Date: Tue, 27 Dec 2011 20:16:46 +0200 From: Maxim Ignatenko <gelraen.ua@gmail.com> To: Doug Barton <dougb@freebsd.org> Cc: freebsd-rc@freebsd.org Subject: Re: conf/163508: [rc.subr] [patch] Add " enable" and " disable" commands to rc.subr Message-ID: <CABWTX-YK7dpfHStsu_DTwbNu=K=8gSwiLzTM-8QgK60wpOcB_A@mail.gmail.com> In-Reply-To: <4EF9519B.8090409@FreeBSD.org> References: <201112241230.pBOCUF3h064098@freefall.freebsd.org> <D9E8E12B-7E7F-4164-802F-4F6FE7DFB397@bsdimp.com> <4EF64915.4030006@FreeBSD.org> <DE3E9178-9610-4014-AABA-32C66823C1B8@bsdimp.com> <4EF8105D.3030907@FreeBSD.org> <CABWTX-Z9aPJpwdjOz6ZXRykGpDC0sJW0wpSAwr=pZpnL1Qwm6g@mail.gmail.com> <4EF90CE7.7050008@FreeBSD.org> <CABWTX-Z8g7Tom8dJSH2Q=Hq38qy=WFdhtwzmSeoLe=jig9Mzaw@mail.gmail.com> <4EF9519B.8090409@FreeBSD.org>
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On 27 December 2011 07:03, Doug Barton <dougb@freebsd.org> wrote:
> On 12/26/2011 20:36, Maxim Ignatenko wrote:
>> On 27 December 2011 02:10, Doug Barton <dougb@freebsd.org> wrote:
>>> On 12/26/2011 09:26, Maxim Ignatenko wrote:
>>>> On 26 December 2011 08:12, Doug Barton <dougb@freebsd.org> wrote:
>>>>> On 12/24/2011 15:08, Warner Losh wrote:
>>>>>>
>>>>>> On Dec 24, 2011, at 2:50 PM, Doug Barton wrote:
>>>>>>
>>>>>>> On 12/24/2011 08:46, Warner Losh wrote:
>>>>>>>> Also, let's not reject =C2=A0it before it is done. =C2=A0Let's rej=
ect it
>>>>>>>> when it actually doesn't handle the cases that are interesting.
>>>>>>>> No sense in cutting off a good feature because of some
>>>>>>>> theoretical problem. =C2=A0It is a problem we have sometimes in th=
e
>>>>>>>> project...
>>>>>>>
>>>>>>> Warner,
>>>>>>>
>>>>>>> You seemed to have missed the bit where I said, "We've already been
>>>>>>> down this path once before, and it turns out to be way harder to do
>>>>>>> this right than it looks at first glance."
>>>>>>
>>>>>> No, I get that totally. =C2=A0I just don't care. =C2=A0The fact that=
others
>>>>>> have failed shouldn't mean we should discourage others from trying.
>>>>>> We shouldn't be shooting arrows at people before they are given a
>>>>>> chance to produce something good or bad, or when they do shooting
>>>>>> them without evaluating their work.
>>>>>
>>>>> You do get that the OP included a patch, right?
>>>>>
>>>>>>> Just as an example of potential problems, imagine a scenario where
>>>>>>> the user has foo_enable=3DNO in rc.conf, but the service keeps
>>>>>>> starting up anyway.
>>>>>>
>>>>>> Most people call that a bug, or at least POLA. =C2=A0The few cases i=
n the
>>>>>> tree where bar_enable=3Dyes forces foo_enable=3Dyes can be dealt wit=
h.
>>>>>
>>>>> No, you seem to be missing my point. Because of the way that rc.d
>>>>> processes the various *conf* options the last match "wins." So let's =
say
>>>>> that you had foo_enable=3D0 in /etc/rc.conf; but one of the conf file=
s
>>>>> that's processed later has foo_enable=3D1. If that's the last match, =
it
>>>>> gets started. This is one of the many concerns regarding trying to
>>>>> automatically enable or disable things.
>>>>>
>>>>
>>>> Proposed patch searches all files (except /etc/defaults/rc.conf) that
>>>> are included by load_rc_config() in _reverse_ order, so even if there
>>>> are some other files included in rc.conf,
>>>
>>> It's unusual, but not impossible for files to actually be included in
>>> /etc/rc.conf. What I think you're referring to is the files included by
>>> rc.d.
>>>
>>>> foo_enable=3DNO gets added to
>>>> the end of last processed file and we still have foo enabled.
>>>
>>> I reviewed your patch, I understand how it works. I still think you're
>>> missing my concern. Imagine this scenario:
>>>
>>> 1. foo gets enabled by something (a port, whatever).
>>> 2. User notices that foo is enabled, doesn't understand why, and adds
>>> "foo_enable=3Dno" to /etc/rc.conf.
>>> 3. Because foo_enable=3Dyes is in a conf file other than /etc/rc.conf,
>>> which is included later, it gets started again on next reboot.
>>
>> By default, there are only 2 files included after /etc/rc.conf:
>> /etc/rc.conf.local and /etc/rc.conf.d/${name}. Or you meant some other
>> files included manually (from where?)?
>
> How many files are necessary to make the scenario I described confusing?
>
By default, /etc/rc.conf.d and /etc/rc.conf.local doesn't exists and
all changes will be done in /etc/rc.conf. If some of those exists,
user should be aware of it anyway. So, what exactly will be confusing?
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