kconfig/[mn]conf: handle backspace (^H) key

BugLink: https://bugs.launchpad.net/bugs/1830176

[ Upstream commit 9c38f1f0 ]

Backspace is not working on some terminal emulators which do not send the
key code defined by terminfo. Terminals either send '^H' (8) or '^?' (127).
But currently only '^?' is handled. Let's also handle '^H' for those
terminals.
Signed-off-by: Changbin Du <changbin.du@gmail.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Sasha Levin (Microsoft) <sashal@kernel.org>
Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

scripts/kconfig/lxdialog/inputbox.c

@@ -126,7 +126,8 @@ int dialog_inputbox(const char *title, const char *prompt, int height, int width
 			case KEY_DOWN:
 				break;
 			case KEY_BACKSPACE:
-			case 127:
+			case 8:   /* ^H */
+			case 127: /* ^? */
 				if (pos) {
 					wattrset(dialog, dlg.inputbox.atr);
 					if (input_x == 0) {

scripts/kconfig/nconf.c

@@ -1046,7 +1046,7 @@ static int do_match(int key, struct match_state *state, int *ans)
 		state->match_direction = FIND_NEXT_MATCH_UP;
 		*ans = get_mext_match(state->pattern,
 				state->match_direction);
-	} else if (key == KEY_BACKSPACE || key == 127) {
+	} else if (key == KEY_BACKSPACE || key == 8 || key == 127) {
 		state->pattern[strlen(state->pattern)-1] = '\0';
 		adj_match_dir(&state->match_direction);
 	} else

scripts/kconfig/nconf.gui.c

@@ -439,7 +439,8 @@ int dialog_inputbox(WINDOW *main_window,
 		case KEY_F(F_EXIT):
 		case KEY_F(F_BACK):
 			break;
-		case 127:
+		case 8:   /* ^H */
+		case 127: /* ^? */
 		case KEY_BACKSPACE:
 			if (cursor_position > 0) {
 				memmove(&result[cursor_position-1],