Bug#1110771: xterm: allowC1Printable (-k8) does the opposite of what it says

[Vincent Lefevre <vincent@vinc17.net>]

On 2025-08-11 02:36:14 +0200, Vincent Lefevre wrote:
> On 2025-08-11 02:24:51 +0200, Vincent Lefevre wrote:
> > Well, the sequence should have been safe with my xterm settings,
> > because I had set allowC1Printable to true for this purpose.
> > The issue is that allowC1Printable does the opposite of what
> > it says. So data that should have been safe are actually unsafe
> > with "*allowC1Printable: true"!
> 
> This seems to be fixed in #401 (but this may also be due to another
> change).

As a summary:

* With xterm 398-1, the command

  /usr/bin/xterm -k8 -hold -e 'printf "\x9a"'

gives

  ^[[?64;1;2;6;9;15;16;17;18;21;22;28c

(i.e. \x9a is interpreted as DECID, which is unexpected), and the
command

  /usr/bin/xterm +k8 -hold -e 'printf "\x9a"'

gives the character "�".

* With xterm 399-1 and 401-1, the command

  /usr/bin/xterm -k8 -hold -e 'printf "\x9a"'

gives an xterm without any visible content, but when I double-click
on the first cell, I get a rectangle character. Then when I use the
"unicode" command and paste this character, I get

U+009A SINGLE CHARACTER INTRODUCER

The command

  /usr/bin/xterm +k8 -hold -e 'printf "\x9a"'

gives the character "�" like 398-1.

-- 
Vincent Lefèvre <vincent@vinc17.net> - Web: <https://www.vinc17.net/>
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Work: CR INRIA - computer arithmetic / Pascaline project (LIP, ENS-Lyon)