Date: Sun, 15 Nov 2020 12:34:13 -0700 From: Scott Long <scottl@samsco.org> To: Brandon Bergren <bdragon@FreeBSD.org> Cc: Jessica Clarke <jrtc27@freebsd.org>, Scott Long <scottl@FreeBSD.org>, src-committers <src-committers@freebsd.org>, svn-src-all <svn-src-all@freebsd.org>, svn-src-head <svn-src-head@freebsd.org> Subject: Re: svn commit: r367701 - head/lib/libutil Message-ID: <A572CEDC-5869-4BAF-95D1-6B9AC50C0ED6@samsco.org> In-Reply-To: <a54c3d86-8499-4c2b-a83f-9db79a12e3ec@www.fastmail.com> References: <202011150748.0AF7mqW3016900@repo.freebsd.org> <D5492BB4-A282-4E35-B02F-1216769FDA51@freebsd.org> <A39C12CC-D3D6-4166-9089-7466FA1C2B2D@samsco.org> <329C4753-BB97-4C67-8CDA-39EB67E16CE8@freebsd.org> <EBD050A5-70AE-43E8-A9E1-CCD3BCA11180@samsco.org> <f9904238-3923-40c1-b478-c5249821ed09@www.fastmail.com> <44B80F15-2BE7-4B7C-BC3D-B65511480E58@freebsd.org> <a54c3d86-8499-4c2b-a83f-9db79a12e3ec@www.fastmail.com>
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It is a magical namespace, in that it comes from libc, not from the =
kernel. Please make sure that you=E2=80=99ve installed a more recent =
libc, I guess? I just did a full build and install, and I=E2=80=99m =
unable to replicate the problem. Maybe there=E2=80=99s a static-linked =
pkg running around somewhere? I=E2=80=99m at a loss for better ideas.
Scott
> On Nov 15, 2020, at 12:30 PM, Brandon Bergren <bdragon@FreeBSD.org> =
wrote:
>=20
> I think the problem is that user.* is somehow magically namespaced, so =
doing a "dumb" sysctlbyname will get the wrong one.
>=20
> sysctl (the tool) does:
> __sysctl("sysctl.name2oid =
user.localbase",2,0xfffffbfffde98,0xfffffbfffda98,0x810809000,14) =3D 0 =
(0x0)
> __sysctl("sysctl.oidfmt =
user.localbase",4,0xfffffbfffdef8,0xfffffbfffd690,0x0,0) =3D 0 (0x0)
> __sysctl("sysctl.name { 8.21 =
}",4,0xfffffbfffc8f8,0xfffffbfffc480,0x0,0) =3D 0 (0x0)
> __sysctl("sysctl.oidfmt =
user.localbase",4,0xfffffbfffd0f8,0xfffffbfffc488,0x0,0) =3D 0 (0x0)
> __sysctl("user.localbase",2,0x0,0xfffffbfffc480,0x0,0) =3D 0 (0x0)
> __sysctl("user.localbase",2,0x81080a000,0xfffffbfffd0f8,0x0,0) =3D 0 =
(0x0)
>=20
> and picks up /usr/local.
>=20
> whereas libutil is currently just doing
> =
__sysctlbyname("user.localbase",14,0xfffffbfffd4f8,0xfffffbfffd440,0x0,0) =
=3D 0 (0x0)
>=20
> which is returning the builtin "" from the static kernel variable.
>=20
> On Sun, Nov 15, 2020, at 1:26 PM, Jessica Clarke wrote:
>> On 15 Nov 2020, at 19:10, Brandon Bergren <bdragon@FreeBSD.org> =
wrote:
>>>=20
>>> On powerpc64 and powerpc64le, there is some really weird behavior =
happening around the sysctl itself:
>>>=20
>>> 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=3D/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=3Dvalue] [-4|-6] <command> [<args>]
>>>=20
>>> For more information on available commands and options see 'pkg =
help'.
>>> root@crow:~ #=20
>>>=20
>>>=20
>>> 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.
>>=20
>> That's odd. What does truss say?
>>=20
>> Jess
>>=20
>>> On Sun, Nov 15, 2020, at 1:06 PM, Scott Long wrote:
>>>>=20
>>>>> On Nov 15, 2020, at 12:01 PM, Jessica Clarke <jrtc27@freebsd.org> =
wrote:
>>>>>>=20
>>>>>> 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=E2=80=99ll
>>>>>> look at it some more.
>>>>>=20
>>>>> 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.
>>>>>=20
>>>>=20
>>>> Yep, I wasn=E2=80=99t happy with ENOMEM either but I couldn=E2=80=99t=
find anything better.
>>>>=20
>>>>> 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.
>>>>>=20
>>>>=20
>>>> Done.
>>>>=20
>>>>> I'd be happy to give a review on Phabricator if/when you have a =
new
>>>>> patch.
>>>>>=20
>>>>=20
>>>> https://reviews.freebsd.org/D27227
>>>>=20
>>>> Thanks,
>>>> Scott
>>>>=20
>>>>=20
>>>=20
>>> --=20
>>> Brandon Bergren
>>> bdragon@FreeBSD.org
>>=20
>>=20
>=20
> --=20
> Brandon Bergren
> bdragon@FreeBSD.org
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