Add 'nc' flag to gettytab -- no carrier. Forces non-blocking open and

setting of CLOCAL. Necessary for 3 wire RS-232 setups with dumb
terminals.

PR:		5959

libexec/getty/gettytab.5

@@ -145,6 +145,7 @@ hangup line on last close
 .It "lo	str" Ta Pa /usr/bin/login Ta
 .No "program to exec when name obtained"
 .It "mb	bool	false	do flow control based on carrier"
+.It "nc	bool	false	terminal does not supply carrier (set clocal)"
 .It "nl	bool	false	terminal has (or might have) a newline character"
 .It "np	bool	false	terminal uses no parity (i.e. 8-bit characters)"
 .It "nx	str	default	next table (for auto speed selection)"

libexec/getty/gettytab.h

@@ -170,5 +170,6 @@ struct gettyflags {
 #define DX	gettyflags[20].value
 #define	NP	gettyflags[21].value
 #define	MB	gettyflags[22].value
-#define HW	gettyflags[23].value
+#define	HW	gettyflags[23].value
+#define	NC	gettyflags[24].value
 

libexec/getty/init.c

@@ -146,5 +146,6 @@ struct	gettyflags gettyflags[] = {
 	{ "np", 0 },			/* no parity at all (8bit chars) */
 	{ "mb", 0 },			/* do MDMBUF flow control */
 	{ "hw", 0 },			/* do CTSRTS flow control */
+	{ "nc", 0 },			/* set clocal (no carrier) */
 	{ 0 }
 };

libexec/getty/main.c

@@ -270,8 +270,8 @@ main(argc, argv)
 				(void)tcsetattr(STDIN_FILENO, TCSANOW, &tmode);
 				exit(1);
 			}
-		} else { /* blocking open */
-			if (!opentty(ttyn, O_RDWR))
+		} else { /* maybe blocking open */
+			if (!opentty(ttyn, O_RDWR | (NC ? O_NONBLOCK : 0 )))
 				exit(1);
 		}
 	    }
@@ -293,6 +293,7 @@ main(argc, argv)
 	tmode.c_oflag = TTYDEF_OFLAG;
 	tmode.c_lflag = TTYDEF_LFLAG;
 	tmode.c_cflag = TTYDEF_CFLAG;
+	tmode.c_cflag |= (NC ? CLOCAL : 0);
 	omode = tmode;
 
 	for (;;) {