[rrd-developers] rrd_fetch seek issue

[Daniel.Pocock at barclayscapital.com]

If an RRD hasn't been updated recently, and I try to invoke rrd_fetch
for a more recent time interval, it tries to seek on the file anyway - I
only discovered this issue when the RRD hadn't updated for over 2 hours,
and it tried to seek beyond the end of the file, causing this "seek
error in RRA" from rrd_fetch.c:

    /* fill the gap at the start if needs be */

    if (start_offset <= 0)
        rra_pointer = rrd.rra_ptr[chosen_rra].cur_row + 1;
    else
        rra_pointer = rrd.rra_ptr[chosen_rra].cur_row + 1 +
start_offset;

    if (rrd_seek(rrd_file, (rra_base + (rra_pointer * (*ds_cnt)
                                        * sizeof(rrd_value_t))),
                 SEEK_SET) != 0) {
        rrd_set_error("seek error in RRA");
        goto err_free_data;


This suggests more range checking is needed on both the start and finish
times and how they relate to the last_update time for the RRD.

Regards,

Daniel
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