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

Thomas Wolff towo@towo.net
Fri Feb 21 09:43:00 GMT 2020

On 21.02.2020 10:32, Corinna Vinschen wrote:
> On Feb 20 17:38, Corinna Vinschen wrote:
>> On Feb 20 17:22, Thomas Wolff wrote:
>>> On 20.02.2020 17:04, Corinna Vinschen wrote:
>>>> On Feb 20 23:49, Takashi Yano wrote:
>>>>> On Thu, 20 Feb 2020 15:22:45 +0100
>>>>> Corinna Vinschen wrote:
>>>>>> On Feb 20 23:13, Takashi Yano wrote:
>>>>>>> On Thu, 20 Feb 2020 14:44:59 +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?
>>>>>> I'd like that, but this may be a problem in terms of backward
>>>>>> compatibility.  The behaviour is so old, it actually precedes even the
>>>>>> import of Cygwin code into the original CVS repository, 20 years ago...
>>>>> If so, can't we say it is the *specification* of TERM=cygwin
>>>>> that NUL moves the cursor right?
>>>> Good point.  Yes, in that case it's "working as designed" and
>>>> we just leave it as is.  I push my patch.
>>> See `man 5 terminfo`: if NUL does anything else than just padding, the
>>> terminfo entry must contain a pad or npc entry, which it doesn't.
>>> Trouble to be expected. I'd rather suggest to align the design with
>>> applications' expectations.
>> Is that the cygwin terminfo or the xterm terminfo you're talking about?
>> In case of the cygwin terminfo, that would mean the cygwin terminal
>> emulation behaves differently from the terminfo for ages.  I guess
>> you're right then, we should fix this in the cygwin terminal emulation
>> to make sure it behaves as descibed in its terminfo.
>> In case of the xterm terminfo, that would be no problem because my patch
>> drops the cursor movement for NUL.
> Yeah, never mind, I checked the cygwin terminfo entry myself.
> I pushed a patch removing the cursor movement on NUL and added
> a matching comment instead.
Great, thanks! And sorry I'm sometimes a bit slow to respond...

More information about the Cygwin-patches mailing list