[rrd-developers] problems with rrd_update() when updating rrd file
kevin brintnall
kbrint at rufus.net
Wed Jun 2 01:54:07 CEST 2010
Hi Tomas,
I've discovered the problem... it's not coming from your call to rrd_update
at all, but rather from your call to rrd_info. Without your test case it
would have been very difficult to find.
Prior to r1504, rrd_info only accepted filenames as arguments. It simply
checked argc to ensure that it was large enough and then iterated over the
argv array. In this case, you are passing arguments to it (--template)
that it does not understand. Thus, the error. The error message is
misleading because it uses argv[0], which you are passing as "update"...
Remove --template,etc and it will work just fine.
The call to rrd_update returns -1 because rrd_test_error() fails due to the
error message set by rrd_info. It's prudent to either handle or clear the
RRD error after each call.
A couple questions for Tobi...
(1) should rrd_update_r() call rrd_clear_error() at the top? Its return
call depends on rrd_test_error(). Would it make sense to save/clear/reset
the error? Not sure on this.
(2) Should we expose rrd_info_r ?
-kb
On Tue, Jun 1, 2010 at 7:42 AM, Tomáš Macek <maca02 at atlas.cz> wrote:
> Hm, so rrd_clear_error() did the job. I inserted call of rrd_clear_error()
> before each rrd_*() calling and program works (see the line with
> "attention" comment). I've tried to simplify things as possible and here
> it is, maybe this will help to anyone else to solve his problems... Am I
> doing everything right now?
>
> Tomas
>
> -------------------------
>
> #include <stdio.h>
> #include <sys/types.h>
> #include <unistd.h>
> #include <stdlib.h>
> #include <stdarg.h>
> #include <rrd.h>
>
> void rrd_cmd(char *cmdstr) {
> char *strptr = NULL, *str = NULL;
> char *argv[64];
> int error = 0, i = 0;
> rrd_info_t *it = NULL;
> char rrdcmd[2048] = "";
>
> snprintf(rrdcmd, 2048, "%s", cmdstr);
>
> i = 0;
>
> /* memset update, create *argv[] */
> memset(argv, 0, 64 * sizeof(char *));
>
> for (strptr = rrdcmd; strptr != NULL;) {
> while ((str = strsep(&strptr, " ")) != NULL && str != '\0') {
> argv[i] = str;
> i++;
> }
> }
>
> rrd_clear_error(); /* attention!!! */
> it = rrd_info(i, argv);
> rrd_info_free(it);
> rrd_clear_error(); /* attention!!! */
> error = rrd_update(i, argv);
> if (error == -1) {
> printf("Error: RRD_UPDATE command: %s\n", rrd_get_error());
> rrd_clear_error();
> }
> }
>
> int update_rrd_cmd(char *rrd_name, char *ds_string, char *n_value_string,
> char *buff, int n) {
> memset(buff, 0, n);
> snprintf(buff, n, "update %s --template %s %s", rrd_name, ds_string,
> n_value_string);
> printf("%s: buff = %s\n", __FUNCTION__, buff);
> return 0;
> }
>
> int main(void) {
> char buff[2048] = "";
> update_rrd_cmd("./testfile.rrd", "ds0:ds1", "N:123:456", buff, 2048);
> rrd_cmd(buff);
> return 0;
> }
>
>
> On Tue, 01 Jun 2010 08:20:18 +0200, Tomáš Macek <maca02 at atlas.cz> wrote:
>
> > Hello again,
> > this problem is present since 1.4.0. I know it, because I've tried every
> > version since 1.3.8 (works), through 1.3.9 (works), 1.4.0 - 1.4.3 does
> > not
> > work at all with syntax error as described below. Everytime I compiled
> > and
> > tried the same source code and linked with the proper library version.
> > What has changed in the API of rrd_update() in 1.4.0? I really don't
> > understand what I'm doing wrong. Any hints/help appreciated, looking at
> > the CHANGES file did not helped me.
> >
> > Tomas
> >
> >
> > On Thu, 20 May 2010 12:28:25 +0200, Tomáš Macek <maca02 at atlas.cz> wrote:
> >
> >> Hi, I have RHEL 5.5 with rrdtool 1.4.3 and I'm using it's API for
> >> updating
> >> rrd files. The problem is that when I pass arguments to the rrd_update()
> >> function, it always returns error saying "Usage: rrdtool update
> >> [--daemon
> >> <addr>] <file>". The same code worked really fine on 1.3.8. I looked at
> >> the CHANGELOG file and there was some line saying, that something has
> >> changed on checking optarg parameters.
> >>
> >> This is from gdb just before I pass the array into rrd_update()
> >> function:
> >> -----------
> >> Breakpoint 2, rrd_cmd (rrdcmd=0x634dc0 "update", cmd=1, di_cnt=2) at
> >> rrd_op.c:215
> >> 215 error = rrd_update(i, argv);
> >> (gdb) p argv
> >> $26 = {0x634dc0 "update", 0x634dc7 "cac_ap2aeth.rrd",
> >> 0x634e06 "--template", 0x634e11 "ds0:ds1", 0x634e19
> >> "N:2325779922:3582706806", 0x0 <repeats 59 times>}
> >> -----------
> >>
> >> and after program goes thourgh rrd_update(), the argv array looks like
> >> this:
> >> -----------
> >> 216 if (error == -1) {
> >> (gdb) p argv
> >> $28 = {0x634dc0 "update", 0x634e06 "--template", 0x634e11 "ds0:ds1",
> >> 0x634dc7 "cac_ap2aeth.rrd", 0x634e19 "N:2325779922:3582706806",
> >> 0x0 <repeats 59 times>}
> >> -----------
> >>
> >> Please, notice the replaced arguments after rrd_update()... I don't
> >> know,
> >> what I'm doing wrong, the code under 1.3.8 library worked just fine and
> >> according to the man rrdupdate the arguments are fine. Hope I'm not
> >> missing something stupid, but I was not able to find anything strange in
> >> rrd_update() function in the rrd_update.c.
> >> Let me know, if you need something more from me, thank you
> >>
> >> Regards, Tomas
> >>
> >> _______________________________________________
> >> rrd-developers mailing list
> >> rrd-developers at lists.oetiker.ch
> >> https://lists.oetiker.ch/cgi-bin/listinfo/rrd-developers
> >
> > _______________________________________________
> > rrd-developers mailing list
> > rrd-developers at lists.oetiker.ch
> > https://lists.oetiker.ch/cgi-bin/listinfo/rrd-developers
>
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--
kevin brintnall =~ /kbrint at rufus.net/
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