On 03 Mar 2015 21:46, Dmitry V. Levin wrote:
> On Tue, Mar 03, 2015 at 01:23:53PM -0500, Mike Frysinger wrote:
> > On 03 Mar 2015 21:01, Dmitry V. Levin wrote:
> > > On Tue, Mar 03, 2015 at 12:47:19PM -0500, Mike Frysinger wrote:
> > > > build warnings:
> > > > there's still random -Wsign-compare warnings, but i guess we don't care
> > > > about those
> > >
> > > There are exactly 3 different -Wsign-compare warning messages:
> > > socketutils.c:145: warning: comparison between signed and unsigned
> > > integer expressions [-Wsign-compare]
> > > netlink_inet_diag.c:67: warning: comparison between signed and unsigned
> > > integer expressions [-Wsign-compare]
> > > netlink_unix_diag.c:75: warning: comparison between signed and unsigned
> > > integer expressions [-Wsign-compare]
> > >
> > > The only way to fix them is to fix NLMSG_OK macro defined
> > > in <linux/netlink.h>.
> >
> > hmm, i'm not so sure. the kernel headers declare:
> > struct nlmsghdr {
> > __u32 nlmsg_len; /* Length of message including header */
> > ...
> > #define NLMSG_OK(nlh,len) ((len) >= (int)sizeof(struct nlmsghdr) && \
> > (nlh)->nlmsg_len >= sizeof(struct nlmsghdr) && \
> > (nlh)->nlmsg_len <= (len))
> >
> > and the strace code does:
> > ssize_t ret;
> > struct nlmsghdr *h;
> > ...
> > NLMSG_OK(h, ret);
> >
> > if the kernel headers provided a function instead of a macro, it'd be:
> > static bool NLMSG_OK(const struct nlmsghdr *nlh, __u32 len) {...}
> >
> > which is to say, the API of this macro is that it takes a u32 len, but
> > we're
> > passing it a ssize_t (as that is what recvmsg/etc... returns). it is
> > annoying
> > that there's a type mismatch here, but i think the problem is still on our
> > side
> > to sort out:
> > NLMSG_OK(h, (size_t)ret)
>
> If we pass (size_t)ret to NLMSG_OK, it would result to
> ((size_t)ret) >= (int)sizeof(struct nlmsghdr)
> and this code generates the same -Wsign-compare warning.
> I actually tried it some time ago.blah lame. i'll try sending a patch upstream and see what they say. -mike
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