Cleaning up types in php_stdiop_cast

The whole php_stdiop_cast is a proper mess. It defines php_socket_t fd but then it uses PHP_STDIOP_GET_FD which is defined as

#define PHP_STDIOP_GET_FD(anfd, data)	anfd = (data)->file ? fileno((data)->file) : (data)->fd

which is actually always int. I assume that there are some users (external code) that casting and assume that php_socket_t is returned but I think this is incorrect and they should not assume that and it should be fixed there using proper casting. That would leave plain wrapper operating just on fd which is what I think it should.

Then why does it need to even SOCK_ERR here if it's not for socket in the first place? I think it should be redefined just to -1 or some new macro created (e.g. PHP_FD_ERR).

Originally posted by @bukka in https://github.com/php/php-src/pull/17506#discussion_r1921536084

Commencez par php_stdiop_cast et la définition de PHP_STDIOP_GET_FD, puis suivez les appelants et les utilisations de SOCK_ERR ; l’issue ne nomme aucun fichier ni test. Le travail est terminé lorsque le wrapper utilise un type de descripteur de fichier et un sentinel d’erreur cohérents, sans dépendre d’une hypothèse non prise en charge concernant un cast externe, et que les attentes de compatibilité concernées ont été vérifiées.