From 08d4acf6df9a2cd5282efd339e89b74b913004ff Mon Sep 17 00:00:00 2001
From: stsp <stsp@openbsd.org>
Date: Tue, 13 Apr 2021 14:20:23 +0000
Subject: [PATCH] Fix merging of files that lack a final \n at EOF after a
 block of common lines.

Problem reported by Josh Rickmar.
ok millert@
---
 usr.bin/cvs/diff3.c       | 4 +++-
 usr.bin/diff3/diff3prog.c | 4 +++-
 usr.bin/rcs/diff3.c       | 4 +++-
 3 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/usr.bin/cvs/diff3.c b/usr.bin/cvs/diff3.c
index f0fee1c1925..70c625301b8 100644
--- a/usr.bin/cvs/diff3.c
+++ b/usr.bin/cvs/diff3.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: diff3.c,v 1.64 2020/06/26 07:28:47 stsp Exp $	*/
+/*	$OpenBSD: diff3.c,v 1.65 2021/04/13 14:20:23 stsp Exp $	*/
 
 /*
  * Copyright (C) Caldera International Inc.  2001-2002.
@@ -743,6 +743,8 @@ duplicate(struct range *r1, struct range *r2)
 		do {
 			c = getc(fp[0]);
 			d = getc(fp[1]);
+			if (c == -1 && d == -1)
+				break;
 			if (c == -1 || d== -1)
 				return (-1);
 			nchar++;
diff --git a/usr.bin/diff3/diff3prog.c b/usr.bin/diff3/diff3prog.c
index a56bfc7ce7a..f9f0004bab5 100644
--- a/usr.bin/diff3/diff3prog.c
+++ b/usr.bin/diff3/diff3prog.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: diff3prog.c,v 1.20 2020/06/26 07:28:47 stsp Exp $	*/
+/*	$OpenBSD: diff3prog.c,v 1.21 2021/04/13 14:20:23 stsp Exp $	*/
 
 /*
  * Copyright (C) Caldera International Inc.  2001-2002.
@@ -494,6 +494,8 @@ duplicate(struct range *r1, struct range *r2)
 		do {
 			c = getc(fp[0]);
 			d = getc(fp[1]);
+			if (c == -1 && d == -1)
+				break;
 			if (c == -1 || d== -1)
 				trouble();
 			nchar++;
diff --git a/usr.bin/rcs/diff3.c b/usr.bin/rcs/diff3.c
index ebe04a3b705..98643c5d740 100644
--- a/usr.bin/rcs/diff3.c
+++ b/usr.bin/rcs/diff3.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: diff3.c,v 1.44 2020/06/26 07:28:46 stsp Exp $	*/
+/*	$OpenBSD: diff3.c,v 1.45 2021/04/13 14:20:24 stsp Exp $	*/
 
 /*
  * Copyright (C) Caldera International Inc.  2001-2002.
@@ -838,6 +838,8 @@ duplicate(struct range *r1, struct range *r2)
 		do {
 			c = getc(fp[0]);
 			d = getc(fp[1]);
+			if (c == -1 && d == -1)
+				break;
 			if (c == -1 || d== -1)
 				return (-1);
 			nchar++;
-- 
2.20.1