Fix two small bugs in tcsetattr().

- According to POSIX, tcsetattr() must not fail when any of the bits in
  the structure are unsupported, but it must leave the unsupported flags
  alone.

- The CIGNORE flag (set by TCSASOFT, extension) was not cleared from
  c_cflag, which means using it would cause it to be applied during its
  entire lifespan. Eventually make sure we clear the flag.

I don't really like CIGNORE, but I think we must keep it alive right
now. With our new TTY layer, we don't actually need this mechanism,
because if you leave c_cflag, c_ispeed and c_ospeed alone, we won't make
a call into the device driver anyway.

Reported by:	naddy
Tested by:	naddy

1 files changed, 6 insertions, 7 deletions

diff --git a/sys/kern/tty.c b/sys/kern/tty.c
index aaa43fc..15a48a4 100644
--- a/sys/kern/tty.c
+++ b/sys/kern/tty.c
@@ -1332,12 +1332,11 @@ tty_generic_ioctl(struct tty *tp, u_long cmd, void *data, struct thread *td)
 		if (t->c_ispeed == 0)
 			t->c_ispeed = t->c_ospeed;
 
-		/* Don't allow invalid flags to be set. */
-		if ((t->c_iflag & ~TTYSUP_IFLAG) != 0 ||
-		    (t->c_oflag & ~TTYSUP_OFLAG) != 0 ||
-		    (t->c_lflag & ~TTYSUP_LFLAG) != 0 ||
-		    (t->c_cflag & ~TTYSUP_CFLAG) != 0)
-			return (EINVAL);
+		/* Discard any unsupported bits. */
+		t->c_iflag &= TTYSUP_IFLAG;
+		t->c_oflag &= TTYSUP_OFLAG;
+		t->c_lflag &= TTYSUP_LFLAG;
+		t->c_cflag &= TTYSUP_CFLAG;
 
 		/* Set terminal flags through tcsetattr(). */
 		if (cmd == TIOCSETAW || cmd == TIOCSETAF) {
@@ -1361,7 +1360,7 @@ tty_generic_ioctl(struct tty *tp, u_long cmd, void *data, struct thread *td)
 
 			/* XXX: CLOCAL? */
 			
-			tp->t_termios.c_cflag = t->c_cflag;
+			tp->t_termios.c_cflag = t->c_cflag & ~CIGNORE;
 			tp->t_termios.c_ispeed = t->c_ispeed;
 			tp->t_termios.c_ospeed = t->c_ospeed;