Re: ERANGE strikes again on my Windows build; RFH

From: Jonathan Nieder <jrnieder@gmail.com>
Date: Dec 30, 2019, 18:49 UTC
Message-ID: <20191230184948.GC57251@google.com>
In-Reply-To: <54522fee-0796-df46-a3cf-4331537ecf59@kdbg.org>

Johannes Sixt wrote:

> Am 30.12.19 um 19:06 schrieb Jonathan Nieder:

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>>                                                                    when
>> errno is meaningful for a function for a given return value, the usual
>> convention is
>>
>>  (1) it *always* sets errno for errors, not conditionally
>
> You seem to understand that errno isn't set somewhere where it should be
> set.

On the contrary: this caller is using errno as an error *indicator* instead of a way of *distinguishing* between errors (or to put it another way, this caller is treating `errno == 0` as a meaningful condition). This means the calling code is buggy.

[...]

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>> Do you have more details about the case where read_object is expected
>> to produce errno == 0?  I'm wondering whether we forgot to set 'errno
>> = ENOENT' explicitly somewhere.
>
> I don't think that forgetting to set ENOENT is the problem.
>
> It happens reproducibly in test 5 of t0410-partial-clone:

Thanks, will try it out.