In g2_addgrid.c, there is always a memory leak when a grid with extended data is used

[edwardhartnett]

In g2_addgrid() we have this code:

        if (mapgrid->needext)
        {
            free(mapgrid);
            mapgrid = extgridtemplate(igds[4], igdstmpl);
        }

This causes extra memory to be allocated in gridtemplates.c:

    if (number == 120)
    {
        new->extlen = list[1] * 2;
        new->ext = malloc(sizeof(g2int) * new->extlen);

Note that the ext pointer now has memory allocated. But when it's time to free this data, there is no call to free the ext memory (from g2_addgrid.c):

    /* Pack template extension, if appropriate. */
    j = mapgrid->maplen;
    if (mapgrid->needext && mapgrid->extlen > 0)
    {
        for (i = 0; i < mapgrid->extlen; i++)
        {
            nbits = abs(mapgrid->ext[i]) * 8;
            if (mapgrid->ext[i] >= 0 || igdstmpl[j] >= 0)
                sbit(cgrib, igdstmpl + j, iofst, nbits);
            else
            {
                sbit(cgrib, &one, iofst, 1);
                temp = abs(igdstmpl[j]);
                sbit(cgrib, &temp, iofst + 1, nbits - 1);
            }
            iofst = iofst + nbits;
            j++;
        }
    }
    free(mapgrid);

Note that mapgrid is freed, but mapgrid->ext needs to be freed first.