[rrd-developers] Bug#251701: fix #182217 breaks librrdp-perl

[Sebastian Harl]

Hi Tobi,

On Wed, Apr 08, 2009 at 07:32:38AM +0200, Tobias Oetiker wrote:
> Yesterday Sebastian Harl wrote:
> > On Tue, Apr 07, 2009 at 10:34:08PM +0200, Tobias Oetiker wrote:
> > > Today Sebastian Harl wrote:
> > > > On Tue, Apr 07, 2009 at 07:25:47PM +0200, Tobias Oetiker wrote:
> > > > > the RRDp code will NOT work when there is a newline inside the graph
> > > > > but this has always been the case ...
> > > >
> > > > ... a newline followed by the string "OK" ... </nitpick> ;-)
> > >
> > > look at the RRDp code, I don't think it looks for \nOK it is happy
> > > with \n
> >
> > RRDp::read() loops until it finds a line starting with either 'ERROR' or
> > 'OK'. In fact, a PNG includes lots of newline characters, so this would
> > not work at all otherwise.
> 
> so lets put the question differently. Did it ever work?

I don't know, I've never used RRDp. However, since the bug reporter
specifically talks about that some other fix _breaks_ RRDp [1], I assume
that it worked for him before.

> And if so why.

Well, the bug reporter mentions that, supposedly, the fix for Debian bug
#182217 [2] (reported back in 2003) was the original cause for the
problem. Without that fix, the output of "rrdtool graph - [...]" would
be followed by one line including the image size. So, at that time, the
output of the image data would always be terminated by a newline.

[1] http://bugs.debian.org/251701#5
[2] http://bugs.debian.org/182217

> Otherwhise the solution is simple, update the docs and mention
> that it does NOT work and if someone is so minded, update RRDp to
> support graphv

Well, that's basically what I proposed initially - I would have gone for
reporting an error if "graph -" is used in RRDp::cmd though. When I was
asking for someone to provide a patch, I had support for graphv in mind.
Sorry, if that wasn't clear in the first place. Anyway, those two
changes would be a perfectly valid solution for this problem imho.

Cheers,
Sebastian

-- 
Sebastian "tokkee" Harl +++ GnuPG-ID: 0x8501C7FC +++ http://tokkee.org/

Those who would give up Essential Liberty to purchase a little Temporary
Safety, deserve neither Liberty nor Safety.         -- Benjamin Franklin

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