#50264 [Com]: Possible pcre memory leak

ID: 50264 Comment by: laszlo dot janszky at gmail dot com Reported By: laszlo dot janszky at gmail dot com Status: Open Bug Type: PCRE related Operating System: Windows XP PHP Version: 5.3.1 New Comment: If I remove the recursive part (?:\\}(?<block>.*?(?:(?0).*?)*?)\\{/(?P=function))? from the end of the regex, then it works fine... Previous Comments: ------------------------------------------------------------------------ [2009-11-22 18:47:14] laszlo dot janszky at gmail dot com Description: ------------ I have a huge recursive regex (about 500bytes), which needs a lot of memory for backtrace. The regex matches on templates like {command1 arg1=$arg1 arg2=$arg2|modifier2 arg3="text"|modifier3:modarg31:modarg32} etc.... If I use the regex with preg_match_all, then the backtrace memory usage depends on the count of the commands superexponential. So: R^2 = 0,9977 (R^2 for trendline) ln ln M = 0,0787 * N + 1,9304 [M] = used backtrack memory in bytes [N] = number of command calls It don't think that more than 1Mb memory usage is normal for a 0.0002Mb string. The recursion memory usage is normal(under 1kb). I'm pretty disappointed because I can't use my template engine because of a badly written pcre engine. Reproduce code: --------------- $template1=' {display var=$link} {display var=$link} {display var=$link} {display var=$link} {display var=$link} {display var=$link} {display var=$link} {display var=$link} {display var=$link} {display var=$link} '; $template2=' {display var=$link} {display var=$link} {display var=$link} {display var=$link} test test test test test test test test test test test test test test test test test test test test test test test test test test test test test test test test test test test test test test test test test test test test test test test test test test '; $regex='%\\{(?<function>(?:\\w+))(?:(?<list>\\s(?:[\\w_]+(?:\\s[\\w_]+)*\\s)?(?:\\$\\w+(?:->\\w+|\\.\\w+)*|"(?:.*?)"|\\d+(?:\\.\\d+)?)(?:\\|\\w+(?::(?:\\$\\w+(?:->\\w+|\\.\\w+)*|"(?:.*?)"|\\d+(?:\\.\\d+)?))*)*(?:\\s[\\w_]+(?:\\s[\\w_]+)*\\s(?:\\$\\w+(?:->\\w+|\\.\\w+)*|"(?:.*?)"|\\d+(?:\\.\\d+)?)(?:\\|\\w+(?::(?:\\$\\w+(?:->\\w+|\\.\\w+)*|"(?:.*?)"|\\d+(?:\\.\\d+)?))*)*)*(?:\\s[\\w_]+(?:\\s[\\w_]+)*)?)|(?<hash>(?:\\s\\w+=(?:\\$\\w+(?:->\\w+|\\.\\w+)*|"(?:.*?)"|\\d+(?:\\.\\d+)?)(?:\\|\\w+(?::(?:\\$\\w+(?:->\\w+|\\.\\w+)*|"(?:.*?)"|\\d+(?:\\.\\d+)?))*)*)*))(?:\\}(?<block>.*?(?:(?0).*?)*?)\\{/(?P=function))?\\}%usD'; $one_Mb=1024*1024; $one_kb=1024; ini_set('pcre.backtrack_limit', $one_Mb); ini_set('pcre.recursion_limit', $one_kb); preg_match_all($regex,$template1,$matches1,PREG_SET_ORDER); preg_match_all($regex,$template2,$matches2,PREG_SET_ORDER); echo 'test1:<br />'; echo (!count($matches1)?'failed':'ok').'<br />'; echo 'test2:<br />'; echo (!count($matches2)?'failed':'ok').'<br />'; Expected result: ---------------- test1: ok test2: ok Actual result: -------------- test1: failed test2: ok ------------------------------------------------------------------------ -- Edit this bug report at http://bugs.php.net/?id=50264&edit=1