Re: [PATCH v2 4/8] unpack-trees: stop recursing into sparse directories

>
> From: Derrick Stolee <dstolee@microsoft.com>
>
> When walking trees using traverse_trees_recursive() and
> unpack_callback(), we must not attempt to walk into a sparse directory
> entry. There are no index entries within that directory to compare to
> the tree object at that position, so skip over the entries of that tree.
>
> This code is used in many places, so the only way to test it is to start
> removing the command_requres_full_index option from one builtin at a
> time and carefully test that its use of unpack_trees() behaves correctly
> with a sparse-index. Such tests will be added by later changes.
>
> Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
> ---
>  unpack-trees.c | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/unpack-trees.c b/unpack-trees.c
> index 3af797093095..67777570f829 100644
> --- a/unpack-trees.c
> +++ b/unpack-trees.c
> @@ -1256,6 +1256,7 @@ static int unpack_callback(int n, unsigned long mask, unsigned long dirmask, str
>         struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
>         struct unpack_trees_options *o = info->data;
>         const struct name_entry *p = names;
> +       unsigned unpack_tree = 1;
>
>         /* Find first entry with a real name (we could use "mask" too) */
>         while (!p->mode)
> @@ -1297,12 +1298,16 @@ static int unpack_callback(int n, unsigned long mask, unsigned long dirmask, str
>                                         }
>                                 }
>                                 src[0] = ce;
> +
> +                               if (S_ISSPARSEDIR(ce->ce_mode))
> +                                       unpack_tree = 0;
>                         }
>                         break;
>                 }
>         }
>
> -       if (unpack_nondirectories(n, mask, dirmask, src, names, info) < 0)
> +       if (unpack_tree &&
> +           unpack_nondirectories(n, mask, dirmask, src, names, info) < 0)
>                 return -1;
>
>         if (o->merge && src[0]) {
> @@ -1332,7 +1337,8 @@ static int unpack_callback(int n, unsigned long mask, unsigned long dirmask, str
>                         }
>                 }
>
> -               if (traverse_trees_recursive(n, dirmask, mask & ~dirmask,
> +               if (unpack_tree &&
> +                   traverse_trees_recursive(n, dirmask, mask & ~dirmask,
>                                              names, info) < 0)
>                         return -1;
>                 return mask;
> --
> gitgitgadget