On Sun, Aug 06, 2017 at 07:52:17AM +0800, JingPiao Chen wrote:
> On Sun, Aug 06, 2017 at 02:10:16AM +0300, Dmitry V. Levin wrote:
> > On Tue, Aug 01, 2017 at 07:48:41AM +0800, JingPiao Chen wrote:
> > > Prepare for NETLINK_KOBJECT_UEVENT decode. The messages
> > > of NETLINK_KOBJECT_UEVENT do not contain nlmsghdr.
> > [...]
> > > (decode_nlmsghdr_with_payload): Skip family specific decoders
> > > for type < NLMSG_MIN_TYPE && type != NLMSG_DONE.
> > [...]
> > > @@ -182,7 +177,7 @@ decode_nlmsg_type(const uint16_t type, const unsigned
> > > int family)
> > > const struct xlat *xlat = netlink_types;
> > > const char *dflt = "NLMSG_???";
> > >
> > > - if (type != NLMSG_DONE && family < ARRAY_SIZE(nlmsg_types)) {
> > > + if (type >= NLMSG_MIN_TYPE && family < ARRAY_SIZE(nlmsg_types)) {
> >
> > Why? How this is related to the rest of NETLINK_KOBJECT_UEVENT change?
>
> Previous code when type < NLMSG_MIN_TYPE && type != NLMSG_DONE,
> family = -2 (NL_FAMILY_DEFAULT), family < ARRAY_SIZE(nlmsg_types) filter
> this case. Now get family ignore the nlmsg_type.
> When type < NLMSG_MIN_TYPE && type != NLMSG_DONE, family is not
> a negative. family < ARRAY_SIZE(nlmsg_types) can not filter this case.
>
> Related commit:
> v4.17-43-g1b63425, v4.17-44-g8700030: These commit introduce get_fd_nl_family.
> And get family only when type >= NLMSG_MIN_TYPE.
>
> v4.17-123-g54aed21: This commit changed get family when
> type >= NLMSG_MIN_TYPE || type == NLMSG_DONE.Sorry, this explanation made me even more confused than before. I'll try to re-read the code to get an inspiration. -- ldv
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