From: Matthew Leach <matthew@mattleach.net>
To: Eli Zaretskii <eliz@gnu.org>
Cc: 37564@debbugs.gnu.org
Subject: bug#37564: [PATCH] don't export LINES and COLUMNS env vars in term to fix ncurses applications
Date: Tue, 01 Oct 2019 16:47:35 +0100 [thread overview]
Message-ID: <87tv8slb6w.fsf@mattleach.net> (raw)
In-Reply-To: <83eezxatsv.fsf@gnu.org> (Eli Zaretskii's message of "Tue, 01 Oct 2019 09:01:04 +0300")
[-- Attachment #1: Type: text/plain, Size: 1344 bytes --]
Eli Zaretskii <eliz@gnu.org> writes:
>> From: Matthew Leach <matthew@mattleach.net>
>> Date: Mon, 30 Sep 2019 20:59:04 +0100
>>
>> The attached patch removes the exporting of the LINES and COLUMNS
>> environment variables in term-mode. Exporting these variables causes
>> issues for ncurses applications. For example, when running:
>>
>> emacs -Q
>> M-x term
>> <ret> (to select /bin/bash)
>> htop (to run htop)
>>
>> and resizing the window (especially making it smaller) can make the
>> program impossible to read.
>
> Thanks, but I don't think we can make this change unconditionally,
> because not all applications that heed LINES and COLUMNS use ncurses.
I'm curious as to which programs you are referring? AFAIK, if a program
tries to read the LINES and COLUMNS environment variables, using
`getenv()', they don't exist. Running 'echo $LINES' on a bash terminal
seems to actually do an ioctl to obtain the value of LINES.
Nevertheless, if a program does read the LINES and COLUMNS variables,
these values will be wrong if the window has been resized (try and
compile the attached C snippet and run in term mode while resizing the
window). Should that be considered as a separate bug?
> I wonder if we can do better than just providing a defcustom.
I could make this a defcustom if that would get the patch in?
Thanks,
--
Matt
[-- Attachment #2: winch2.c --]
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#include <stdio.h>
#include <signal.h>
#include <unistd.h>
#include <sys/ioctl.h>
void handle_sig()
{
struct winsize w;
ioctl(STDOUT_FILENO, TIOCGWINSZ, &w);
printf("getenv: %s %s\n", getenv("LINES"), getenv("COLUMNS"));
printf("ioctl: %d %d\n", w.ws_row, w.ws_col);
}
int main()
{
signal(SIGWINCH, handle_sig);
fgetc(stdin);
return 0;
}
next prev parent reply other threads:[~2019-10-01 15:47 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-30 19:59 bug#37564: [PATCH] don't export LINES and COLUMNS env vars in term to fix ncurses applications Matthew Leach
2019-10-01 6:01 ` Eli Zaretskii
2019-10-01 15:47 ` Matthew Leach [this message]
2019-10-01 16:07 ` Eli Zaretskii
2019-10-01 18:33 ` Matthew Leach
2019-10-01 18:58 ` Eli Zaretskii
2019-10-01 19:14 ` Eli Zaretskii
2019-10-01 19:24 ` Matthew Leach
2019-10-02 2:28 ` Eli Zaretskii
2019-10-03 17:51 ` Glenn Morris
2019-10-04 18:48 ` Matthew Leach
2020-01-20 19:10 ` Stefan Kangas
2020-01-20 19:30 ` Eli Zaretskii
2020-01-21 0:58 ` Glenn Morris
2020-01-21 17:11 ` Eli Zaretskii
2020-01-21 18:10 ` Matthew Leach
2020-01-22 3:38 ` Glenn Morris
2020-01-22 15:46 ` Eli Zaretskii
2020-06-04 16:01 ` Glenn Morris
2020-08-15 12:37 ` Lars Ingebrigtsen
2020-01-24 18:08 ` Stefan Kangas
2020-01-21 3:04 ` Stefan Kangas
2019-10-04 18:47 ` Matthew Leach
2019-10-07 4:11 ` Lars Ingebrigtsen
2019-10-07 9:16 ` Andreas Schwab
2019-10-08 16:38 ` Lars Ingebrigtsen
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