[PATCH v3 0/2] vt: bracketed paste and cursor position

[PATCH v3 0/2] vt: bracketed paste and cursor position

[Nicolas Pitre]

A different kind of VT console update this time. These patches:

- add bracketed paste support to the VT console

- overcome a /dev/vcsa limitation with cursor position retrieval

In v1 those were submitted together to avoid merge conflicts. Those conflicts
no longer exist but here they are together again for coherence sake.

Changes from v1 (https://lore.kernel.org/all/20250514015554.19978-1-nico@fluxnic.net):

- Changed TIOCL_GETCURSORPOS to VT_GETCONSIZECSRPOS with proper structure.
  Moved to the VT_ space to benefit from unambigous pointer argument and
  vt_compat_ioctl() wrapper. Also motivated by the fact that usage require
  both display size and cursor position so those are joined in one syscall.
- Code simplifications suggested by Jiri.

Changes from v2 (https://lore.kernel.org/all/20250514194710.6709-1-nico@fluxnic.net):

- Define VT_GETCONSIZECSRPOS using _IOR().
- Replace unsigned short with __u16 in struct vt_consizecsrpos.

diffstat:
 drivers/tty/vt/selection.c     | 31 +++++++++++++++++++++++++++----
 drivers/tty/vt/vt.c            | 15 +++++++++++++++
 drivers/tty/vt/vt_ioctl.c      | 16 ++++++++++++++++
 include/linux/console_struct.h |  1 +
 include/uapi/linux/tiocl.h     |  1 +
 include/uapi/linux/vt.h        | 11 +++++++++++
 6 files changed, 71 insertions(+), 4 deletions(-)

[PATCH v3 1/2] vt: bracketed paste support

[Nicolas Pitre]

From: Nicolas Pitre <npitre@baylibre.com>

This is comprised of 3 aspects:

- Take note of when applications advertise bracketed paste support via
  "\e[?2004h" and "\e[?2004l".

- Insert bracketed paste markers ("\e[200~" and "\e[201~") around pasted
  content in paste_selection() when bracketed paste is active.

- Add TIOCL_GETBRACKETEDPASTE to return bracketed paste status so user
  space daemons implementing cut-and-paste functionality (e.g. gpm,
  BRLTTY) may know when to insert bracketed paste markers.

Link: https://en.wikipedia.org/wiki/Bracketed-paste

Signed-off-by: Nicolas Pitre <npitre@baylibre.com>
Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
---
 drivers/tty/vt/selection.c     | 31 +++++++++++++++++++++++++++----
 drivers/tty/vt/vt.c            | 15 +++++++++++++++
 include/linux/console_struct.h |  1 +
 include/uapi/linux/tiocl.h     |  1 +
 4 files changed, 44 insertions(+), 4 deletions(-)

diff --git a/drivers/tty/vt/selection.c b/drivers/tty/vt/selection.c
index 791e2f1f7c0b..24b0a53e5a79 100644
--- a/drivers/tty/vt/selection.c
+++ b/drivers/tty/vt/selection.c
@@ -403,6 +403,12 @@ int paste_selection(struct tty_struct *tty)
 	DECLARE_WAITQUEUE(wait, current);
 	int ret = 0;
 
+	bool bp = vc->vc_bracketed_paste;
+	static const char bracketed_paste_start[] = "\033[200~";
+	static const char bracketed_paste_end[]   = "\033[201~";
+	const char *bps = bp ? bracketed_paste_start : NULL;
+	const char *bpe = bp ? bracketed_paste_end : NULL;
+
 	console_lock();
 	poke_blanked_console();
 	console_unlock();
@@ -414,7 +420,7 @@ int paste_selection(struct tty_struct *tty)
 
 	add_wait_queue(&vc->paste_wait, &wait);
 	mutex_lock(&vc_sel.lock);
-	while (vc_sel.buffer && vc_sel.buf_len > pasted) {
+	while (vc_sel.buffer && (vc_sel.buf_len > pasted || bpe)) {
 		set_current_state(TASK_INTERRUPTIBLE);
 		if (signal_pending(current)) {
 			ret = -EINTR;
@@ -427,10 +433,27 @@ int paste_selection(struct tty_struct *tty)
 			continue;
 		}
 		__set_current_state(TASK_RUNNING);
+
+		if (bps) {
+			bps += tty_ldisc_receive_buf(ld, bps, NULL, strlen(bps));
+			if (*bps != '\0')
+				continue;
+			bps = NULL;
+		}
+
 		count = vc_sel.buf_len - pasted;
-		count = tty_ldisc_receive_buf(ld, vc_sel.buffer + pasted, NULL,
-					      count);
-		pasted += count;
+		if (count) {
+			pasted += tty_ldisc_receive_buf(ld, vc_sel.buffer + pasted,
+							NULL, count);
+			if (vc_sel.buf_len > pasted)
+				continue;
+		}
+
+		if (bpe) {
+			bpe += tty_ldisc_receive_buf(ld, bpe, NULL, strlen(bpe));
+			if (*bpe == '\0')
+				bpe = NULL;
+		}
 	}
 	mutex_unlock(&vc_sel.lock);
 	remove_wait_queue(&vc->paste_wait, &wait);
diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
index efb761454166..ed39d9cb4432 100644
--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -1870,6 +1870,14 @@ int mouse_reporting(void)
 	return vc_cons[fg_console].d->vc_report_mouse;
 }
 
+/* invoked via ioctl(TIOCLINUX) */
+static int get_bracketed_paste(struct tty_struct *tty)
+{
+	struct vc_data *vc = tty->driver_data;
+
+	return vc->vc_bracketed_paste;
+}
+
 enum {
 	CSI_DEC_hl_CURSOR_KEYS	= 1,	/* CKM: cursor keys send ^[Ox/^[[x */
 	CSI_DEC_hl_132_COLUMNS	= 3,	/* COLM: 80/132 mode switch */
@@ -1880,6 +1888,7 @@ enum {
 	CSI_DEC_hl_MOUSE_X10	= 9,
 	CSI_DEC_hl_SHOW_CURSOR	= 25,	/* TCEM */
 	CSI_DEC_hl_MOUSE_VT200	= 1000,
+	CSI_DEC_hl_BRACKETED_PASTE = 2004,
 };
 
 /* console_lock is held */
@@ -1932,6 +1941,9 @@ static void csi_DEC_hl(struct vc_data *vc, bool on_off)
 		case CSI_DEC_hl_MOUSE_VT200:
 			vc->vc_report_mouse = on_off ? 2 : 0;
 			break;
+		case CSI_DEC_hl_BRACKETED_PASTE:
+			vc->vc_bracketed_paste = on_off;
+			break;
 		}
 }
 
@@ -2157,6 +2169,7 @@ static void reset_terminal(struct vc_data *vc, int do_clear)
 	vc->state.charset	= 0;
 	vc->vc_need_wrap	= 0;
 	vc->vc_report_mouse	= 0;
+	vc->vc_bracketed_paste	= 0;
 	vc->vc_utf              = default_utf8;
 	vc->vc_utf_count	= 0;
 
@@ -3483,6 +3496,8 @@ int tioclinux(struct tty_struct *tty, unsigned long arg)
 		break;
 	case TIOCL_BLANKEDSCREEN:
 		return console_blanked;
+	case TIOCL_GETBRACKETEDPASTE:
+		return get_bracketed_paste(tty);
 	default:
 		return -EINVAL;
 	}
diff --git a/include/linux/console_struct.h b/include/linux/console_struct.h
index 20f564e98552..59b4fec5f254 100644
--- a/include/linux/console_struct.h
+++ b/include/linux/console_struct.h
@@ -145,6 +145,7 @@ struct vc_data {
 	unsigned int	vc_need_wrap	: 1;
 	unsigned int	vc_can_do_color	: 1;
 	unsigned int	vc_report_mouse : 2;
+	unsigned int	vc_bracketed_paste : 1;
 	unsigned char	vc_utf		: 1;	/* Unicode UTF-8 encoding */
 	unsigned char	vc_utf_count;
 		 int	vc_utf_char;
diff --git a/include/uapi/linux/tiocl.h b/include/uapi/linux/tiocl.h
index b32acc229024..88faba506c3d 100644
--- a/include/uapi/linux/tiocl.h
+++ b/include/uapi/linux/tiocl.h
@@ -36,5 +36,6 @@ struct tiocl_selection {
 #define TIOCL_BLANKSCREEN	14	/* keep screen blank even if a key is pressed */
 #define TIOCL_BLANKEDSCREEN	15	/* return which vt was blanked */
 #define TIOCL_GETKMSGREDIRECT	17	/* get the vt the kernel messages are restricted to */
+#define TIOCL_GETBRACKETEDPASTE	18	/* get whether paste may be bracketed */
 
 #endif /* _LINUX_TIOCL_H */
-- 
2.49.0

[PATCH v3 2/2] vt: add VT_GETCONSIZECSRPOS to retrieve console size and cursor position

[Nicolas Pitre]

From: Nicolas Pitre <npitre@baylibre.com>

The console dimension and cursor position are available through the
/dev/vcsa interface already. However the /dev/vcsa header format uses
single-byte fields therefore those values are clamped to 255.

As surprizing as this may seem, some people do use 240-column 67-row
screens (a 1920x1080 monitor with 8x16 pixel fonts) which is getting
close to the limit. Monitors with higher resolution are not uncommon
these days (3840x2160 producing a 480x135 character display) and it is
just a matter of time before someone with, say, a braille display using
the Linux VT console and BRLTTY on such a screen reports a bug about
missing and oddly misaligned screen content.

Let's add VT_GETCONSIZECSRPOS for the retrieval of console size and cursor
position without byte-sized limitations. The actual console size limit as
encoded in vt.c is 32767x32767 so using a short here is appropriate. Then
this can be used to get the cursor position when /dev/vcsa reports 255.

The screen dimension may already be obtained using TIOCGWINSZ and adding
the same information to VT_GETCONSIZECSRPOS might be redundant. However
applications that care about cursor position also care about display
size and having 2 separate system calls to obtain them separately is
wasteful. Also, the cursor position can be queried by writing "\e[6n" to
a tty and reading back the result but that may be done only by the actual
application using that tty and not a sideline observer.

Signed-off-by: Nicolas Pitre <npitre@baylibre.com>
---
 drivers/tty/vt/vt_ioctl.c | 16 ++++++++++++++++
 include/uapi/linux/vt.h   | 11 +++++++++++
 2 files changed, 27 insertions(+)

diff --git a/drivers/tty/vt/vt_ioctl.c b/drivers/tty/vt/vt_ioctl.c
index 4b91072f3a4e..83a3d49535e5 100644
--- a/drivers/tty/vt/vt_ioctl.c
+++ b/drivers/tty/vt/vt_ioctl.c
@@ -951,6 +951,22 @@ int vt_ioctl(struct tty_struct *tty,
 					(unsigned short __user *)arg);
 	case VT_WAITEVENT:
 		return vt_event_wait_ioctl((struct vt_event __user *)arg);
+
+	case VT_GETCONSIZECSRPOS:
+	{
+		struct vt_consizecsrpos concsr;
+
+		console_lock();
+		concsr.con_cols = vc->vc_cols;
+		concsr.con_rows = vc->vc_rows;
+		concsr.csr_col = vc->state.x;
+		concsr.csr_row = vc->state.y;
+		console_unlock();
+		if (copy_to_user(up, &concsr, sizeof(concsr)))
+			return -EFAULT;
+		return 0;
+	}
+
 	default:
 		return -ENOIOCTLCMD;
 	}
diff --git a/include/uapi/linux/vt.h b/include/uapi/linux/vt.h
index e9d39c48520a..e5b0c492aa18 100644
--- a/include/uapi/linux/vt.h
+++ b/include/uapi/linux/vt.h
@@ -2,6 +2,8 @@
 #ifndef _UAPI_LINUX_VT_H
 #define _UAPI_LINUX_VT_H
 
+#include <linux/ioctl.h>
+#include <linux/types.h>
 
 /*
  * These constants are also useful for user-level apps (e.g., VC
@@ -84,4 +86,13 @@ struct vt_setactivate {
 
 #define VT_SETACTIVATE	0x560F	/* Activate and set the mode of a console */
 
+/* get console size and cursor position */
+struct vt_consizecsrpos {
+	__u16 con_rows;		/* number of console rows */
+	__u16 con_cols;		/* number of console columns */
+	__u16 csr_row;		/* current cursor's row */
+	__u16 csr_col;		/* current cursor's column */
+};
+#define VT_GETCONSIZECSRPOS	_IOR('V', 0x10, struct vt_consizecsrpos)
+
 #endif /* _UAPI_LINUX_VT_H */
-- 
2.49.0