bug#24941: Early termination bug in grep 2.26

[Jim Meyering]

On Tue, Nov 15, 2016 at 2:13 PM, Norihiro Tanaka <address@hidden> wrote:
>
> On Tue, 15 Nov 2016 11:35:15 -0800
> Jim Meyering <address@hidden> wrote:
>
>> I suppose you mean in addition to the S_ISFIFO test? That sounds good.
>> We should retain the optimization when reading from stdin that is a
>> non-pipe.
>
> This can also happen in stdin.  If we redirect stdout to /dev/null,
> grep-2.26 exits immediately and prompt is returned.
>
> - grep-2.25
>
> $ grep . >/dev/null
> a  <<input a and newline
> b  <<input b and newline
> c  <<input c and newline
>
> - grep-2.26
>
> $ src/grep . >/dev/null
> a  <<input a and newline
> $

Good point. While I suspect that would be much less likely to cause
trouble in practice, I would now rephrase:

  We should retain the optimization when reading from stdin that is
neither a pipe nor a tty.