Re: does numeric only name of jails not allowed (bug?)

On 8/9/25 06:01, Anthony Pankov wrote:
> Hello Kyle,
> 
>> This is an artifact of how numeric names work.  When you use a purely numeric name, it's taken as both the jid and the name.  jail(8) has some logic up-front that will set one or the other variable based on the name, but it omits the other.
> 
> I think to prevent ambiguity there must be a possibility or requirement to quote jail name to force interpretation as a string.
> Using "47777" instead of 47777 doesn't help for now.
> 

What ambiguity are you referring to here?  In context it's pretty 
unambiguous, the name is the thing that appears before an opening brace.

>> When you use a purely numeric name, it's taken as both the jid
> I've never hear about this feature. But I'm in doubt how to guarantee jail startup with jid=name=10 along system functioning. If non-numeric jail occupied jid 10 then jail 10  will not start?

This is not new, jails have operated this way for 15+ years (since 
numeric names were first allowed).  Indeed, if it's already occupied 
then the jail already exists and it will not start.

> However, thinking of jid uniqueness in a wider area than localhost definitely leads us to use a bigger numbers. In such a case using hexadecimal format seems to be beneficial. Then there will be some code to interpret numeric names in decimal/hexadecimal format. So there will be some not so small branch of code  for numeric jail name. And, again, to split  this branch from pure string names I suggest to use name quotation to enforce string interpretation.
>

The kernel and jail(8) only do this for base 10 numbers; hex does not 
get resolved to base 10, and you end up with a jail that has a hex name 
and a jid allocated in the usual way.  I'm not sure what else you're 
writing about here, because it's really not that complicated: if it 
coerces to a number in base 10 it's the jid, otherwise it's the name. 
Jails without a name use the jid as their name.

This review will fix the bug I noted in my previous e-mail:
https://reviews.freebsd.org/D51831

Thanks,

Kyle Evans

> 
> Friday, August 8, 2025, 8:24:32 PM, you wrote:
> 
>> On 8/6/25 09:37, Anthony Pankov wrote:
>>> Dear freebsd-hackers.
>>>> It seems there is no sign that numeric only name is prohibited:
>>>> "
>>> The jail name.  This is an arbitrary string that identifies a
>>>                jail (except it may not contain a ďż˝.ďż˝).
>>> "
>>>> But
>>> # head jail-47777.conf
>>> ...
>>> 47777 {
>>>           host.hostname = "${name}";
>>> ...
>>>> # jail -c 47777
>>> jail: 47777: host.hostname: variable "name" not found
>>>> If I add letter prefix, say w47777, it worked.
>>>> Because of strange error "variable "name" not found" it seems like a bug. Does it?
>>>
>> This is an artifact of how numeric names work.  When you use a purely numeric name, it's taken as both the jid and the name.  jail(8) has some logic up-front that will set one or the other variable based on the name, but it omits the other.
> 
>> I have this almost fixed in 15.0, but trying your example I've found a bug in it -- setting the name, we need to use the string_param() of the KP_JID param as the `value`; the current use of KP_JID's cfparam for `p` to add_param() will adopt the name of KP_JID, which is a peculiarity that I wasn't aware of.
> 
>> Thanks,
> 
>> Kyle Evans
> 
> 
>