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.

diff --git a/cgram/cgram.c b/cgram/cgram.c
index 7eaf592d73059e8c8b5ea5fa44510cc532468229..98f8bece421afd0839e9851a2da6302c254e1c9a 100644 (file)
--- a/cgram/cgram.c
+++ b/cgram/cgram.c
@@ -325,7 +325,7 @@ loop(void)
                        done = true;
                        break;
                default:
                        done = true;
                        break;
                default:

-                       if (isalpha(ch)) {
+                       if (isascii(ch) && isalpha(ch)) {

                                if (substitute(ch)) {
                                        if (curx < strlen(lines.v[cury])) {
                                                curx++;
                                if (substitute(ch)) {
                                        if (curx < strlen(lines.v[cury])) {
                                                curx++;