Re: [PATCH v3 4/8] unpack-trees: fix nested sparse-dir search

>
> From: Derrick Stolee <dstolee@microsoft.com>
>
> The iterated search in find_cache_entry() was recently modified to
> include a loop that searches backwards for a sparse directory entry that
> matches the given traverse_info and name_entry. However, the string
> comparison failed to actually concatenate those two strings, so this
> failed to find a sparse directory when it was not a top-level directory.
>
> This caused some errors in rare cases where a 'git checkout' spanned a
> diff that modified files within the sparse directory entry, but we could
> not correctly find the entry.

>
> Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
> ---
>  unpack-trees.c | 18 +++++++++++++-----
>  1 file changed, 13 insertions(+), 5 deletions(-)
>
> diff --git a/unpack-trees.c b/unpack-trees.c
> index 5786645f315..df1f4437723 100644
> --- a/unpack-trees.c
> +++ b/unpack-trees.c
> @@ -1255,9 +1255,10 @@ static int sparse_dir_matches_path(const struct cache_entry *ce,
>  static struct cache_entry *find_cache_entry(struct traverse_info *info,
>                                             const struct name_entry *p)
>  {
> -       struct cache_entry *ce;
> +       struct cache_entry *ce = NULL;
>         int pos = find_cache_pos(info, p->path, p->pathlen);
>         struct unpack_trees_options *o = info->data;
> +       struct strbuf full_path = STRBUF_INIT;
>
>         if (0 <= pos)
>                 return o->src_index->cache[pos];
> @@ -1273,6 +1274,10 @@ static struct cache_entry *find_cache_entry(struct traverse_info *info,
>         if (pos < 0 || pos >= o->src_index->cache_nr)
>                 return NULL;
>
> +       strbuf_addstr(&full_path, info->traverse_path);
> +       strbuf_add(&full_path, p->path, p->pathlen);
> +       strbuf_addch(&full_path, '/');
> +
>         /*
>          * Due to lexicographic sorting and sparse directory
>          * entries ending with a trailing slash, our path as a
> @@ -1283,17 +1288,20 @@ static struct cache_entry *find_cache_entry(struct traverse_info *info,
>         while (pos >= 0) {
>                 ce = o->src_index->cache[pos];
>
> -               if (strncmp(ce->name, p->path, p->pathlen))
> -                       return NULL;
> +               if (strncmp(ce->name, full_path.buf, full_path.len)) {
> +                       ce = NULL;
> +                       break;
> +               }
>
>                 if (S_ISSPARSEDIR(ce->ce_mode) &&
>                     sparse_dir_matches_path(ce, info, p))
> -                       return ce;
> +                       break;
>
>                 pos--;
>         }
>
> -       return NULL;
> +       strbuf_release(&full_path);
> +       return ce;
>  }
>
>  static void debug_path(struct traverse_info *info)
> --
> gitgitgadget