[Bug 565481] [NEW] PHP preg_match doesn't match matching string

[jsalvata]

Public bug reported:

Binary package hint: php5

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 (php5-common 5.2.10.dfsg.1-2ubuntu6.4):

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".

I tried reporting this upstream, but bugs.php.net doesn't allow
reporting bugs for versions earlier than 5.2.13.

ProblemType: Bug
Architecture: i386
Date: Sat Apr 17 19:11:27 2010
DistroRelease: Ubuntu 9.10
NonfreeKernelModules: nvidia wl
Package: php5-common 5.2.10.dfsg.1-2ubuntu6.4
ProcEnviron:
 LANGUAGE=ca_ES.UTF-8
 PATH=(custom, user)
 LANG=ca_ES.UTF-8
 SHELL=/bin/bash
ProcVersionSignature: Ubuntu 2.6.31-20.58-generic
SourcePackage: php5
Uname: Linux 2.6.31-20-generic i686

** Affects: php5 (Ubuntu)
     Importance: Undecided
         Status: New


** Tags: apport-bug i386

-- 
PHP preg_match doesn't match matching string
https://bugs.launchpad.net/bugs/565481
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