[libvirt] [PATCH v2 4/4] util: alloc: Note that VIR_AUTOPTR/VIR_AUTOCLEAN must not be used with vectors

[Erik Skultety]

On Thu, Feb 28, 2019 at 02:56:36PM +0100, Peter Krempa wrote:
> On Wed, Feb 27, 2019 at 15:05:18 +0100, Erik Skultety wrote:
> > On Tue, Feb 26, 2019 at 04:48:26PM +0100, Peter Krempa wrote:
> > > We'd free only the first element of the vector leaking the rest.
> > >
> > > Signed-off-by: Peter Krempa <pkrempa at redhat.com>
> > > ---
> > >  src/util/viralloc.h | 6 ++++++
> > >  1 file changed, 6 insertions(+)
> > >
> > > diff --git a/src/util/viralloc.h b/src/util/viralloc.h
> > > index 15451d4673..572b7d1c1c 100644
> > > --- a/src/util/viralloc.h
> > > +++ b/src/util/viralloc.h
> > > @@ -650,6 +650,9 @@ void virAllocTestHook(void (*func)(int, void*), void *data);
> > >   * the variable declared with it by calling the function
> > >   * defined by VIR_DEFINE_AUTOPTR_FUNC when the variable
> > >   * goes out of scope.
> > > + *
> > > + * Note that this macro must NOT be used with vectors! The cleaning function
> > > + * will not free any elements beyond the first.
> >
> > s/cleaning/freeing/
> >
> > I understand, but if you have happen to have a dedicated list type, then you'd
> > have a dedicated destructor, so both of these would be okay with vectors. On
>
> Note that the function registered via __attribute(cleanup ... gets only
> the pointer to the stack'd variable as an argument. This means that you
> can do only 'value-terminated' (NULL, -1, ... ) lists.
>
> Anything requiring count of elements will need to be encapsulated in a
> struct which makes it a container. Thus the comment does not apply.

Yeah, true.

Erik