On Tue, Jan 10, 2017 at 10:00:31AM +0000, Daniel P. Berrange wrote:
> If we mandate use of gcc / clang, then we wouldn't need to hide it
> behind a macro - we'd be able to use it inline. That said, using a
> macro makes it smaller and gives a bit of standardization. eg with
> libguestfs style:
>
> #define CLEANUP_FREE __attribute__((cleanup(free)))
> #define CLEANUP_OBJECT_UNREF __attribute__((cleanup(virObjectUnref)))
>
> CLEANUP_FREE char *str;
> CLEANUP_OBJECT_UNREF virDomainPtr dom;
>
> vs full inline style:
>
> __attribute__((cleanup(free))) char *str;
> __attribute__((cleanup(virObjectUnref))) virDomainPtr dom;
>
> That said I see systemd took a halfway house
>
> #define _cleanup_(x) __attribute__((cleanup(x)))
>
> _cleanup(free) char *str;
> _cleanup(virObjectUnref) virDomainPtr dom;
I think it's not quite as simple as that because GCC passes
the pointer to the pointer. libguestfs uses:
#define CLEANUP_FREE __attribute__((cleanup(guestfs_int_cleanup_free)))
...
void
guestfs_int_cleanup_free (void *ptr)
{
free (* (void **) ptr);
}
Rich.
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Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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