db_sqlite: Fix some mis-placed NULL checks during row reallocs

(cherry picked from commit 1cc9f5d)

modules/db_sqlite/res.c

@@ -299,29 +299,31 @@ int db_sqlite_realloc_rows(db_res_t* res, const unsigned int rows)
  struct db_row* res_rows;
  db_val_t *prev_values;
 
- res->rows = pkg_realloc(RES_ROWS(res),rows * (sizeof(db_row_t)));
- memset( res->rows + RES_ROW_N(res), 0 ,
- (rows - RES_ROW_N(res)) * (sizeof(db_row_t)));
+ if (RES_ROW_N(res) >= rows)
+ return 0;
 
- res_rows = res->rows;
+ res_rows = res->rows = pkg_realloc(RES_ROWS(res),rows * sizeof *res_rows);
  if (!res_rows) {
  LM_ERR("no memory left\n");
  return -1;
  }
 
+ memset(res_rows + RES_ROW_N(res), 0 ,
+ (rows - RES_ROW_N(res)) * sizeof *res_rows);
+
  prev_values = res_rows[0].values;
 
  res_rows[0].values =
  pkg_realloc(res_rows[0].values, rows * sizeof(db_val_t) * RES_COL_N(res));
- memset( res_rows[0].values + RES_COL_N(res)*RES_ROW_N(res),
- 0, (rows - RES_ROW_N(res)) * sizeof(db_val_t) * RES_COL_N(res));
-
  if (! res_rows[0].values) {
  LM_ERR("no memory left\n");
  res_rows[0].values = prev_values;
  return -1;
  }
 
+ memset( res_rows[0].values + RES_COL_N(res)*RES_ROW_N(res),
+ 0, (rows - RES_ROW_N(res)) * sizeof(db_val_t) * RES_COL_N(res));
+
  /* if the values was relocated, we need to re-point all values to the new block,
  * otherwise only fix the new ones */
  start = (res_rows[0].values == prev_values?RES_ROW_N(res):0);
@@ -330,7 +332,7 @@ int db_sqlite_realloc_rows(db_res_t* res, const unsigned int rows)
  for( i=start ; i<rows ; i++ ) {
  /* the values of the row i */
  res_rows[i].values = res_rows[0].values + RES_COL_N(res)*i;
- res->rows[i].n = RES_COL_N(res);
+ res_rows[i].n = RES_COL_N(res);
  }
 
  return 0;