELECT query>";
$result=mysql_query( $q ) or die("mysql:".mysql_error());

$main_address=mysql_fetch_array( $result, MYSQL_ASSOC );

$q="<longish SELECT query>";
$result=mysql_query( $q ) or die(mysql_error());

$billing_address=mysql_fetch_array( $result, MYSQL_ASSOC );

$q="<longish SELECT query>";
$result=mysql_query( $q ) or die(mysql_error());

$technical_address=mysql_fetch_array( $result, MYSQL_ASSOC );

$editmain=strcasecmp($_REQUEST['contact'],"main")==0;
//$editbilling=strcasecmp($_REQUEST['contact'],"billing")==0;
//$edittechnical=strcasecmp($_REQUEST['contact'],"technical")==0;

?>

If I uncomment either of the last 2 commented-out statements, I get a
segfault.
I'm using php 4.3.4 and apache 2.0.49 on linux 2.4.24. mysql is 4.0.15.


/Per Jessen, Zurich

Per Jessen

22 years ago

Per Jessen wrote:

>
>         $editmain=strcasecmp($_REQUEST['contact'],"main")==0;
>         //$editbilling=strcasecmp($_REQUEST['contact'],"billing")==0;
>         //$edittechnical=strcasecmp($_REQUEST['contact'],"technical")==0;
>

OK,
I've now guarded the above with :

if ( isset($_REQUEST['contact']) )
{
$editmain=strcmp($_REQUEST['contact'],"main")==0;
$editbilling=strcmp($_REQUEST['contact'],"billing")==0;
$edittechnical=strcasecmp($_REQUEST['contact'],"technical")==0;
}

and the segfault is gone.  Still, a segfault just because I'm using an unset
global?  And why only on the 2nd or later statement?


/Per Jessen, Zurich

Antony Dovgal

22 years ago

On Thu, 15 Apr 2004 12:44:20 +0200
Per Jessen <per@computer.org> wrote:

> Per Jessen wrote:
>
> >
> >         $editmain=strcasecmp($_REQUEST['contact'],"main")==0;
> >         //$editbilling=strcasecmp($_REQUEST['contact'],"billing")==0;
> >         //$edittechnical=strcasecmp($_REQUEST['contact'],"technical")==0;
> >
>
> OK,
> I've now guarded the above with :
>
> if ( isset($_REQUEST['contact']) )
> {
>         $editmain=strcmp($_REQUEST['contact'],"main")==0;
>         $editbilling=strcmp($_REQUEST['contact'],"billing")==0;
>         $edittechnical=strcasecmp($_REQUEST['contact'],"technical")==0;
> }
>
> and the segfault is gone.  Still, a segfault just because I'm using an unset
> global?  And why only on the 2nd or later statement?
>

Read this first: http://bugs.php.net/how-to-report.php
Try a CVS snapshot and generate a backtrace - this would help more than your code.

---
WBR,
Antony Dovgal aka tony2001
tony2001@phpclub.net || antony@dovgal.com

Derick Rethans

22 years ago

On Thu, 15 Apr 2004, Per Jessen wrote:

> I'm *certain* it is caused by a mistake in *my* code, but I feel it isn't
> exactly appropriate for php to segfault because of a user error?

Right, it's not supposed to do so. Please make a backtrace of the
segfault (with gdb), or try with valgrind to see what goes wrong.

Derick

Per Jessen

22 years ago

Derick Rethans wrote:

> On Thu, 15 Apr 2004, Per Jessen wrote:
>
>> I'm *certain* it is caused by a mistake in *my* code, but I feel it isn't
>> exactly appropriate for php to segfault because of a user error?
>
> Right, it's not supposed to do so. Please make a backtrace of the
> segfault (with gdb), or try with valgrind to see what goes wrong.

I'll try with a CVS snapshot later, but for now I've opened
http://bugs.php.net/bug.php?id=28006 and added the backtrace from my current
php (4.3.4).


/Per Jessen, Zurich