char passwd[256];

static int
pam_conv(int num_msg, const struct pam_message **msg,
		struct pam_response **resp, void *appdata_ptr)
{
	int retval = PAM_CONV_ERR;
	for (int i=0; i<num_msg; i++) {
		if (msg[i]->msg_style == PAM_PROMPT_ECHO_OFF &&
				strncmp(msg[i]->msg, "Password: ", 10) == 0) {
			struct pam_response *resp_msg = malloc(sizeof(struct pam_response));
			if (!resp_msg)
				die("malloc failed\n");
			char *password = malloc(strlen(passwd) + 1);
			if (!password)
				die("malloc failed\n");
			memset(password, 0, strlen(passwd) + 1);
			strcpy(password, passwd);
			resp_msg->resp_retcode = 0;
			resp_msg->resp = password;
			resp[i] = resp_msg;
			retval = PAM_SUCCESS;
		}
	}
	return retval;
}