#32330 [Asn]: session_destroy, "Failed to initialize storage module", custom session handler

From: Date: Fri, 18 Mar 2005 23:55:19 +0000
Subject: #32330 [Asn]: session_destroy, "Failed to initialize storage module", custom session handler
References: 1  Groups: php.bugs 
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 ID:               32330
 Updated by:       mfischer@php.net
 Reported By:      mfischer@php.net
 Status:           Assigned
 Bug Type:         Session related
 Operating System: *
 PHP Version:      4CVS, 5CVS (2005-03-17)
 Assigned To:      sniper
 New Comment:

Good catch, thanks.


Previous Comments:
------------------------------------------------------------------------

[2005-03-17 10:37:29] sniper@php.net

I see that the php_session_destroy() is called in php_session_decode()
too..


------------------------------------------------------------------------

[2005-03-17 10:14:08] mfischer@php.net

I unfortunately lack the time to verify this with a new php
installation currently.

By looking at
http://cvs.php.net/co.php/php-src/ext/session/session.c?r=1.336.2.50
(latest commit of 4_3 branch) the relevant parts of the code haven't
changed. PS(mod_data) is still set to NULL in php_rinit_session_globals
which is called from php_session_destroy, this when a user from PHP
calls session_destroy(), the custom session save handlers are removed.

Thanks

------------------------------------------------------------------------

[2005-03-16 09:29:18] mfischer@php.net

Description:
------------
When I use custom session handling functions and use the following
session functions in this order:

[...]
session_set_save_handler(...)
[...]
session_start()
[...]
session_destroy()
[...]
session_start()

I get

"Fatal error: session_start(): Failed to initialize storage module:
user (path: /var/lib/php4) in test.php on line 9"

After session_destroy is called, the functions assigned with
session_set_save_handler() do not work anymore and have to be assigned
again.

By calling session_set_save_handler() again after session_destroy() it
will work.

This applies to 4.9.10 and 5.0.3 as well.

I think the cause is in session.c in php_session_destroy:
[...]
    if (PS(mod)->s_destroy(&PS(mod_data), PS(id) TSRMLS_CC) == FAILURE)
{
        retval = FAILURE;
        php_error_docref(NULL TSRMLS_CC, E_WARNING, "Session object
destruction failed");
    }

    php_rshutdown_session_globals(TSRMLS_C);
    php_rinit_session_globals(TSRMLS_C);
[...]

First, the user defined destroy-handler is called then
php_rshutdown_session_globals and then php_rinit_session_globals. In
php_rinit_session_globals PS(mod_data) is cleared

static void php_rinit_session_globals(TSRMLS_D)
{
    PS(id) = NULL;
    PS(session_status) = php_session_none;
    PS(mod_data) = NULL;
    PS(http_session_vars) = NULL;
}

which is a struct for the user defined functions.

The current documentation says:
"session_destroy() destroys all of the data associated with the current
session."

But it seems to do more: it also clears any custom set session save
handlers which unexpected.


Reproduce code:
---------------
<?php
	function dummy() { }

	session_set_save_handler('dummy', 'dummy', 'dummy',
'dummy', 'dummy',
'dummy');

	session_start();
	session_destroy();
	# comment in the next line and the test works
	#session_set_save_handler('dummy', 'dummy', 'dummy',
'dummy', 'dummy',
'dummy');
	session_start();
?>


Expected result:
----------------
No fatal error message

Actual result:
--------------
Fatal error: session_start(): Failed to initialize storage module: user


------------------------------------------------------------------------


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