WARNING - OLD ARCHIVES

This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
   
 
 
Xen 
 
Home Products Support Community News
 
   
 

xen-devel

Re: [Xen-devel] Re: Error reporting capabilities for libxc

On Mon, Oct 23, 2006 at 11:15:21PM +0100, Ian Pratt wrote:
> > > Would we be better off returning an error code and a set of
> parameters,
> > > requiring a call-back into the library to get the string?
> > 
> > That assumes that there is a static mapping between an error code
> > and the error description, which there isn't. The error description
> > can contain info about actual bits of metadata which were incorrect.
> > For example when reporting an invalid ELF architecture, it can tell
> > you exactly what ELF arch was found & what was expected.
> 
> That's precisely my point. The various bits of metadata can be
> parameters passed back along with the error code. It's possible that
> some callers will be able to do things with the metadata that are more
> useful than just printing the string. I guess the error parameters could
> be returned as a va_list. Many callers would just call back into the
> library to get the appropriate error string.

Ahh, I mis-read your comment a little. That is certainly one possibility
although I'm not entirely a fan of va_list as an API - perhaps either a
struct with a handful of generic data fields for returning metadata, or
a union switched on the error code would work - it'd be nice to be able
to copy all the bits around without needing memory allocation in any of
the error handling paths.

Regards,
Dan.
-- 
|=- Red Hat, Engineering, Emerging Technologies, Boston.  +1 978 392 2496 -=|
|=-           Perl modules: http://search.cpan.org/~danberr/              -=|
|=-               Projects: http://freshmeat.net/~danielpb/               -=|
|=-  GnuPG: 7D3B9505   F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505  -=| 

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel