Re: [dev] [st] Strange behaviour of backspace under csh under st

From: Jinsong Zhao <jszhao_AT_yeah.net>
Date: Thu, 7 Nov 2024 21:56:43 +0800

On 2024/11/7 9:37, Steffen Nurpmeso wrote:
> Jinsong Zhao wrote in
> <09350f56-59c1-4a2f-b7cc-9063e0c241b2_AT_yeah.net>:
> |I was trying to use st on a FreeBSD workstation, and my shell is csh.
> |When I use backspace to delete the Chinese character, I observe strange
> |behavior.
> |
> |On the first,
> |zjs_AT_freebsd:~ % 中文|
> |
> |After pressing a backspace key,
> |zjs_AT_freebsd:~ % |
> |
> |After pressing ctrl + l to refresh st,
> |zjs_AT_freebsd:~ % 中|
> |
> |The vertical bar indicates the cursor position.
> |
> |This behavior is observed under bash, but not under sh.
> |
> |Any hint would be greatly appreciated.
>
> Which locale is it that you are using? I think (pretty sure) st
> supports only UTF-8 locales, so that is one thing. Cannot be any
> of those
> zh_CN.GB18030.src
> zh_CN.GB2312.src
> zh_CN.GBK.src
> zh_CN.eucCN.src
> zh_TW.Big5.src
> that i see in origin/main:share/colldef; try locale -a aka
> zh_CN.utf8 or better BSD-style zh_CN.UTF-8.

my locale is C.UTF-8.

The problem disappeared after I upgraded st to 0.9.2. The problem
occurred on my FreeBSD 14.1 with st-0.9.1 installed using pkg, FreeBSD's
package management system.

Sorry for the noise. I should check the latest version of st before
posting here.

Best,

Jinsong

> Also .. now looking .. st simply assumes it can hand-join UTF-8 to
> UTF-32 and take that as a wchar_t for using the wcwidth(3)
> function that is part of FreeBSD. Now letting aside the fact that
> the Citrus library they used when i was looking for real last
> (many years ago after which Daroussin then implemented something
> to be able to generate actualized character mapping tables and
> more from Unicode aka ICU releases *if* i get that right) had some
> special things which violate(d) that assumption back in the day,
> i cannot tell whether (a) this is still true (b) this has ever
> been true for zh_, especially not with UTF-8. (Likely not.)
>
> The issue as such seems to me pretty known in that backspace does
> not seem to erase all bytes for real, so that a repaint brings
> back garbage.
>
> --steffen
> |
> |Der Kragenbaer, The moon bear,
> |der holt sich munter he cheerfully and one by one
> |einen nach dem anderen runter wa.ks himself off
> |(By Robert Gernhardt)
> |
> |And in Fall, feel "The Dropbear Bard"s ball(s).
> |
> |The banded bear
> |without a care,
> |Banged on himself fore'er and e'er
> |
> |Farewell, dear collar bear
Received on Thu Nov 07 2024 - 14:56:43 CET