What's the practical use of the error close() returns?

[Elazar Leibovich]

Thanks!

You nailed it! closing a file twice is an error that makes sense to be
issued at close. So simple, how could I miss it?

(as mentioned earlier, the "no space left" could just as well happen after
the file was closed, so I don't mind that much it's not reported on a
close())

On Fri, Jul 27, 2012 at 12:29 PM, Orna Agmon Ben-Yehuda
<ladypine at gmail.com>wrote:

> My practical answer:
>
> I always check fclose() . It happened to me that it returned errors when
> the file I was trying to close was already closed (which usually meant  I
> had a bug, because I closed one file  twice, another never. It also failed
> with "no space left on device", when it was trying to flush the rest of the
> data that was on the way to the file.
>
> Orna
>
>
> On Thu, Jul 26, 2012 at 11:49 PM, Elazar Leibovich <elazarl at gmail.com>wrote:
>
>> I was always intrigued by this unix tidbit, closing a file can return an
>> error. In practice, it is rarely checked (as far as I've seen)
>>
>> What does it mean? If I understand it correctly, recent write can lie
>> about its success.
>>
>> But when do you really need it? If you have a piece of information you
>> want to make sure it hits the disk, the reasonable thing to do is to fsync
>> the file, and check the error of the fsync. If you don't care about it that
>> much, then don't check the error, you don't have much to do even if it
>> failed. It seems to me that one can make close return void, and point the
>> one who wishes to make sure data hit the disk to fsync.
>>
>> What's the practical use case, where you care about close() error, but
>> you don't care enough to need an fsync.
>>
>> Another question is, why let write lie about its success, what does it
>> gain you? Let close return void, and force write never to defer its error
>> reporting.
>>
>> _______________________________________________
>> Linux-il mailing list
>> Linux-il at cs.huji.ac.il
>> http://mailman.cs.huji.ac.il/mailman/listinfo/linux-il
>>
>>
>
>
> --
> Orna Agmon Ben-Yehuda.
> http://ladypine.org
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.cs.huji.ac.il/pipermail/linux-il/attachments/20120727/c6788d01/attachment.html>