[rrd-users] ERROR: attempting to write beyond end of file

[Stefan Brandl]

On Tue, Jan 18, 2011 at 09:37:54AM +0100, Tobias Oetiker wrote:
> Hi Stefan,
> 
> Today Stefan Brandl wrote:
> 
> > On Tue, Jan 18, 2011 at 08:46:26AM +0100, Tobias Oetiker wrote:
> > > Hi Stefan,
> > >
> > > Yesterday Stefan Brandl wrote:
> > >
> > > > As far I can see, this is already implemented in 2170.
> > >
> > > yes it is ...
> > >
> > > > With mmap disabled the error is gone,
> > > > but with mmap I still get:
> > > >
> > > > noc at lowrider:~$ /opt/rrdtool-1.4.5.002170/bin/rrdtool create tester.rrd DS:inet:GAUGE:600:0:U RRA:AVERAGE:0.5:1:600
> > > > noc at lowrider:~$ /opt/rrdtool-1.4.5.002170/bin/rrdtool resize tester.rrd 0 GROW 100
> > > > ERROR: attempting to write beyond end of file
> > > > noc at lowrider:~$
> > >
> > > beats me ... I can not reproduce this here ... and valgrind can not
> > > find a fault either ...
> > >
> >
> > Hm very strange, but at least one other user has the same problem:
> > http://osdir.com/ml/debian-bugs-dist/2010-07/msg05757.html
> >
> > > what is realy strange about this error is, that it is not a system
> > > messsage but rather an internal check in the rrdtool code which
> > > thinks there is something wrong ...
> > >
> >
> > Can I do anything to debug this?
> > While writing this E-Mail i did some tests.
> > 2170 with mmap disabled works as expected, no error ist given.
> > And now the "strange" thing:
> > If I create a rrd file with mmap enabled (or any older version
> > of rrdtool) I get the above error when resizing.
> > Despite of the error, I get a resize.rrd.
> > And the resulting resize.rrd doesn't differ from the one
> > created with 2170 with mmap disabled.
> > So the error message seems just to be cosmetical and no real error.
> 
> it is bound to be something like that ... off by one ... you could
> add some code to the error message to have rrdtool tell you the
> position it gets and the position it expects ... maybe it is some
> strange off by one thing ...
> 

Sorry Tobi, but my C-Programming knowledge is very limited,
not to say non-existent :-(
Could you tell me, where to put what code to further debug this?


Thanks
 Stefan