[PATCH] Cygwin: console: Ignore 0x00 on write().

[Takashi Yano]

On Thu, 20 Feb 2020 14:44:59 +0100
Corinna Vinschen wrote:
> On Feb 20 14:35, Corinna Vinschen wrote:
> > On Feb 20 20:51, Takashi Yano wrote:
> > > - In xterm compatible mode, 0x00 on write() behaves incompatible
> > >   with real xterm. In xterm, 0x00 completely ignored. Therefore,
> > >   0x00 is ignored by console with this patch.
> > > ---
> > >  winsup/cygwin/fhandler_console.cc | 10 ++++++++++
> > >  1 file changed, 10 insertions(+)
> > > [...]
> > 
> > Counter-proposal:
> > 
> > diff --git a/winsup/cygwin/fhandler_console.cc b/winsup/cygwin/fhandler_console.cc
> > index 66e645aa1774..1b3aa0f34aa6 100644
> > --- a/winsup/cygwin/fhandler_console.cc
> > +++ b/winsup/cygwin/fhandler_console.cc
> > [...]
> 
> Btw., I tested this with
> 
>   write (1, "A\0B\0C\0D", 7);
> 
> it turned out that this results in broken output even with your patch.
> The reason is that a NUL byte must not (cannot) be evaluated by 
> dev_console::str_to_con() -> sys_cp_mbstowcs().  The latter doesn't
> handle embedded NUL bytes gracefully.

Indeed. Your patch is much better.

On Thu, 20 Feb 2020 14:35:31 +0100
Corinna Vinschen wrote:
> But, here's a question: Why do we move the cursor to the right at all?
> I assume this is compatible with legacy mode, right?

Hmm. This may be a bug of legacy console.
https://en.wikipedia.org/wiki/Null_character
says
(some terminals, however, incorrectly display it as space)

What about ignoring NUL in legacy mode too?

-- 
Takashi Yano <takashi.yano@nifty.ne.jp>