From: Corinna Vinschen <corinna-cygwin@cygwin.com>
To: cygwin@cygwin.com
Subject: Re: X server sets VMIN? (was Re: Under /bin/script, characters get printed in four-character chunks)
Date: Wed, 25 Mar 2015 16:59:00 -0000 [thread overview]
Message-ID: <20150325160504.GE3017@calimero.vinschen.de> (raw)
In-Reply-To: <641C04A3-5059-48A5-830D-4B095935366B@Denis-Excoffier.org>
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On Mar 25 16:26, Denis Excoffier wrote:
> On 2015-03-24 20:53, Corinna Vinschen wrote:
> > - However, if you start xterm from the X server tray icon and then
> > call `stty -a' in it, min is set to 4 and script will misbehave.
> > If you call `stty min 1' before calling script, script will work
> > as expected again.
> >
> > So, why does the X server (or whatever controls starting applications
> > from the X server tray icon) set VMIN to 4?
> >
>
> It seems that this has something to do with tcsh (and not with XWin).
> If you arrange your environment in order that the xterm launches /bin/bash
> (instead of tcsh), you get min=0 under 'stty -a' and /bin/script behaves
> as expected. If afterwards, in such an xterm, you run '/bin/csh -f', you get
> min=4.
>
> Consider the following:
>
> diff -uNr tcsh-6.18.01-original/ed.init.c tcsh-6.18.01-patched/ed.init.c
> --- tcsh-6.18.01-original/ed.init.c 2006-08-24 22:56:08.000000000 +0200
> +++ tcsh-6.18.01-patched/ed.init.c 2015-03-25 15:56:33.000000000 +0100
> @@ -65,7 +65,7 @@
> (uc)CDSWTCH, (uc)CERASE2, (uc)CSTART, (uc)CSTOP,
> (uc)CWERASE, (uc)CSUSP, (uc)CDSUSP, (uc)CREPRINT,
> (uc)CDISCARD, (uc)CLNEXT, (uc)CSTATUS, (uc)CPAGE,
> - (uc)CPGOFF, (uc)CKILL2, (uc)CBRK, (uc)CMIN,
> + (uc)CPGOFF, (uc)CKILL2, (uc)CBRK, (uc)1,
> (uc)CTIME
> },
> {
>
> In the original code, CMIN is set to CEOF and CEOF is set to Control-D, hence
> min=4. With the patch above, all seems to go well. But this does not
> explain why the min=4 is not permanent.
Thanks for looking into that. I'm not sure either why this doesn't
occur all the time, but the culprit seems to be this snippet in
ed.term.h:
#ifndef CMIN
# define CMIN CEOF
#endif /* CMIN */
The default value for CEOF is '\4'. And no header on Cygwin defines
CMIN, so this looks like two bugs in one (buy one, get one free).
Per `git blame' this code in tcsh is from 1991, so maybe we have two
20th century bugs here.
I'll ask the tcsh maintainer and add a definition for CMIN to 1 (as on
Linux) to the headers for the next Cygwin version.
Thanks,
Corinna
--
Corinna Vinschen Please, send mails regarding Cygwin to
Cygwin Maintainer cygwin AT cygwin DOT com
Red Hat
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prev parent reply other threads:[~2015-03-25 16:05 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-02-27 19:06 [ANNOUNCEMENT] (last?) TEST RELEASE: Cygwin 1.7.35-0.5 Corinna Vinschen
2015-02-27 19:50 ` Habermann, David (D)
2015-02-28 0:06 ` Andrey Repin
2015-02-28 4:06 ` Denis Excoffier
2015-02-28 13:27 ` Corinna Vinschen
2015-02-28 20:26 ` Denis Excoffier
2015-02-28 21:32 ` Corinna Vinschen
2015-03-24 19:44 ` Under /bin/script, characters get printed in four-character chunks Denis Excoffier
2015-03-24 20:29 ` X server sets VMIN? (was Re: Under /bin/script, characters get printed in four-character chunks) Corinna Vinschen
2015-03-25 16:05 ` Denis Excoffier
2015-03-25 16:59 ` Corinna Vinschen [this message]
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