[Libguestfs] [PATCH 5/7] New APIs: add-domain and add-libvirt-dom.

[Richard W.M. Jones]

On Wed, Nov 10, 2010 at 11:58:40AM +0000, Daniel P. Berrange wrote:
> On Wed, Nov 10, 2010 at 11:46:31AM +0000, Richard W.M. Jones wrote:
> > diff --git a/src/guestfs.h b/src/guestfs.h
> > index 0f4f9fd..be7398a 100644
> > --- a/src/guestfs.h
> > +++ b/src/guestfs.h
> > @@ -79,6 +79,11 @@ extern void guestfs_set_private (guestfs_h *g, const char *key, void *data);
> >  extern void *guestfs_get_private (guestfs_h *g, const char *key);
> >  
> >  /*--- Structures and actions ---*/
> > +
> > +/* Hack to avoid needing to include <libvirt.h> */
> > +typedef struct _virDomain virDomain;
> > +typedef virDomain *virDomainPtr;
> > +
> >  #include <rpc/types.h>
> >  #include <rpc/xdr.h>
> >  #include <guestfs-structs.h>
> 
> Surely this will break any application whose code does
> 
>   #include <libvirt/libvirt.h>
>   #include <guestfs.h>
> 
> because they'll get a duplicated definition of virDomain from
> both headers. 

I checked and it works fine both ways round.  It would break if
libvirt changed the definition, but you've boxed yourself into a
corner there by documenting the current definition:

http://libvirt.org/html/libvirt-libvirt.html

> IMHO, this hack is a waste of time and it is better to just
> #include <libvirt/libvirt.h> from the header files instead.

The problem is libvirt would no longer be an optional dependency for
programmers using libguestfs.

> A build time dependancy on the libvirt client is really not
> a burden, when you consider that weight of the entire build
> chain you already have to pull in. Even with the build time
> dep, you can still have the dep be optional at runtime via
> your use of dlopen().

In some quarters libvirt is not welcome and libguestfs doesn't depend
on libvirt being there, but will use it if available to provide
enhanced features.

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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