Re: [libvirt] [PATCH] object: Add sanity check on correct parent class

Checking that the derived class is larger than the requested parent class saves us from some obvious mistakes, but as written, it does not catch all the cases; in particular, it is easy to forget to update a VIR_CLASS_NEW when changing the 'parent' member from virObject to virObjectLockabale, but where the size checks don't catch that. Add a parameter for one more layer of sanity checking. Note that I did NOT change the fact that we require derived classes to be larger (as the difference in size makes it easy to tell classes apart), which means that even if a derived class has no functionality to add (but rather exists for compiler-enforced type-safety), it must still include a dummy member. But I did fix the wording of the error message to match the code. Signed-off-by: Eric Blake <eblake(a)redhat.com&gt; --- Here's hoping Coverity doesn't have a false-positive complaint about the error message being a potential dereference of NULL (the only time 'parent == NULL' is when 'parentsize == 0', based on the fact that our syntax checks forbid raw calls to virClassNew() except for "virObject" itself - but Coverity likely won't see that). src/util/virobject.h | 5 ++++- src/util/virobject.c | 8 +++++--- 2 files changed, 9 insertions(+), 4 deletions(-)