there is a problem in the file ext/posix/posix.c in function posix_uname, if i read the documentation about this function i can get some informations of the utsname struct. Well under linux you can use a machine domain name, (not yet implemented in FreeBSD). well the 'domainname' are not implemented on php but it's writed on the docs :

/* {{{ proto array posix_uname(void)
   Get system name (POSIX.1, 4.4.1) */
PHP_FUNCTION(posix_uname)
{
        struct utsname u;

        uname(&u);

        if (array_init(return_value) == FAILURE) {
                RETURN_FALSE;
        }
        add_assoc_string(return_value, "sysname",  u.sysname,  1);
        add_assoc_string(return_value, "nodename", u.nodename, 1);
        add_assoc_string(return_value, "release",  u.release, 1);
        add_assoc_string(return_value, "version",  u.version, 1);
        add_assoc_string(return_value, "machine",  u.machine, 1);
}
/* }}} */

i'v fix it :

/* {{{ proto array posix_uname(void)
   Get system name (POSIX.1, 4.4.1) */
PHP_FUNCTION(posix_uname)
{
        struct utsname u;

        uname(&u);

        if (array_init(return_value) == FAILURE) {
                RETURN_FALSE;
        }
        add_assoc_string(return_value, "sysname",  u.sysname,  1);
        add_assoc_string(return_value, "nodename", u.nodename, 1);
        add_assoc_string(return_value, "release",  u.release, 1);
        add_assoc_string(return_value, "version",  u.version, 1);
        add_assoc_string(return_value, "machine",  u.machine, 1);
#ifdef __USE_GNU
        add_assoc_string(return_value, "domainname", u.domainname, 1);
#endif
}
/* }}} */

if you don't want to correct it, please delete the wrong information in the documentations.

Regards,
Vergoz Michael
SYSDOOR