#19297 [NEW]: Php fails to update a globally defined reference's value

From: pkeshish@yahoo.com Operating system: Linux PHP version: 4.2.2 PHP Bug Type: Scripting Engine problem Bug description: Php fails to update a globally defined reference's value <?php // Dear Php developers/users, // // *-> Background // I'm re-posting this bug (http://bugs.php.net/bug.php?id=17959) // since the original one has been its status changed to // 'Analyzed' and even after providing a new example that needs // new analysis there are no means for me to change its status to // 'Open' or anything else other than 'Closed'. // // I have sent email to hholzgra@php.net (person assigned to bug) // asking him about it but never have heard back from him // (neither by email nor update on the bug's comment page). // // Therefore, it seems that if I don't re-post this bug it will // NEVER get any attention and possibly never get fixed. // // *-> Bug report // Php fails to change/update a globally defined reference's // value from within a user defined function using either of the // following methods of accessing the reference variable: // // global $ptr; // where $ptr is the reference variable // $GLOBALS['ptr'] // // hholzgra@php.net explained (in original bug #17959) that I // should not expect the first method to work as it is a "short // hand" for "$ptr = &$GLOBALS['ptr'];" and a new assignment to // local-to-function $ptr only changes the local reference and // not the intended global one. Btw, I find this a counter // intuitive behavior on the Php's part. I think "global $var" // should act more like a C++ reference rather than a C pointer. // // After considering explanation of what exactly 'global $ptr' // is i changed my code to strictly use $GLOBALS['ptr']. However, // after doing so my program still didn't function properly! // // I had to work a bit harder to come up with a simplified example // for you. I believe i have done so below. // // Please pay close attention to the notes w/in comments explaining // strange conditions that would make this sample code to work as // expected. Now I'm certain there EXISTS a serious problem with // the Php engine when processing this code. // // Thanks, // --patrick // // *-> Sample code // define array we plan to navigate. $top = array ( 'name' => 'top', 'A' => array ( 'name' => 'A', 'A_a' => array ( 'name' => 'A_a', 'fn_1' => 'Aa_fn_1', 'fn_2' => 'Aa_fn_2', 'fn_3' => 'Aa_fn_3', 'A_a_1' => array ( 'name' => 'A_a_1', 'fn_1' => 'Aa1_fn_1', 'fn_2' => 'Aa1_fn_2', ), 'A_a_2' => array ( 'name' => 'A_a_2', 'fn_1' => 'Aa2_fn_1', 'fn_2' => 'Aa2_fn_2', ), ), ), ); // setup "parent references" for each of the nodes. $top['parent'] = null; $top['A']['parent'] = &$top; $top['A']['A_a']['parent'] = &$top['A']; $top['A']['A_a']['A_a_1']['parent'] = &$top['A']['A_a']; $top['A']['A_a']['A_a_2']['parent'] = &$top['A']['A_a']; //$top['A']['A_a']['A_a_1']['parent'] = &$top['A']['A_a']; // // Note! // Here if we uncomment the above line the sample code will // magically WORK! // // Why does the order of initialization matter!? And will the // code now break elsewhere? // setup our reference to $top. $ptr is what should change // on every call to change_ptr(name). $ptr = &$top; // change_ptr( name ) does the following w/some verbose // messages to display the state of variables in question. // // if ( ptr[name] ) // ptr = ptr[name]; // function change_ptr( $name ) { printf( " change_ptr($name) " ); if ( $GLOBALS['ptr'][$name] ) { // Setting up string for later printing. $before_change = sprintf( "before: \$GLOBALS['ptr']['name'] = %s", $GLOBALS['ptr']['name'] ); $GLOBALS['ptr'] = &$GLOBALS['ptr'][$name]; $after_change = sprintf( "after: \$GLOBALS['ptr']['name'] = %s", $GLOBALS['ptr']['name'] ); printf( "<font color=\"green\"><b>CHANGED</b></font>:\n" ); printf( " %s\n %s", $before_change, $after_change ); } else printf( "<font color=\"red\"><b>NO CHANGE!</b></font>" ); printf( "<br>\n" ); } ?> <pre> <? // All of the following calls should succeed and print // 'CHANGED'. However, you will notice that the last call // will fail to change $ptr to point to the 'parent' of // $top['A']['A_a']['A_a_2']. // change_ptr('A'); change_ptr('A_a'); change_ptr('A_a_1'); change_ptr('parent'); change_ptr('A_a_2'); change_ptr('parent'); ?> </pre> ?> -- Edit bug report at http://bugs.php.net/?id=19297&edit=1 -- Try a CVS snapshot: http://bugs.php.net/fix.php?id=19297&r=trysnapshot Fixed in CVS: http://bugs.php.net/fix.php?id=19297&r=fixedcvs Fixed in release: http://bugs.php.net/fix.php?id=19297&r=alreadyfixed Need backtrace: http://bugs.php.net/fix.php?id=19297&r=needtrace Try newer version: http://bugs.php.net/fix.php?id=19297&r=oldversion Not developer issue: http://bugs.php.net/fix.php?id=19297&r=support Expected behavior: http://bugs.php.net/fix.php?id=19297&r=notwrong Not enough info: http://bugs.php.net/fix.php?id=19297&r=notenoughinfo Submitted twice: http://bugs.php.net/fix.php?id=19297&r=submittedtwice register_globals: http://bugs.php.net/fix.php?id=19297&r=globals