I think the problem is that user.* is somehow magically namespaced, so doing a
"dumb" sysctlbyname will get the wrong one.
sysctl (the tool) does:
__sysctl("sysctl.name2oid
user.localbase",2,0xfffffbfffde98,0xfffffbfffda98,0x810809000,14) = 0 (0x0)
__sysctl("sysctl.oidfmt
user.localbase",4,0xfffffbfffdef8,0xfffffbfffd690,0x0,0) = 0 (0x0)
__sysctl("sysctl.name { 8.21 }",4,0xfffffbfffc8f8,0xfffffbfffc480,0x0,0) = 0
(0x0)
__sysctl("sysctl.oidfmt
user.localbase",4,0xfffffbfffd0f8,0xfffffbfffc488,0x0,0) = 0 (0x0)
__sysctl("user.localbase",2,0x0,0xfffffbfffc480,0x0,0) = 0 (0x0)
__sysctl("user.localbase",2,0x81080a000,0xfffffbfffd0f8,0x0,0) = 0 (0x0)
and picks up /usr/local.
whereas libutil is currently just doing
__sysctlbyname("user.localbase",14,0xfffffbfffd4f8,0xfffffbfffd440,0x0,0) = 0
(0x0)
which is returning the builtin "" from the static kernel variable.
On Sun, Nov 15, 2020, at 1:26 PM, Jessica Clarke wrote:
> On 15 Nov 2020, at 19:10, Brandon Bergren <bdra...@freebsd.org> wrote:
> >
> > On powerpc64 and powerpc64le, there is some really weird behavior happening
> > around the sysctl itself:
> >
> > root@crow:~ # pkg
> > The package management tool is not yet installed on your system.
> > Do you want to fetch and install it now? [y/N]: N
> > root@crow:~ # sysctl user.localbase
> > user.localbase: /usr/local
> > root@crow:~ # pkg
> > The package management tool is not yet installed on your system.
> > Do you want to fetch and install it now? [y/N]: N
> > root@crow:~ # sysctl user.localbase=/usr/local
> > user.localbase: /usr/local -> /usr/local
> > root@crow:~ # pkg
> > pkg: not enough arguments
> > Usage: pkg [-v] [-d] [-l] [-N] [-j <jail name or id>|-c <chroot path>|-r
> > <rootdir>] [-C <configuration file>] [-R <repo config dir>] [-o var=value]
> > [-4|-6] <command> [<args>]
> >
> > For more information on available commands and options see 'pkg help'.
> > root@crow:~ #
> >
> >
> > I would double check very closely that the sysctl is being called
> > correctly, the sysctl tool manages to read it out, but libutil does not.
>
> That's odd. What does truss say?
>
> Jess
>
> > On Sun, Nov 15, 2020, at 1:06 PM, Scott Long wrote:
> >>
> >>> On Nov 15, 2020, at 12:01 PM, Jessica Clarke <jrt...@freebsd.org> wrote:
> >>>>
> >>>> I felt similar concerns, but my misunderstanding of strlcpy() drove the
> >>>> result. Since the use case for getlocalbase() lends itself to also use
> >>>> strlcat()/strlcpy(), I was trying to replicate the API semantics of
> >>>> those,
> >>>> at least to the limit of my understanding. Thanks for the feedback, I’ll
> >>>> look at it some more.
> >>>
> >>> Thanks. ENOMEM also feels inappropriate as no allocation is taking
> >>> place. Perhaps ENAMETOOLONG, which is used in similar cases for things
> >>> like gethostbyname? Though sysctlbyname uses ENOMEM instead... sigh.
> >>>
> >>
> >> Yep, I wasn’t happy with ENOMEM either but I couldn’t find anything better.
> >>
> >>> Also, if pathlen has already been checked against SSIZE_MAX (giving
> >>> EINVAL) and tmplen against pathlen there's no need to then check tmplen
> >>> against SSIZE_MAX.
> >>>
> >>
> >> Done.
> >>
> >>> I'd be happy to give a review on Phabricator if/when you have a new
> >>> patch.
> >>>
> >>
> >> https://reviews.freebsd.org/D27227
> >>
> >> Thanks,
> >> Scott
> >>
> >>
> >
> > --
> > Brandon Bergren
> > bdra...@freebsd.org
>
>
--
Brandon Bergren
bdra...@freebsd.org
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