vt: add modifier support to cursor keys

Generate xterm-style CSI sequences with modifier parameters for arrow
keys when Shift, Alt, or Ctrl are held. For example, Shift+Up produces
ESC [ 1 ; 2 A instead of plain ESC [ A.

The modifier encoding follows the standard xterm convention:
  mod = 1 + (shift ? 1 : 0) + (alt ? 2 : 0) + (ctrl ? 4 : 0)

When no modifiers are pressed, the original behavior is preserved.

Explicit keymap bindings for modified cursor keys (e.g., "shift keycode
103 = Find") take precedence over this automatic modifier encoding.

Signed-off-by: Nicolas Pitre <npitre@baylibre.com>
Link: https://patch.msgid.link/20260203045457.1049793-2-nico@fluxnic.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Nicolas Pitre 2026-02-02 23:52:46 -05:00 committed by Greg Kroah-Hartman
parent 24728b93fa
commit 4af70f1516

View File

@ -765,14 +765,39 @@ static void k_fn(struct vc_data *vc, unsigned char value, char up_flag)
pr_err("k_fn called with value=%d\n", value);
}
/*
* Compute xterm-style modifier parameter for CSI sequences.
* Returns 1 + (shift ? 1 : 0) + (alt ? 2 : 0) + (ctrl ? 4 : 0)
*/
static int csi_modifier_param(void)
{
int mod = 1;
if (shift_state & (BIT(KG_SHIFT) | BIT(KG_SHIFTL) | BIT(KG_SHIFTR)))
mod += 1;
if (shift_state & (BIT(KG_ALT) | BIT(KG_ALTGR)))
mod += 2;
if (shift_state & (BIT(KG_CTRL) | BIT(KG_CTRLL) | BIT(KG_CTRLR)))
mod += 4;
return mod;
}
static void k_cur(struct vc_data *vc, unsigned char value, char up_flag)
{
static const char cur_chars[] = "BDCA";
int mod;
if (up_flag)
return;
applkey(vc, cur_chars[value], vc_kbd_mode(kbd, VC_CKMODE));
mod = csi_modifier_param();
if (mod > 1) {
char buf[] = { 0x1b, '[', '1', ';', '0' + mod, cur_chars[value], 0x00 };
puts_queue(vc, buf);
} else {
applkey(vc, cur_chars[value], vc_kbd_mode(kbd, VC_CKMODE));
}
}
static void k_pad(struct vc_data *vc, unsigned char value, char up_flag)