* Called to set up the pty.
 * 
 * Returns an error message, or NULL on success.
 *
 * Also places the canonical host name into `realhost'. It must be
 * freed by the caller.
 */
static char *pty_init(void *frontend, void **backend_handle,
static char *pty_init(void *frontend, void **backend_handle, Config *cfg,
		      char *host, int port, char **realhost, int nodelay)
{
    int slavefd;
    pid_t pid, pgrp;

    pty_frontend = frontend;
    *backend_handle = NULL;	       /* we can't sensibly use this, sadly */

    pty_term_width = cfg.width;
    pty_term_height = cfg.height;
    pty_term_width = cfg->width;
    pty_term_height = cfg->height;

    if (pty_master_fd < 0)
	pty_open_master();

    /*
     * Set the backspace character to be whichever of ^H and ^? is
     * specified by bksp_is_delete.
     */
    {
	struct termios attrs;
	tcgetattr(pty_master_fd, &attrs);
	attrs.c_cc[VERASE] = cfg.bksp_is_delete ? '\177' : '\010';
	attrs.c_cc[VERASE] = cfg->bksp_is_delete ? '\177' : '\010';
	tcsetattr(pty_master_fd, TCSANOW, &attrs);
    }

    /*
     * Stamp utmp (that is, tell the utmp helper process to do so),
     * or not.
     */
    if (!cfg.stamp_utmp)
    if (!cfg->stamp_utmp)
	close(pty_utmp_helper_pipe);   /* just let the child process die */
    else {
	char *location = get_x_display(pty_frontend);
	int len = strlen(location)+1, pos = 0;   /* +1 to include NUL */
	while (pos < len) {
	    int ret = write(pty_utmp_helper_pipe, location+pos, len - pos);
	    if (ret < 0) {

	setpgrp();
	close(open(pty_name, O_WRONLY, 0));
	setpgrp();
	/* Close everything _else_, for tidiness. */
	for (i = 3; i < 1024; i++)
	    close(i);
	{
	    char term_env_var[10 + sizeof(cfg.termtype)];
	    sprintf(term_env_var, "TERM=%s", cfg.termtype);
	    char term_env_var[10 + sizeof(cfg->termtype)];
	    sprintf(term_env_var, "TERM=%s", cfg->termtype);
	    putenv(term_env_var);
	}
	/*
	 * SIGINT and SIGQUIT may have been set to ignored by our
	 * parent, particularly by things like sh -c 'pterm &' and
	 * some window managers. Reverse this for our child process.
	 */
	putty_signal(SIGINT, SIG_DFL);
	putty_signal(SIGQUIT, SIG_DFL);
	if (pty_argv)
	    execvp(pty_argv[0], pty_argv);
	else {
	    char *shell = getenv("SHELL");
	    char *shellname;
	    if (cfg.login_shell) {
	    if (cfg->login_shell) {
		char *p = strrchr(shell, '/');
		shellname = smalloc(2+strlen(shell));
		p = p ? p+1 : shell;
		sprintf(shellname, "-%s", p);
	    } else
		shellname = shell;
	    execl(getenv("SHELL"), shellname, NULL);

    } else {
	pty_child_pid = pid;
	pty_child_dead = FALSE;
    }      

    return NULL;
}

/*
 * Stub routine (we don't have any need to reconfigure this backend).
 */
static void pty_reconfig(void *handle, Config *cfg)
{
}

/*
 * Called to send data down the pty.
 */
static int pty_send(void *handle, char *buf, int len)
{
    if (pty_master_fd < 0)

	return -1;		       /* not dead yet */
    else
	return pty_exit_code;
}

Backend pty_backend = {
    pty_init,
    pty_reconfig,
    pty_send,
    pty_sendbuffer,
    pty_size,
    pty_special,
    pty_socket,
    pty_exitcode,
    pty_sendok,
    pty_ldisc,
    pty_provide_ldisc,
    pty_provide_logctx,
    pty_unthrottle,
    1
};