Re: [PATCH 09/17] midx: do not require packs to be sorted in lexicographic order

> Note that this produces MIDXs which may be incompatible with earlier
> versions of Git that have stricter requirements on the layout of packs
> within a MIDX. This patch does *not* modify the version number of the
> MIDX format, since existing versions of Git already know to gracefully
> ignore a MIDX with packs that appear out-of-order.

> @@ -656,17 +652,37 @@ int cmp_idx_or_pack_name(const char *idx_or_pack_name,
>  	return strcmp(idx_or_pack_name, idx_name);
>  }
>  
> +
> +static int midx_pack_names_cmp(const void *a, const void *b, void *m_)
> +{
> +	struct multi_pack_index *m = m_;
> +	return strcmp(m->pack_names[*(const size_t *)a],
> +		      m->pack_names[*(const size_t *)b]);
> +}
> +
>  static int midx_contains_pack_1(struct multi_pack_index *m,
>  				const char *idx_or_pack_name)
>  {
>  	uint32_t first = 0, last = m->num_packs;
>  
> +	if (!m->pack_names_sorted) {
> +		uint32_t i;
> +
> +		ALLOC_ARRAY(m->pack_names_sorted, m->num_packs);
> +
> +		for (i = 0; i < m->num_packs; i++)
> +			m->pack_names_sorted[i] = i;
> +
> +		QSORT_S(m->pack_names_sorted, m->num_packs, midx_pack_names_cmp,
> +			m);
> +	}
> +
>  	while (first < last) {
>  		uint32_t mid = first + (last - first) / 2;
>  		const char *current;
>  		int cmp;
>  
> -		current = m->pack_names[mid];
> +		current = m->pack_names[m->pack_names_sorted[mid]];
>  		cmp = cmp_idx_or_pack_name(idx_or_pack_name, current);
>  		if (!cmp)
>  			return 1;