Re: [libvirt] RFC: Use __attribute__ ((cleanup) in libvirt ?

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. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com virt-builder quickly builds VMs from scratch http://libguestfs.org/virt-builder.1.html -- libvir-list mailing list libvir-list(a)redhat.com https://www.redhat.com/mailman/listinfo/libvir-list