[pacman-dev] Scripts bombing with no args

[Allan McRae]

On 30/07/11 11:16, Dave Reisner wrote:
> On Sat, Jul 30, 2011 at 10:58:46AM +1000, Allan McRae wrote:
>> On 29/07/11 22:38, Dave Reisner wrote:
>>> On Fri, Jul 29, 2011 at 07:01:29PM +1000, Allan McRae wrote:
>>>> On 29/07/11 03:14, Dave Reisner wrote:
>>>>> On Thu, Jul 28, 2011 at 11:18:15AM -0500, Dan McGee wrote:
>>>>>> Allan or Dave, mind taking a look at this? We should show usage info,
>>>>>> as rankmirrors and pacman-key do without args, instead of this silly
>>>>>> behavior.
>>>>>>
>>>>>> -Dan
>>>>>>
>>>>>> dmcgee at galway ~/projects/pacman (master)
>>>>>> $ ./scripts/repo-add
>>>>>> ==>    ERROR: '' does not have a valid archive extension.
>>>>>
>>>>> We never check for $1 being unset before proceeding. Probably my
>>>>> mistake when I did some refactoring of repo-add.
>>>>>
>>>>>> dmcgee at galway ~/projects/pacman (master)
>>>>>> $ ./scripts/pkgdelta
>>>>>> ./scripts/pkgdelta: line 147: $1: unbound variable
>>>>>>
>>>>>
>>>>> 'set -u' with 'set -e'? Ugly...
>>>>
>>>> Care to explain why?  Using this in our cleanup scripts would have
>>>> prevented the Arch repos disappearing on more than one occasion....
>>>>
>>>
>>> Because the combination of these two flags causes scripts to fail in
>>> mysterious and unexpected ways. Also, it won't save you from set but
>>> empty vars, which I suspect would be just as dangerous as unset vars in
>>> the situation you allude to. Just validate the user inputs. It makes
>>> things more obvious to an outside reader of the code, as well as
>>> consumers of the script.
>>>
>>
>> FYI, this is the story I am referring to:
>>
>> http://archlinux.me/brain0/2009/08/16/shit-happens-when-you-party-naked-or-use-crappy-shell-scripts/
>>
>> I'm still a fan of keeping set -u and -e...  It may not save you
>> from everything, but it does stop some things.
>>
>> Allan
>>
>
> I think that story only reinforces my point that you should be
> validating what you take in as input. Should a script bomb out in the
> middle of operation due to an unbound var triggering errexit, you may be
> left in some unknown or inconsistant state. It then means you have to
> add an ERR trap, figure out where you are, and take the appropriate
> action, if any, to restore sanity. It's unwieldy and vague, and explicit
> validation at key checkpoints will always be a more robust (and more
> readable) solution.
>
> I'll leave it up to you to decide which direction to go in. We really
> just wanted to fix the lack of usage on bad command line args. imo,
> pkgdelta needs a lot more help than just validation of input, but that's
> for another patch(set).
>

I will give you patch an "ack" as in the end I have never actually used 
the pkgdelta script so really do not care that much! :P

Allan