From b4408559c1e6e0df3ce61a198f9a4d1f444ecb87 Mon Sep 17 00:00:00 2001
From: rillig <rillig@NetBSD.org>
Date: Sun, 21 Feb 2021 16:37:26 +0000
Subject: cgram: fix undefined behavior when pressing function keys

The key codes for function keys are outside of the "range representable
by an unsigned char".  This resulted in parts of the screen being
cleaned.
---
 cgram/cgram.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/cgram/cgram.c b/cgram/cgram.c
index 7eaf592d..98f8bece 100644
--- a/cgram/cgram.c
+++ b/cgram/cgram.c
@@ -325,7 +325,7 @@ loop(void)
 			done = true;
 			break;
 		default:
-			if (isalpha(ch)) {
+			if (isascii(ch) && isalpha(ch)) {
 				if (substitute(ch)) {
 					if (curx < strlen(lines.v[cury])) {
 						curx++;
-- 
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