Segmentation Fault - Basic Test of RRDTool 1.2.19

[Mark Easton]

Yes, I am a beginner on this - trying to work out how to use it. I can create an RRD file, can update values to it and then fetch those values. But when I come to do a graph I get a segmentation fault.

//Create graph

sprintf(argstr, "temperature.rrd --start %ld --step 60 DS:temp:GAUGE:120:-273:5000 RRA:AVERAGE:0.5:1:1200 RRA:MIN:0.5:60:400 RRA:MAX:0.5:60:400 RRA:AVERAGE:0.5:60:400", start_time);  // evey min for 20 hours : every 10 minutes for 400 hours (max, min, ave)

ret = wrap_rrd_create( argstr);

//Add in many values using this
sprintf(str, "temperature.rrd %ld:%f", (long)next_time, value);
ret = wrap_rrd_update( str);

//When I do a fetch I can see that the values have loaded correctly, so now using the same start and end time I want to produce a temp.png file

//Create Graph - but this returns a segmentation fault (core dumped)
sprintf(argstr, "temp.png --start %lu --end %lu DEF:mytemp=temperature.rrd:temp:AVERAGE", (long)start_time, (long)end_time);

ret = wrap_rrd_graph( argstr);

//And now I get a segmentation fault. What am I doing wrong please?

TIA
Mark

[Sam Umbach]

On 4/16/07, Mark Easton <mark.easton@...> wrote:
>
> //Create Graph - but this returns a segmentation fault (core dumped)
> sprintf(argstr, "temp.png --start %lu --end %lu
> DEF:mytemp=temperature.rrd:temp:AVERAGE", (long)start_time, (long)end_time);
>
> ret = wrap_rrd_graph( argstr);

rrd_wrapper from the contrib section of the rrdtool website is dated
17-Dec-2001.  It has not been kept up and isn't compatible with
rrdtool 1.2.x.  Actually, I'm not sure how you got it to compile; I
receive the following error:

$ gcc -o test -lrrd main.c rrdwrap.c
rrdwrap.c: In function 'wrap_rrd_graph':
rrdwrap.c:165: error: too few arguments to function 'rrd_graph'

I would guess you have an old version of rrd.h and rrd_tool.h, but
somehow linking to the 1.2.x version of the library (librrd.so).  I've
attached a patch against rrdwrap.c that at least makes it compile (and
fixes a memory leak).

As you can see, rrd_wrapper is out-of-date and unmaintained.  I urge
you to consider using the librrd API directly.  Look at main() in
src/rrd_tool.c you'll see how the command-line rrdtool does this.

-Sam

[rrdwrap.patch]

---

--- rrdwrap.c.orig 2007-04-16 19:35:26.000000000 -0400
+++ rrdwrap.c 2007-04-16 19:39:39.000000000 -0400
@@ -156,15 +156,24 @@
  i, argc,
  xsize, // must be passed to the rrd_graph function but does not need to be initialised
  ysize; // must be passed to the rrd_graph function but does not need to be initialised
+ double
+ ymin, // must be passed to the rrd_graph function but does not need to be initialised
+ ymax; // must be passed to the rrd_graph function but does not need to be initialised
 
  if((argv = string_to_argv(argstr, &argc)) != NULL)
  {
  optind=0; /* reset gnu getopt */
  opterr=0; /* no error messages */
 
- i = rrd_graph(argc, argv, prdata, &xsize, &ysize);
+ i = rrd_graph(argc, argv, prdata, &xsize, &ysize, NULL, &ymin, &ymax);
 
  // free up the memory
+ if (prdata) {
+ for(i=0;prdata[i];i++) {
+ free(prdata[i]);
+ }
+ free(prdata);
+ }
  Free_argv(argv);
 
  return i;

---

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[Mark Easton]

>rrd_wrapper from the contrib section of the rrdtool website is dated
>17-Dec-2001.  It has not been kept up and isn't compatible with
>rrdtool 1.2.x.  Actually, I'm not sure how you got it to compile;

Yes I know, I wrote my own rrd_wrap which works against rrd_tool.c.

When I run "rrdtool graph" command line I also dont get a graph. It just retunds to std out "0x0".

[Sam Umbach]

On 4/16/07, Mark Easton <mark.easton@...> wrote:
>
> >rrd_wrapper from the contrib section of the rrdtool website is dated
> >17-Dec-2001.  It has not been kept up and isn't compatible with
> >rrdtool 1.2.x.  Actually, I'm not sure how you got it to compile;
>
> Yes I know, I wrote my own rrd_wrap which works against rrd_tool.c.

Well, then please post the source code if you'd like help with that seg fault.

> When I run "rrdtool graph" command line I also dont get a graph. It just
> retunds to std out "0x0".

The command line you put together doesn't have any output lines
(LINE{1,2,3}, AREA, STACK, GPRINT).  Check out the tutorial on the
website for some example rrdtool graph commands that work.

-Sam

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