Our virObject code relies heavily on the fact that the first
member of the class struct is type of virObject (or some
derivation of if). Let's check for that.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
---
 src/util/virobject.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/util/virobject.h b/src/util/virobject.h
index 128d3ba2d2..e174c17eb8 100644
--- a/src/util/virobject.h
+++ b/src/util/virobject.h
@@ -76,10 +76,12 @@ virClassPtr virClassForObjectRWLockable(void);
 # endif
 
 # define VIR_CLASS_NEW(prnt, name) \
+    verify(offsetof(name, parent) == 0); \
     if (!(name##Class = virClassNew(prnt, #name, sizeof(name), name##Dispose))) \
         return -1;
 
 # define VIR_CLASS_NEW_GOTO(prnt, name, label) \
+    verify(offsetof(name, parent) == 0); \
     if (!(name##Class = virClassNew(prnt, #name, sizeof(name), name##Dispose))) \
         goto label;
 
-- 
2.16.1

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On Tue, Apr 17, 2018 at 10:20:52AM +0200, Michal Privoznik wrote:
> Our virObject code relies heavily on the fact that the first
> member of the class struct is type of virObject (or some
> derivation of if). Let's check for that.
> 
> Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
> ---
>  src/util/virobject.h | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/src/util/virobject.h b/src/util/virobject.h
> index 128d3ba2d2..e174c17eb8 100644
> --- a/src/util/virobject.h
> +++ b/src/util/virobject.h
> @@ -76,10 +76,12 @@ virClassPtr virClassForObjectRWLockable(void);
>  # endif
>  
>  # define VIR_CLASS_NEW(prnt, name) \
> +    verify(offsetof(name, parent) == 0); \
>      if (!(name##Class = virClassNew(prnt, #name, sizeof(name), name##Dispose))) \
>          return -1;
>  
>  # define VIR_CLASS_NEW_GOTO(prnt, name, label) \
> +    verify(offsetof(name, parent) == 0); \
>      if (!(name##Class = virClassNew(prnt, #name, sizeof(name), name##Dispose))) \
>          goto label;

With the suggestion in my previous patch, you wuold need to use
verify_expr() instead of verify, to allow VIR_CLASS_NEW to be used
in an expression.


Regards,
Daniel
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