[Freeipa-devel] Proposed changes to the HBAC grammar

[Stephen Gallagher]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

On 11/18/2010 09:31 AM, Adam Young wrote:
> On 11/18/2010 07:09 AM, Stephen Gallagher wrote:
> On 11/17/2010 04:51 PM, Adam Young wrote:
>   
>>>> On 11/17/2010 04:31 PM, Simo Sorce wrote:
>>>>     
>>>>> On Wed, 17 Nov 2010 16:07:24 -0500
>>>>> Stephen Gallagher<sgallagh at redhat.com>   wrote:
>>>>>
>>>>>
>>>>>       
>>>>>> This will require two changes to the HBAC schema. First of all, we
>>>>>> plan to drop the week-of-the-month concept entirely and replace it
>>>>>> with septet-of-the-month. This is being done to eliminate the
>>>>>> ambiguity entirely. Secondly, we will need to describe
>>>>>> day-of-the-septet in the grammar (where the day of the septet
>>>>>> describes the name of the weekday, and not its numerical position
>>>>>> within the septet, as that would be a useless and complex duplication
>>>>>> of the day-of-the-month concept).
>>>>>>
>>>>>>
>>>>>>          
>>>>> I think we can keep using 1-7 in the septet with the
>>>>> understanding that 1 is always Monday, 2 is always Tuesday and so on.
>>>>>
>>>>> Simo.
>>>>>
>>>>>
>>>>>        
>>>> I'd like to propose that we have a goal to be as close to the Cron
>>>> grammar as practicable. So we should allow 0 or 7 for Sunday. This is in
>>>> keeping with your proposal.
>>>>
>>>>
>>>>
>>>> Here are the examples from the crontab 5 manpage;
>>>>
>>>> # run five minutes after midnight, every day
>>>> 5 0 * * * $HOME/bin/daily.job>>  $HOME/tmp/out 2>&1
>>>> # run at 2:15pm on the first of every month -- output mailed to paul
>>>> 15 14 1 * * $HOME/bin/monthly
>>>> # run at 10 pm on weekdays, annoy Joe
>>>> 0 22 * * 1-5 mail -s "Its 10pm" joe%Joe,%%Where are your kids?%
>>>> 23 0-23/2 * * * echo "run 23 minutes after midn, 2am, 4am ..., everyday"
>>>> 5 4 * * sun echo "run at 5 after 4 every sunday"
>>>>
>>>>
>>>>
>>>> I'm not sure that 'First Wednesday of the month' is possible with this
>>>> grammar, either. Yet, somehow, it has survived many years.
>>>>
>>>>      
> 
> 0 8 1-7 * 3   (read, 08:00 on the Wednesday that falls between the 1st
> and 7th day of the 6th month)
>    
>> Yep: except you meant every month.
> 

Whoops. I had that example written down earlier from some theoretical
constructs I was working on, and just changed that to * but forgot to
change the comment.


> 
>> OK.  So  we add a duration to this grammar, declare victory and go home.
> 
>> I propose adding a hyphen and then duration in days:hours:minutes
> 
>> 0 8 1-7 * 3 : 0:0:30   #from 8 - 8:30
> 
>> 0 8 1-7 * 3 : 0:2:0 #from 8 - 10:
> 
>> 0 8 1-7 * 3 : 2:0:0   #For 48 hours
> 

I'm not sure we want to do that. I still think we want to try to use our
existing representation internally, as long as we can map them
bi-directionally in a reasonable way.

Mostly because rewriting the time rules parser is a big job that I'd
like to see us avoid if possible.

- -- 
Stephen Gallagher
RHCE 804006346421761

Delivering value year after year.
Red Hat ranks #1 in value among software vendors.
http://www.redhat.com/promo/vendor/
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.11 (GNU/Linux)
Comment: Using GnuPG with Fedora - http://enigmail.mozdev.org/

iEYEARECAAYFAkzlOVsACgkQeiVVYja6o6NN7wCdEu+kb5vWoi3k0KW9WJpbi8l9
fP4AoKcpR5XUzeKmHTWeUxo4VzTWJDRv
=Hvbm
-----END PGP SIGNATURE-----