Re: Confusing "Success" error message

[Tim Rühsen]

On 11/8/19 3:03 PM, Andries E. Brouwer wrote:
> On Fri, Nov 08, 2019 at 09:55:48AM +0100, Tim Rühsen wrote:
>> On 11/8/19 12:03 AM, Andries E. Brouwer wrote:
> 
>>> The hope is probably that errno is the errno from gethttp.
>>> But does time() preserve errno?
>>> And does datetime_str() preserve errno?
>>> It calls fmttime() which calls localtime() and strftime().
>>
>> Libc functions only touch errno if there *is* an error
> 
> Libc functions are free to call other functions internally,
> and such internal calls may fail where the outer level call
> does not fail. So even if a libc function does not return
> an error, errno can have changed.
> If it is needed later, errno should be saved immediately after a
> failing system call.
> 
> In this particular case I see
> 
> % man localtime
> ERRORS
>        EOVERFLOW
>               The result cannot be represented.
> 
> so under unusual circumstances datetime_str() can change errno.

Sure it does - but never to 0 (Success). And that is what the OP is
reporting.

Regards, Tim

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