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[v2,2/8] vt: make sure displayed double-width characters are remembered as such

Message ID 20250507141535.40655-3-nico@fluxnic.net
State Superseded
Headers show
Series [v2,1/8] vt: ucs.c: fix misappropriate in_range() usage | expand

Commit Message

Nicolas Pitre May 7, 2025, 2:13 p.m. UTC 
From: Nicolas Pitre <npitre@baylibre.com>

And to do so we ensure the Unicode screen buffer is initialized when
double-width characters are encountered.

Signed-off-by: Nicolas Pitre <npitre@baylibre.com>
---
 drivers/tty/vt/vt.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)
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Patch

diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
index 24c6cd2eed78..58fa1b285f22 100644
--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -2930,8 +2930,15 @@  static int vc_process_ucs(struct vc_data *vc, int *c, int *tc)
 {
 	u32 prev_c, curr_c = *c;
 
-	if (ucs_is_double_width(curr_c))
+	if (ucs_is_double_width(curr_c)) {
+		/*
+		 * The Unicode screen memory is allocated only when
+		 * required. This is one such case as we need to remember
+		 * which displayed characters are double-width.
+		 */
+		vc_uniscr_check(vc);
 		return 2;
+	}
 
 	if (!ucs_is_zero_width(curr_c))
 		return 1;