Exploding check commands batman ...

[Andreas Ericsson]

Paul L. Allen wrote:
> Andreas Ericsson writes:
> 
>> I'm working on overloading the plugins a bit to support behaviour like 
>> this. It will require the arguments in the check_command definition to 
>> be enclosed in quotes (due to how POSIX getopt() works), but will 
>> otherwise work nicely.
> 
> 
> Sounds good.
> 
>> I believe it's best left out of Nagios. String mangling is rather 
>> expensive and error-prone. Checking if(str[0] == 0) from the command 
>> executed is a fairly simple process.
> 
> 
> Somewhat more complex for the perl plugins since they generally use
> the strict pragma.


That's something I'm willing to live with. Most of the plugins that 
would benefit to any greater extent from overloading are written in C 
anyways (check_snmp, check_tcp, check_http).


>  Easy for options which take string arguments and
> where the string "0" is never valid or sensible:


The string "0" and str[0] = 0 are two quite different things. The second 
is just an optimized way of writing if(strlen(str) == 0).


> $opt_x ||= $opt_x_default;
> A little extra work for options which take numeric arguments and where the
> numeric value 0 is valid and sensible but some other numeric value is
> the default:
> $opt_x = $opt_x_default if ($x eq '');
> A bigger problem for numerics if you expect the plugin to cope gracefully
> if somebody manages to not pass "" as the argument for the option and the
> option is therefore unitialized:


Making them cope gracefully is exactly what I meant by making them 
overloaded.


> $opt_x = $opt_x_default if (not defined($x) or $x eq '');
> or:
> $opt_x .= '' # ensure $opt_x is initialized with something
> $opt_x = $opt_x_default if ($x eq '');
> That's the price you have to pay for asking perl to do run-time checking.
> Then again, the GetOpt module shouldn't be letting you get away with
> specifying an option that requires an argument without giving an argument,
> but I'm sure somebody will find a way.


POSIX quite clearly states that empty arguments are still arguments. Any 
implementation doing otherwise is decidedly broken, even if it errs on 
the side of prudence.

-- 
Andreas Ericsson                   andreas.ericsson at op5.se
OP5 AB                             www.op5.se
Lead Developer


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