Re: [PATCH] dir.c: avoid stat() in valid_cached_dir()

["Ævar Arnfjörð Bjarmason" <avarab@gmail.com>]

On Thu, Dec 28 2017, Nguyễn Thái Ngọc Duy jotted:

> stat() may follow a symlink and return stat data of the link's target
> instead of the link itself. We are concerned about the link itself.
>
> Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
> ---
>  I noticed this while looking at the untracked cache bug [1] but
>  because it's not directly related to that bug, I'm submitting it
>  separately here.
>
>  [1] https://public-inbox.org/git/CACsJy8AmbKSp0mDLRaDCWn45veeNc03B-Gq8r8PQPrDt9bM_EA@mail.gmail.com/

I'm slowly trying to piece together a re-submission of this whole
series, if this is a bug and not just an optimziation shouldn't there be
some test case that demonstrates this bug?

>  dir.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/dir.c b/dir.c
> index 7c4b45e30e..edcb7bb462 100644
> --- a/dir.c
> +++ b/dir.c
> @@ -1809,7 +1809,7 @@ static int valid_cached_dir(struct dir_struct *dir,
>  	 */
>  	refresh_fsmonitor(istate);
>  	if (!(dir->untracked->use_fsmonitor && untracked->valid)) {
> -		if (stat(path->len ? path->buf : ".", &st)) {
> +		if (lstat(path->len ? path->buf : ".", &st)) {
>  			invalidate_directory(dir->untracked, untracked);
>  			memset(&untracked->stat_data, 0, sizeof(untracked->stat_data));
>  			return 0;