Re: screen on 64-bit mangles mintty/buffer

[Corinna Vinschen <corinna-cygwin@cygwin.com>]

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On May 15 22:54, Shaddy Baddah wrote:
> Hi Corinna,
> 
> 
> On 2014-05-15 17:17+1000, Corinna Vinschen wrote:
> >
> >
> >Nice detective work, really.  The goldstar is well deservered :)
> >
> >On May 15 04:00, Shaddy Baddah wrote:
> >>I quickly worked out that the code has a bug for "%i". At some point
> >>the code was changed to push and pop the parameters being passed (0 and
> >>39 in my eg.). However, the "%i" select/case block was incrementing the
> >>arguments in a no longer used array for parameters:
> >>
> >>
> >>	    case 'i':
> >>		if (p_is_s[0] == 0)
> >>		    param[0]++;
> >>		if (p_is_s[1] == 0)
> >>		    param[1]++;
> >>		break;
> >
> >Unfortunately there's no newer upstream release and this bug is present
> >in the ncurses 5.9 version in Fedora 20 as well.  From what I gather from the
> >surrounding code, I *assume* something like this could fix it
> >
> >             case 'i':
> >                 y = npop();
> >                 x = npop();
> >                 if (p_is_s[0] == 0)
> >                     y++;
> >                 if (p_is_s[1] == 0)
> >                     x++;
> >                 npush(x);
> >                 npush(y);
> >                 break;
> >
> >I'm not sure the relation between x, y, and the p_is_s indices is
> >correct, though.
> 
> Yes, that's the code that I thought of as well, and same, I'd have to
> get my head around the exact order of p_is_s (unfortunate name), etc.
> 
> When you say the bug is present in ncurses 5.9, is there any application
> that is directly affected? I ask as screen being affected was sort of a
> fluke. It's configure script should have detected terminfo notation was
> available for use, and used the equivalent entry for "cs".

Well, according to Murphy, if there's a bug, it will be hit.

One of them is, for instance, tcsh, which still uses the termcap
functions deliberately for compatibility with old systems, even when
linked against [n]curses[w].  Fortunately tcsh doesn't try to use really
fancy terminal sequences...

There are very likely more projects out there doing that.  And on many
systems the only way to get the termcap functions is to use ncurses.


Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Maintainer                 cygwin AT cygwin DOT com
Red Hat

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