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Re: [Nagios-devel] Strange characters in output when

Posted: Thu Jul 12, 2007 10:03 am
by Guest
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Hi List,

I've played a little bit with the actual cvs code and I can say:

1. Yes - it's a bug ;)
2. No - I don't have a patch
3. Yes - I think I've found the killer
4. No - I don't know what there's going on - but perhaps others can
explain.

My testing environment:

1. Edit the /bin/p1.pl on line
after line 294:

untie *STDOUT;

add:
print "PRIVATE DEBUG p1.pl says: $plugin_output\n";

or trust me when I say: in p1.pl the output is fine!

2. change base/checks.c around line 639 so that we have:

perl_plugin_output=POPpx;
printf("PRIVATE DEBUG: Nagios says after POPpx: %s\n",perl_plugin_output);
// Trust me Output is fine

pclose_result=POPi;
printf("PRIVATE DEBUG: Nagios says after POPi: %s\n",perl_plugin_output);
PUTBACK;
printf("PRIVATE DEBUG: Nagios says after PUTBACK: %s\n",perl_plugin_output);
FREETMPS;
printf("PRIVATE DEBUG: Nagios says after FREETMPS:
%s\n",perl_plugin_output);
LEAVE;
printf("PRIVATE DEBUG: Nagios says LEAVE: %s\n",perl_plugin_output);


My Output after compile and force a ePN Plugin Check:
PRIVATE DEBUG: p1.pl says: CRITICAL - Test down
PRIVATE DEBUG: Nagios says after POPpx: CRITICAL - Test down
PRIVATE DEBUG: Nagios says after POPi: CRITICAL - Test down
PRIVATE DEBUG: Nagios says after PUTBACK: CRITICAL - Test down
PRIVATE DEBUG: Nagios says after FREETMPS:
PRIVATE DEBUG: Nagios says LEAVE:

So.. there seem to be a problem with FREETMPS...

On http://perldoc.perl.org/perlcall.html there is the info:

###
The FREETMPS /LEAVE pair will get rid of any values returned by the
Perl subroutine (see next example), plus it will also dump the mortal
SVs we have created. Having ENTER /SAVETMPS at the beginning of the
code makes sure that no other mortals are destroyed.
###

I can imagine that the FREETMPS is destroying to much of the stack where
the var plugin_output lives... but this is only a thought.

Are there any Perl / C gurus out there who can explain this behavior?

Regards
Hendrik
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