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Commit 63f3a16d authored by Adam Borowski's avatar Adam Borowski Committed by Greg Kroah-Hartman
Browse files

vt: detect and ignore OSC codes. 



These can be used to send commands consisting of an arbitrary string to the
terminal, most often used to set a terminal's window title or to redefine
the colour palette.  Our console doesn't use OSC, unlike everything else,
which can lead to junk being displayed if a process sends such a code
unconditionally.

The rules for termination follow established practice rather than Ecma-48.
Ecma-48 requires the string to use only byte values 0x08..0x0D and
0x20..0x7E, terminated with either ESC \ or 0x9C.  This would disallow using
8-bit characters, which are reasonable for example in window titles.
A widespread idiom is to terminate with 0x07.  The behaviour for other
control characters differs between terminal emulators, I followed libvte and
xterm:
* 0x07 and ESC anything terminate
* nothing else terminates, all 8-bit values including 0x9C are considered a
  part of the string

Signed-off-by: default avatarAdam Borowski <kilobyte@angband.pl>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent b290af68

drivers/tty/vt/vt.c

+11 −3
Original line number Diff line number Diff line
@@ -1592,7 +1592,7 @@ static void restore_cur(struct vc_data *vc) 


enum { ESnormal, ESesc, ESsquare, ESgetpars, ESfunckey,

	EShash, ESsetG0, ESsetG1, ESpercent, ESignore, ESnonstd,

	ESpalette };

	ESpalette, ESosc };



/* console_lock is held (except via vc_init()) */

static void reset_terminal(struct vc_data *vc, int do_clear)
@@ -1652,11 +1652,15 @@ static void do_con_trol(struct tty_struct *tty, struct vc_data *vc, int c) 
	 *  Control characters can be used in the _middle_

	 *  of an escape sequence.

	 */

	if (vc->vc_state == ESosc && c>=8 && c<=13) /* ... except for OSC */

		return;

	switch (c) {

	case 0:

		return;

	case 7:

		if (vc->vc_bell_duration)

		if (vc->vc_state == ESosc)

			vc->vc_state = ESnormal;

		else if (vc->vc_bell_duration)

			kd_mksound(vc->vc_bell_pitch, vc->vc_bell_duration);

		return;

	case 8:
@@ -1767,7 +1771,9 @@ static void do_con_trol(struct tty_struct *tty, struct vc_data *vc, int c) 
		} else if (c=='R') {   /* reset palette */

			reset_palette(vc);

			vc->vc_state = ESnormal;

		} else

		} else if (c>='0' && c<='9')

			vc->vc_state = ESosc;

		else

			vc->vc_state = ESnormal;

		return;

	case ESpalette:
@@ -2021,6 +2027,8 @@ static void do_con_trol(struct tty_struct *tty, struct vc_data *vc, int c) 
			vc->vc_translate = set_translate(vc->vc_G1_charset, vc);

		vc->vc_state = ESnormal;

		return;

	case ESosc:

		return;

	default:

		vc->vc_state = ESnormal;

	}