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Bug #54306 Parsing bug if a pattern looking like closing ASP tag appears in comment
Submitted: 2011-03-18 12:04 UTC Modified: 2011-12-27 10:13 UTC
From: gingko at gingko dot homeip dot net Assigned:
Status: Not a bug Package: Scripting Engine problem
PHP Version: 5.2.17 OS: Linux Debian 5 'Lenny'
Private report: No CVE-ID: None
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 [2011-03-18 12:04 UTC] gingko at gingko dot homeip dot net 
Description:
------------
A parsing error occurs if a pattern looking like a closing ASP tag appears inside a line comment (beginning by '//'), in a PHP engine having 'asp_tags = On' in the 'php.ini' file.

If I remove the "//" comment, I have a big "Line 2" visible, and there is no bug.
If I use a "/* */" style comment instead, there is no bug.
If I put quotes around "140%" in the "size" attribute, there is no bug.
If I set the "asp_tags" options to "Off", or if I remove it, there is no bug.
Removing the 'if' condition around the comment results in another kind of problem (no error, but part of HTML code visible).

I found this because I was trying to install the latest version of OCS Inventory (http://www.ocsinventory-ng.org/), and I didn't understand why I got a white page and a PHP parse error after the first step of installation: I have 'asp_tags = On' in 'php.ini', and there is effectively a commented out '%>' pattern in their code.

Looks like a little to Bug #4879 (more than 10 years old).

Test script:
---------------
<html>
 <head><title>Asp tag bug</title></head>
 <body>
  Line 1<br>
<?php
  if (true) {
  //echo "<font size=140%>Line 2</font><br>";
  }
?>
  Line 3<br>
 </body>
</html>


Expected result:
----------------
Two text lines in browsers's Window :

"Line 1"
"Line 3"

Actual result:
--------------
A white page, and the following error in Apache log :
PHP Parse error:  syntax error, unexpected $end in /var/www/[...]/asp_tag_bug.php on line 13

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 [2011-03-18 12:26 UTC] carsten_sttgt at gmx dot de 
That's the normal behavior. See:
http://de.php.net/manual/en/language.basic-syntax.comments.php

"%>" is returning to HTML mode. But at this point the opened "{" from the if is not closed, and it's not closed till the end of the file. That's the error message.
 [2011-03-18 13:25 UTC] gingko at gingko dot homeip dot net 
Ok, so why ONLY in comments?
Why only in LINE comments?

And more, does it really make sense to allow closing PHP mode with an ASP tag that is not even matching an opening "<%" ASP tag, but rather only matching a "<?php" opening tag?

Shouldn't the "?>" and "%>" tags be only able to close the corresponding "<?php"/"<?" and "<%" tags?

If you look better at my sample, you will see that the "%>" accidental pattern is not completely unlikely to happen (for at least as long as HTML will tolerate to have this kind of attribute's values not enclosed in quotes).

I think that the time that I needed for finding that problem could be by itself a good reason for changing something there.
 [2011-03-18 14:00 UTC] carsten_sttgt at gmx dot de 
> Ok, so why ONLY in comments?

This also happens outside a comment.
| <?php
|  if (true) {
|  echo "foo";
|  %>
|  }
| ?>

Of course, in your case:
| echo "<font size=140%>Line 2</font><br>";
"%>" is inside a string and not parsed.


> Why only in LINE comments?

Because that's how the manual is describing comments:
| The "one-line" comment styles only comment to the end of the line
| or the current block of PHP code, whichever comes first.
(And a block is ending at "?>" or "%>".)

vs.:
| 'C' style comments end at the first */ encountered.


> Shouldn't the "?>" and "%>" tags be only able to close
> the corresponding "<?php"/"<?" and "<%" tags?

Maybe a idea for a feature request.

Conclusion:
The manual is clear how PHP is working in this situation. So it's the fault of OCS Inventory (not thinking about a PHP installation with enables ASP tags)
 [2011-12-27 10:13 UTC] stas@php.net
-Status: Open +Status: Bogus
 [2011-12-27 10:13 UTC] stas@php.net 
Thank you for taking the time to write to us, but this is not
a bug. Please double-check the documentation available at
http://www.php.net/manual/ and the instructions on how to report
a bug at http://bugs.php.net/how-to-report.php
 
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