svn commit: r367701 - head/lib/libutil

[Scott Long]

It is a magical namespace, in that it comes from libc, not from the kernel.  Please make sure that you’ve installed a more recent libc, I guess?  I just did a full build and install, and I’m unable to replicate the problem.  Maybe there’s a static-linked pkg running around somewhere?  I’m at a loss for better ideas.

Scott


> On Nov 15, 2020, at 12:30 PM, Brandon Bergren <bdragon at FreeBSD.org> wrote:
> 
> 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 <bdragon at FreeBSD.org> wrote:
>>> 
>>> On powerpc64 and powerpc64le, there is some really weird behavior happening around the sysctl itself:
>>> 
>>> root at 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 at crow:~ # sysctl user.localbase
>>> user.localbase: /usr/local
>>> root at 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 at crow:~ # sysctl user.localbase=/usr/local
>>> user.localbase: /usr/local -> /usr/local
>>> root at 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 at 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 <jrtc27 at 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
>>> bdragon at FreeBSD.org
>> 
>> 
> 
> -- 
>  Brandon Bergren
>  bdragon at FreeBSD.org