linux-kernel - Re: [Breakage] Git v2.21.0-rc0

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Message-ID: <20190208193157.GA30952@sigill.intra.peff.net>
Date:   Fri, 8 Feb 2019 14:31:57 -0500
From:   Jeff King <peff@...f.net>
To:     "Randall S. Becker" <rsbecker@...bridge.com>
Cc:     'Junio C Hamano' <gitster@...ox.com>, git@...r.kernel.org,
        'Linux Kernel' <linux-kernel@...r.kernel.org>,
        git-packagers@...glegroups.com
Subject: Re: [Breakage] Git v2.21.0-rc0 - t5318 (NonStop)

On Fri, Feb 08, 2019 at 02:26:17PM -0500, Randall S. Becker wrote:

> > > For this, we could use truncate -s count file instead of dd to get a
> > > fixed size file of nulls. This would remove the need for /dev/zero in
> > > t5318 (the patch below probably will wrap badly in my mailer so I can
> > > submit a real patch separately.
> > 
> > I don't think "truncate" is portable, though.
> 
> It is available AFAIK on Linux, POSIX, and Windows under Cygwin.
> That's more than /dev/zero has anyway. I have the patch ready if you
> want it.

Is it POSIX? Certainly truncate() is, but I didn't think the
command-line tool was. If it really is available everywhere, then yeah,
I'd be fine with it.

> > > > Other cases don't seem to actually care that they're getting NULs,
> > > > and are just redirecting stdin from /dev/zero to get an infinite
> > > > amount of input. They could probably use "yes" for that.
> > >
> > > What about reading from /dev/null?
> > 
> > That would yield zero bytes, not an infinite number of them.
> 
> So something like: yes | tr 'y' '\0' | stuff?

Exactly (if we even care about them being NULs; otherwise, we can omit
the "tr" invocation).

-Peff