Bug #54157 [NEW]: Destruction of some global variables before session write handler callback
From:
Operating system: Linux
PHP version: 5.3SVN-2011-03-03 (SVN)
Package: Scripting Engine problem
Bug Type: Bug
Bug description:Destruction of some global variables before session write handler callback
Description:
------------
The request function of the session module calls custom session save
handlers. Because modules are shut down after zend_call_destructors() is
called, this exposes the weird and apparently broken behaviour of
zend_call_destructors() to the user space.
Its effect is to delete all global variables with a reference count of 1,
but only if they hold an object. Global variables which are referenced from
anywhere, including other global variables, are not deleted.
Ideally, I would like session save handlers to have reliable access to
global variables. That probably means calling them before the user-defined
__destruct() functions, say with an extra hook into php_request_shutdown().
Failing that, I would like the behaviour to be consistent and predictable,
so that we don't end up with strange regressions like the one observed
here:
http://www.mediawiki.org/wiki/Special:Code/MediaWiki/83140#c14601
Test script:
---------------
<?php
function noop() {}
function save() {
debug_zval_dump( $GLOBALS['a'] );
debug_zval_dump( $GLOBALS['b'] );
debug_zval_dump( $GLOBALS['c'] );
}
class Foo {}
$a = new Foo;
$b = new Foo;
$c =& $b;
session_set_save_handler( 'noop', 'noop', 'noop', 'save',
'noop', 'noop'
);
session_start();
Expected result:
----------------
object(Foo)#1 (0) refcount(2){
}
object(Foo)#2 (0) refcount(1){
}
object(Foo)#2 (0) refcount(1){
}
Actual result:
--------------
Notice: Undefined index: a in
/home/tstarling/src/php/stuff/weird-shutdown_destructors.php on line 5
NULL refcount(1)
object(Foo)#2 (0) refcount(1){
}
object(Foo)#2 (0) refcount(1){
}
--
Edit bug report at http://bugs.php.net/bug.php?id=54157&edit=1
--
Try a snapshot (PHP 5.2): http://bugs.php.net/fix.php?id=54157&r=trysnapshot52
Try a snapshot (PHP 5.3): http://bugs.php.net/fix.php?id=54157&r=trysnapshot53
Try a snapshot (trunk): http://bugs.php.net/fix.php?id=54157&r=trysnapshottrunk
Fixed in SVN: http://bugs.php.net/fix.php?id=54157&r=fixed
Fixed in SVN and need be documented: http://bugs.php.net/fix.php?id=54157&r=needdocs
Fixed in release: http://bugs.php.net/fix.php?id=54157&r=alreadyfixed
Need backtrace: http://bugs.php.net/fix.php?id=54157&r=needtrace
Need Reproduce Script: http://bugs.php.net/fix.php?id=54157&r=needscript
Try newer version: http://bugs.php.net/fix.php?id=54157&r=oldversion
Not developer issue: http://bugs.php.net/fix.php?id=54157&r=support
Expected behavior: http://bugs.php.net/fix.php?id=54157&r=notwrong
Not enough info: http://bugs.php.net/fix.php?id=54157&r=notenoughinfo
Submitted twice: http://bugs.php.net/fix.php?id=54157&r=submittedtwice
register_globals: http://bugs.php.net/fix.php?id=54157&r=globals
PHP 4 support discontinued: http://bugs.php.net/fix.php?id=54157&r=php4
Daylight Savings: http://bugs.php.net/fix.php?id=54157&r=dst
IIS Stability: http://bugs.php.net/fix.php?id=54157&r=isapi
Install GNU Sed: http://bugs.php.net/fix.php?id=54157&r=gnused
Floating point limitations: http://bugs.php.net/fix.php?id=54157&r=float
No Zend Extensions: http://bugs.php.net/fix.php?id=54157&r=nozend
MySQL Configuration Error: http://bugs.php.net/fix.php?id=54157&r=mysqlcfg
Thread (7 messages)
- tstarling at wikimedia dot org