linux-kernel - [PATCH 01/11] vt: minor cleanup to vc_translate

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Message-ID: <20250410011839.64418-2-nico@fluxnic.net>
Date: Wed,  9 Apr 2025 21:13:53 -0400
From: Nicolas Pitre <nico@...xnic.net>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jiri Slaby <jirislaby@...nel.org>
Cc: Nicolas Pitre <npitre@...libre.com>,
	Dave Mielke <Dave@...lke.cc>,
	linux-serial@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH 01/11] vt: minor cleanup to vc_translate_unicode()

From: Nicolas Pitre <npitre@...libre.com>

Make it clearer when a sequence is bad.

Signed-off-by: Nicolas Pitre <npitre@...libre.com>
---
 drivers/tty/vt/vt.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
index f5642b3038..b5f3c8a818 100644
--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -2817,7 +2817,7 @@ static int vc_translate_unicode(struct vc_data *vc, int c, bool *rescan)
 	if ((c & 0xc0) == 0x80) {
 		/* Unexpected continuation byte? */
 		if (!vc->vc_utf_count)
-			return 0xfffd;
+			goto bad_sequence;
 
 		vc->vc_utf_char = (vc->vc_utf_char << 6) | (c & 0x3f);
 		vc->vc_npar++;
@@ -2829,17 +2829,17 @@ static int vc_translate_unicode(struct vc_data *vc, int c, bool *rescan)
 		/* Reject overlong sequences */
 		if (c <= utf8_length_changes[vc->vc_npar - 1] ||
 				c > utf8_length_changes[vc->vc_npar])
-			return 0xfffd;
+			goto bad_sequence;
 
 		return vc_sanitize_unicode(c);
 	}
 
 	/* Single ASCII byte or first byte of a sequence received */
 	if (vc->vc_utf_count) {
-		/* Continuation byte expected */
+		/* A continuation byte was expected */
 		*rescan = true;
 		vc->vc_utf_count = 0;
-		return 0xfffd;
+		goto bad_sequence;
 	}
 
 	/* Nothing to do if an ASCII byte was received */
@@ -2858,11 +2858,14 @@ static int vc_translate_unicode(struct vc_data *vc, int c, bool *rescan)
 		vc->vc_utf_count = 3;
 		vc->vc_utf_char = (c & 0x07);
 	} else {
-		return 0xfffd;
+		goto bad_sequence;
 	}
 
 need_more_bytes:
 	return -1;
+
+bad_sequence:
+	return 0xfffd;
 }
 
 static int vc_translate(struct vc_data *vc, int *c, bool *rescan)
-- 
2.49.0