[PATCH] Enabling the echo of ctrl-C (and the like)

[Joe Peterson <joe@skyrush.com>]

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Attached is a patch that turns on INTR/QUIT/SUSP echoing in the N_TTY
line discipline (e.g. ctrl-C will appear as "^C" if stty echoctl is set
and ctrl-C is set as INTR).

Linux seems to be the only unix-like OS (recently I've verified this on
Solaris, BSD, and Mac OS X) that does *not* behave this way, and I
really miss this as a good visual confirmation of the interrupt of a
program in the console or xterm.  I remember this fondly from many Unixs
I've used over the years as well.  Bringing this to Linux also seems
like a good way to make it yet more compliant with standard unix-like
behavior.

The fix is pretty trivial.  Let me know if you think this is a candidate
for inclusion in the kernel.

					Thanks, Joe

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--- linux-2.6.22-gentoo-r9/drivers/char/n_tty.c	2007-07-08 17:32:17.000000000 -0600
+++ linux-2.6.22-gentoo-r9.new/drivers/char/n_tty.c	2007-12-06 07:16:56.000000000 -0700
@@ -760,7 +760,22 @@
 		signal = SIGTSTP;
 		if (c == SUSP_CHAR(tty)) {
 send_signal:
-			isig(signal, tty, 0);
+			/*
+			 * Echo character, and then send the signal.
+			 * Note that we do not use isig() here because we want
+			 * the order to be:
+			 * 1) flush, 2) echo, 3) signal
+			 */
+			if (!L_NOFLSH(tty)) {
+				n_tty_flush_buffer(tty);
+				if (tty->driver->flush_buffer)
+					tty->driver->flush_buffer(tty);
+			}
+			if (L_ECHO(tty)) {
+				echo_char(c, tty);
+			}
+			if (tty->pgrp)
+				kill_pgrp(tty->pgrp, signal, 1);
 			return;
 		}
 	}