# Correct use of zend_list_delete

- Thread: https://externals.io/message/19935
- Original archive: https://news-web.php.net/php.internals/19935
- Started by Marco Bambini on 2005-11-09T13:40:39+00:00
- Messages: 2
- Reply by email to internals@lists.php.net
- More for agents: search with https://externals.io/search.md?q={query} · JSON API at https://externals.io/api · documentation at https://externals.io/llms.txt

---

## #19935 — Marco Bambini — 2005-11-09T13:40:39+00:00

URL: https://externals.io/message/19935#19935

Maybe this is a question too simple for this list, but I am writing  
my first php extension (using php 4.4 SDK) so please, be patient...
My extension (rsql) returns a custom struct to php so my code in my  
rsql_connect looks like:

ZEND_FUNCTION(rsql_connect)
{
	....
	RETURN_RESOURCE(zend_list_insert(rsqldb, rsql_connection));
}

The relevant code is:

ZEND_FUNCTION(rsql_disconnect)
{
	...
	ZEND_FETCH_RESOURCE2(rsqldb, void*, theConnectionParameter, -1,  
kConnIDString, rsql_connection, rsql_pconnection);
	if (rsqldb) zend_list_delete(Z_LVAL_PP(theConnectionParameter));
	if (rsqldb) myCustomFree(rsqldb);
}

static void rsql_realconnectionclose(zend_rsrc_list_entry *rsrc)
{
	void *rsqldb;
	if (rsrc != NULL)
	{
		rsqldb = rsrc->ptr;
		if (rsqldb != NULL)
		{
			rsqlserver_disconnect(rsqldb, kTRUE);
			rsqldb = NULL;
			
			if (persistent == kTRUE)
				RSQL_G(num_persistent)--;
		}
	}
}


PHP_MINIT_FUNCTION(rsql)
{
	rsql_connection = zend_register_list_destructors_ex 
(rsql_realconnectionclose, NULL, kConnIDString, module_number);
}

What is the issue I encounter with this code?
This php code crashes:

for ($i=0; $i<10; $i++){

	$dbconn = rsql_connect("127.0.0.1","admin","admin");
	if (is_resource($dbconn) == 0){
		print "Connection to database server failed.";
	 `exit()`;
	}
	
	rsql_disconnect($dbconn);

}

and also this one:

for ($i=0; $i<10; $i++){

	$dbconn = rsql_connect("127.0.0.1","admin","admin");
	if (is_resource($dbconn) == 0){
		print "Connection to database server failed.";
	 `exit()`;
	}

}

What I think is that when rsql_disconnect is called explicitly or by  
the destructor (rsql_realconnectionclose) my custom struct isn't  
really deleted from the zend_list.

I really appreciate any help for my issue...

Thanks a lot,
Marco Bambini

---

## #19945 — Wez Furlong — 2005-11-10T10:54:26+00:00

URL: https://externals.io/message/19935#19945 · In reply to: #19935

> ZEND_FUNCTION(rsql_disconnect)
> {
>         ...
>         ZEND_FETCH_RESOURCE2(rsqldb, void*, theConnectionParameter, -1,
> kConnIDString, rsql_connection, rsql_pconnection);
>         if (rsqldb) zend_list_delete(Z_LVAL_PP(theConnectionParameter));
>         if (rsqldb) myCustomFree(rsqldb);

Removing the call to myCustomFree should solve your problem; the list
destructor is calling it once for you, and you're then trying to free
somthing that is no longer valid.

--Wez