Re: [Minios-devel] [UNIKRAFT PATCH v2 01/10] errptr.h: include errno.h

[Simon Kuenzer <simon.kuenzer@xxxxxxxxx>]

Hey Costin,

On 24.08.2018 10:04, Costin Lupu wrote:
> Hi Simon,
>
> On 08/23/2018 02:37 PM, Simon Kuenzer wrote:
> > Hey Costin,
> >
> > On 23.08.2018 12:59, Costin Lupu wrote:
> > > Given that definitions from errptr.h are using together
> > > with errno numbers, it would make sense to simply include
> > > errno.h in errptr.h.
> > >
> > > Signed-off-by: Costin Lupu <costin.lupu@xxxxxxxxx>
> > > ---
> > >    include/uk/errptr.h | 1 +
> > >    1 file changed, 1 insertion(+)
> > >
> > > diff --git a/include/uk/errptr.h b/include/uk/errptr.h
> > > index 5806f73..27aa7d8 100644
> > > --- a/include/uk/errptr.h
> > > +++ b/include/uk/errptr.h
> > > @@ -36,6 +36,7 @@
> > >    #ifndef __UK_ERRPTR_H__
> > >    #define __UK_ERRPTR_H__
> > >    +#include <errno.h>
> > >    #include <uk/arch/types.h>
> > >      #ifndef MAXERRNO
> > hum, errptr is just a mechanism to return error codes on functions that
> > only return pointers as data type. This header does itself not depend on
> > errno, nothing is used from errno. The idea was that you can use this
> > mechanism even with your own defined error codes. So, I would keep the
> > inclusion of errno.h separate. Just include errno.h on your libraries
> > API when these error codes are used there.
> Maybe it would have been better to say in the commit message that
> errptr.h is *usually* used together with errno.h. But I still believe it
> makes sense to include errno.h here, Linux does it too. Otherwise, in
> 90% of cases we would have two includes instead of one.
This is what I prefer. Another reason is that the headers in the 
/include folder should not have any dependency to libraries because 
libraries could be potentially switched off. If there is no errno.h - I 
know this is an extreme example - but this would break the errptr.h 
header. An alternative would be to move errptr into an own library where 
we are able to specify dependencies. So, there we could depend errptr.h 
to a libc and including errno.h would make sense. But I think this would 
be too much for this particular case and we rather go for the two 
includes for the 90% of the cases.
> Costin
Cheers,

Simon

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