PAM "items"

To get a PAM item:
extern int pam_get_item(const pam_handle_t* pamh,
                                                           int item_type,
                                                           const void** item);
this returns (in '*item') the value of the item with the given item type.

To set a PAM item:
extern int pam_set_item(const pam_handle_t* pamh,
                                                           int item_type,
                                                           const void* item);
this sets the value of the item with the given item type, to the value given by 'item'.

"item_type" may be one of:
PAM_SERVICE - the service name of the application.
PAM_USER - the name of the user being authenticated (but this value should NOT be used).
PAM_TTY - the terminal name (/dev/.. for a tty, $DISPLAY for an X connection).
PAM_RHOST - the remote host from which the user connected.
PAM_RUSER - the remote user that tries to access the local machine.
PAM_CONV - the conversation structure used to converse with the application (normally set by the application).
PAM_USER_PROMPT - the string used when asking for the user name.
PAM_AUTHTOK - the authentication token of the user. used to pass the token from
one module to the other, to avoid re-asking the user for the password.
PAM_OLDAUTHTOK - the old authentication token. used by pam_sm_chauthtok.