Re: [PATCH] shallow: verify shallow file after taking lock

> On Thu, Feb 27, 2014 at 04:10:12AM -0500, Jeff King wrote:
>
>> I also notice that check_shallow_file_for_update returns early if
>> !is_shallow. Is that safe? Is it possible for another process to have
>> made us shallow since the program began? In that case, we would have to
>> stat() the file always, then complain if it exists and !is_shallow.

>
> That patch would look like this:
>
> diff --git a/shallow.c b/shallow.c
> index 75da07a..e05a241 100644
> --- a/shallow.c
> +++ b/shallow.c
> @@ -139,13 +139,13 @@ void check_shallow_file_for_update(void)
>  {
>         struct stat st;
>
> -       if (!is_shallow)
> -               return;
> -       else if (is_shallow == -1)
> +       if (is_shallow == -1)
>                 die("BUG: shallow must be initialized by now");
>
>         if (stat(git_path("shallow"), &st))
>                 die("shallow file was removed during fetch");
> +       else if (!is_shallow)
> +               die("shallow file appeared during fetch");
>         else if (st.st_mtime != shallow_stat.st_mtime
>  #ifdef USE_NSEC
>                  || ST_MTIME_NSEC(st) != ST_MTIME_NSEC(shallow_stat)
>
> but again, I'm not really clear on whether this is possible.
>
> -Peff