Re: [PATCH v3 1/3] Introduce die_errno() that appends strerror(errno) to die()

From: Andreas Ericsson <ae@op5.se>
Date: Jun 9, 2009, 09:29 UTC
Message-ID: <4A2E2B8F.3020005@op5.se>
In-Reply-To: <20090609085328.GA25721@coredump.intra.peff.net>

Jeff King wrote:

Show 22 quoted lines

> On Tue, Jun 09, 2009 at 10:22:30AM +0200, Thomas Rast wrote:
> 
>>> Aren't you assuming that strerror(errno) has no '%'-signs here, which is
>>> what kicked off the whole discussion?
>> True, of course.  Hrm.
>>
>> So do we go back to v2 (for 1/3) and ask future callers to never use
>> custom formats with die_errno, or should I write a version that
>> doubles the % characters while tacking the error message onto the
>> format?
> 
> Personally, I think it is fine to assume that the format and arguments
> to die(), die_errno(), and to the die_routine() are all
> printf-compatible. That is how it has always been until now, and I don't
> see any callers who would want to change that.
> 
> This is all internal to git.  It's not as if we are talking about a
> library being called by arbitrary code, and we want to leave doors open
> for arbitrary clients. libgit2 would probably take a different approach
> (though I imagine their general strategy is never to die(), but to
> always return an error condition, anyway).
>

Yup. libgit2 sets an internal git_errno variable and returns an error code for each error it encounters, and we're referring callers to regular "errno" to find out more about *why* a particular git_errno condition was encountered.

We might want to give applications an easy way to die with a sensible error message, but that's so far in the future that it's not worth bothering with.

-- 
Andreas Ericsson                   andreas.ericsson@op5.se
OP5 AB                             www.op5.se
Tel: +46 8-230225                  Fax: +46 8-230231

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