Bug #42424 [Com]: PHP5/PCRE fails to match long strings when ungreedy

Edit report at http://bugs.php.net/bug.php?id=42424&edit=1 ID: 42424 Comment by: php at richardneill dot org Reported by: adam-phpbugs at adam dot gs Summary: PHP5/PCRE fails to match long strings when ungreedy Status: Bogus Type: Bug Package: PCRE related Operating System: Any PHP Version: 5.2.3 Block user comment: N Private report: N New Comment: This isn't bogus; it should at the very least raise an error E_NOTICE. I've just spent 7 hours tracking down a problem caused by this bug. and generating you a helpful report: http://www.richardneill.org/tmp/preg-error2.txt I do understand the rationale for the limits (though personally, I think they are 3 orders of magnitude too small, and I'd much rather my script segfaulted rather than silently introducing subtle processing errors to my data). Could we at least make sure that with display_errors (E_ALL) we get some kind of notification? At minimum, a notice would do, though ideally, this should be a fatal error. Previous Comments: ------------------------------------------------------------------------ [2007-08-27 11:17:15] jani@php.net In PHP 5.2.0 two new PCRE ini options were added to prevent possible stack overflows and crashes. One of them is pcre.backtrack_limit. When you set it high enough your script works as it did earlier (where no such limits existed!) $ php -dpcre.backtrack_limit=100001 t.php int(1) int(1) int(1) int(1) ------------------------------------------------------------------------ [2007-08-25 13:16:29] adam-phpbugs at adam dot gs Description: ------------ PHP5/PCRE will fail to match on long strings when UNGREEDY, the boundary is around 100k of data. FWIW, same results if you change x* to x+ down there. Reproduce code: --------------- <?php $data=sprintf("<span>%s</span>",str_repeat("x",99996)); var_dump(preg_match("#<span>(x*?)</span>#",$data)); $data=sprintf("<span>%s</span>",str_repeat("x",99997)); var_dump(preg_match("#<span>(x*?)</span>#",$data)); $data=sprintf("<span>%s</span>",str_repeat("x",99997)); var_dump(preg_match("#<span>(x*)</span>#U",$data)); $data=sprintf("<span>%s</span>",str_repeat("x",99997)); var_dump(preg_match("#<span>(x*)</span>#",$data)); ?> Expected result: ---------------- all 4 expressions should match, this is what occurs with PHP 4.4.7. Actual result: -------------- under PHP 5.2.3: only the first and 4th expression match under PHP 4.4.7: all 4 match. ------------------------------------------------------------------------ -- Edit this bug report at http://bugs.php.net/bug.php?id=42424&edit=1