Re: On the behaviour of the checkwinsize shopt from within a subshell

[Koichi Murase]

2023年2月21日(火) 20:28 Koichi Murase <myoga.murase@gmail.com>:
> I recently noticed that `checkwinsize' stopped working in the trap
> string and the `bind -x' context from Bash 5.2, which broke my script.

The behavioral change in the trap handlers and `bind -x' seems to have
been introduced in the following commit.

https://git.savannah.gnu.org/cgit/bash.git/commit/?h=devel&id=b6a567e7f13406952cbb1d1adb2f00b2260a871e

This is the related report.

https://lists.gnu.org/archive/html/bug-bash/2022-03/msg00018.html

This is the related change at that time:

> diff --git a/CWRU/CWRU.chlog b/CWRU/CWRU.chlog
> index ef39921f..f86f0cbe 100644
> --- a/CWRU/CWRU.chlog
> +++ b/CWRU/CWRU.chlog
> @@ -3341,3 +3341,13 @@ parse.y
>     `make visible' flag or through sh_strvis if we're not running the
>     prompt string through word expansions. Fixes issue reported by
>     Josh Harcome <joshharc@gmail.com> back in mid-January
> +
> +          3/11
> +          ----
> +jobs.c
> + - wait_for: don't call get_tty_state() if readline is dispatching
> +   (RL_STATE_DISPATCHING) with the terminal settings changed
> +   (RL_STATE_TERMPREPPED), the same way we don't if we are running a
> +   command for programmable completion. Fixes bug with SIGINT reverting
> +   to the saved readline terminal settings reported by
> +   Markus Napierkowski <markus.napierkowski@cyberus-technology.de>
> diff --git a/jobs.c b/jobs.c
> index 25289f4a..77d9dc35 100644
> --- a/jobs.c
> +++ b/jobs.c
> @@ -3117,7 +3117,7 @@ if (job == NO_JOB)
>     else
>  #if defined (READLINE)
>       /* We don't want to do this if we are running a process during
> -        programmable completion. */
> -     if (RL_ISSTATE (RL_STATE_COMPLETING) == 0)
> +        programmable completion or a command bound to `bind -x'. */
> +     if (RL_ISSTATE 
> (RL_STATE_COMPLETING|RL_STATE_DISPATCHING|RL_STATE_TERMPREPPED) == 0)
>  #endif
>       get_tty_state ();

`checkwinsize' had been processed in `get_tty_state ()' in bash-5.1
and before.  As explained in the change log, we do not want to call
`get_tty_state ()' in this context, but we can instead directly call
`get_new_window_size ()' to only process `checkwinsize'.  I attach a
possible patch [r0039.checkwinsizeA.patch.txt] for this.  Or another
option might be to directly call `ioctl (fd, TIOCGWINSZ, &ws)' there
[r0039.checkwinsizeB.patch.txt].

Note: The patch just tries to fix the regression in 5.2 but does not
change the behavior within subshells.
--
Koichi

r0039.checkwinsizeA.patch.txt
Description: Text document

r0039.checkwinsizeB.patch.txt
Description: Text document