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From: Johannes Sixt <j6t@kdbg.org>
To: Junio C Hamano <gitster@pobox.com>
Cc: randall.s.becker@rogers.com, git@vger.kernel.org,
	"Randall S. Becker" <rsbecker@nexbridge.com>
Subject: Re: [Fix v2] t5562: remove dependency on /dev/zero
Date: Sat, 9 Feb 2019 22:54:48 +0100	[thread overview]
Message-ID: <8da682c1-aad2-ab83-9e46-6b7d4a6c68bd@kdbg.org> (raw)
In-Reply-To: <xmqqwom8izu1.fsf@gitster-ct.c.googlers.com>

Am 09.02.19 um 19:25 schrieb Junio C Hamano:
> Johannes Sixt <j6t@kdbg.org> writes:
> 
>> How many bytes are needed here? yes() in test-lib.sh generates only 99
>> 'y', if I am not mistaken.
> 
> I think we will not use "yes" in the end for this topic, which makes
> this comment totally irrelevant to the thread, but I wonder why we
> have the limit of 99 there?  It cannot be "we do not want to worry
> about sigpipe" affecting the end result of the test (after all the
> reader may stop reading from after reading just one, and the status
> of the upstream process that would die with sigpipe is lost anyway).
> 
> It turns out it is about sigpipe ;-) but in somewhat a different
> way.  To prevent others from wasting their time wondering about
> this, probably we want to have something like the attached?

That would certainly be helpful!

-- Hannes

> 
>  t/README      | 9 +++++++++
>  t/test-lib.sh | 6 +++++-
>  2 files changed, 14 insertions(+), 1 deletion(-)
> 
> diff --git a/t/README b/t/README
> index 1326fd7505..f4e1a82657 100644
> --- a/t/README
> +++ b/t/README
> @@ -927,6 +927,15 @@ library for your script to use.
>     test_oid_init or test_oid_cache.  Providing an unknown key is an
>     error.
>  
> + - yes [<string>]
> +
> +   This is often seen in modern UNIX but some platforms lack it, so
> +   the test harness overrides the platform implementation with a
> +   more limited one.  Use this only when feeding a handful lines of
> +   output to the downstream---unlike the real version, it generates
> +   only up to 99 lines.
> +
> +
>  Prerequisites
>  -------------
>  
> diff --git a/t/test-lib.sh b/t/test-lib.sh
> index 42b1a0aa7f..541a37f4c0 100644
> --- a/t/test-lib.sh
> +++ b/t/test-lib.sh
> @@ -1313,7 +1313,11 @@ then
>  	fi
>  fi
>  
> -# Provide an implementation of the 'yes' utility
> +# Provide an implementation of the 'yes' utility; the upper bound
> +# limit is there to help Windows that cannot stop this loop from
> +# wasting cycles when the downstream stops reading, so do not be
> +# tempted to turn it into an infinite loop. cf. 6129c930 ("test-lib:
> +# limit the output of the yes utility", 2016-02-02)
>  yes () {
>  	if test $# = 0
>  	then
> 


      parent reply	other threads:[~2019-02-09 21:54 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-08 22:07 [Fix v2] t5562: remove dependency on /dev/zero randall.s.becker
2019-02-08 22:37 ` Jeff King
2019-02-08 23:38 ` Junio C Hamano
2019-02-09 17:00   ` Randall S. Becker
2019-02-09  8:46 ` Johannes Sixt
2019-02-09 18:25   ` Junio C Hamano
2019-02-09 19:07     ` Randall S. Becker
2019-02-09 21:54     ` Johannes Sixt [this message]

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