* before deltas depending on them, a good heuristic is to start
         * resolving deltas in the same order as their position in the pack.
         */
-       sorted_by_pos = xmalloc(nr_ref_deltas * sizeof(*sorted_by_pos));
+       ALLOC_ARRAY(sorted_by_pos, nr_ref_deltas);
        for (i = 0; i < nr_ref_deltas; i++)
                sorted_by_pos[i] = &ref_deltas[i];
        qsort(sorted_by_pos, nr_ref_deltas, sizeof(*sorted_by_pos), delta_pos_compare);
                if (!(off & 0x80000000))
                        continue;
                off = off & 0x7fffffff;
+               check_pack_index_ptr(p, &idx2[off * 2]);
                if (idx2[off * 2])
                        continue;
                /*
 
        curr_pack = open_pack_file(pack_name);
        parse_pack_header();
-       objects = xcalloc(nr_objects + 1, sizeof(struct object_entry));
+       objects = xcalloc(st_add(nr_objects, 1), sizeof(struct object_entry));
        if (show_stat)
-               obj_stat = xcalloc(nr_objects + 1, sizeof(struct object_stat));
+               obj_stat = xcalloc(st_add(nr_objects, 1), sizeof(struct object_stat));
        ofs_deltas = xcalloc(nr_objects, sizeof(struct ofs_delta_entry));
        parse_pack_objects(pack_sha1);
        resolve_deltas();
        if (show_stat)
                show_pack_info(stat_only);
 
-       idx_objects = xmalloc((nr_objects) * sizeof(struct pack_idx_entry *));
+       ALLOC_ARRAY(idx_objects, nr_objects);
        for (i = 0; i < nr_objects; i++)
                idx_objects[i] = &objects[i].idx;
        curr_index = write_idx_file(index_name, idx_objects, nr_objects, &opts, pack_sha1);