From: Junio C Hamano <gitster@pobox.com>
Date: Thu, 17 Jul 2008 07:25:44 GMT
Subject: Re: [PATCH 1/2] t/test-lib.sh: Let test_must_fail fail on signals only
Message-ID: <7vabghkm4n.fsf@gitster.siamese.dyndns.org>
In-Reply-To: <487EF31D.8090007@viscovery.net>

Johannes Sixt <j.sixt@viscovery.net> writes:

> Jeff King schrieb:
>> On Wed, Jul 16, 2008 at 11:31:41PM -0700, Junio C Hamano wrote:
>>> Is it that somebody do not want 255 exit value, or anything that has 7th
>>> bit set?  2488df8 (builtin run_command: do not exit with -1., 2007-11-13)
>>> suggests otherwise at least for Windows runtime, so what we currently have
>>> that does extra truncation ourselves might be sufficient.
>> 
>> Johannes will have to answer that; however, the truncation there does
>> leave the extra 7th bit. Maybe & 0x7f would be more appropriate?
>
> I never found out the real reason why -1 would not be recognized as
> "failure"; the conclusion of my debugging session was that MSYS bash has
> an issue, and I chose to append '& 0xff' because the documentation of
> WEXITSTATUS() says that it can receive only 8 bits of the exit() code. The
> intention of 2488df8 was to keep as much information as possible. But if
> that extra information hurts, we should better truncate to 7 bits.
>
> The source code of Windows's C runtime suggests that any value that fits
> in 4 bytes can be supplied to exit() and can be received by cwait()
> (Windows's version of waitpid()); but I haven't looked at how MSYS
> implements waitpit() and whether it can receive that much information.

Well, POSIX cannot do that much anyway, but does allow 8-bit, so I'd say
the current code is fine.