From dc7e7b3e7dbff2636fe6a2d2ae95a757f87a9fbc Mon Sep 17 00:00:00 2001
From: mpi <mpi@openbsd.org>
Date: Mon, 8 Jan 2018 11:52:14 +0000
Subject: [PATCH] Translate the TIOCSBRK & TIOCCBRK ioctl(2)s issued on a
 pty(4) slave to corresponding user mode ioctls.

If the master part of the pseudo terminal previously enabled TIOCUCNTL,
it will now receive the TIOCUCNTL_{S,C}BRK commands.  This allows to
send BREAKS commands over a pty(4) independently of the serial terminal
emulator used.

Guidance and ok nicm@, ok ccardenas@, looks ok to deraadt@
---
 share/man/man4/pty.4 | 16 ++++++++++++++--
 sys/kern/tty_pty.c   | 16 +++++++++++++++-
 sys/sys/ttycom.h     |  6 ++++--
 3 files changed, 33 insertions(+), 5 deletions(-)

diff --git a/share/man/man4/pty.4 b/share/man/man4/pty.4
index 737b9cbf36c..ca8e9d8c851 100644
--- a/share/man/man4/pty.4
+++ b/share/man/man4/pty.4
@@ -1,4 +1,4 @@
-.\"	$OpenBSD: pty.4,v 1.23 2016/06/30 15:59:30 tedu Exp $
+.\"	$OpenBSD: pty.4,v 1.24 2018/01/08 11:52:14 mpi Exp $
 .\"	$NetBSD: pty.4,v 1.4 1998/03/21 03:14:30 fair Exp $
 .\"
 .\" Copyright (c) 1983, 1991, 1993
@@ -30,7 +30,7 @@
 .\"
 .\"     @(#)pty.4	8.2 (Berkeley) 11/30/93
 .\"
-.Dd $Mdocdate: June 30 2016 $
+.Dd $Mdocdate: January 8 2018 $
 .Dt PTY 4
 .Os
 .Sh NAME
@@ -204,6 +204,18 @@ The
 .Dv UIOCCMD Ns (0)
 is a no-op that may be used to probe for
 the existence of this facility.
+.Pp
+While this mode is in use, any of the
+.Dv TIOCSBRK
+and
+.Dv TIOCCBRK
+ioctl requests issued on the slave part of the pseudo terminal will be
+translated to a
+.Dv TIOCUCNTL_SBRK
+or
+.Dv TIOCUCNTL_CBRK
+user command on the master side.
+.Pp
 As with
 .Dv TIOCPKT
 mode, command operations may be detected with a
diff --git a/sys/kern/tty_pty.c b/sys/kern/tty_pty.c
index 970cb044942..d16fb827a8c 100644
--- a/sys/kern/tty_pty.c
+++ b/sys/kern/tty_pty.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: tty_pty.c,v 1.81 2018/01/02 06:38:45 guenther Exp $	*/
+/*	$OpenBSD: tty_pty.c,v 1.82 2018/01/08 11:52:14 mpi Exp $	*/
 /*	$NetBSD: tty_pty.c,v 1.33.4.1 1996/06/02 09:08:11 mrg Exp $	*/
 
 /*
@@ -861,6 +861,20 @@ ptyioctl(dev_t dev, u_long cmd, caddr_t data, int flag, struct proc *p)
 	if (error < 0)
 		 error = ttioctl(tp, cmd, data, flag, p);
 	if (error < 0) {
+		/*
+		 * Translate TIOCSBRK/TIOCCBRK to user mode ioctls to
+		 * let the master interpret BREAK conditions.
+		 */
+		switch (cmd) {
+		case TIOCSBRK:
+			cmd = UIOCCMD(TIOCUCNTL_SBRK);
+			break;
+		case TIOCCBRK:
+			cmd = UIOCCMD(TIOCUCNTL_CBRK);
+			break;
+		default:
+			break;
+		}
 		if (pti->pt_flags & PF_UCNTL &&
 		    (cmd & ~0xff) == UIOCCMD(0)) {
 			if (cmd & 0xff) {
diff --git a/sys/sys/ttycom.h b/sys/sys/ttycom.h
index cb4f9476bf1..cee568d4ec1 100644
--- a/sys/sys/ttycom.h
+++ b/sys/sys/ttycom.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ttycom.h,v 1.15 2017/06/29 04:23:12 deraadt Exp $	*/
+/*	$OpenBSD: ttycom.h,v 1.16 2018/01/08 11:52:14 mpi Exp $	*/
 /*	$NetBSD: ttycom.h,v 1.4 1996/05/19 17:17:53 jonathan Exp $	*/
 
 /*-
@@ -116,8 +116,10 @@ struct tstamps {
 #define	TIOCGWINSZ	_IOR('t', 104, struct winsize)	/* get window size */
 #define	TIOCSWINSZ	_IOW('t', 103, struct winsize)	/* set window size */
 #define	TIOCUCNTL	_IOW('t', 102, int)	/* pty: set/clr usr cntl mode */
-#define	TIOCSTAT	_IO('t', 101)		/* generate status message */
 #define		UIOCCMD(n)	_IO('u', n)	/* usr cntl op "n" */
+#define		TIOCUCNTL_SBRK (TIOCSBRK & 0xff)/* set break bit, usr ctnl */
+#define		TIOCUCNTL_CBRK (TIOCCBRK & 0xff)/* clear break bit, usr ctnl */
+#define	TIOCSTAT	_IO('t', 101)		/* generate status message */
 #define	TIOCGSID	_IOR('t', 99, int)	/* get sid of tty */
 #define	TIOCCONS	_IOW('t', 98, int)	/* become virtual console */
 #define	TIOCSCTTY	 _IO('t', 97)		/* become controlling tty */
-- 
2.20.1