linux-kernel - [PATCH 12/11] vt: remove zero-white-space handling from conv_uni_to

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Message-ID: <6o2ss437-6nps-s943-1n38-54np5587r08s@syhkavp.arg>
Date: Thu, 10 Apr 2025 15:38:13 -0400 (EDT)
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 12/11] vt: remove zero-white-space handling from
 conv_uni_to_pc()

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

This is now taken care of by ucs_is_zero_width(). And in the case where
we do want a padding from some zero-width code point then we should also
give the legacy displays a space character to work with.

Signed-off-by: Nicolas Pitre <npitre@...libre.com>
---

This is a fix for a small issue discovered during everyday usage.
I didn't think it is worth resending the whole series for this but
if you prefer otherwise please let me know.

diff --git a/drivers/tty/vt/consolemap.c b/drivers/tty/vt/consolemap.c
index 82d70083fe..bb4bb272eb 100644
--- a/drivers/tty/vt/consolemap.c
+++ b/drivers/tty/vt/consolemap.c
@@ -870,8 +870,6 @@ int conv_uni_to_pc(struct vc_data *conp, long ucs)
 		return -4;		/* Not found */
 	else if (ucs < 0x20)
 		return -1;		/* Not a printable character */
-	else if (ucs == 0xfeff || (ucs >= 0x200b && ucs <= 0x200f))
-		return -2;			/* Zero-width space */
 	/*
 	 * UNI_DIRECT_BASE indicates the start of the region in the User Zone
 	 * which always has a 1:1 mapping to the currently loaded font.  The
diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
index dc84f9c6b7..0d1d663c78 100644
--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -2964,13 +2964,15 @@ static int vc_con_write_normal(struct vc_data *vc, int tc, int c,
 					goto out;
 				}
 			}
+			/* padding for the legacy display like done below */
+			tc = ' ';
 		}
 	}
 
 	/* Now try to find out how to display it */
 	tc = conv_uni_to_pc(vc, tc);
 	if (tc & ~charmask) {
-		if (tc == -1 || tc == -2)
+		if (tc == -1)
 			return -1; /* nothing to display */
 
 		/* Glyph not found */