Re: [PATCH] Cygwin: pty: Treat CR/NL in accept_input() the same as in transfer_input()

Hi Takashi,

On 6/23/2026 6:04 AM, Takashi Yano wrote:
> Hi Mark,
> 
> Thanks for reviewing!
> 
> On Tue, 23 Jun 2026 00:41:11 -0700
> Mark Geisert wrote:
>> Hi Takashi,
>>
>> On 6/12/2026 5:47 AM, Takashi Yano wrote:
>>> In transfer_input(), CR and NL in the data transferred to nat-pipe
>>> is treated as follows:
>>>     1) If pseudo console is activated, convert NL to CR.
>>>     2) If pseudo console is disabled, convert CR to NL.
>>> This conversion is necessary to ensure non-cygwin apps can handle
>>> CR/NL as expected. Therefor, CR and NL should be treated as the
>>> same way in accept_input() if the data is sent to nat-pipe.
>>
>> The above block is fine.
>>
>>> Usually, when pseudo console is activated, the input data for non-
>>> cygwin app is not treated by accept_input. However, accept_input()
>>> handle the input data in pseudo console enabled mode, only in a
>>> very short duration when pseudo console is about to setup, because
>>> master::write() calls line_edit() in the pcon_start mode. If pseudo
>>> console is disabled, accept_input() handles them, however usually
>>> ICRNL flag is set, so line_edit() do this conversion. However, if
>>> this flag is not set, the conversion added by this patch is needed
>>> as well.
>>
>> This block I'm having a bit of trouble to follow.  Can you possibly
>> reword to describe it in more orderly fashion?
> 
> What about:
>    In the previous implementation, problems rarely occurred because
>    accept_input() normally does not handle input for non-cygwin apps
>    when the pseudo console is active. Under typical conditions, such
>    input is snet to pseudo console directly by WriteFile(), so
               ^^^^
>    accept_input() is not involved and no onversion issues arise.
                                            ^^^^^^^^^
> 
>    There is, however, a brief period during pseudo console initialization
>    in which accept_input *does* handle the input. This happens because
>    master::write() invokes line_edit() while in pcons_start mode. During
>    this short window, the input is processed in pseudo-console-enabled
>    mode, and the usual conversion behaviour may not apply.
> 
>    When the pseudo console is disabled, accept_input() always handles
>    the input, and in most cases the ICRNL flag is set by shell, so
>    line_edit() performs the CR->NL conversion. But if the flag is not
>    set, this conversion does not occur. Therefore, the additional
>    conversion introduced by this patch is required to ensure consistent
>    behaviour in both cases.

Much better!  Please fix the minor typos indicated and it will LGTM.
OK to push.

..mark