PHP segfaults due Exception in SaxXmlParser

Discussion:

Daniel Jakob

2012-05-01 08:36:48 UTC

Hi list

After upgrading TAL to 1.2.2, I found a little problem which makes TAL
quite unuseable in scenarios, when you are not able to control the given
xhtml source. Maybe, the problem depends on newer php versions and/or
eaccelerator.

SaxXmlParser::parseString() throws a PHPTAL_ParserException which isn't
catched by the try/catch block which leads directly to an apache
segfault.
The only exception which gets catched is the PHPTAL_TemplateException.
The ParserException subclasses the TemplateException but - however - php
doesn't care about it. This happens every time when I access the script
BUT not the first time. Setting forceReparse to true also 'fixes' the
problem so I assume, the problem is somewhere between the phptal cache
files and the exceptions in php. Maybe, the eaccelerator is involved,
too.
What definitely helps is to explicitly catch PHPTAL_ParserException at
the end of the switch-block (like the TemplateException does).

A sample:

test.xhtml:

<html>
<body>
I kill the parser
</body>
</html>

test.php:

require_once('phptal/PHPTAL.php');
$template = new PHPTAL('test.xhtml');
$template->setOutputMode(PHPTAL::XML);
$template->execute();

Expected result:
PHPTAL Exception
Attribute style in is defined more than once

Actual result:
Apache segmentation fault

Used environments:
1. Gentoo amd64, apache 2.22, php 5.3.11, eaccelerator 0.9.6.1
2. Gentoo amd64, apache 2.22, php 5.3.9, eaccelerator 0.9.6.1
3. Ubuntu x86, apache 2.22, php 5.3.6, eaccelerator 0.9.6.1

Maybe, someone has a clue. At least, this report may help anyone having
the same problem :)

cu

Daniel

a***@public.gmane.org

2012-05-01 12:43:08 UTC

Permalink

I highly doubt that apache is seg-faulting. If you are getting a 500 that could just mean that your error reporting is off.
Sent via BlackBerry by AT&T

-----Original Message-----
From: Daniel Jakob <***@sc-networks.com>
Sender: phptal-***@lists.motion-twin.com
Date: Tue, 01 May 2012 10:36:48
To: <***@lists.motion-twin.com>
Reply-To: Template Attribute Language for PHP <***@lists.motion-twin.com>
Subject: [PHPTAL] PHP segfaults due Exception in SaxXmlParser

Hi list

After upgrading TAL to 1.2.2, I found a little problem which makes TAL
quite unuseable in scenarios, when you are not able to control the given
xhtml source. Maybe, the problem depends on newer php versions and/or
eaccelerator.

SaxXmlParser::parseString() throws a PHPTAL_ParserException which isn't
catched by the try/catch block which leads directly to an apache
segfault.
The only exception which gets catched is the PHPTAL_TemplateException.
The ParserException subclasses the TemplateException but - however - php
doesn't care about it. This happens every time when I access the script
BUT not the first time. Setting forceReparse to true also 'fixes' the
problem so I assume, the problem is somewhere between the phptal cache
files and the exceptions in php. Maybe, the eaccelerator is involved,
too.
What definitely helps is to explicitly catch PHPTAL_ParserException at
the end of the switch-block (like the TemplateException does).

A sample:

test.xhtml:

<html>
<body>
I kill the parser
</body>
</html>

test.php:

require_once('phptal/PHPTAL.php');
$template = new PHPTAL('test.xhtml');
$template->setOutputMode(PHPTAL::XML);
$template->execute();

Expected result:
PHPTAL Exception
Attribute style in is defined more than once

Actual result:
Apache segmentation fault

Used environments:
1. Gentoo amd64, apache 2.22, php 5.3.11, eaccelerator 0.9.6.1
2. Gentoo amd64, apache 2.22, php 5.3.9, eaccelerator 0.9.6.1
3. Ubuntu x86, apache 2.22, php 5.3.6, eaccelerator 0.9.6.1

Maybe, someone has a clue. At least, this report may help anyone having
the same problem :)

cu

Daniel

_______________________________________________
PHPTAL mailing list
***@lists.motion-twin.com
http://lists.motion-twin.com/mailman/listinfo/phptal

Daniel Jakob

2012-05-01 14:09:02 UTC

Permalink

Post by a***@public.gmane.org
I highly doubt that apache is seg-faulting. If you are getting a 500 that could just mean that your error reporting is off.

You're right for versions prior to 1.2.2. But in the current version, it
really leads to a crash of the child process. The crash shows up in the
apache error log.

[Tue May 01 10:05:06 2012] [notice] child pid 24285 exit signal
Segmentation fault (11)
[Tue May 01 10:24:32 2012] [notice] child pid 24252 exit signal
Segmentation fault (11)

Post by a***@public.gmane.org
-----Original Message-----
Date: Tue, 01 May 2012 10:36:48
Subject: [PHPTAL] PHP segfaults due Exception in SaxXmlParser
Hi list
After upgrading TAL to 1.2.2, I found a little problem which makes TAL
quite unuseable in scenarios, when you are not able to control the given
xhtml source. Maybe, the problem depends on newer php versions and/or
eaccelerator.
SaxXmlParser::parseString() throws a PHPTAL_ParserException which isn't
catched by the try/catch block which leads directly to an apache
segfault.
The only exception which gets catched is the PHPTAL_TemplateException.
The ParserException subclasses the TemplateException but - however - php
doesn't care about it. This happens every time when I access the script
BUT not the first time. Setting forceReparse to true also 'fixes' the
problem so I assume, the problem is somewhere between the phptal cache
files and the exceptions in php. Maybe, the eaccelerator is involved,
too.
What definitely helps is to explicitly catch PHPTAL_ParserException at
the end of the switch-block (like the TemplateException does).
<html>
<body>
I kill the parser
</body>
</html>
require_once('phptal/PHPTAL.php');
$template = new PHPTAL('test.xhtml');
$template->setOutputMode(PHPTAL::XML);
$template->execute();
PHPTAL Exception
Attribute style in is defined more than once
Apache segmentation fault
1. Gentoo amd64, apache 2.22, php 5.3.11, eaccelerator 0.9.6.1
2. Gentoo amd64, apache 2.22, php 5.3.9, eaccelerator 0.9.6.1
3. Ubuntu x86, apache 2.22, php 5.3.6, eaccelerator 0.9.6.1
Maybe, someone has a clue. At least, this report may help anyone having
the same problem :)
cu
Daniel
_______________________________________________
PHPTAL mailing list
http://lists.motion-twin.com/mailman/listinfo/phptal
_______________________________________________
PHPTAL mailing list
http://lists.motion-twin.com/mailman/listinfo/phptal

Hisateru Tanaka

2012-05-01 15:45:30 UTC

Permalink

I know that eAccelerator can't handle try-catch block correctly at least in my experience.
In the other hand, PHPTAL uses its special exception handler if exception is finally
passed to outside. They might relate each other on modern PHP, I guess...

How would below(ugly code) work?

// setup $template here

try {
echo $template->execute();
$__dummy = 1; // Avoiding eAccelerator's bug.
}
catch(Exception $e) {
$exception = $e;
}
if(isset($exception)) {
// echo and exit or...
$handler = new PHPTAL_ExceptionHandler($template->getEncoding());
$handler->_defaultExceptionHandler($exception);
}

Post by Daniel Jakob

Post by a***@public.gmane.org
I highly doubt that apache is seg-faulting. If you are getting a 500 that could just mean that your error reporting is off.

You're right for versions prior to 1.2.2. But in the current version, it
really leads to a crash of the child process. The crash shows up in the
apache error log.
[Tue May 01 10:05:06 2012] [notice] child pid 24285 exit signal
Segmentation fault (11)
[Tue May 01 10:24:32 2012] [notice] child pid 24252 exit signal
Segmentation fault (11)

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PHPTAL mailing list
http://lists.motion-twin.com/mailman/listinfo/phptal

--
Hisateru Tanaka
tanakahisateru-***@public.gmane.org