diff options
| author | Nicolas Pitre <npitre@baylibre.com> | 2025-04-17 14:45:12 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-04-26 11:22:04 +0200 |
| commit | 5617aeb14a4381e4ee61778c91ed90a615275f39 (patch) | |
| tree | 370d391654b1311094daf34c18d887353ef3acc0 /drivers/tty/vt/vt.c | |
| parent | b5c574995d842d241d810f3a6a3ebb03c52d57fa (diff) | |
vt: pad double-width code points with a zero-width space
In the Unicode screen buffer, we follow double-width code points with a
space to maintain proper column alignment. This, however, creates
semantic problems when e.g. using cut and paste.
Let's use a better code point for the column padding's purpose i.e. a
zero-width space rather than a full space. This way the combination
retains a width of 2.
Signed-off-by: Nicolas Pitre <npitre@baylibre.com>
Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20250417184849.475581-11-nico@fluxnic.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty/vt/vt.c')
| -rw-r--r-- | drivers/tty/vt/vt.c | 11 |
1 files changed, 8 insertions, 3 deletions
diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c index 76554c2040bf..1bd1878094a0 100644 --- a/drivers/tty/vt/vt.c +++ b/drivers/tty/vt/vt.c @@ -2923,6 +2923,7 @@ static void vc_con_rewind(struct vc_data *vc) vc->vc_need_wrap = 0; } +#define UCS_ZWS 0x200b /* Zero Width Space */ #define UCS_VS16 0xfe0f /* Variation Selector 16 */ static int vc_process_ucs(struct vc_data *vc, int *c, int *tc) @@ -2941,8 +2942,8 @@ static int vc_process_ucs(struct vc_data *vc, int *c, int *tc) /* * Let's merge this zero-width code point with the preceding * double-width code point by replacing the existing - * whitespace padding. To do so we rewind one column and - * pretend this has a width of 1. + * zero-width space padding. To do so we rewind one column + * and pretend this has a width of 1. * We give the legacy display the same initial space padding. */ vc_con_rewind(vc); @@ -3065,7 +3066,11 @@ static int vc_con_write_normal(struct vc_data *vc, int tc, int c, tc = conv_uni_to_pc(vc, ' '); if (tc < 0) tc = ' '; - next_c = ' '; + /* + * Store a zero-width space in the Unicode screen given that + * the previous code point is semantically double width. + */ + next_c = UCS_ZWS; } out: |