[patch] mc-4.8.31-clear-PROMPT_COMMAND.patch

mc-4.8.31-clear-PROMPT_COMMAND.patch (text/plain), 3.14 KB, created by kfm on 2024-04-22 00:53:46 UTC

From 833da535e3d4fe0144241ae624a703f23885fa77 Mon Sep 17 00:00:00 2001
From: Kerin Millar <[e-mail]>
Date: Mon, 22 Apr 2024 01:33:51 +0100
Subject: [PATCH] src/subshell/common.c: clear PROMPT_COMMAND in the course of
 adjusting it

Unless mc is launched with the superlatively misnamed -u or --nosubshell
options, it will launch its embedded shell as an interactive instance.
Further, in the case that the shell is bash, mc will convey a fairly
complicated sequence of commands to initialise the shell, one of which
is as follows.

PROMPT_COMMAND=${PROMPT_COMMAND:+$PROMPT_COMMAND\n}'pwd>&%d;kill -STOP $$'

There, %d is replaced by g_snprintf() with the file descriptor of a pipe
from which mc reads. This is rather clumsy. Moroever, it is incorrect
because it is possible for PROMPT_COMMAND to be an array, as is
supported since the release of Bash 5.1. In that case, mc will adjust
the first element of the array, which is clearly not the intent.

As far as Gentoo is concerned, matters are complicated by the fact that:

- Gentoo's system-wide bashrc defines PROMPT_COMMAND as an array
- Gentoo's PROMPT_COMMAND alters window and/or pane titles by default
- Midnight Commander performs its own, opinionated, title manipulation

One possibility would be to have Gentoo refrain from populating
PROMPT_COMMAND in the event that bash is running as a subprocess of mc.
The prospect of Gentoo developing a collection of application-specific
hacks in bashrc context seems unappealing, however.

Instead, let's patch mc to clear PROMPT_COMMAND in the course of
defining it. One disavantage in doing it this way is that PROMPT_COMMAND
customisations applied by ~/.bashrc will be disregarded. Still, try as I
might, I could not think of a plausible scenario in which this would
negatively impact upon the use of mc.

This patch is not intended to be upstreamable. The Midnight Commander
developers would probably prefer a patch that renders it array-aware, so
that it can append its command, if necessary. For Gentoo, it seems
simpler just to let mc do as it wishes and not stand in its way, so to
speak.

It should be noted that defining PROMPT_COMMAND as an array containing a
single element is safe, even for versions of bash older than 5.1.

Signed-off-by: Kerin Millar <[e-mail]>
Bug: https://bugs.gentoo.org/930401
---
 src/subshell/common.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/subshell/common.c b/src/subshell/common.c
index 4827da044..3d6a81bef 100644
--- a/src/subshell/common.c
+++ b/src/subshell/common.c
@@ -1090,7 +1090,7 @@ init_subshell_precmd (char *precmd, size_t buff_size)
                     " bind -x '\"\\e" SHELL_BUFFER_KEYBINDING "\":\"mc_print_command_buffer\"'\n"
                     " bind -x '\"\\e" SHELL_CURSOR_KEYBINDING
                     "\":\"echo $BASH_VERSINFO:$READLINE_POINT >&%d\"'\n"
-                    " PROMPT_COMMAND=${PROMPT_COMMAND:+$PROMPT_COMMAND\n}'pwd>&%d;kill -STOP $$'\n"
+                    " PROMPT_COMMAND=('pwd>&%d;kill -STOP $$')\n"
                     "PS1='\\u@\\h:\\w\\$ '\n", command_buffer_pipe[WRITE],
                     command_buffer_pipe[WRITE], subshell_pipe[WRITE]);
         break;
-- 
2.44.0