From: Junio C Hamano <gitster@pobox•com>
To: Eric Sunshine <sunshine@sunshineco•com>
Cc: Johannes Schindelin <johannes.schindelin@gmx•de>,
"git\@vger.kernel.org" <git@vger•kernel.org>,
Johannes Sixt <j6t@kdbg•org>
Subject: Re: [PATCH] mingw: emulate write(2) that fails with a EPIPE
Date: Wed, 16 Dec 2015 12:36:21 -0800 [thread overview]
Message-ID: <xmqqmvtacere.fsf@gitster.mtv.corp.google.com> (raw)
In-Reply-To: <CAPig+cQzCHtyVs47=ASs5V2BSV7gpVszbdTFydiRhnz3gtD2Qw@mail.gmail.com> (Eric Sunshine's message of "Wed, 16 Dec 2015 14:47:15 -0500")
Eric Sunshine <sunshine@sunshineco•com> writes:
>> + if (result < 0 && errno == EINVAL && buf) {
>
> Here, errno is EINVAL...
>
>> + /* check if fd is a pipe */
>> + HANDLE h = (HANDLE) _get_osfhandle(fd);
>> + if (GetFileType(h) == FILE_TYPE_PIPE)
>> + errno = EPIPE;
>> + else
>> + errno = EINVAL;
>
> Does any of the code between the outer 'if' and this point clobber
> errno, or are you merely assigning EINVAL for robustness against
> future changes?
I do think it is a good idea to reassign 'errno' here to stress on
the fact that we return EPIPE only when we positively know that we
were reading from a pipe, and otherwise we won't change the original
errno at all.
But at the same time, if other things that are called before we
figure out if we were reading from a pipe could affect errno, I
wonder if that is an indication of a bug--an error return from
system functions that the code is not responding to. For example,
can _get_osfhandle() fail and when it does what would we see?
Perhaps NULL in h?
next prev parent reply other threads:[~2015-12-16 20:36 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-16 12:14 [PATCH] mingw: emulate write(2) that fails with a EPIPE Johannes Schindelin
2015-12-16 18:35 ` Junio C Hamano
2015-12-17 9:39 ` Johannes Schindelin
2015-12-17 16:40 ` Junio C Hamano
2015-12-17 17:08 ` Johannes Schindelin
2015-12-16 19:47 ` Eric Sunshine
2015-12-16 20:36 ` Junio C Hamano [this message]
2015-12-17 9:37 ` Johannes Schindelin
2015-12-17 17:08 ` [PATCH v2] " Johannes Schindelin
2015-12-17 19:22 ` Junio C Hamano
2015-12-18 16:10 ` Johannes Schindelin
2015-12-18 20:57 ` Johannes Sixt
2015-12-21 16:59 ` Junio C Hamano
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