[rrd-developers] Re: PATCH: rrd_graph / setlocale / librrd

[Peter Stamfest]

On Thu, 24 Apr 2003, Stanislav Sinyagin wrote:

> Date: Thu, 24 Apr 2003 00:38:51 -0700 (PDT)
> From: Stanislav Sinyagin <ssinyagin at yahoo.com>
> To: rrd-developers at list.ee.ethz.ch
> Subject: [rrd-developers] Re: PATCH: rrd_graph / setlocale / librrd
> 
> Hi, 
> 
> and what about the Perl binding? Should it be patched too?
> 
> 

Well, it has nothing to do with the language bindings themselves. I just
wanted to indicate that language-bindings are often used in a very general
context. Eg. you might have a perl script using RRD. Both RRD and the
program as a wholemight deal with locales. If RRD just sets the locale
every time you call rrd_graph it might influence other program 
parts having set a different locale.

Suppose:

-----------------------------------------------
#!/usr/bin/perl

use RRD;    # does this exist? 
use POSIX;

$loc = POSIX::setlocale(LC_ALL, "es_AR.ISO8859-1");

# call 

RRD::graph(...);

# locale might have been changed

$now_string = POSIX::strftime "%a %b %e %H:%M:%S %Y", localtime;

# $now_string may not be what you want it to be

-----------------------------------------------


Actually, in the above example you might want RRD::graph to use the
previously set locale, but instead it uses the locale specified in
the environment (which might be different from the one desired
explicitly).

Rule of thumb:  A library should not have any unexpected side-effects.

To answer the question: I do not see a need to patch anything outside RRD 
but all programs using librrd ;-)

Language bindings themselves should also not have unexpected side effects,
thus I do not see an immediate effect on language bindings themselves. 
They should definitly not call setlocale but leave that job to the 
programs using the binding.


peter



> 
> --- Peter Stamfest <peter at stamfest.at> wrote:
> > I just stumbled across a possible problem in rrd_graph. That function uses 
> > to call tzset and setlocale. When using librrd this is not desirable, as 
> > this might override any settings done by the application linking 
> > with librrd (language bindings come to mind). Besides, it is possibly not 
> > thread-safe ;-) ).
> > 
> > Here is a patch to move these calls into the rrdtool binary and removing 
> > them from librrd. 
> > 
> > This adds a new requirement for software using librrd: tzset and setlocale 
> > have to be called from the calling application.
> 
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