From: Nicolas Pitre <npitre@baylibre.com>
Date: Thu, 10 Apr 2025 01:14:00 +0000 (-0400)
Subject: vt: support Unicode recomposition
X-Git-Tag: v6.16-rc1~29^2~81
X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=cd6937d42bca46f2143544918e535d6fd22b71b7;p=linux-block.git

vt: support Unicode recomposition

Try replacing any decomposed Unicode sequence by the corresponding
recomposed code point. Code point to glyph correspondance works best
after recomposition, and this apply mostly to single-width code points
therefore we can't preserve them in their decomposed form anyway.

With all the infrastructure in place this is now trivial to do.

Signed-off-by: Nicolas Pitre <npitre@baylibre.com>
Link: https://lore.kernel.org/r/20250410011839.64418-9-nico@fluxnic.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
index 5d53feeb5d2b..e3d35c4f9204 100644
--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -2953,8 +2953,15 @@ static int vc_con_write_normal(struct vc_data *vc, int tc, int c,
 				 * double-width.
 				 */
 			} else {
-				/* Otherwise zero-width code points are ignored */
-				goto out;
+				/* try recomposition */
+				prev_c = ucs_recompose(prev_c, c);
+				if (prev_c != 0) {
+					vc_con_rewind(vc);
+					c = prev_c;
+				} else {
+					/* Otherwise zero-width code points are ignored */
+					goto out;
+				}
 			}
 		}
 	}