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.
Not following Ecma-48, this commit recognizes 7-bit forms (ESC ] ... 0x07,
ESC ] .. ESC \) but not 8-bit (0x9D ... 0x9C).
Signed-off-by: Adam Borowski <[email protected]>
---
drivers/tty/vt/vt.c | 14 +++++++++++---
1 file changed, 11 insertions(+), 3 deletions(-)
diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
index 61b1137..0377c52 100644
--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -1590,7 +1590,7 @@ static void restore_cur(struct vc_data *vc)
enum { ESnormal, ESesc, ESsquare, ESgetpars, ESgotpars, 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)
@@ -1650,11 +1650,15 @@ 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:
@@ -1765,7 +1769,9 @@ 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:
@@ -2023,6 +2029,8 @@ static void do_con_trol(struct tty_struct *tty, struct vc_data *vc, int c)
return;
default:
vc->vc_state = ESnormal;
+ case ESosc:
+ return;
}
}
--
1.8.5.2
On Wed, Jan 15, 2014 at 07:21:04AM +0100, Adam Borowski wrote:
> 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.
>
> Not following Ecma-48, this commit recognizes 7-bit forms (ESC ] ... 0x07,
> ESC ] .. ESC \) but not 8-bit (0x9D ... 0x9C).
>
> Signed-off-by: Adam Borowski <[email protected]>
Where is this documented?
> ---
> drivers/tty/vt/vt.c | 14 +++++++++++---
> 1 file changed, 11 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
> index 61b1137..0377c52 100644
> --- a/drivers/tty/vt/vt.c
> +++ b/drivers/tty/vt/vt.c
> @@ -1590,7 +1590,7 @@ static void restore_cur(struct vc_data *vc)
>
> enum { ESnormal, ESesc, ESsquare, ESgetpars, ESgotpars, 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)
> @@ -1650,11 +1650,15 @@ 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:
> @@ -1765,7 +1769,9 @@ 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:
> @@ -2023,6 +2029,8 @@ static void do_con_trol(struct tty_struct *tty, struct vc_data *vc, int c)
> return;
> default:
> vc->vc_state = ESnormal;
> + case ESosc:
> + return;
Why below the default: case?
thanks,
greg k-h
On Thu, Feb 13, 2014 at 10:39:12AM -0800, Greg Kroah-Hartman wrote:
> On Wed, Jan 15, 2014 at 07:21:04AM +0100, Adam Borowski wrote:
> > 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.
> >
> > Not following Ecma-48, this commit recognizes 7-bit forms (ESC ] ... 0x07,
> > ESC ] .. ESC \) but not 8-bit (0x9D ... 0x9C).
> >
> > Signed-off-by: Adam Borowski <[email protected]>
>
> Where is this documented?
It's a mix of Ecma-48 and undocumented practice. Ecma-48 says:
# 8.3.89
# OSC - OPERATING SYSTEM COMMAND
# Notation: (C1)
# Representation: 0x9D or ESC 0x5D (])
#
# OSC is used as the opening delimiter of a control string for operating
# system use. The command string following may consist of a sequence of
# bit combinations in the range 0x08 to 0x0D and 0x20 to 0x7E. The
# control string is closed by the terminating delimiter STRING TERMINATOR
# (ST). The interpretation of the command string depends on the relevant
# operating system.
# 8.3.143
# ST - STRING TERMINATOR
# Notation: (C1)
# Representation: 0x9C or ESC 0x5C (\)
#
# ST is used as the closing delimiter of a control string opened by
# APPLICATION PROGRAM COMMAND (APC), DEVICE CONTROL STRING (DCS),
# OPERATING SYSTEM COMMAND (OSC), PRIVACY MESSAGE (PM), or START OF STRING
# (SOS).
... which doesn't define the behaviour for characters 0x00..0x07, 0x0E..0x1F
or 0x7F..0xFF. Somehow, using 0x07 for termination became a widespread
idiom, used more often than proper ESC \. For this reason, implementations
I know all recognize 0x07 as a terminator. The behaviour for other
characters differs, ie, is truly undefined.
As, unlike what Ecma-48 says, using 8-bit characters in a window title is a
reasonable thing to do, I'd allow 0x80..0xFF as non-terminators. I have no
idea what to do with remaining control characters: the current patch allows
them to be interpreted, as it's usually the case for control characters
inside terminal codes. I did not research other implementation here.
I did not recognize 0x9C as ST for two reasons: 1. it'd break non-ASCII
characters that happen to include this byte, and 2. Linux already fails to
recognize 8-bit control codes (with one exception: 0x9B stands for ESC [).
Should I put the above explanation somewhere? As a comment? In the commit
message? Or does it need to be elaborated even further?
> > ---
> > drivers/tty/vt/vt.c | 14 +++++++++++---
> > 1 file changed, 11 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
> > index 61b1137..0377c52 100644
> > --- a/drivers/tty/vt/vt.c
> > +++ b/drivers/tty/vt/vt.c
> > @@ -1590,7 +1590,7 @@ static void restore_cur(struct vc_data *vc)
> >
> > enum { ESnormal, ESesc, ESsquare, ESgetpars, ESgotpars, 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)
> > @@ -1650,11 +1650,15 @@ 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:
> > @@ -1765,7 +1769,9 @@ 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:
> > @@ -2023,6 +2029,8 @@ static void do_con_trol(struct tty_struct *tty, struct vc_data *vc, int c)
> > return;
> > default:
> > vc->vc_state = ESnormal;
> > + case ESosc:
> > + return;
>
> Why below the default: case?
Just to shave a line and a return statement. From your objection, I guess
this goes against the coding standards, right?
Meow!
--
A tit a day keeps the vet away.
On Sun, Feb 16, 2014 at 03:37:59AM +0100, Adam Borowski wrote:
> On Thu, Feb 13, 2014 at 10:39:12AM -0800, Greg Kroah-Hartman wrote:
> > On Wed, Jan 15, 2014 at 07:21:04AM +0100, Adam Borowski wrote:
> > > 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.
> > >
> > > Not following Ecma-48, this commit recognizes 7-bit forms (ESC ] ... 0x07,
> > > ESC ] .. ESC \) but not 8-bit (0x9D ... 0x9C).
> > >
> > > Signed-off-by: Adam Borowski <[email protected]>
> >
> > Where is this documented?
>
> It's a mix of Ecma-48 and undocumented practice. Ecma-48 says:
>
> # 8.3.89
> # OSC - OPERATING SYSTEM COMMAND
> # Notation: (C1)
> # Representation: 0x9D or ESC 0x5D (])
> #
> # OSC is used as the opening delimiter of a control string for operating
> # system use. The command string following may consist of a sequence of
> # bit combinations in the range 0x08 to 0x0D and 0x20 to 0x7E. The
> # control string is closed by the terminating delimiter STRING TERMINATOR
> # (ST). The interpretation of the command string depends on the relevant
> # operating system.
>
> # 8.3.143
> # ST - STRING TERMINATOR
> # Notation: (C1)
> # Representation: 0x9C or ESC 0x5C (\)
> #
> # ST is used as the closing delimiter of a control string opened by
> # APPLICATION PROGRAM COMMAND (APC), DEVICE CONTROL STRING (DCS),
> # OPERATING SYSTEM COMMAND (OSC), PRIVACY MESSAGE (PM), or START OF STRING
> # (SOS).
>
> ... which doesn't define the behaviour for characters 0x00..0x07, 0x0E..0x1F
> or 0x7F..0xFF. Somehow, using 0x07 for termination became a widespread
> idiom, used more often than proper ESC \. For this reason, implementations
> I know all recognize 0x07 as a terminator. The behaviour for other
> characters differs, ie, is truly undefined.
>
> As, unlike what Ecma-48 says, using 8-bit characters in a window title is a
> reasonable thing to do, I'd allow 0x80..0xFF as non-terminators. I have no
> idea what to do with remaining control characters: the current patch allows
> them to be interpreted, as it's usually the case for control characters
> inside terminal codes. I did not research other implementation here.
>
> I did not recognize 0x9C as ST for two reasons: 1. it'd break non-ASCII
> characters that happen to include this byte, and 2. Linux already fails to
> recognize 8-bit control codes (with one exception: 0x9B stands for ESC [).
>
>
> Should I put the above explanation somewhere? As a comment? In the commit
> message? Or does it need to be elaborated even further?
In the commit message would be best.
> > > @@ -2023,6 +2029,8 @@ static void do_con_trol(struct tty_struct *tty, struct vc_data *vc, int c)
> > > return;
> > > default:
> > > vc->vc_state = ESnormal;
> > > + case ESosc:
> > > + return;
> >
> > Why below the default: case?
>
> Just to shave a line and a return statement. From your objection, I guess
> this goes against the coding standards, right?
Yes it does.
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: Adam Borowski <[email protected]>
---
drivers/tty/vt/vt.c | 14 +++++++++++---
1 file changed, 11 insertions(+), 3 deletions(-)
diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
index b7bde54..3ad0b61 100644
--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -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;
}
--
1.9.0