Kernel support for erase2 character.

Submitted by:	Rui Pedro Mendes Salgueiro <rps@mat.uc.pt>

sys/kern/tty.c

@@ -459,9 +459,9 @@ ttyinput(c, tp)
 		 * processing takes place.
 		 */
 		/*
-		 * erase (^H / ^?)
+		 * erase or erase2 (^H / ^?)
 		 */
-		if (CCEQ(cc[VERASE], c)) {
+		if (CCEQ(cc[VERASE], c) || CCEQ(cc[VERASE2], c) ) {
 			if (tp->t_rawq.c_cc)
 				ttyrub(unputc(&tp->t_rawq), tp);
 			goto endcase;
@@ -2010,8 +2010,17 @@ ttyrub(c, tp)
 			(void)ttyoutput('\\', tp);
 		}
 		ttyecho(c, tp);
-	} else
+	} else {
 		ttyecho(tp->t_cc[VERASE], tp);
+		/*
+		 * This code may be executed not only when an ERASE key
+		 * is pressed, but also when ^U (KILL) or ^W (WERASE) are.
+		 * So, I didn't think it was worthwhile to pass the extra
+		 * information (which would need an extra parameter,
+		 * changing every call) needed to distinguish the ERASE2
+		 * case from the ERASE.
+		 */
+	}
 	--tp->t_rocount;
 }
 

sys/sys/termios.h

@@ -56,8 +56,9 @@
 #define VKILL		5	/* ICANON */
 #ifndef _POSIX_SOURCE
 #define	VREPRINT 	6	/* ICANON together with IEXTEN */
+#define VERASE2 	7	/* ICANON */
 #endif
-/*			7	   spare 1 */
+/*			7	   ex-spare 1 */
 #define VINTR		8	/* ISIG */
 #define VQUIT		9	/* ISIG */
 #define VSUSP		10	/* ISIG */

sys/sys/ttydefaults.h

@@ -61,6 +61,7 @@
 #define	CEOF		CTRL('d')
 #define	CEOL		0xff		/* XXX avoid _POSIX_VDISABLE */
 #define	CERASE		0177
+#define	CERASE2		CTRL('h')
 #define	CINTR		CTRL('c')
 #define	CSTATUS		CTRL('t')
 #define	CKILL		CTRL('u')
@@ -90,7 +91,7 @@
 #ifdef TTYDEFCHARS
 static cc_t	ttydefchars[NCCS] = {
 	CEOF,	CEOL,	CEOL,	CERASE, CWERASE, CKILL, CREPRINT,
-	_POSIX_VDISABLE, CINTR,	CQUIT,	CSUSP,	CDSUSP,	CSTART,	CSTOP,	CLNEXT,
+	CERASE2, CINTR,	CQUIT,	CSUSP,	CDSUSP,	CSTART,	CSTOP,	CLNEXT,
 	CDISCARD, CMIN,	CTIME,  CSTATUS, _POSIX_VDISABLE
 };
 #undef TTYDEFCHARS