[libvirt] [PATCH v3 04/11] util: netlink: use VIR_AUTOPTR for aggregate types

[Erik Skultety]

On Mon, Aug 13, 2018 at 10:23:02PM +0530, Sukrit Bhatnagar wrote:
> On Mon, 13 Aug 2018 at 18:10, Erik Skultety <eskultet at redhat.com> wrote:
> >
> > On Thu, Aug 09, 2018 at 09:42:12AM +0530, Sukrit Bhatnagar wrote:
> > > By making use of GNU C's cleanup attribute handled by the
> > > VIR_AUTOPTR macro for declaring aggregate pointer variables,
> > > majority of the calls to *Free functions can be dropped, which
> > > in turn leads to getting rid of most of our cleanup sections.
> > >
> > > Signed-off-by: Sukrit Bhatnagar <skrtbhtngr at gmail.com>
> > > ---
> > >  src/util/virnetlink.c | 72 ++++++++++++++++++++-------------------------------
> > >  1 file changed, 28 insertions(+), 44 deletions(-)
> > >
> > > diff --git a/src/util/virnetlink.c b/src/util/virnetlink.c
> > > index fcdc09d..66e80e2 100644
> > > --- a/src/util/virnetlink.c
> > > +++ b/src/util/virnetlink.c
> > > @@ -297,15 +297,16 @@ int virNetlinkCommand(struct nl_msg *nl_msg,
> > >                        uint32_t src_pid, uint32_t dst_pid,
> > >                        unsigned int protocol, unsigned int groups)
> > >  {
> > > -    int ret = -1;
> > >      struct sockaddr_nl nladdr = {
> > >              .nl_family = AF_NETLINK,
> > >              .nl_pid    = dst_pid,
> > >              .nl_groups = 0,
> > >      };
> > >      struct pollfd fds[1];
> > > -    VIR_AUTOPTR(virNetlinkHandle) nlhandle = NULL;
> > >      int len = 0;
> > > +    VIR_AUTOPTR(virNetlinkHandle) nlhandle = NULL;
> >
> > unjustified code movement...
> >
> > > +
> > > +    *respbuflen = 0;
> >
> > unnecessary initialization..
>
> We need *respbuflen to be 0 if -1 is returned. So if this initialization is
> removed, we need to add `*respbuflen = 0;` in the cleanup section below.

Why exactly do we need it? If -1 is to be returned, the caller should not be
touching the pointers afterwards, if they are, it's a bug in the caller. Quick
grepping on usage of virNetlinkCommand didn't show anything suspicious - we
always either return immediately or jump to cleanup for that matter.

Erik