From: theultramage at gmail dot com Operating system: Windows Vista PHP version: 6CVS-2009-06-19 (snap) PHP Bug Type: SimpleXML related Bug description: xpath() returns FALSE for legitimate query
Description: ------------ SimpleXML's xpath() implementation contains code that returns FALSE for some queries where it should be returning an empty container object. In revision 1.79 of simplexml.c (http://cvs.php.net/viewvc.cgi/php-src/ext/simplexml/simplexml.c?r1=1.78&r2=1.79) the call to xmlXPathEval() was hotfixed to avoid crashing if the query errored. However, the author also added a check against "retval->nodesetval", treating NULL as an error situation. I believe this was an incorrect decision. There is a scenario where 'nodesetval' will be NULL - when querying for the attribute of a non-matching element ('/foo/@attr' when there are no 'foo' nodes); in all other 'bad' queries that I tried, 'nodesetval' came initialized and containing zero nodes. So, we can see that for certain queries, simplexml will give an incorrect result. This was already pointed out on 18-dec-2005 by an user comment on the php simplexml::xpath documentation page. I have sent an inquiry to the xml mailing list (http://mail.gnome.org/archives/xml/2009-June/msg00019.html) asking for clarification, however I believe that the current logic is incorrect. I checked php's DOM module src and libxml's xpath1.c code example, and they do not consider it a problem (DOM initializes empty DOMNodeList, example sets count to 0). Alternatively, the code should not be messing with what is apparently internal structures, and instead use the API for processing, if one is available. Reproduce code: --------------- <?php $xml = '<?xml version="1.0" encoding="utf-8"?><dummy/>'; $db = new SimpleXMLElement($xml); if( FALSE !== $db->xpath("/foo/@attr") ) echo "OK"; else echo "Error!"; ?> Expected result: ---------------- xpath() should return an empty array. Actual result: -------------- xpath() returns FALSE. -- Edit bug report at http://bugs.php.net/?id=48601&edit=1 -- Try a CVS snapshot (PHP 5.2): http://bugs.php.net/fix.php?id=48601&r=trysnapshot52 Try a CVS snapshot (PHP 5.3): http://bugs.php.net/fix.php?id=48601&r=trysnapshot53 Try a CVS snapshot (PHP 6.0): http://bugs.php.net/fix.php?id=48601&r=trysnapshot60 Fixed in CVS: http://bugs.php.net/fix.php?id=48601&r=fixedcvs Fixed in CVS and need be documented: http://bugs.php.net/fix.php?id=48601&r=needdocs Fixed in release: http://bugs.php.net/fix.php?id=48601&r=alreadyfixed Need backtrace: http://bugs.php.net/fix.php?id=48601&r=needtrace Need Reproduce Script: http://bugs.php.net/fix.php?id=48601&r=needscript Try newer version: http://bugs.php.net/fix.php?id=48601&r=oldversion Not developer issue: http://bugs.php.net/fix.php?id=48601&r=support Expected behavior: http://bugs.php.net/fix.php?id=48601&r=notwrong Not enough info: http://bugs.php.net/fix.php?id=48601&r=notenoughinfo Submitted twice: http://bugs.php.net/fix.php?id=48601&r=submittedtwice register_globals: http://bugs.php.net/fix.php?id=48601&r=globals PHP 4 support discontinued: http://bugs.php.net/fix.php?id=48601&r=php4 Daylight Savings: http://bugs.php.net/fix.php?id=48601&r=dst IIS Stability: http://bugs.php.net/fix.php?id=48601&r=isapi Install GNU Sed: http://bugs.php.net/fix.php?id=48601&r=gnused Floating point limitations: http://bugs.php.net/fix.php?id=48601&r=float No Zend Extensions: http://bugs.php.net/fix.php?id=48601&r=nozend MySQL Configuration Error: http://bugs.php.net/fix.php?id=48601&r=mysqlcfg
