Bug #51663 [NEW]: PHP preg_match doesn't match string which should match

From: Date: Sun, 25 Apr 2010 22:37:04 +0000
Subject: Bug #51663 [NEW]: PHP preg_match doesn't match string which should match
Groups: php.bugs 
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From:             
Operating system: Ubuntu
PHP version:      5.3.2
Package:          PCRE related
Bug Type:         Bug
Bug description:PHP preg_match doesn't match string which should match

Description:
------------
This regular expression:
/^(?:[^\[\]{}']+|'[^']*')+:(?:[^\[\]{}']+|'[^']*')+$/
matches this string: a:bbbbbbbbbbbbbbb
in Perl (5.10.0-24ubuntu4):

perl <<__END__
print 'a:bbbbbbbbbbbbb' =~
q/^(?:[^\[\]{}']+|'[^']*')+:(?:[^\[\]{}']+|'[^']*')+$/;
print "\n";
__END__
1

and pcretest (libpcre3 7.8-3):

pcretest <<__END__
/^(?:[^\[\]{}']+|'[^']*')+:(?:[^\[\]{}']+|'[^']*')+$/
a:bbbbbbbbbbbbbbb
__END__
PCRE version 7.8 2008-09-05

  re> data> 0: a:bbbbbbbbbbbbbbb
data>

Not, however, in PHP (5.3.2):
$ ./php --version
PHP 5.3.2 (cli) (built: Apr 25 2010 23:58:33)
Copyright (c) 1997-2010 The PHP Group
Zend Engine v2.3.0, Copyright (c) 1998-2010 Zend Technologies
$ ./php <<__END__

<?=
preg_match("/^(?:[^\[\]{}']+|'[^']*')+:(?:[^\[\]{}']+|'[^']*')+$/",
"a:bbbbbbbbbbbbb") ?>

__END__
0

The bug is pretty sensible to changes in the input. Removing a couple of
"b"s makes it match. I don't know which aspects of the regexp cause it to
fail.

For confirmation that this is indeed a bug without having to decypher the
regexp, here's proof:

<?php
$A='(?:[^\[\]{}\']+|\'[^\']*\')+';
$a= 'a';
$B=":$A";
$b= ':bbbbbbbbbbbbbbb';
print_r(preg_match("/^$A$/", "$a"));
print_r(preg_match("/^$B$/", "$b"));
print_r(preg_match("/^$A$B$/", "$a$b"));
print_r("\n");

This outputs "110", which is impossible since if /^$A$/ matches "$a" and
/^$B$/ matches "$b", /^$A$B$/ should definitely match "$a$b".

Test script:
---------------
<?=
preg_match("/^(?:[^\[\]{}']+|'[^']*')+:(?:[^\[\]{}']+|'[^']*')+$/",
"a:bbbbbbbbbbbbb") ? "pass" : "fail" ?>


Expected result:
----------------
pass

Actual result:
--------------
fail

-- 
Edit bug report at http://bugs.php.net/bug.php?id=51663&edit=1
-- 
Try a snapshot (PHP 5.2):            http://bugs.php.net/fix.php?id=51663&r=trysnapshot52
Try a snapshot (PHP 5.3):            http://bugs.php.net/fix.php?id=51663&r=trysnapshot53
Try a snapshot (PHP 6.0):            http://bugs.php.net/fix.php?id=51663&r=trysnapshot60
Fixed in SVN:                        http://bugs.php.net/fix.php?id=51663&r=fixed
Fixed in SVN and need be documented: http://bugs.php.net/fix.php?id=51663&r=needdocs
Fixed in release:                    http://bugs.php.net/fix.php?id=51663&r=alreadyfixed
Need backtrace:                      http://bugs.php.net/fix.php?id=51663&r=needtrace
Need Reproduce Script:               http://bugs.php.net/fix.php?id=51663&r=needscript
Try newer version:                   http://bugs.php.net/fix.php?id=51663&r=oldversion
Not developer issue:                 http://bugs.php.net/fix.php?id=51663&r=support
Expected behavior:                   http://bugs.php.net/fix.php?id=51663&r=notwrong
Not enough info:                     http://bugs.php.net/fix.php?id=51663&r=notenoughinfo
Submitted twice:                     http://bugs.php.net/fix.php?id=51663&r=submittedtwice
register_globals:                    http://bugs.php.net/fix.php?id=51663&r=globals
PHP 4 support discontinued:          http://bugs.php.net/fix.php?id=51663&r=php4
Daylight Savings:                    http://bugs.php.net/fix.php?id=51663&r=dst
IIS Stability:                       http://bugs.php.net/fix.php?id=51663&r=isapi
Install GNU Sed:                     http://bugs.php.net/fix.php?id=51663&r=gnused
Floating point limitations:          http://bugs.php.net/fix.php?id=51663&r=float
No Zend Extensions:                  http://bugs.php.net/fix.php?id=51663&r=nozend
MySQL Configuration Error:           http://bugs.php.net/fix.php?id=51663&r=mysqlcfg

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