From 35d84bc06bc0e3642d0d5e2e77e3432af05d62d3 Mon Sep 17 00:00:00 2001
From: miod <miod@openbsd.org>
Date: Fri, 8 May 2015 19:12:51 +0000
Subject: [PATCH] Add a new `don't read back' flag for variables, to prevent
 reading their value after modifying them. Give this flag to `display.focus',
 since screen switching is asynchronous, and reading back will return the
 screen we are switching from if the switch has not completed yet.

Also, disallow -= and += syntax for display.focus, as it doesn't make any sense.
---
 sbin/wsconsctl/display.c   | 4 ++--
 sbin/wsconsctl/wsconsctl.c | 8 +++++---
 sbin/wsconsctl/wsconsctl.h | 3 ++-
 3 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/sbin/wsconsctl/display.c b/sbin/wsconsctl/display.c
index 87505a82c18..6f789291142 100644
--- a/sbin/wsconsctl/display.c
+++ b/sbin/wsconsctl/display.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: display.c,v 1.19 2013/10/20 22:07:57 miod Exp $	*/
+/*	$OpenBSD: display.c,v 1.20 2015/05/08 19:12:51 miod Exp $	*/
 /*	$NetBSD: display.c,v 1.1 1998/12/28 14:01:16 hannken Exp $ */
 
 /*-
@@ -56,7 +56,7 @@ struct field display_field_tab[] = {
     { "depth",		&depth,		FMT_UINT,	FLG_RDONLY },
     { "emulations",	&emuls,		FMT_EMUL,	FLG_RDONLY },
     { "screentypes",	&screens,	FMT_SCREEN,	FLG_RDONLY },
-    { "focus",		&focus,		FMT_INT,	FLG_MODIFY },
+    { "focus",		&focus,		FMT_INT,	FLG_NORDBACK },
     { "brightness",	&brightness,	FMT_PC,		FLG_MODIFY|FLG_INIT },
     { "contrast",	&contrast,	FMT_PC,		FLG_MODIFY|FLG_INIT },
     { "backlight",	&backlight,	FMT_PC,		FLG_MODIFY|FLG_INIT },
diff --git a/sbin/wsconsctl/wsconsctl.c b/sbin/wsconsctl/wsconsctl.c
index 4d0878bf27f..38b13bdf78e 100644
--- a/sbin/wsconsctl/wsconsctl.c
+++ b/sbin/wsconsctl/wsconsctl.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: wsconsctl.c,v 1.28 2012/07/14 08:28:47 shadchin Exp $	*/
+/*	$OpenBSD: wsconsctl.c,v 1.29 2015/05/08 19:12:51 miod Exp $	*/
 /*	$NetBSD: wsconsctl.c,v 1.2 1998/12/29 22:40:20 hannken Exp $ */
 
 /*-
@@ -264,8 +264,10 @@ main(int argc, char *argv[])
 				if (f->flags & FLG_WRONLY) {
 					pr_field(devname, f, setsep);
 				} else {
-					f->flags |= FLG_GET;
-					(*sw->getval)(devfd);
+					if (!(f->flags & FLG_NORDBACK)) {
+						f->flags |= FLG_GET;
+						(*sw->getval)(devfd);
+					}
 					if (f->flags & FLG_DEAD)
 						continue;
 					pr_field(devname, f, setsep);
diff --git a/sbin/wsconsctl/wsconsctl.h b/sbin/wsconsctl/wsconsctl.h
index 655c8cb794e..7ee37706d95 100644
--- a/sbin/wsconsctl/wsconsctl.h
+++ b/sbin/wsconsctl/wsconsctl.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: wsconsctl.h,v 1.14 2013/10/20 22:07:57 miod Exp $	*/
+/*	$OpenBSD: wsconsctl.h,v 1.15 2015/05/08 19:12:51 miod Exp $	*/
 /*	$NetBSD: wsconsctl.h 1.1 1998/12/28 14:01:17 hannken Exp $ */
 
 /*-
@@ -53,6 +53,7 @@ struct field {
 #define FLG_WRONLY	0x0002		/* variable cannot be displayed */
 #define FLG_NOAUTO	0x0004		/* skip variable on -a flag */
 #define FLG_MODIFY	0x0008		/* variable may be modified with += */
+#define	FLG_NORDBACK	0x0010		/* do not read back variable after write */
 #define FLG_GET		0x0100		/* read this variable from driver */
 #define FLG_SET		0x0200		/* write this variable to driver */
 #define FLG_INIT	0x0400		/* init (read) before write */
-- 
2.20.1