Shaoxuan Yuan wrote:
> Using check_dir_in_index without checking if the directory is on-disk
> could get a false positive for partially sparsified directory.
>
> Add a note in the documentation to warn potential user.
>
> Signed-off-by: Shaoxuan Yuan <shaoxuan.yuan02@xxxxxxxxx>
> ---
> builtin/mv.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/builtin/mv.c b/builtin/mv.c
> index 4729bb1a1a..c8b9069db8 100644
> --- a/builtin/mv.c
> +++ b/builtin/mv.c
> @@ -132,6 +132,11 @@ static int index_range_of_same_dir(const char *src, int length,
> * Return 0 if such directory exist (i.e. with any of its contained files not
> * marked with CE_SKIP_WORKTREE, the directory would be present in working tree).
> * Return 1 otherwise.
> + *
> + * Note: *always* check the directory is not on-disk before this function
> + * (i.e. using lstat());
> + * otherwise it may return a false positive for a partially sparsified
> + * directory.
To me, a comment like this indicates that either the function is not doing
what it should be doing, or its name doesn't properly describe the
function's behavior.
Per the function description:
Check if an out-of-cone directory should be in the index. Imagine
this case that all the files under a directory are marked with
'CE_SKIP_WORKTREE' bit and thus the directory is sparsified.
But neither the name of the function ('check_dir_in_index') nor the
function's behavior (hence the comment you're adding here) match that
description.
Since this function is intended to verify that a directory 1) exists in the
index, and 2) is *entirely* sparse, I have two suggestions:
* Change the description to specify that the non-existence of the directory
on disk is an *assumption*, not an opportunity for a "false positive."
It's a subtle distinction, but it clarifies that the function should be
used only when the caller already knows the directory is empty. For
example:
/*
* Given the path of a directory that does not exist on-disk, check whether the
* directory contains any entries in the index with the SKIP_WORKTREE flag
* enabled.
*
* Return 1 if such index entries exist.
* Return 0 otherwise.
*/
* 'check_dir_in_index' doesn't reflect the "is not on disk" prerequisite, so
the function name can be updated to clarify that (e.g.,
'empty_dir_has_sparse_contents')
> */
> static int check_dir_in_index(const char *name)
> {
