[PATCH man v2 0/2] TIOCLINUX.2const: Document TIOCL_SETSEL selection modes

[PATCH man v2 0/2] TIOCLINUX.2const: Document TIOCL_SETSEL selection modes

[Günther Noack]

Hi!

TIOCLINUX's TIOCL_SETSEL sub-code has another layer of sub-operations,
called "selection modes" (even though not all of them actually deal
with the mouse selection).

Going forward, the CAP_SYS_ADMIN requirement will be different for
some of these selection modes, which prompted me to at least list the
different selection modes with a short description.  I am leaving
CAP_SYS_ADMIN documentation as it is for now and will send another
patch once these semantics are finalized [1] [2].

Thanks,
–Günther

[1] <https://lore.kernel.org/all/20250221.0a947528d8f3@gnoack.org/>
[2] <https://lore.kernel.org/all/20250223205449.7432-2-gnoack3000@gmail.com/>

History:

V2:
 * Split into a "restructuring" and a "new documentation" commit
 * Use non-breaking space \~
 * Put URIs in <>
 * Added a helpful link to console_codes(4) regarding mouse reporting

Günther Noack (2):
  TIOCLINUX.2const: Restructure documentation for TIOCL_SETSEL selection
    modes
  TIOCLINUX.2const: Document missing TIOCL_SETSEL selection modes

 man/man2const/TIOCLINUX.2const | 52 ++++++++++++++++++++++++++++++----
 1 file changed, 47 insertions(+), 5 deletions(-)


base-commit: fe7e094e78139a4ac5ee31b2321b77041c725794
-- 
2.48.1

[PATCH man v2 1/2] TIOCLINUX.2const: Restructure documentation for TIOCL_SETSEL selection modes

[Günther Noack]

* Indent the documented selection modes into tagged paragraphs.
* Document constants from the header file (tiocl.h) instead of numbers.

Signed-off-by: Günther Noack <gnoack3000@gmail.com>
---
 man/man2const/TIOCLINUX.2const | 23 ++++++++++++++++++-----
 1 file changed, 18 insertions(+), 5 deletions(-)

diff --git a/man/man2const/TIOCLINUX.2const b/man/man2const/TIOCLINUX.2const
index c0acdd0ea..5db3f6ea6 100644
--- a/man/man2const/TIOCLINUX.2const
+++ b/man/man2const/TIOCLINUX.2const
@@ -65,11 +65,24 @@ are the ending
 column and row.
 (Upper left corner is row=column=1.)
 .I sel_mode
-is 0 for character-by-character selection,
-1 for word-by-word selection,
-or 2 for line-by-line selection.
-The indicated screen characters are highlighted and saved
-in a kernel buffer.
+may be one of the following operations:
+.RS
+.TP
+.B TIOCL_SELCHAR
+Select character-by-character.
+The indicated screen characters are highlighted
+and saved in a kernel buffer.
+.TP
+.B TIOCL_SELWORD
+Select word-by-word.
+The indicated screen characters are highlighted
+and saved in a kernel buffer.
+.TP
+.B TIOCL_SELLINE
+Select line-by-line.
+The indicated screen characters are highlighted
+and saved in a kernel buffer.
+.RE
 .IP
 Since Linux 6.7, using this subcode requires the
 .B CAP_SYS_ADMIN
-- 
2.48.1

[PATCH man v2 2/2] TIOCLINUX.2const: Document missing TIOCL_SETSEL selection modes

[Günther Noack]

Documents the following TIOCL_SETSEL sub-operations:

* TIOCL_SELPOINTER
* TIOCL_SELCLEAR
* TIOCL_SELMOUSEREPORT

These previously undocumented selection modes for the Linux console
are implemented in drivers/tty/vt/selection.c.  The name "selection
mode" is slightly misleading as not all of them actually manipulate
the kernel's mouse selection buffer.

Cc: Jared Finder <jared@finder.org>
Cc: Hanno Böck <hanno@hboeck.de>
Cc: Jann Horn <jannh@google.com>
Cc: Jiri Slaby <jirislaby@kernel.org>
Cc: jwilk@jwilk.net
Signed-off-by: Günther Noack <gnoack3000@gmail.com>
---
 man/man2const/TIOCLINUX.2const | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/man/man2const/TIOCLINUX.2const b/man/man2const/TIOCLINUX.2const
index 5db3f6ea6..3aa1c7eb2 100644
--- a/man/man2const/TIOCLINUX.2const
+++ b/man/man2const/TIOCLINUX.2const
@@ -82,6 +82,35 @@ and saved in a kernel buffer.
 Select line-by-line.
 The indicated screen characters are highlighted
 and saved in a kernel buffer.
+.TP
+.B TIOCL_SELPOINTER
+Show the pointer at position
+.RI ( xe ,\~ ye ).
+.TP
+.B TIOCL_SELCLEAR
+Remove the current selection highlight, if any,
+from the console holding the selection.
+.TP
+.B TIOCL_SELMOUSEREPORT
+Make the terminal report
+.RI ( xs ,\~ ys )
+as the current mouse location
+using the
+.BR xterm (1)
+mouse tracking protocol
+(see
+.BR console_codes (4)).
+The lower 4 bits of
+.I sel_mode
+.RB ( TIOCL_SELBUTTONMASK )
+indicate the desired button press and
+modifier key information for the mouse event.
+.\" <https://invisible-island.net/xterm/ctlseqs/ctlseqs.html#h3-Normal-tracking-mode>
+.IP
+If mouse reporting is not enabled for the terminal,
+this operation yields an
+.B EINVAL
+error.
 .RE
 .IP
 Since Linux 6.7, using this subcode requires the
-- 
2.48.1

Re: [PATCH man v2 1/2] TIOCLINUX.2const: Restructure documentation for TIOCL_SETSEL selection modes

[Jared Finder]

I'm not a regular kernel developer, so feel free to ignore my 
recommendations if they are not aligned with the level of documentation 
usually provided.

On 2025-02-23 13:36, Günther Noack wrote:
> * Indent the documented selection modes into tagged paragraphs.
> * Document constants from the header file (tiocl.h) instead of numbers.
> 
> Signed-off-by: Günther Noack <gnoack3000@gmail.com>
> ---
>  man/man2const/TIOCLINUX.2const | 23 ++++++++++++++++++-----
>  1 file changed, 18 insertions(+), 5 deletions(-)
> 
> diff --git a/man/man2const/TIOCLINUX.2const 
> b/man/man2const/TIOCLINUX.2const
> index c0acdd0ea..5db3f6ea6 100644
> --- a/man/man2const/TIOCLINUX.2const
> +++ b/man/man2const/TIOCLINUX.2const
> @@ -65,11 +65,24 @@ are the ending
>  column and row.
>  (Upper left corner is row=column=1.)
>  .I sel_mode
> -is 0 for character-by-character selection,
> -1 for word-by-word selection,
> -or 2 for line-by-line selection.
> -The indicated screen characters are highlighted and saved
> -in a kernel buffer.
> +may be one of the following operations:
> +.RS
> +.TP
> +.B TIOCL_SELCHAR
> +Select character-by-character.
> +The indicated screen characters are highlighted
> +and saved in a kernel buffer.

I would recommend also saying

> +.TP
> +.B TIOCL_SELWORD
> +Select word-by-word.
> +The indicated screen characters are highlighted
> +and saved in a kernel buffer.

I would recommend also saying something like "The start is expanded 
backward and the end is expanded forwards to select entire words."

> +.TP
> +.B TIOCL_SELLINE
> +Select line-by-line.
> +The indicated screen characters are highlighted
> +and saved in a kernel buffer.
> +.RE

Similarly, mention how the start / end is expanded here too.

>  .IP
>  Since Linux 6.7, using this subcode requires the
>  .B CAP_SYS_ADMIN

   -- MJF

Re: [PATCH man v2 2/2] TIOCLINUX.2const: Document missing TIOCL_SETSEL selection modes

[Jared Finder]

Similarly to the other part of the patch, feel free to ignore my 
comments if they're not aligned with the usual documentation details.

On 2025-02-23 13:36, Günther Noack wrote:
> Documents the following TIOCL_SETSEL sub-operations:
> 
> * TIOCL_SELPOINTER
> * TIOCL_SELCLEAR
> * TIOCL_SELMOUSEREPORT
> 
> These previously undocumented selection modes for the Linux console
> are implemented in drivers/tty/vt/selection.c.  The name "selection
> mode" is slightly misleading as not all of them actually manipulate
> the kernel's mouse selection buffer.
> 
> Cc: Jared Finder <jared@finder.org>
> Cc: Hanno Böck <hanno@hboeck.de>
> Cc: Jann Horn <jannh@google.com>
> Cc: Jiri Slaby <jirislaby@kernel.org>
> Cc: jwilk@jwilk.net
> Signed-off-by: Günther Noack <gnoack3000@gmail.com>
> ---
>  man/man2const/TIOCLINUX.2const | 29 +++++++++++++++++++++++++++++
>  1 file changed, 29 insertions(+)
> 
> diff --git a/man/man2const/TIOCLINUX.2const 
> b/man/man2const/TIOCLINUX.2const
> index 5db3f6ea6..3aa1c7eb2 100644
> --- a/man/man2const/TIOCLINUX.2const
> +++ b/man/man2const/TIOCLINUX.2const
> @@ -82,6 +82,35 @@ and saved in a kernel buffer.
>  Select line-by-line.
>  The indicated screen characters are highlighted
>  and saved in a kernel buffer.
> +.TP
> +.B TIOCL_SELPOINTER
> +Show the pointer at position
> +.RI ( xe ,\~ ye ).

nit: Technically, "at the greater position of start or end".  See how ps 
and pe are swapped if ps > pe in vc_selection().

> +.TP
> +.B TIOCL_SELCLEAR
> +Remove the current selection highlight, if any,
> +from the console holding the selection.

I'd recommend stating explicitly if this affects the stored characters. 
(I believe it does not.)

> +.TP
> +.B TIOCL_SELMOUSEREPORT
> +Make the terminal report
> +.RI ( xs ,\~ ys )
> +as the current mouse location
> +using the
> +.BR xterm (1)
> +mouse tracking protocol
> +(see
> +.BR console_codes (4)).
> +The lower 4 bits of
> +.I sel_mode
> +.RB ( TIOCL_SELBUTTONMASK )
> +indicate the desired button press and
> +modifier key information for the mouse event.
> +.\" 
> <https://invisible-island.net/xterm/ctlseqs/ctlseqs.html#h3-Normal-tracking-mode>
> +.IP
> +If mouse reporting is not enabled for the terminal,
> +this operation yields an
> +.B EINVAL
> +error.
>  .RE
>  .IP
>  Since Linux 6.7, using this subcode requires the

   -- MJF

Re: [PATCH man v2 1/2] TIOCLINUX.2const: Restructure documentation for TIOCL_SETSEL selection modes

[Alejandro Colomar]

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Hi Günther, Jared,

On Sun, Feb 23, 2025 at 03:13:35PM -0800, Jared Finder wrote:
> I'm not a regular kernel developer, so feel free to ignore my
> recommendations if they are not aligned with the level of documentation
> usually provided.
> 
> On 2025-02-23 13:36, Günther Noack wrote:
> > * Indent the documented selection modes into tagged paragraphs.
> > * Document constants from the header file (tiocl.h) instead of numbers.
> > 
> > Signed-off-by: Günther Noack <gnoack3000@gmail.com>

I have no comments of my own.  What do you want to do about the ones
from Jared?


Have a lovely day!
Alex

> > ---
> >  man/man2const/TIOCLINUX.2const | 23 ++++++++++++++++++-----
> >  1 file changed, 18 insertions(+), 5 deletions(-)
> > 
> > diff --git a/man/man2const/TIOCLINUX.2const
> > b/man/man2const/TIOCLINUX.2const
> > index c0acdd0ea..5db3f6ea6 100644
> > --- a/man/man2const/TIOCLINUX.2const
> > +++ b/man/man2const/TIOCLINUX.2const
> > @@ -65,11 +65,24 @@ are the ending
> >  column and row.
> >  (Upper left corner is row=column=1.)
> >  .I sel_mode
> > -is 0 for character-by-character selection,
> > -1 for word-by-word selection,
> > -or 2 for line-by-line selection.
> > -The indicated screen characters are highlighted and saved
> > -in a kernel buffer.
> > +may be one of the following operations:
> > +.RS
> > +.TP
> > +.B TIOCL_SELCHAR
> > +Select character-by-character.
> > +The indicated screen characters are highlighted
> > +and saved in a kernel buffer.
> 
> I would recommend also saying
> 
> > +.TP
> > +.B TIOCL_SELWORD
> > +Select word-by-word.
> > +The indicated screen characters are highlighted
> > +and saved in a kernel buffer.
> 
> I would recommend also saying something like "The start is expanded backward
> and the end is expanded forwards to select entire words."
> 
> > +.TP
> > +.B TIOCL_SELLINE
> > +Select line-by-line.
> > +The indicated screen characters are highlighted
> > +and saved in a kernel buffer.
> > +.RE
> 
> Similarly, mention how the start / end is expanded here too.
> 
> >  .IP
> >  Since Linux 6.7, using this subcode requires the
> >  .B CAP_SYS_ADMIN
> 
>   -- MJF

-- 
<https://www.alejandro-colomar.es/>

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Re: [PATCH man v2 1/2] TIOCLINUX.2const: Restructure documentation for TIOCL_SETSEL selection modes

[Günther Noack]

Hello Jared!

On Sun, Feb 23, 2025 at 03:13:35PM -0800, Jared Finder wrote:
> I'm not a regular kernel developer, so feel free to ignore my
> recommendations if they are not aligned with the level of documentation
> usually provided.

Thank you! No, it's absolutely appreciated.

You are right that the console IOCTLs are generally under-documented.
I do not have the time to fix that all up, but I am happy to fix it
for the pieces that I'm touching.

> On 2025-02-23 13:36, Günther Noack wrote:
> > * Indent the documented selection modes into tagged paragraphs.
> > * Document constants from the header file (tiocl.h) instead of numbers.
> > 
> > Signed-off-by: Günther Noack <gnoack3000@gmail.com>
> > ---
> >  man/man2const/TIOCLINUX.2const | 23 ++++++++++++++++++-----
> >  1 file changed, 18 insertions(+), 5 deletions(-)
> > 
> > diff --git a/man/man2const/TIOCLINUX.2const
> > b/man/man2const/TIOCLINUX.2const
> > index c0acdd0ea..5db3f6ea6 100644
> > --- a/man/man2const/TIOCLINUX.2const
> > +++ b/man/man2const/TIOCLINUX.2const
> > @@ -65,11 +65,24 @@ are the ending
> >  column and row.
> >  (Upper left corner is row=column=1.)
> >  .I sel_mode
> > -is 0 for character-by-character selection,
> > -1 for word-by-word selection,
> > -or 2 for line-by-line selection.
> > -The indicated screen characters are highlighted and saved
> > -in a kernel buffer.
> > +may be one of the following operations:
> > +.RS
> > +.TP
> > +.B TIOCL_SELCHAR
> > +Select character-by-character.
> > +The indicated screen characters are highlighted
> > +and saved in a kernel buffer.
> 
> I would recommend also saying

This sentence is truncated, and there is no special expansion logic in
this case.  I left it as it is for now, unless there is something
better to say here.

> > +.TP
> > +.B TIOCL_SELWORD
> > +Select word-by-word.
> > +The indicated screen characters are highlighted
> > +and saved in a kernel buffer.
> 
> I would recommend also saying something like "The start is expanded backward
> and the end is expanded forwards to select entire words."

Changing it to

  Select word-by-word,
  expanding the selection outwards to align with word boundaries.

Does it sound reasonable to you?

> > +.TP
> > +.B TIOCL_SELLINE
> > +Select line-by-line.
> > +The indicated screen characters are highlighted
> > +and saved in a kernel buffer.
> > +.RE
> 
> Similarly, mention how the start / end is expanded here too.

Made it

  Select line-by-line,
  expanding the selection outwards to select full lines.

–Günther

Re: [PATCH man v2 2/2] TIOCLINUX.2const: Document missing TIOCL_SETSEL selection modes

[Günther Noack]

Hello!

On Sun, Feb 23, 2025 at 03:19:02PM -0800, Jared Finder wrote:
> On 2025-02-23 13:36, Günther Noack wrote:
> >  man/man2const/TIOCLINUX.2const | 29 +++++++++++++++++++++++++++++
> >  1 file changed, 29 insertions(+)
> > 
> > diff --git a/man/man2const/TIOCLINUX.2const
> > b/man/man2const/TIOCLINUX.2const
> > index 5db3f6ea6..3aa1c7eb2 100644
> > --- a/man/man2const/TIOCLINUX.2const
> > +++ b/man/man2const/TIOCLINUX.2const
> > @@ -82,6 +82,35 @@ and saved in a kernel buffer.
> >  Select line-by-line.
> >  The indicated screen characters are highlighted
> >  and saved in a kernel buffer.
> > +.TP
> > +.B TIOCL_SELPOINTER
> > +Show the pointer at position
> > +.RI ( xe ,\~ ye ).
> 
> nit: Technically, "at the greater position of start or end".  See how ps and
> pe are swapped if ps > pe in vc_selection().

Thanks, that is a good point, I had missed that.

I happens at a central place in the code, where it technically affects
all operations except for TIOCL_SELMOUSEREPORT, but it only makes a
difference in the documentation of TIOCL_SELPOINTER.


> > +.TP
> > +.B TIOCL_SELCLEAR
> > +Remove the current selection highlight, if any,
> > +from the console holding the selection.
> 
> I'd recommend stating explicitly if this affects the stored characters. (I
> believe it does not.)

Thanks, added.

–Günther

Re: [PATCH man v2 1/2] TIOCLINUX.2const: Restructure documentation for TIOCL_SETSEL selection modes

[Günther Noack]

On Sun, Mar 02, 2025 at 08:06:26AM +0100, Alejandro Colomar wrote:
> I have no comments of my own.  What do you want to do about the ones
> from Jared?

Thanks for the reminder!

These suggestions all made sense, I replied in-line and sent a V3.

–Günther