RE: [PATCH v3 2/4] terminal: don't assume stdin is /dev/tty

From: <rsbecker@nexbridge.com>
To: "'Junio C Hamano'" <gitster@pobox.com>
Cc: "'Phillip Wood'" <phillip.wood123@gmail.com>,
	"'Git Mailing List'" <git@vger.kernel.org>,
	"'Phillip Wood'" <phillip.wood@dunelm.org.uk>,
	"'Ævar Arnfjörð Bjarmason'" <avarab@gmail.com>,
	"'Carlo Arenas'" <carenas@gmail.com>,
	"'Johannes Schindelin'" <Johannes.Schindelin@gmx.de>,
	"'Ramsay Jones'" <ramsay@ramsayjones.plus.com>
Subject: RE: [PATCH v3 2/4] terminal: don't assume stdin is /dev/tty
Date: Tue, 15 Mar 2022 15:38:46 -0400	[thread overview]
Message-ID: <031801d838a4$4d3c7770$e7b56650$@nexbridge.com> (raw)
In-Reply-To: <xmqqilsfdok0.fsf@gitster.g>

On March 15, 2022 3:05 PM, Junio C Hamano wrote:
>To: rsbecker@nexbridge.com
>Cc: 'Phillip Wood' <phillip.wood123@gmail.com>; 'Git Mailing List'
><git@vger.kernel.org>; 'Phillip Wood' <phillip.wood@dunelm.org.uk>; 'Ævar
>Arnfjörð Bjarmason' <avarab@gmail.com>; 'Carlo Arenas' <carenas@gmail.com>;
>'Johannes Schindelin' <Johannes.Schindelin@gmx.de>; 'Ramsay Jones'
><ramsay@ramsayjones.plus.com>
>Subject: Re: [PATCH v3 2/4] terminal: don't assume stdin is /dev/tty
>
><rsbecker@nexbridge.com> writes:
>
>>>The check before closing it is wrong.  It should be
>>>
>>>	if (0 <= term_fd)
>>
>> Should this expression succeed if term_fd == stdin? I might be missing the point
>here.
>
>We could use "if (0 < term_fd)" to make this guard both about avoiding to call
>close() on an uninitialized FD and also about avoiding to close standard input.  I'd
>prefer to see them handled separately as these live at different conceptual levels
>(i.e. closing -1 is a no-no no matter what, closing 0 is bad if it is what we did not
>open but what the caller supplied us via the SAVE_TERM_STDIN bit, but it may be
>warranted if it was what we obtained from an earlier call to open("/dev/tty") we
>did ourselves).

Thanks. This is one of those situations where explaining magic numbers is important. I appreciate the insight.

Regards,
Randall