back->special(backhandle, TS_SUSP);
ldisc->back->special(ldisc->backhandle, TS_SUSP);
void ldisc_send(char *buf, int len, int interactive){    int keyflag = 0;    /*     * Called with len=0 when the options change. We must inform     * the front end in case it needs to know.     */    if (len == 0) {	void ldisc_update(int echo, int edit);	ldisc_update(ECHOING, EDITING);	return;    }    /*     * Notify the front end that something was pressed, in case     * it's depending on finding out (e.g. keypress termination for     * Close On Exit).      */    frontend_keypress();    /*     * Less than zero means null terminated special string.     */    if (len < 0) {	len = strlen(buf);	keyflag = KCTRL('@');    }    /*     * Either perform local editing, or just send characters.     */    if (EDITING) {	while (len--) {	    int c;	    c = *buf++ + keyflag;	    if (!interactive && c == '\r')		c += KCTRL('@');	    switch (term_quotenext ? ' ' : c) {		/*		 * ^h/^?: delete one char and output one BSB		 * ^w: delete, and output BSBs, to return to last		 * space/nonspace boundary		 * ^u: delete, and output BSBs, to return to BOL		 * ^c: Do a ^u then send a telnet IP		 * ^z: Do a ^u then send a telnet SUSP		 * ^\: Do a ^u then send a telnet ABORT		 * ^r: echo "^R\n" and redraw line		 * ^v: quote next char		 * ^d: if at BOL, end of file and close connection,		 * else send line and reset to BOL		 * ^m: send line-plus-\r\n and reset to BOL		 */	      case KCTRL('H'):	      case KCTRL('?'):	       /* backspace/delete */		if (term_buflen > 0) {		    if (ECHOING)			bsb(plen(term_buf[term_buflen - 1]));		    term_buflen--;		}		break;	      case CTRL('W'):	       /* delete word */		while (term_buflen > 0) {		    if (ECHOING)			bsb(plen(term_buf[term_buflen - 1]));		    term_buflen--;		    if (term_buflen > 0 &&			isspace(term_buf[term_buflen - 1]) &&			!isspace(term_buf[term_buflen]))			break;		}		break;	      case CTRL('U'):	       /* delete line */	      case CTRL('C'):	       /* Send IP */	      case CTRL('\\'):	       /* Quit */	      case CTRL('Z'):	       /* Suspend */		while (term_buflen > 0) {		    if (ECHOING)			bsb(plen(term_buf[term_buflen - 1]));		    term_buflen--;		}		back->special(backhandle, TS_EL);                /*                 * We don't send IP, SUSP or ABORT if the user has                 * configured telnet specials off! This breaks                 * talkers otherwise.                 */                if (!cfg.telnet_keyboard)                    goto default_case;		if (c == CTRL('C'))		    back->special(backhandle, TS_IP);		if (c == CTRL('Z'))		    back->special(backhandle, TS_SUSP);		if (c == CTRL('\\'))		    back->special(backhandle, TS_ABORT);		break;	      case CTRL('R'):	       /* redraw line */		if (ECHOING) {		    int i;		    c_write("^R\r\n", 4);		    for (i = 0; i < term_buflen; i++)			pwrite(term_buf[i]);		}		break;	      case CTRL('V'):	       /* quote next char */		term_quotenext = TRUE;		break;	      case CTRL('D'):	       /* logout or send */		if (term_buflen == 0) {		    back->special(backhandle, TS_EOF);		} else {		    back->send(backhandle, term_buf, term_buflen);		    term_buflen = 0;		}		break;		/*		 * This particularly hideous bit of code from RDB		 * allows ordinary ^M^J to do the same thing as		 * magic-^M when in Raw protocol. The line `case		 * KCTRL('M'):' is _inside_ the if block. Thus:		 * 		 *  - receiving regular ^M goes straight to the		 *    default clause and inserts as a literal ^M.		 *  - receiving regular ^J _not_ directly after a		 *    literal ^M (or not in Raw protocol) fails the		 *    if condition, leaps to the bottom of the if,		 *    and falls through into the default clause		 *    again.		 *  - receiving regular ^J just after a literal ^M		 *    in Raw protocol passes the if condition,		 *    deletes the literal ^M, and falls through		 *    into the magic-^M code		 *  - receiving a magic-^M empties the line buffer,		 *    signals end-of-line in one of the various		 *    entertaining ways, and _doesn't_ fall out of		 *    the bottom of the if and through to the		 *    default clause because of the break.		 */	      case CTRL('J'):		if (cfg.protocol == PROT_RAW &&		    term_buflen > 0 && term_buf[term_buflen - 1] == '\r') {		    if (ECHOING)			bsb(plen(term_buf[term_buflen - 1]));		    term_buflen--;		    /* FALLTHROUGH */	      case KCTRL('M'):	       /* send with newline */		    if (term_buflen > 0)			back->send(backhandle, term_buf, term_buflen);		    if (cfg.protocol == PROT_RAW)			back->send(backhandle, "\r\n", 2);		    else if (cfg.protocol == PROT_TELNET && cfg.telnet_newline)			back->special(backhandle, TS_EOL);		    else			back->send(backhandle, "\r", 1);		    if (ECHOING)			c_write("\r\n", 2);		    term_buflen = 0;		    break;		}		/* FALLTHROUGH */	      default:		       /* get to this label from ^V handler */                default_case:		if (term_buflen >= term_bufsiz) {		    term_bufsiz = term_buflen + 256;		    term_buf = saferealloc(term_buf, term_bufsiz);		}		term_buf[term_buflen++] = c;		if (ECHOING)		    pwrite((unsigned char) c);		term_quotenext = FALSE;		break;	    }	}    } else {	if (term_buflen != 0) {	    back->send(backhandle, term_buf, term_buflen);	    while (term_buflen > 0) {		bsb(plen(term_buf[term_buflen - 1]));		term_buflen--;	    }	}	if (len > 0) {	    if (ECHOING)		c_write(buf, len);	    if (keyflag && cfg.protocol == PROT_TELNET && len == 1) {		switch (buf[0]) {		  case CTRL('M'):		    if (cfg.protocol == PROT_TELNET && cfg.telnet_newline)			back->special(backhandle, TS_EOL);		    else			back->send(backhandle, "\r", 1);		    break;		  case CTRL('?'):		  case CTRL('H'):		    if (cfg.telnet_keyboard) {			back->special(backhandle, TS_EC);			break;		    }		  case CTRL('C'):		    if (cfg.telnet_keyboard) {			back->special(backhandle, TS_IP);			break;		    }		  case CTRL('Z'):		    if (cfg.telnet_keyboard) {			back->special(backhandle, TS_SUSP);			break;		    }		  default:		    back->send(backhandle, buf, len);		    break;		}	    } else		back->send(backhandle, buf, len);	}    }}