PASSWORD_PROMPT
retval = pam_get_authtok(pamh, PAM_AUTHTOK, &pass, PASSWORD_PROMPT);
retval = pam_get_authtok(pamh, PAM_OLDAUTHTOK, &pass, PASSWORD_PROMPT);
retval = pam_get_authtok(pamh, PAM_AUTHTOK, &pass, PASSWORD_PROMPT);