From 1dc81cee5c19142c0efe7d2c10b9b4694a218954 Mon Sep 17 00:00:00 2001
From: David du Colombier <0intro@gmail.com>
Date: Sun, 7 Apr 2002 00:00:00 +0000
Subject: [PATCH] Plan 9 from Bell Labs 2002-04-07

---
 pc/fns.h      |  1 +
 port/devenv.c | 19 +++++++++++++++----
 2 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/pc/fns.h b/pc/fns.h
index 7571974bc81406b152cd59b2dc4aba2209efd015..3b9245d35734b4c9aa8ea9b91cf2fc0b1a440825 100644
--- a/pc/fns.h
+++ b/pc/fns.h
@@ -50,6 +50,7 @@ void	i8253init(void);
 void	i8253enable(void);
 uvlong	i8253read(uvlong*);
 void	i8259init(void);
+int	i8259isr(int);
 int	i8259enable(Vctl*);
 int	i8259vecno(int);
 int	i8259disable(int);
diff --git a/port/devenv.c b/port/devenv.c
index 9e0031cc4a5db6f003db30f2783b7b308d0cc05e..a3705aa8120ba0152d430e3540ffb12adc3c894c 100644
--- a/port/devenv.c
+++ b/port/devenv.c
@@ -90,6 +90,7 @@ envopen(Chan *c, int omode)
 {
 	Egrp *eg;
 	Evalue *e;
+	int trunc;
 
 	eg = envgrp(c);
 	if(c->qid.type & QTDIR) {
@@ -97,21 +98,31 @@ envopen(Chan *c, int omode)
 			error(Eperm);
 	}
 	else {
+		trunc = omode & OTRUNC;
 		if(omode != OREAD && !envwriteable(c))
 			error(Eperm);
-		rlock(eg);
+		if(trunc)
+			wlock(eg);
+		else
+			rlock(eg);
 		e = envlookup(eg, nil, c->qid.path);
 		if(e == 0) {
-			runlock(eg);
+			if(trunc)
+				wunlock(eg);
+			else
+				runlock(eg);
 			error(Enonexist);
 		}
-		if((omode & OTRUNC) && e->value) {
+		if(trunc && e->value) {
 			e->qid.vers++;
 			free(e->value);
 			e->value = 0;
 			e->len = 0;
 		}
-		runlock(eg);
+		if(trunc)
+			wunlock(eg);
+		else
+			runlock(eg);
 	}
 	c->mode = openmode(omode);
 	c->flag |= COPEN;